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1+use std::collections::{HashMap, HashSet};
2+use std::path::{Path, PathBuf};
3+use std::rc::Rc;
4+
5+use crate::ast::*;
6+use crate::diagnostic::code;
7+pub use crate::diagnostic::{Diagnostic, Severity};
8+use crate::interp::{self, Sink};
9+use crate::syntax::{self, DirectiveArgs, LetForm, NodeKind, Segment, Tree};
10+use crate::value::{self, Value};
11+
12+// ---------------------------------------------------------------------------
13+// Public types
14+// ---------------------------------------------------------------------------
15+
16+pub struct ParseResult {
17+ pub document: Document,
18+ pub diagnostics: Vec<Diagnostic>,
19+ pub included_files: Vec<PathBuf>,
20+}
21+
22+/// An error that stops one line from being evaluated.
23+type ParseError = Diagnostic;
24+
25+// ---------------------------------------------------------------------------
26+// Internal types
27+// ---------------------------------------------------------------------------
28+
29+#[derive(Clone)]
30+struct FnDef {
31+ /// The parameters in the order they are declared; one without a
32+ /// default is required.
33+ params: Vec<syntax::Param>,
34+ /// The definition's line and its text (when it is one physical line),
35+ /// and its node, for diagnostics about a default.
36+ line: usize,
37+ source: Option<String>,
38+ node: usize,
39+ body: Vec<syntax::Node>,
40+ /// The file it is defined in, when that isn't the file being compiled
41+ /// (see `ParseContext::current_file`).
42+ file: Option<String>,
43+ /// The slots its body declares (`@slot NAME`), in order.
44+ slots: Vec<String>,
45+ /// Whether its body has a `@children` for the content of a call.
46+ has_children: bool,
47+ /// Its scoped `@style`: its class (`hl-fn-NAME-HASH`), and the
48+ /// stylesheet nested under it, written into the page once the function
49+ /// is called (see `Document::scoped_css`).
50+ scoped: Option<(String, String)>,
51+ /// What was visible where it was defined: its body and its defaults
52+ /// see this, plus its parameters.
53+ env: Env,
54+ /// It is named like a built-in element and its body calls that name
55+ /// outside any `@if`, meaning the element (`@let @nav` around `@nav`):
56+ /// it would call itself forever, so a call writes nothing (the
57+ /// definition's error says so).
58+ wraps_itself: bool,
59+}
60+
61+impl FnDef {
62+ fn is_param(&self, name: &str) -> bool {
63+ self.params.iter().any(|p| p.name == name)
64+ }
65+}
66+
67+/// What a name means: every `@let`, parameter, loop variable and `@data`
68+/// binds one, and they share one namespace.
69+#[derive(Clone)]
70+enum Binding {
71+ Value(Value),
72+ Bundle(Rc<Vec<Attribute>>),
73+ Function(Rc<FnDef>),
74+}
75+
76+/// The names visible at a line: one frame per block it is in (the
77+/// standard library, the file, an element's children, an `@if` branch, an
78+/// iteration of `@each`, a function's body), the innermost last. A
79+/// definition goes into the innermost frame, so it is visible from its
80+/// line to the end of its block. A function keeps the frames visible
81+/// where it is defined; a frame is shared until one side changes it.
82+#[derive(Clone, Default)]
83+struct Env {
84+ frames: Vec<Rc<HashMap<String, Binding>>>,
85+}
86+
87+impl Env {
88+ fn push(&mut self) {
89+ self.frames.push(Rc::default());
90+ }
91+
92+ fn pop(&mut self) {
93+ self.frames.pop();
94+ }
95+
96+ /// Give `name` a meaning in the innermost frame, replacing what it
97+ /// meant there and hiding what it means outside it.
98+ fn define(&mut self, name: &str, binding: Binding) {
99+ if self.frames.is_empty() {
100+ self.push();
101+ }
102+ if let Some(frame) = self.frames.last_mut() {
103+ Rc::make_mut(frame).insert(name.to_string(), binding);
104+ }
105+ }
106+
107+ /// What `name` means here: the innermost definition.
108+ fn get(&self, name: &str) -> Option<&Binding> {
109+ self.frames.iter().rev().find_map(|frame| frame.get(name))
110+ }
111+
112+ fn value(&self, name: &str) -> Option<&Value> {
113+ match self.get(name)? {
114+ Binding::Value(value) => Some(value),
115+ _ => None,
116+ }
117+ }
118+
119+ fn bundle(&self, name: &str) -> Option<&Rc<Vec<Attribute>>> {
120+ match self.get(name)? {
121+ Binding::Bundle(attrs) => Some(attrs),
122+ _ => None,
123+ }
124+ }
125+
126+ fn function(&self, name: &str) -> Option<&Rc<FnDef>> {
127+ match self.get(name)? {
128+ Binding::Function(function) => Some(function),
129+ _ => None,
130+ }
131+ }
132+
133+ /// Every name visible here, with what it means.
134+ fn visible(&self) -> HashMap<&str, &Binding> {
135+ let mut names = HashMap::new();
136+ for frame in &self.frames {
137+ for (name, binding) in frame.iter() {
138+ names.insert(name.as_str(), binding);
139+ }
140+ }
141+ names
142+ }
143+
144+ /// The names of the values visible here.
145+ fn value_names(&self) -> Vec<&str> {
146+ self.visible()
147+ .into_iter()
148+ .filter(|(_, binding)| matches!(binding, Binding::Value(_)))
149+ .map(|(name, _)| name)
150+ .collect()
151+ }
152+
153+ /// The names of the bundles visible here.
154+ fn bundle_names(&self) -> Vec<&str> {
155+ self.visible()
156+ .into_iter()
157+ .filter(|(_, binding)| matches!(binding, Binding::Bundle(_)))
158+ .map(|(name, _)| name)
159+ .collect()
160+ }
161+}
162+
163+impl interp::Scope for Env {
164+ fn get(&self, name: &str) -> Option<Value> {
165+ self.value(name).cloned()
166+ }
167+}
168+
169+struct ParseContext {
170+ /// Source line currently being parsed, for diagnostics raised deep
171+ /// inside helpers that don't take a line number.
172+ current_line: usize,
173+ /// What the `@page` said, once one has run
174+ page: Option<Page>,
175+ /// Where that `@page` is, for the error a second one gets
176+ page_at: Option<String>,
177+ meta_tags: Vec<(String, String)>,
178+ head_blocks: Vec<String>,
179+ /// The first `@meta` or `@head` that ran, for the warning a file
180+ /// without `@page` gets: a fragment has no `<head>` for them.
181+ head_at: Option<usize>,
182+ /// What each name means at the line being evaluated.
183+ env: Env,
184+ /// Every function whose definition ran, by name (the last one), for
185+ /// the checks of code that never runs.
186+ defined_functions: HashMap<String, Rc<FnDef>>,
187+ css_vars: Vec<(String, String)>,
188+ custom_css: Vec<String>,
189+ /// The scoped `@style` of each function called so far
190+ scoped_css: Vec<String>,
191+ og_tags: Vec<(String, String)>,
192+ diagnostics: Vec<Diagnostic>,
193+ base_path: Option<PathBuf>,
194+ included_files: Vec<PathBuf>,
195+ include_stack: Vec<PathBuf>,
196+ fn_call_stack: Vec<String>,
197+ file_cache: HashMap<PathBuf, String>,
198+ /// Track which @let variables are referenced (for unused warnings)
199+ used_variables: HashSet<String>,
200+ /// Track which functions are called (for unused warnings)
201+ used_functions: HashSet<String>,
202+ /// Track which attribute bundles are referenced (for unused warnings)
203+ used_defines: HashSet<String>,
204+ /// Line numbers of @let definitions (name -> line)
205+ let_lines: HashMap<String, usize>,
206+ /// Line numbers of function definitions (name -> line)
207+ fn_lines: HashMap<String, usize>,
208+ /// Line numbers of attribute bundle definitions (name -> line)
209+ define_lines: HashMap<String, usize>,
210+ /// Syntax nodes evaluated at least once, by id.
211+ visited: HashSet<usize>,
212+ /// The id the next parsed tree starts at, so ids are unique across
213+ /// the file, its includes and the standard library.
214+ next_id: usize,
215+ /// The file's tree and those of the files it includes, with the
216+ /// include chain that leads to each, for the checks of code that never
217+ /// runs.
218+ trees: Vec<(Rc<Tree>, Option<String>)>,
219+ /// The files each `@include` line brought in (by the line's node id),
220+ /// with the include chain that leads to each, so the checks of
221+ /// `@slot` and `@children` see an included file's lines where the
222+ /// `@include` is written.
223+ included_by: Rc<IncludedBy>,
224+ /// Every function defined anywhere in the file or the files it
225+ /// includes, whether or not its definition runs.
226+ namespace: HashSet<String>,
227+ /// The line being evaluated, and its text as written when it is one
228+ /// physical line, for diagnostics that point at a column.
229+ current_source: (usize, Option<String>),
230+ /// Variable diagnostics already reported, so a line evaluated many
231+ /// times (in a loop, in a function) reports each problem once.
232+ /// Keyed by the syntax node (ids are unique across files), line,
233+ /// column and message.
234+ reported: HashSet<(usize, usize, Option<usize>, String)>,
235+ /// The id of the syntax node being evaluated.
236+ current_node: usize,
237+ /// The file whose lines are being evaluated, when it isn't the file
238+ /// being compiled: the standard library, or an included file (by its
239+ /// include chain).
240+ current_file: Option<String>,
241+ /// A call went deeper than [`MAX_CALL_DEPTH`]: the calls it is nested
242+ /// in expand to nothing, until the outermost one returns.
243+ too_deep: bool,
244+ /// A bundle's attributes are being read: a name that could be a
245+ /// parameter of the function the bundle is passed to is checked where
246+ /// the bundle is used instead.
247+ in_bundle: bool,
248+ /// `@page`'s attributes are being read: a name close to `favicon` is
249+ /// a misspelled word of `@page`'s.
250+ in_page: bool,
251+}
252+
253+/// How deeply function calls may nest, so that a function that calls
254+/// itself without an `@if` that stops it is an error instead of a hang.
255+const MAX_CALL_DEPTH: usize = 64;
256+
257+/// A CSS rule at the top level of a stylesheet that starts with `&`
258+/// (outside any `{}`, strings and comments).
259+fn has_top_level_ampersand(css: &str) -> bool {
260+ let mut depth = 0usize;
261+ let mut chars = css.chars().peekable();
262+ let mut at_rule_start = true;
263+ while let Some(c) = chars.next() {
264+ match c {
265+ '/' if chars.peek() == Some(&'*') => {
266+ chars.next();
267+ let mut last = ' ';
268+ for c in chars.by_ref() {
269+ if last == '*' && c == '/' {
270+ break;
271+ }
272+ last = c;
273+ }
274+ continue;
275+ }
276+ '"' | '\'' => {
277+ for d in chars.by_ref() {
278+ if d == c {
279+ break;
280+ }
281+ }
282+ }
283+ '{' => depth += 1,
284+ '}' => depth = depth.saturating_sub(1),
285+ '&' if depth == 0 && at_rule_start => return true,
286+ _ => {}
287+ }
288+ at_rule_start = match c {
289+ '{' | '}' | ';' => true,
290+ c if c.is_whitespace() => at_rule_start,
291+ _ => false,
292+ };
293+ }
294+ false
295+}
296+
297+/// Whether a file is a library (see [`Tree::is_library`]), with the files
298+/// its `@include` lines name read relative to `base`.
299+fn is_library_file(
300+ tree: &Tree,
301+ base: Option<&Path>,
302+ ctx: &mut ParseContext,
303+ seen: &mut Vec<PathBuf>,
304+) -> bool {
305+ tree.is_library_with(&mut |path| {
306+ if path.contains('$') {
307+ return false;
308+ }
309+ let resolved = base.map_or_else(|| PathBuf::from(path), |base| base.join(path));
310+ if seen.contains(&resolved) {
311+ return false;
312+ }
313+ seen.push(resolved.clone());
314+ let Ok(text) = ctx.read_file(&resolved) else {
315+ return false;
316+ };
317+ let included = syntax::parse(&text);
318+ is_library_file(&included, resolved.parent(), ctx, seen)
319+ })
320+}
321+
322+/// The frames around the file's top level: the standard library's and
323+/// the file's own (see [`load_prelude`]).
324+const FILE_FRAMES: usize = 2;
325+
326+/// Evaluates a syntax tree (see `syntax.rs`) into the document's nodes.
327+struct Evaluator;
328+
329+impl ParseContext {
330+ /// Bind a value to `name` in the innermost block.
331+ fn bind(&mut self, name: &str, value: Value) {
332+ self.env.define(name, Binding::Value(value));
333+ }
334+
335+ /// Evaluate an expression (see `expr.rs`) written at `line` and
336+ /// `column` (when known), reporting its errors there.
337+ fn eval(
338+ &mut self,
339+ src: &str,
340+ line: usize,
341+ column: Option<usize>,
342+ ) -> Option<crate::expr::Value> {
343+ track_var_refs(src, &mut self.used_variables);
344+ match crate::expr::eval(src, &self.env) {
345+ Ok(value) => Some(value),
346+ Err(error) => {
347+ // Without the line to point into, show the expression
348+ let shown = matches!(&self.current_source, (current, Some(_)) if *current == line);
349+ let before = self.diagnostics.len();
350+ self.report(error.at(0), line, column);
351+ if !shown && let Some(diagnostic) = self.diagnostics.get_mut(before) {
352+ diagnostic.source_line = Some(src.into());
353+ }
354+ None
355+ }
356+ }
357+ }
358+
359+ /// Evaluate a condition; an invalid one is reported and counts as false.
360+ fn condition(&mut self, src: &str, line: usize, column: Option<usize>) -> bool {
361+ self.eval(src, line, column)
362+ .is_some_and(|value| value.truthy())
363+ }
364+
365+ /// Fill in one slot of htmlang text written at `line` and `column`
366+ /// (when known), for `sink`: its escapes stand for themselves and its
367+ /// variables are filled in (see `interp.rs`). What can't be filled is
368+ /// left as written and reported; the flag says whether everything was
369+ /// filled.
370+ fn fill(
371+ &mut self,
372+ raw: &str,
373+ line: usize,
374+ column: Option<usize>,
375+ sink: Sink,
376+ ) -> (String, bool) {
377+ let (filled, ok) = self.fill_protected(raw, line, column, sink);
378+ (restore_escapes(&filled), ok)
379+ }
380+
381+ /// [`fill`](Self::fill) for text.
382+ fn interpolate_text(&mut self, raw: &str, line: usize, column: Option<usize>) -> String {
383+ self.fill(raw, line, column, Sink::Text).0
384+ }
385+
386+ /// [`fill`](Self::fill), with the escapes still placeholders (see
387+ /// [`protect_escapes`]).
388+ fn fill_protected(
389+ &mut self,
390+ raw: &str,
391+ line: usize,
392+ column: Option<usize>,
393+ sink: Sink,
394+ ) -> (String, bool) {
395+ let mut protected = protect_escapes(raw);
396+ if sink == Sink::Css {
397+ protected = keep_css_string_escapes(&protected);
398+ }
399+ if !protected.contains('$') {
400+ return (protected, true);
401+ }
402+ track_var_refs(&protected, &mut self.used_variables);
403+ let (out, problems) = interp::interpolate_for(&protected, &self.env, sink);
404+ let filled = problems.is_empty();
405+ for mut problem in problems {
406+ match &mut problem {
407+ interp::Problem::Undefined { offset, .. }
408+ | interp::Problem::CustomProperty { offset, .. }
409+ | interp::Problem::Invalid { offset, .. }
410+ | interp::Problem::Record { offset, .. } => {
411+ // An offset into the protected text, as one into `raw`
412+ *offset = protected[..*offset]
413+ .chars()
414+ .map(|c| escape_of(c).map_or(c.len_utf8(), str::len))
415+ .sum();
416+ }
417+ }
418+ self.report(problem, line, column);
419+ }
420+ (out, filled)
421+ }
422+
423+ /// Fill in a value slot (an attribute's value, a `@let` value, `@meta`'s
424+ /// value) for `sink`, and say whether it is quoted text: one `"..."`, or
425+ /// one variable that holds quoted text. Quoted text keeps its quotes
426+ /// only in CSS.
427+ fn fill_value(
428+ &mut self,
429+ raw: &str,
430+ line: usize,
431+ column: Option<usize>,
432+ sink: Sink,
433+ ) -> (String, Option<Quoted>, bool) {
434+ if let Some(inner) = syntax::quoted_string(raw) {
435+ let (css, ok) = self.fill(raw, line, column, Sink::Css);
436+ // Already reported by the CSS pass, so filled in quietly
437+ let (text, _) = interp::interpolate(&protect_escapes(inner), &self.env);
438+ let quoted = Quoted {
439+ text: restore_escapes(&text),
440+ css,
441+ };
442+ let out = match sink {
443+ Sink::Css => quoted.css.clone(),
444+ Sink::Text => quoted.text.clone(),
445+ };
446+ return (out, Some(quoted), ok);
447+ }
448+ let (out, ok) = self.fill(raw, line, column, sink);
449+ let quoted = whole_reference(raw, &self.env).and_then(|path| {
450+ match interp::resolve(&path, &self.env)? {
451+ Value::Quoted(quoted) => Some(quoted),
452+ _ => None,
453+ }
454+ });
455+ (out, quoted, ok)
456+ }
457+
458+ /// The value of a value slot (a `@let` value, the source of `@each`, a
459+ /// parameter's value or default), written at `line` and `column`:
460+ ///
461+ /// - exactly one `$name` or `${...}` is the value it holds or gives,
462+ /// whatever its type (a list, a record, quoted text);
463+ /// - one `"..."` is quoted text;
464+ /// - commas outside quotes, brackets and `${...}`, and not escaped
465+ /// (`\,`), make a list, which prints as written;
466+ /// - `A..B` or `A..B step N` with whole numbers is a range;
467+ /// - anything else is text, with its variables filled in.
468+ ///
469+ /// What can't be filled in is reported; the flag says whether
470+ /// everything was.
471+ fn slot_value(&mut self, raw: &str, line: usize, column: Option<usize>) -> (Value, bool) {
472+ let trimmed = raw.trim();
473+ let column = column.map(|c| c + (raw.len() - raw.trim_start().len()));
474+ if let Some(value) = self.whole_value(trimmed, line, column) {
475+ return value;
476+ }
477+ if syntax::quoted_string(trimmed).is_some() {
478+ let (text, quoted, ok) = self.fill_value(trimmed, line, column, Sink::Text);
479+ return (quoted.map_or(Value::Str(text), Value::Quoted), ok);
480+ }
481+ let parts = syntax::split_list(trimmed);
482+ if parts.len() > 1 {
483+ // Each item is a value of its own; the list prints as written
484+ let mut items = Vec::new();
485+ let mut written = String::new();
486+ let mut ok = true;
487+ let mut end = 0;
488+ for part in parts {
489+ let item = &trimmed[part.clone()];
490+ let lead = item.len() - item.trim_start().len();
491+ written.push_str(&trimmed[end..part.start + lead]);
492+ end = part.start + lead + item.trim().len();
493+ if item.trim().is_empty() {
494+ continue;
495+ }
496+ let at = column.map(|c| c + part.start + lead);
497+ let (value, text, filled) = self.item_value(item.trim(), line, at);
498+ ok &= filled;
499+ written.push_str(&text);
500+ items.push(value);
501+ }
502+ written.push_str(&trimmed[end..]);
503+ let list = value::List {
504+ items: Rc::new(items),
505+ written: Some(written.into()),
506+ };
507+ return (Value::List(list), ok);
508+ }
509+ let (text, ok) = self.fill(trimmed, line, column, Sink::Text);
510+ match value::written_range(&text) {
511+ Some(Ok(range)) => (range, ok),
512+ Some(Err(message)) => {
513+ self.report(
514+ interp::Problem::Invalid { message, offset: 0 },
515+ line,
516+ column,
517+ );
518+ (Value::list(Vec::new()), false)
519+ }
520+ None => (Value::Str(text), ok),
521+ }
522+ }
523+
524+ /// An item of a list written in the source (see
525+ /// [`slot_value`](Self::slot_value)), and how it is written in the
526+ /// list's text.
527+ fn item_value(
528+ &mut self,
529+ item: &str,
530+ line: usize,
531+ column: Option<usize>,
532+ ) -> (Value, String, bool) {
533+ let (value, ok) = match self.whole_value(item, line, column) {
534+ Some(value) => value,
535+ None if syntax::quoted_string(item).is_some() => {
536+ let (text, quoted, ok) = self.fill_value(item, line, column, Sink::Text);
537+ (quoted.map_or(Value::Str(text), Value::Quoted), ok)
538+ }
539+ None => {
540+ let (text, ok) = self.fill(item, line, column, Sink::Text);
541+ (Value::Str(text), ok)
542+ }
543+ };
544+ // Quoted text keeps its quotes in the list's text, as written
545+ let text = value
546+ .quoted_css()
547+ .map_or_else(|| value.to_string(), str::to_string);
548+ (value, text, ok)
549+ }
550+
551+ /// The value of a slot that is exactly one `$name` or `${...}`, with its
552+ /// type; `None` when it is anything else.
553+ fn whole_value(
554+ &mut self,
555+ raw: &str,
556+ line: usize,
557+ column: Option<usize>,
558+ ) -> Option<(Value, bool)> {
559+ let after = raw.strip_prefix('$')?;
560+ let (reference, len) = interp::reference(after, &self.env)?;
561+ if len != after.len() {
562+ return None;
563+ }
564+ track_var_refs(raw, &mut self.used_variables);
565+ let problem = match reference {
566+ interp::Reference::Var(path) => match interp::resolve(&path, &self.env) {
567+ Some(value) => return Some((value, true)),
568+ None => interp::Problem::Undefined {
569+ name: path,
570+ offset: 0,
571+ },
572+ },
573+ interp::Reference::Expr(source) => match crate::expr::eval(source, &self.env) {
574+ Ok(value) => return Some((value, true)),
575+ Err(crate::expr::Error::Invalid(message)) => {
576+ interp::Problem::Invalid { message, offset: 0 }
577+ }
578+ Err(error) => error.at(2),
579+ },
580+ };
581+ self.report(problem, line, column);
582+ Some((Value::Str(raw.to_string()), false))
583+ }
584+
585+ /// Report a variable that can't be filled in, or an invalid `${...}`,
586+ /// at `offset` from `column`.
587+ fn report(&mut self, problem: interp::Problem, line: usize, column: Option<usize>) {
588+ let (line_text, column) = match &self.current_source {
589+ // The column is only shown with the line it points into
590+ (current, Some(text)) if *current == line => (Some(text.clone()), column),
591+ _ => (None, None),
592+ };
593+ let diagnostic = match problem {
594+ interp::Problem::Undefined { name, offset } => {
595+ let column = column.map(|c| c + offset);
596+ let mut diagnostic = self.undefined(&name, line);
597+ if let Some(column) = column {
598+ diagnostic = diagnostic.column(column);
599+ }
600+ diagnostic
601+ }
602+ interp::Problem::Invalid { message, offset } => {
603+ let diagnostic = Diagnostic::error(
604+ code::INVALID_EXPRESSION,
605+ line,
606+ format!("invalid expression: {}", message),
607+ );
608+ match column {
609+ Some(column) => diagnostic.column(column + offset),
610+ None => diagnostic,
611+ }
612+ }
613+ interp::Problem::CustomProperty { name, offset } => {
614+ let diagnostic = Diagnostic::error(
615+ code::INVALID_VALUE,
616+ line,
617+ interp::custom_property_message(&name),
618+ )
619+ .subject(format!("${}", name))
620+ .suggest(Some(format!("var({})", name)));
621+ match column {
622+ Some(column) => diagnostic.column(column + offset),
623+ None => diagnostic,
624+ }
625+ }
626+ interp::Problem::Record { message, offset } => {
627+ let diagnostic = Diagnostic::error(code::INVALID_VALUE, line, message);
628+ match column {
629+ Some(column) => diagnostic.column(column + offset),
630+ None => diagnostic,
631+ }
632+ }
633+ };
634+ let diagnostic = match line_text {
635+ Some(text) => diagnostic.source(text),
636+ None => diagnostic,
637+ };
638+ self.push_once(diagnostic);
639+ }
640+
641+ /// Report a diagnostic unless the node being evaluated already did,
642+ /// so a line evaluated many times (in a loop, in a function) reports
643+ /// each problem once.
644+ fn push_once(&mut self, diagnostic: Diagnostic) {
645+ let key = (
646+ self.current_node,
647+ diagnostic.line,
648+ diagnostic.column,
649+ diagnostic.message.clone(),
650+ );
651+ if self.reported.insert(key) {
652+ self.diagnostics.push(diagnostic);
653+ }
654+ }
655+
656+ /// The error for `$name` with no definition: what the name is if it is
657+ /// something else, or the closest defined name.
658+ fn undefined(&mut self, name: &str, line: usize) -> Diagnostic {
659+ if self.env.bundle(name).is_some() {
660+ // Reported here, so not also as unused
661+ self.used_defines.insert(name.to_string());
662+ return Diagnostic::error(
663+ code::UNDEFINED_VARIABLE,
664+ line,
665+ format!(
666+ "'${}' is an attribute bundle, not a value: it goes in an attribute list \
667+ as a whole attribute, `[${}]`",
668+ name, name
669+ ),
670+ )
671+ .subject(name);
672+ }
673+ if self.env.function(name).is_some() {
674+ self.used_functions.insert(name.to_string());
675+ return Diagnostic::error(
676+ code::UNDEFINED_VARIABLE,
677+ line,
678+ format!(
679+ "'${}' is a function, not a value: it is called as an element, `@{}`",
680+ name, name
681+ ),
682+ )
683+ .subject(name);
684+ }
685+ // `$i-label` where `$i` is defined: a `-` joins a name
686+ if let Some((defined, rest)) = name
687+ .match_indices('-')
688+ .map(|(i, _)| (&name[..i], &name[i..]))
689+ .find(|(before, _)| self.env.value(before).is_some())
690+ {
691+ return Diagnostic::error(
692+ code::UNDEFINED_VARIABLE,
693+ line,
694+ format!(
695+ "undefined variable '${}': a `-` is part of a name. For '${}' followed \
696+ by '{}', write `${{{}}}{}`",
697+ name, defined, rest, defined, rest
698+ ),
699+ )
700+ .subject(name);
701+ }
702+ let suggestion = suggest_var_name(name, &self.env.value_names());
703+ let message = match (&suggestion, self.let_lines.get(name)) {
704+ (Some(closest), _) => format!(
705+ "undefined variable '${}', did you mean '${}'?",
706+ name, closest
707+ ),
708+ // Defined, but not where this line can see it
709+ (None, Some(_)) => format!(
710+ "undefined variable '${}': a `@let` defines it, but not where this line \
711+ can see it. A definition is visible from its line to the end of its \
712+ block, and a function's body sees what is defined above the function",
713+ name
714+ ),
715+ (None, None) => format!("undefined variable '${}'", name),
716+ };
717+ Diagnostic::error(code::UNDEFINED_VARIABLE, line, message)
718+ .subject(name)
719+ .suggest(suggestion)
720+ }
721+
722+ /// Note the node being evaluated, for diagnostics.
723+ fn enter(&mut self, node: &syntax::Node) {
724+ self.current_line = node.span.line;
725+ self.current_node = node.id;
726+ let text =
727+ (node.line_count <= 1).then(|| format!("{}{}", " ".repeat(node.indent), node.source));
728+ self.current_source = (node.span.line, text);
729+ }
730+
731+ /// Parse a file's text into a tree whose ids don't clash with the
732+ /// trees parsed before it.
733+ fn parse_tree(&mut self, text: &str) -> Rc<Tree> {
734+ let tree = syntax::parse_from(text, self.next_id);
735+ self.next_id = tree.end_id;
736+ Rc::new(tree)
737+ }
738+
739+ /// Read a file (once), relative to the current file.
740+ fn read_file(&mut self, resolved: &Path) -> std::io::Result<String> {
741+ if let Some(cached) = self.file_cache.get(resolved) {
742+ return Ok(cached.clone());
743+ }
744+ let text = std::fs::read_to_string(resolved)?;
745+ self.file_cache.insert(resolved.to_path_buf(), text.clone());
746+ Ok(text)
747+ }
748+
749+ fn resolve(&self, filename: &str) -> PathBuf {
750+ match &self.base_path {
751+ Some(base) => base.join(filename),
752+ None => PathBuf::from(filename),
753+ }
754+ }
755+}
756+
757+/// The standard library (`std.hl`): components and bundles defined in
758+/// htmlang itself and available in every file.
759+const PRELUDE: &str = include_str!("std.hl");
760+
761+fn load_prelude(ctx: &mut ParseContext) {
762+ // The library's definitions are in a block of their own, around the
763+ // file's, so the file's own `@let` of the same name hides them
764+ ctx.env.push();
765+ let tree = ctx.parse_tree(PRELUDE);
766+ collect_namespace(&tree.nodes, None, &mut HashSet::new(), ctx);
767+ ctx.current_file = Some("std.hl".to_string());
768+ let _ = Evaluator.eval_block(&tree.nodes, ctx);
769+ ctx.current_file = None;
770+ // Library definitions aren't the file's own: never report them unused.
771+ ctx.fn_lines.clear();
772+ ctx.define_lines.clear();
773+ ctx.let_lines.clear();
774+ ctx.env.push();
775+}
776+
777+pub fn parse(input: &str) -> ParseResult {
778+ parse_with_base(input, None)
779+}
780+
781+pub fn parse_with_base(input: &str, base_path: Option<&Path>) -> ParseResult {
782+ let mut ctx = ParseContext {
783+ current_line: 0,
784+ page: None,
785+ page_at: None,
786+ meta_tags: Vec::new(),
787+ head_blocks: Vec::new(),
788+ head_at: None,
789+ env: Env::default(),
790+ defined_functions: HashMap::new(),
791+ css_vars: Vec::new(),
792+ custom_css: Vec::new(),
793+ scoped_css: Vec::new(),
794+ og_tags: Vec::new(),
795+ diagnostics: Vec::new(),
796+ base_path: base_path.map(|p| p.to_path_buf()),
797+ included_files: Vec::new(),
798+ include_stack: Vec::new(),
799+ fn_call_stack: Vec::new(),
800+ file_cache: HashMap::new(),
801+ used_variables: HashSet::new(),
802+ used_functions: HashSet::new(),
803+ used_defines: HashSet::new(),
804+ let_lines: HashMap::new(),
805+ fn_lines: HashMap::new(),
806+ define_lines: HashMap::new(),
807+ visited: HashSet::new(),
808+ next_id: 0,
809+ trees: Vec::new(),
810+ included_by: Rc::default(),
811+ namespace: HashSet::new(),
812+ current_source: (0, None),
813+ reported: HashSet::new(),
814+ current_node: 0,
815+ current_file: None,
816+ too_deep: false,
817+ in_bundle: false,
818+ in_page: false,
819+ };
820+ load_prelude(&mut ctx);
821+ let tree = ctx.parse_tree(input);
822+ ctx.diagnostics.extend(tree.diagnostics.iter().cloned());
823+ ctx.trees.push((tree.clone(), None));
824+ collect_namespace(
825+ &tree.nodes,
826+ base_path.map(Path::to_path_buf),
827+ &mut HashSet::new(),
828+ &mut ctx,
829+ );
830+ let nodes = Evaluator.eval_block(&tree.nodes, &mut ctx);
831+ check_unevaluated(&mut ctx);
832+ check_slot_places(&mut ctx);
833+ validate_tree(&nodes, None, false, &mut ctx.diagnostics);
834+ // A library's definitions are for the files that include it
835+ let library = is_library_file(&tree, base_path, &mut ctx, &mut Vec::new());
836+ let exported: HashSet<String> = if library {
837+ tree.nodes
838+ .iter()
839+ .filter_map(|node| match node.directive().map(|d| &d.args) {
840+ Some(DirectiveArgs::Let(def)) => Some(def.name.clone()),
841+ _ => None,
842+ })
843+ .collect()
844+ } else {
845+ HashSet::new()
846+ };
847+ check_unused(&mut ctx, &exported);
848+ if let (None, Some(line)) = (&ctx.page, ctx.head_at)
849+ && !library
850+ {
851+ ctx.diagnostics.push(Diagnostic::warning(
852+ code::NO_EFFECT,
853+ line,
854+ "a file without @page is a fragment, which has no <head>: @meta and @head are \
855+ left out of it (give the file a @page, or put them in the page that includes it)"
856+ .to_string(),
857+ ));
858+ }
859+ dedupe(&mut ctx.diagnostics);
860+ // What the file itself defines at its top level
861+ let file = ctx.env.frames.last().cloned().unwrap_or_default();
862+ let mut variables = HashMap::new();
863+ let mut defines = HashMap::new();
864+ for (name, binding) in file.iter() {
865+ match binding {
866+ Binding::Value(value) => {
867+ variables.insert(name.clone(), value.to_string());
868+ }
869+ Binding::Bundle(attrs) => {
870+ defines.insert(name.clone(), attrs.to_vec());
871+ }
872+ Binding::Function(_) => {}
873+ }
874+ }
875+ ParseResult {
876+ document: Document {
877+ page: ctx.page,
878+ meta_tags: ctx.meta_tags,
879+ head_blocks: ctx.head_blocks,
880+ variables,
881+ defines,
882+ css_vars: ctx.css_vars,
883+ custom_css: ctx.custom_css,
884+ scoped_css: ctx.scoped_css,
885+ og_tags: ctx.og_tags,
886+ nodes,
887+ },
888+ diagnostics: ctx.diagnostics,
889+ included_files: ctx.included_files,
890+ }
891+}
892+
893+// ---------------------------------------------------------------------------
894+// Code that never runs: an untaken branch, an uncalled function, a loop over
895+// an empty list
896+// ---------------------------------------------------------------------------
897+
898+/// Collect the functions defined anywhere in `nodes` and in the files they
899+/// include (by a literal path), into `ctx.namespace`.
900+fn collect_namespace(
901+ nodes: &[syntax::Node],
902+ base: Option<PathBuf>,
903+ seen: &mut HashSet<PathBuf>,
904+ ctx: &mut ParseContext,
905+) {
906+ let mut includes = Vec::new();
907+ for node in nodes {
908+ node.walk(&mut |node| match node.directive().map(|d| &d.args) {
909+ Some(DirectiveArgs::Let(def)) if matches!(def.form, LetForm::Function(_)) => {
910+ ctx.namespace.insert(def.name.clone());
911+ }
912+ Some(DirectiveArgs::Text(Some(path))) if node.is_directive("include") => {
913+ includes.push(path.raw.clone());
914+ }
915+ _ => {}
916+ });
917+ }
918+ for path in includes {
919+ let path = path.trim_matches('"');
920+ if path.contains('$') {
921+ continue;
922+ }
923+ let resolved = match &base {
924+ Some(base) => base.join(path),
925+ None => PathBuf::from(path),
926+ };
927+ if !seen.insert(resolved.clone()) {
928+ continue;
929+ }
930+ let Ok(text) = ctx.read_file(&resolved) else {
931+ continue;
932+ };
933+ let tree = syntax::parse(&text);
934+ let parent = resolved.parent().map(Path::to_path_buf);
935+ collect_namespace(&tree.nodes, parent, seen, ctx);
936+ }
937+}
938+
939+/// Check the lines that were never evaluated: element and function names,
940+/// and the attributes of built-in elements (those that don't depend on a
941+/// variable). Names that come from data are only checked when evaluated.
942+fn check_unevaluated(ctx: &mut ParseContext) {
943+ let trees = std::mem::take(&mut ctx.trees);
944+ let mut seen = HashSet::new();
945+ for (tree, chain) in &trees {
946+ let before = ctx.diagnostics.len();
947+ for node in &tree.nodes {
948+ check_unevaluated_node(node, ctx);
949+ }
950+ let mut found = ctx.diagnostics.split_off(before);
951+ if let Some(chain) = chain {
952+ for d in &mut found {
953+ d.message = format!("{}\n in {}", d.message, chain);
954+ }
955+ }
956+ // A file included twice is checked twice: report each problem once
957+ found.retain(|d| seen.insert((d.line, d.message.clone())));
958+ ctx.diagnostics.extend(found);
959+ }
960+ ctx.trees = trees;
961+}
962+
963+fn check_unevaluated_node(node: &syntax::Node, ctx: &mut ParseContext) {
964+ if !ctx.visited.contains(&node.id) {
965+ let line = node.span.line;
966+ // A reference from code that doesn't run still counts as a use
967+ track_var_refs(&node.source, &mut ctx.used_variables);
968+ let before = ctx.diagnostics.len();
969+ match &node.kind {
970+ NodeKind::Element(element) => {
971+ for head in &element.chain {
972+ check_head(head, line, ctx);
973+ }
974+ check_unevaluated_content(node, element, ctx);
975+ if let Some(text) = &element.text {
976+ check_inline_heads(text, line, ctx);
977+ }
978+ }
979+ NodeKind::Text(text) => check_inline_heads(text, line, ctx),
980+ // `@page`'s attributes are checked like an element's (a layout's
981+ // `@page` is in a function that may not run in this file)
982+ NodeKind::Directive(syntax::Directive {
983+ args:
984+ DirectiveArgs::Page {
985+ attrs: Some(list), ..
986+ },
987+ ..
988+ }) => {
989+ let words: Vec<String> = crate::vocab::PAGE_WORDS
990+ .iter()
991+ .map(|w| w.to_string())
992+ .collect();
993+ ctx.in_page = true;
994+ check_attrs(&list.attrs, line, ctx, &words);
995+ ctx.in_page = false;
996+ check_page_tokens(&list.attrs, line, ctx);
997+ }
998+ _ => {}
999+ }
1000+ let text = written_line(node);
1001+ for d in &mut ctx.diagnostics[before..] {
1002+ d.source_line.get_or_insert_with(|| text.as_str().into());
1003+ }
1004+ }
1005+ for child in &node.children {
1006+ check_unevaluated_node(child, ctx);
1007+ }
1008+}
1009+
1010+/// Check the content passed to the calls of a line that was never
1011+/// evaluated: its `@slot NAME` blocks, and, for a function without
1012+/// `@children`, any other content.
1013+fn check_unevaluated_content(
1014+ node: &syntax::Node,
1015+ element: &syntax::ElementLine,
1016+ ctx: &mut ParseContext,
1017+) {
1018+ let calls: Vec<Option<(String, Rc<FnDef>)>> = element
1019+ .chain
1020+ .iter()
1021+ .map(|head| {
1022+ let function = ctx.defined_functions.get(&head.name)?;
1023+ Some((head.name.clone(), function.clone()))
1024+ })
1025+ .collect();
1026+ check_fillers(node, element, &calls, ctx);
1027+ let last = calls.len() - 1;
1028+ for (i, call) in calls.iter().enumerate() {
1029+ let Some((name, function)) = call else {
1030+ continue;
1031+ };
1032+ if function.has_children || function.wraps_itself {
1033+ continue;
1034+ }
1035+ let content = if i == last {
1036+ element.text.is_some() || holds_content(&node.children, ctx)
1037+ } else {
1038+ element.chain[i + 1].name != "slot" || !slot_is_built_in(ctx)
1039+ };
1040+ if content {
1041+ let head = &element.chain[i];
1042+ ctx.push_once(no_children(
1043+ name,
1044+ node.span.line,
1045+ name_column(head, node.span.line),
1046+ ));
1047+ }
1048+ }
1049+}
1050+
1051+/// Check a head that was never evaluated: its name, and its attributes
1052+/// (for a call, see [`check_call`]).
1053+fn check_head(head: &syntax::Head, line: usize, ctx: &mut ParseContext) {
1054+ let is_function =
1055+ ctx.namespace.contains(&head.name) || ctx.defined_functions.contains_key(&head.name);
1056+ if is_function {
1057+ ctx.used_functions.insert(head.name.clone());
1058+ if let Some(function) = ctx.defined_functions.get(&head.name).cloned()
1059+ && !function.wraps_itself
1060+ {
1061+ check_call(head, &function, line, ctx);
1062+ }
1063+ return;
1064+ }
1065+ let kind = match parse_element_kind(&head.name, line, ctx) {
1066+ Ok(kind) => kind,
1067+ Err(e) => {
1068+ ctx.diagnostics.push(e);
1069+ return;
1070+ }
1071+ };
1072+ if let Some(list) = &head.attrs {
1073+ check_attrs(&list.attrs, line, ctx, &[]);
1074+ // A word for laying out children on an element that doesn't lay
1075+ // them out, as where the code runs (see `validate_tree`)
1076+ if !kind.layout().is_container() && !has_no_element(&kind) {
1077+ for attr in &list.attrs {
1078+ let base = crate::vocab::base_attribute(&attr.key);
1079+ if !attr.html
1080+ && attr.choice.is_none()
1081+ && attr.prefixed.is_none()
1082+ && crate::vocab::CONTAINER_ATTRIBUTES.contains(&base)
1083+ && !crate::vocab::split_prefixes(&attr.key)
1084+ .0
1085+ .contains(&"children:")
1086+ {
1087+ ctx.push_once(not_a_container(&kind, line, base).column(attr.span.column));
1088+ }
1089+ }
1090+ }
1091+ }
1092+}
1093+
1094+/// The attributes of a list that is never evaluated that can be checked
1095+/// together: not bundles or `if()`s. Names are checked; a value with a
1096+/// variable in it depends on what the variable holds, so only a literal
1097+/// value is (the other is checked as an empty value).
1098+/// `@page`'s own rules (see `check_page_attr`) for a list that isn't
1099+/// evaluated, as written: a value made from a variable counts as given.
1100+fn check_page_tokens(tokens: &[syntax::Attr], line: usize, ctx: &mut ParseContext) {
1101+ for token in tokens {
1102+ match &token.choice {
1103+ Some(choice) => {
1104+ for branch in &choice.branches {
1105+ check_page_tokens(branch.attrs(), line, ctx);
1106+ }
1107+ }
1108+ // Under prefixes there are only styles
1109+ None if token.key.starts_with('$') || token.prefixed.is_some() => {}
1110+ None => {
1111+ let value = token.value.as_deref().map(|v| v.trim_matches('"'));
1112+ let value = match value {
1113+ Some(v) if v.contains('$') => Some("$"),
1114+ other => other,
1115+ };
1116+ check_page_attr(
1117+ &token.key,
1118+ token.html,
1119+ value,
1120+ line,
1121+ Some(token.span.column),
1122+ ctx,
1123+ );
1124+ }
1125+ }
1126+ }
1127+}
1128+
1129+fn literal_attrs(tokens: &[syntax::Attr]) -> Vec<syntax::Attr> {
1130+ // A prefixed group is checked with its prefixes, as far as its own
1131+ // attributes can be; a prefixed bundle or `if()` depends on what it holds
1132+ let group = |a: &syntax::Attr| {
1133+ let prefixed = a.prefixed.as_ref()?;
1134+ let syntax::Branch::Group { list, trailing } = &prefixed.target else {
1135+ return None;
1136+ };
1137+ let mut list = list.clone();
1138+ list.attrs = literal_attrs(&list.attrs);
1139+ let mut a = a.clone();
1140+ a.prefixed = Some(Box::new(syntax::Prefixed {
1141+ target: syntax::Branch::Group {
1142+ list,
1143+ trailing: trailing.clone(),
1144+ },
1145+ ..(**prefixed).clone()
1146+ }));
1147+ Some(a)
1148+ };
1149+ let groups = tokens.iter().filter_map(group);
1150+ tokens
1151+ .iter()
1152+ .filter(|a| {
1153+ let bundle = a.key.starts_with('$') && a.value.is_none() && !a.html;
1154+ a.choice.is_none() && a.prefixed.is_none() && !bundle
1155+ })
1156+ .map(|a| {
1157+ let mut a = a.clone();
1158+ let variable = |v: &String| v.contains('$');
1159+ if !a.key.contains('$') && a.value.as_ref().is_some_and(variable) {
1160+ a.value = Some(String::new());
1161+ a.raw = format!("{} ", a.key);
1162+ }
1163+ a
1164+ })
1165+ .chain(groups)
1166+ .collect()
1167+}
1168+
1169+/// Check a call that was never evaluated: how it passes its parameters
1170+/// (none written `name=value`, and every one without a default passed,
1171+/// when no bundle or `if()` could pass it), and its other attributes, like
1172+/// those of an element.
1173+fn check_call(head: &syntax::Head, function: &FnDef, line: usize, ctx: &mut ParseContext) {
1174+ let name = head.name.as_str();
1175+ let attrs = head.attrs.as_ref().map_or(&[][..], |list| &list.attrs[..]);
1176+ written_parameter_forms(name, function, attrs, line, ctx);
1177+ if let Some(list) = &head.attrs {
1178+ let params: Vec<String> = function.params.iter().map(|p| p.name.clone()).collect();
1179+ check_attrs(&list.attrs, line, ctx, ¶ms);
1180+ }
1181+ let unknown = attrs
1182+ .iter()
1183+ .any(|a| a.choice.is_some() || (a.key.starts_with('$') && a.value.is_none()));
1184+ if unknown {
1185+ return;
1186+ }
1187+ for param in function.params.iter().filter(|p| p.default.is_none()) {
1188+ if !attrs.iter().any(|a| a.key == param.name) {
1189+ let column = name_column(head, line);
1190+ ctx.push_once(missing_parameter(name, ¶m.name, line, column));
1191+ }
1192+ }
1193+}
1194+
1195+/// Report each parameter a call's list writes `name=value`, with the value
1196+/// as written and its column; returns their names, so the evaluated call
1197+/// doesn't report them again.
1198+fn written_parameter_forms(
1199+ name: &str,
1200+ function: &FnDef,
1201+ attrs: &[syntax::Attr],
1202+ line: usize,
1203+ ctx: &mut ParseContext,
1204+) -> Vec<String> {
1205+ let mut reported = Vec::new();
1206+ for attr in attrs {
1207+ if !(attr.html && function.is_param(&attr.key)) {
1208+ continue;
1209+ }
1210+ let at = if attr.span.line == 0 {
1211+ line
1212+ } else {
1213+ attr.span.line
1214+ };
1215+ let value = attr.value.as_deref().unwrap_or("");
1216+ let diagnostic = parameter_form(name, &attr.key, value, at).column(attr.span.column);
1217+ ctx.push_once(match &ctx.current_source {
1218+ (current, Some(text)) if *current == at => diagnostic.source(text.clone()),
1219+ _ => diagnostic,
1220+ });
1221+ reported.push(attr.key.clone());
1222+ }
1223+ reported
1224+}
1225+
1226+fn check_inline_heads(text: &syntax::Text, line: usize, ctx: &mut ParseContext) {
1227+ for segment in &text.segments {
1228+ if let Segment::Inline(inline) = segment {
1229+ check_head(&inline.head, line, ctx);
1230+ if let Some(text) = &inline.text {
1231+ check_inline_heads(text, line, ctx);
1232+ }
1233+ }
1234+ }
1235+}
1236+
1237+// ---------------------------------------------------------------------------
1238+// Evaluation
1239+// ---------------------------------------------------------------------------
1240+
1241+/// The `@else` lines that continue the `@if` or `@each` before `from`, and
1242+/// the position after them.
1243+fn else_branches(block: &[syntax::Node], from: usize, is_if: bool) -> (Vec<&syntax::Node>, usize) {
1244+ let mut branches = Vec::new();
1245+ let mut next = from;
1246+ let mut i = from;
1247+ while i < block.len() {
1248+ let node = &block[i];
1249+ i += 1;
1250+ if node.is_trivia() {
1251+ continue;
1252+ }
1253+ let condition = match node.directive().map(|d| &d.args) {
1254+ Some(DirectiveArgs::Else { condition }) => condition.is_some(),
1255+ _ => break,
1256+ };
1257+ if condition && !is_if {
1258+ break;
1259+ }
1260+ branches.push(node);
1261+ next = i;
1262+ if !condition {
1263+ break;
1264+ }
1265+ }
1266+ (branches, next)
1267+}
1268+
1269+impl Evaluator {
1270+ fn eval_block(&mut self, block: &[syntax::Node], ctx: &mut ParseContext) -> Vec<Node> {
1271+ let mut nodes = Vec::new();
1272+ let mut i = 0;
1273+ while i < block.len() {
1274+ let node = &block[i];
1275+ i += 1;
1276+ if node.is_trivia() {
1277+ continue;
1278+ }
1279+ let result = match node.directive().map(|d| d.name()) {
1280+ Some(name @ ("if" | "each")) => {
1281+ let (branches, next) = else_branches(block, i, name == "if");
1282+ i = next;
1283+ if name == "if" {
1284+ Ok(Some(self.eval_if(node, &branches, ctx)))
1285+ } else {
1286+ self.eval_each(node, branches.first().copied(), ctx)
1287+ }
1288+ }
1289+ // Reported as a syntax error
1290+ Some("else") => {
1291+ ctx.visited.insert(node.id);
1292+ Ok(None)
1293+ }
1294+ _ => self.eval(node, ctx),
1295+ };
1296+ match result {
1297+ Ok(Some(new_nodes)) => nodes.extend(new_nodes),
1298+ Ok(None) => {}
1299+ // Record the error and go on, to report several in one pass
1300+ Err(mut e) => {
1301+ e.source_line
1302+ .get_or_insert_with(|| node.source.as_str().into());
1303+ ctx.diagnostics.push(e);
1304+ }
1305+ }
1306+ }
1307+ nodes
1308+ }
1309+
1310+ /// Evaluate a block in its own scope: what it defines is visible to
1311+ /// the end of the block, and not after it.
1312+ fn eval_scoped(&mut self, block: &[syntax::Node], ctx: &mut ParseContext) -> Vec<Node> {
1313+ ctx.env.push();
1314+ let nodes = self.eval_block(block, ctx);
1315+ ctx.env.pop();
1316+ nodes
1317+ }
1318+
1319+ /// `@if` with its `@else if` / `@else` branches. Every condition is
1320+ /// checked (and its errors reported); the first that holds picks the
1321+ /// branch.
1322+ fn eval_if(
1323+ &mut self,
1324+ node: &syntax::Node,
1325+ branches: &[&syntax::Node],
1326+ ctx: &mut ParseContext,
1327+ ) -> Vec<Node> {
1328+ let mut chosen = None;
1329+ for branch in std::iter::once(node).chain(branches.iter().copied()) {
1330+ ctx.visited.insert(branch.id);
1331+ ctx.enter(branch);
1332+ let holds = match branch.directive().map(|d| &d.args) {
1333+ Some(DirectiveArgs::Condition(condition))
1334+ | Some(DirectiveArgs::Else {
1335+ condition: Some(condition),
1336+ }) => {
1337+ !condition.raw.is_empty()
1338+ && ctx.condition(
1339+ &condition.raw,
1340+ branch.span.line,
1341+ Some(condition.span.column),
1342+ )
1343+ }
1344+ Some(DirectiveArgs::Else { condition: None }) => true,
1345+ // A syntax error, already reported
1346+ _ => false,
1347+ };
1348+ if holds && chosen.is_none() {
1349+ chosen = Some(&branch.children);
1350+ }
1351+ }
1352+ chosen.map_or_else(Vec::new, |body| self.eval_scoped(body, ctx))
1353+ }
1354+
1355+ fn eval(
1356+ &mut self,
1357+ node: &syntax::Node,
1358+ ctx: &mut ParseContext,
1359+ ) -> Result<Option<Vec<Node>>, ParseError> {
1360+ ctx.visited.insert(node.id);
1361+ ctx.enter(node);
1362+ match &node.kind {
1363+ NodeKind::Blank | NodeKind::Comment => Ok(None),
1364+ // `@code` and `@textarea` show their body as text; `@script`'s
1365+ // goes into the page as it is
1366+ NodeKind::Verbatim(body) if body.escaped => {
1367+ let text = body.text.trim_matches('\n').to_string();
1368+ Ok(Some(vec![Node::Text(vec![TextSegment::Plain(text)])]))
1369+ }
1370+ NodeKind::Verbatim(body) => Ok(Some(vec![Node::Raw(body.text.clone())])),
1371+ NodeKind::Directive(directive) => {
1372+ let mut nodes = self.eval_directive(node, directive, ctx)?;
1373+ // A directive that takes no body: the lines indented under
1374+ // it (a syntax error) are evaluated as its siblings. A
1375+ // @let's body belongs to it even under a value (also an
1376+ // error), so it is never evaluated in place.
1377+ let takes_body = directive.spec.body != BodyKind::None;
1378+ if !takes_body {
1379+ let siblings = self.eval_block(&node.children, ctx);
1380+ nodes.get_or_insert_with(Vec::new).extend(siblings);
1381+ }
1382+ Ok(nodes)
1383+ }
1384+ NodeKind::Element(element) => self.eval_element(node, element, ctx).map(Some),
1385+ NodeKind::Text(text) => {
1386+ let mut nodes = vec![Node::Text(text_segments(text, ctx))];
1387+ // Text takes no body: lines indented under it are its
1388+ // siblings
1389+ nodes.extend(self.eval_block(&node.children, ctx));
1390+ Ok(Some(nodes))
1391+ }
1392+ }
1393+ }
1394+
1395+ fn eval_directive(
1396+ &mut self,
1397+ node: &syntax::Node,
1398+ directive: &syntax::Directive,
1399+ ctx: &mut ParseContext,
1400+ ) -> Result<Option<Vec<Node>>, ParseError> {
1401+ let line_num = node.span.line;
1402+ let content = &node.source;
1403+ match (directive.name(), &directive.args) {
1404+ // @page [lang=en, favicon /f.png, background #f8fafc] Title
1405+ ("page", DirectiveArgs::Page { attrs, title }) => {
1406+ let page = read_page(attrs.as_ref(), title.as_ref(), line_num, ctx);
1407+ // A page has one root: a second `@page` (a layout called
1408+ // twice, or one called after the page's own) is an error
1409+ let here = match &ctx.current_file {
1410+ Some(file) => format!("line {} of {}", line_num, file),
1411+ None => format!("line {}", line_num),
1412+ };
1413+ if let Some(first) = &ctx.page_at {
1414+ let again = if *first == here {
1415+ "this @page runs a second time (in a loop, or in a function called \
1416+ twice)"
1417+ .to_string()
1418+ } else {
1419+ format!("a second @page (this page already has one, on {})", first)
1420+ };
1421+ let diagnostic = Diagnostic::error(
1422+ code::DUPLICATE_PAGE,
1423+ line_num,
1424+ format!(
1425+ "{}: a page has one @page, the root element that styles its <body>",
1426+ again
1427+ ),
1428+ )
1429+ .source(content.clone())
1430+ .subject("@page");
1431+ ctx.diagnostics.push(diagnostic);
1432+ } else {
1433+ ctx.page_at = Some(here);
1434+ ctx.page = Some(page);
1435+ }
1436+ Ok(None)
1437+ }
1438+
1439+ ("let", DirectiveArgs::Let(def)) => {
1440+ let name = def.name.as_str();
1441+ // Values, bundles and functions share one namespace: a
1442+ // definition replaces whatever the name meant in its block
1443+ match &def.form {
1444+ LetForm::Function(function) => {
1445+ self.define_function(name, &function.params, node, ctx);
1446+ }
1447+ // `@let name = EXPR` computes its value (see expr.rs)
1448+ LetForm::Computed(expression) => {
1449+ let value = ctx
1450+ .eval(&expression.raw, line_num, Some(expression.span.column))
1451+ .unwrap_or_else(Value::empty);
1452+ set_variable(name, value, line_num, ctx);
1453+ }
1454+ // Attribute bundle: @let name [attr1, attr2, ...]
1455+ LetForm::Bundle(list) => {
1456+ ctx.in_bundle = true;
1457+ let attrs = parse_attr_list(&list.attrs, line_num, ctx, true, &[]);
1458+ ctx.in_bundle = false;
1459+ ctx.env.define(name, Binding::Bundle(Rc::new(attrs)));
1460+ ctx.define_lines.entry(name.to_string()).or_insert(line_num);
1461+ }
1462+ // `@let size 16px`, `@let fruits apple, banana`,
1463+ // `@let post $posts.0`: see `slot_value`
1464+ LetForm::Value(value) => {
1465+ let (value, _) =
1466+ ctx.slot_value(&value.raw, value.span.line, Some(value.span.column));
1467+ set_variable(name, value, line_num, ctx);
1468+ }
1469+ // Quoted text: `@let arrow "→ "`
1470+ LetForm::Quoted(value) => {
1471+ let raw = format!("\"{}\"", value.raw);
1472+ let column = value.span.column.saturating_sub(1);
1473+ let (text, quoted, _) =
1474+ ctx.fill_value(&raw, value.span.line, Some(column), Sink::Text);
1475+ let value = quoted.map_or(Value::Str(text), Value::Quoted);
1476+ set_variable(name, value, line_num, ctx);
1477+ }
1478+ }
1479+ Ok(None)
1480+ }
1481+
1482+ // @meta NAME VALUE; `og:` names become Open Graph property tags
1483+ ("meta", DirectiveArgs::Text(Some(arg))) => {
1484+ let Some((name, value)) = arg.raw.split_once(char::is_whitespace) else {
1485+ ctx.diagnostics.push(
1486+ Diagnostic::error(
1487+ code::MISSING_ARGUMENT,
1488+ line_num,
1489+ format!("@meta needs a name and a value: `@meta {} VALUE`", arg.raw),
1490+ )
1491+ .source(content.clone()),
1492+ );
1493+ return Ok(None);
1494+ };
1495+ let value_column = arg.span.column + arg.raw.len() - value.trim_start().len();
1496+ // An HTML attribute value: quoted text loses its quotes
1497+ let (value, _, _) =
1498+ ctx.fill_value(value.trim(), line_num, Some(value_column), Sink::Text);
1499+ // The same tag twice says nothing more (a layout called
1500+ // twice): it is written once
1501+ let (tags, tag) = match name.trim().strip_prefix("og:") {
1502+ Some(property) => (&mut ctx.og_tags, (property.to_string(), value)),
1503+ None => (&mut ctx.meta_tags, (name.trim().to_string(), value)),
1504+ };
1505+ if !tags.contains(&tag) {
1506+ tags.push(tag);
1507+ }
1508+ ctx.head_at.get_or_insert(line_num);
1509+ Ok(None)
1510+ }
1511+
1512+ ("head", _) => {
1513+ let text = verbatim_content(node);
1514+ if !text.trim().is_empty() {
1515+ ctx.head_blocks.push(text.trim().to_string());
1516+ ctx.head_at.get_or_insert(line_num);
1517+ }
1518+ Ok(None)
1519+ }
1520+
1521+ // @style: raw CSS
1522+ ("style", _) => {
1523+ let text = verbatim_content(node);
1524+ // Only the @style at the top of a function's body is
1525+ // scoped; anywhere else `&` is `:scope`, the whole page
1526+ if has_top_level_ampersand(&text) {
1527+ ctx.push_once(Diagnostic::warning(
1528+ code::INVALID_VALUE,
1529+ node.span.line,
1530+ "`&` in this @style is the whole page: only an @style at the top of a \
1531+ function's body is scoped to the function, with `&` its root element"
1532+ .to_string(),
1533+ ));
1534+ }
1535+ if !text.trim().is_empty() {
1536+ ctx.custom_css.push(text.trim().to_string());
1537+ }
1538+ Ok(None)
1539+ }
1540+
1541+ // @markdown: an indented block, or a file
1542+ ("markdown", DirectiveArgs::Text(file)) => {
1543+ let Some(file) = file else {
1544+ let md_lines: Vec<String> = verbatim_text(&node.children)
1545+ .lines()
1546+ .map(String::from)
1547+ .collect();
1548+ return Ok(Some(vec![Node::Raw(markdown_to_html(&md_lines))]));
1549+ };
1550+ let filename = ctx.interpolate_text(&file.raw, line_num, Some(file.span.column));
1551+ let resolved = ctx.resolve(&filename);
1552+ let md_text = match ctx.read_file(&resolved) {
1553+ Ok(text) => text,
1554+ Err(e) => {
1555+ ctx.diagnostics.push(
1556+ Diagnostic::error(
1557+ code::UNREADABLE_FILE,
1558+ line_num,
1559+ format!("cannot read markdown '{}': {}", filename, e),
1560+ )
1561+ .source(content.clone()),
1562+ );
1563+ return Ok(None);
1564+ }
1565+ };
1566+ ctx.included_files.push(resolved);
1567+ let md_lines: Vec<String> = md_text.lines().map(|l| l.to_string()).collect();
1568+ Ok(Some(vec![Node::Raw(markdown_to_html(&md_lines))]))
1569+ }
1570+
1571+ ("include", DirectiveArgs::Text(Some(path))) => {
1572+ self.eval_include(node.id, path, line_num, content, ctx)
1573+ }
1574+
1575+ ("data", DirectiveArgs::Data { name, source, .. }) => {
1576+ self.eval_data(name, source, line_num, content, ctx);
1577+ Ok(None)
1578+ }
1579+
1580+ // @raw: the rest of its line, or its indented body, verbatim
1581+ ("raw", _) => {
1582+ let text = verbatim_content(node);
1583+ let text = text.trim_end_matches('\n');
1584+ Ok((!text.is_empty()).then(|| vec![Node::Raw(text.to_string())]))
1585+ }
1586+
1587+ // A header with a syntax error (reported), or a directive
1588+ // without its argument
1589+ _ => Ok(None),
1590+ }
1591+ }
1592+
1593+ fn eval_include(
1594+ &mut self,
1595+ id: usize,
1596+ path: &syntax::Arg,
1597+ line_num: usize,
1598+ content: &str,
1599+ ctx: &mut ParseContext,
1600+ ) -> Result<Option<Vec<Node>>, ParseError> {
1601+ let (filename, column) = match path.raw.strip_prefix('"').and_then(|f| f.strip_suffix('"'))
1602+ {
1603+ Some(quoted) => (quoted, path.span.column + 1),
1604+ None => (path.raw.as_str(), path.span.column),
1605+ };
1606+ let filename = ctx.interpolate_text(filename, line_num, Some(column));
1607+ let resolved = ctx.resolve(&filename);
1608+
1609+ if ctx.include_stack.contains(&resolved) {
1610+ let cycle_chain = format_include_chain(&ctx.include_stack);
1611+ ctx.diagnostics.push(
1612+ Diagnostic::error(
1613+ code::CIRCULAR_INCLUDE,
1614+ line_num,
1615+ format!(
1616+ "circular include '{}' (cycle: {} → {})",
1617+ filename, cycle_chain, filename
1618+ ),
1619+ )
1620+ .source(content),
1621+ );
1622+ return Ok(None);
1623+ }
1624+
1625+ let imported_text = match ctx.read_file(&resolved) {
1626+ Ok(text) => text,
1627+ Err(e) => {
1628+ ctx.diagnostics.push(
1629+ Diagnostic::error(
1630+ code::UNREADABLE_FILE,
1631+ line_num,
1632+ format!("cannot include '{}': {}", filename, e),
1633+ )
1634+ .source(content),
1635+ );
1636+ return Ok(None);
1637+ }
1638+ };
1639+
1640+ ctx.included_files.push(resolved.clone());
1641+ ctx.include_stack.push(resolved.clone());
1642+ let saved_base = ctx.base_path.clone();
1643+ ctx.base_path = resolved.parent().map(|p| p.to_path_buf());
1644+
1645+ let diag_count_before = ctx.diagnostics.len();
1646+ let import_chain = format_include_chain(&ctx.include_stack);
1647+ let tree = ctx.parse_tree(&imported_text);
1648+ ctx.diagnostics.extend(tree.diagnostics.iter().cloned());
1649+ ctx.trees.push((tree.clone(), Some(import_chain.clone())));
1650+ let files = Rc::make_mut(&mut ctx.included_by).entry(id).or_default();
1651+ if !files.iter().any(|(_, chain)| *chain == import_chain) {
1652+ files.push((tree.clone(), import_chain.clone()));
1653+ }
1654+ let saved_file = ctx.current_file.replace(import_chain.clone());
1655+ let defined_before: HashSet<String> = ctx
1656+ .let_lines
1657+ .keys()
1658+ .chain(ctx.define_lines.keys())
1659+ .chain(ctx.fn_lines.keys())
1660+ .cloned()
1661+ .collect();
1662+ let included_nodes = self.eval_block(&tree.nodes, ctx);
1663+ ctx.current_file = saved_file;
1664+ // An included file's definitions aren't reported unused here, where
1665+ // their lines aren't this file's: a library's are there to be
1666+ // picked from, and any other file reports its own when checked
1667+ let keep = |name: &String, _: &mut usize| defined_before.contains(name);
1668+ ctx.let_lines.retain(keep);
1669+ ctx.define_lines.retain(keep);
1670+ ctx.fn_lines.retain(keep);
1671+
1672+ // Annotate new diagnostics with import chain
1673+ for d in &mut ctx.diagnostics[diag_count_before..] {
1674+ d.message = format!("{}\n in {}", d.message, import_chain);
1675+ }
1676+
1677+ ctx.base_path = saved_base;
1678+ ctx.include_stack.pop();
1679+ Ok(Some(included_nodes))
1680+ }
1681+
1682+ /// @data $name file.json values as $name.key
1683+ /// @data $name dir/*.json a list of the files' records
1684+ /// @data $name [...] / {...} inline JSON
1685+ /// @data $name env:NAME [DEFAULT] an environment variable
1686+ fn eval_data(
1687+ &mut self,
1688+ prefix: &str,
1689+ source: &syntax::Arg,
1690+ line_num: usize,
1691+ content: &str,
1692+ ctx: &mut ParseContext,
1693+ ) {
1694+ let prefix = prefix.to_string();
1695+ let filename = source.raw.as_str();
1696+ if let Some(env) = filename.strip_prefix("env:") {
1697+ let (var, default) = match env.split_once(char::is_whitespace) {
1698+ Some((var, default)) => (var, Some(default.trim())),
1699+ None => (env, None),
1700+ };
1701+ let default_column = default.map(|d| source.span.column + filename.len() - d.len());
1702+ let value = std::env::var(var)
1703+ .ok()
1704+ .or_else(|| default.map(|d| ctx.interpolate_text(d, line_num, default_column)));
1705+ if value.is_none() {
1706+ ctx.diagnostics.push(
1707+ Diagnostic::warning(
1708+ code::UNSET_ENVIRONMENT,
1709+ line_num,
1710+ format!(
1711+ "environment variable '{}' is not set and has no default",
1712+ var
1713+ ),
1714+ )
1715+ .source(content),
1716+ );
1717+ }
1718+ ctx.bind(&prefix, Value::Str(value.unwrap_or_default()));
1719+ return;
1720+ }
1721+
1722+ // Inline JSON: @data $links [{"label": "Home", "url": "/"}]
1723+ let (json_text, source) = if filename.starts_with(['[', '{']) {
1724+ (filename.to_string(), "the inline data".to_string())
1725+ } else {
1726+ let filename = ctx.interpolate_text(filename, line_num, Some(source.span.column));
1727+ if filename.contains('*') {
1728+ self.load_data_glob(&prefix, &filename, line_num, content, ctx);
1729+ return;
1730+ }
1731+ let resolved = ctx.resolve(&filename);
1732+ match std::fs::read_to_string(&resolved) {
1733+ Ok(text) => {
1734+ ctx.included_files.push(resolved);
1735+ (text, format!("'{}'", filename))
1736+ }
1737+ Err(e) => {
1738+ ctx.diagnostics.push(
1739+ Diagnostic::error(
1740+ code::UNREADABLE_FILE,
1741+ line_num,
1742+ format!("cannot load data '{}': {}", filename, e),
1743+ )
1744+ .source(content),
1745+ );
1746+ return;
1747+ }
1748+ }
1749+ };
1750+ match parse_json_with_error(&json_text) {
1751+ Ok(json) => ctx.bind(&prefix, json_value(json)),
1752+ Err(detail) => ctx.diagnostics.push(
1753+ Diagnostic::error(
1754+ code::INVALID_JSON,
1755+ line_num,
1756+ format!("invalid JSON in {}: {}", source, detail),
1757+ )
1758+ .source(content),
1759+ ),
1760+ }
1761+ }
1762+
1763+ /// `@data $name dir/*.json`: a list with one record per matching file
1764+ /// (in name order), whose `file` is the file's name without extension.
1765+ fn load_data_glob(
1766+ &mut self,
1767+ name: &str,
1768+ pattern: &str,
1769+ line_num: usize,
1770+ content: &str,
1771+ ctx: &mut ParseContext,
1772+ ) {
1773+ let base = ctx.base_path.clone().unwrap_or_else(|| PathBuf::from("."));
1774+ let pattern_path = Path::new(pattern);
1775+ let dir = match pattern_path.parent() {
1776+ Some(dir) if !dir.as_os_str().is_empty() => base.join(dir),
1777+ _ => base,
1778+ };
1779+ let file_pattern = pattern_path
1780+ .file_name()
1781+ .unwrap_or_default()
1782+ .to_string_lossy()
1783+ .to_string();
1784+ let mut files: Vec<PathBuf> = match std::fs::read_dir(&dir) {
1785+ Ok(entries) => entries
1786+ .flatten()
1787+ .map(|e| e.path())
1788+ .filter(|p| {
1789+ p.file_name()
1790+ .is_some_and(|n| glob_match(&file_pattern, &n.to_string_lossy()))
1791+ })
1792+ .collect(),
1793+ Err(e) => {
1794+ ctx.diagnostics.push(
1795+ Diagnostic::new(
1796+ code::UNREADABLE_FILE,
1797+ Severity::Error,
1798+ line_num,
1799+ format!("cannot read directory for '{}': {}", pattern, e),
1800+ )
1801+ .source(content.to_string()),
1802+ );
1803+ return;
1804+ }
1805+ };
1806+ files.sort();
1807+ let mut records = Vec::new();
1808+ for file in files {
1809+ let stem = file
1810+ .file_stem()
1811+ .unwrap_or_default()
1812+ .to_string_lossy()
1813+ .to_string();
1814+ let text = match std::fs::read_to_string(&file) {
1815+ Ok(text) => text,
1816+ Err(e) => {
1817+ ctx.diagnostics.push(
1818+ Diagnostic::new(
1819+ code::UNREADABLE_FILE,
1820+ Severity::Error,
1821+ line_num,
1822+ format!("cannot load data '{}': {}", file.display(), e),
1823+ )
1824+ .source(content.to_string()),
1825+ );
1826+ continue;
1827+ }
1828+ };
1829+ match parse_json_with_error(&text) {
1830+ Ok(JsonValue::Object(mut pairs)) => {
1831+ if !pairs.iter().any(|(key, _)| key == "file") {
1832+ pairs.push(("file".to_string(), JsonValue::Str(stem)));
1833+ }
1834+ records.push(JsonValue::Object(pairs));
1835+ }
1836+ Ok(_) => ctx.diagnostics.push(
1837+ Diagnostic::new(
1838+ code::INVALID_JSON,
1839+ Severity::Error,
1840+ line_num,
1841+ format!("'{}' should hold a JSON object", file.display()),
1842+ )
1843+ .source(content.to_string()),
1844+ ),
1845+ Err(detail) => ctx.diagnostics.push(
1846+ Diagnostic::new(
1847+ code::INVALID_JSON,
1848+ Severity::Error,
1849+ line_num,
1850+ format!("invalid JSON in '{}': {}", file.display(), detail),
1851+ )
1852+ .source(content.to_string()),
1853+ ),
1854+ }
1855+ ctx.included_files.push(file);
1856+ }
1857+ ctx.bind(name, json_value(JsonValue::Array(records)));
1858+ }
1859+
1860+ /// `@each $item in LIST` or `@each $item, $index in LIST`, with the
1861+ /// `@else` that follows it. LIST is a value (see
1862+ /// [`ParseContext::slot_value`]): a list written with commas, a range,
1863+ /// or one `$name` or `${...}` that holds a list. Each item is bound
1864+ /// whole to `$item`, and each iteration is a block of its own.
1865+ fn eval_each(
1866+ &mut self,
1867+ node: &syntax::Node,
1868+ empty_branch: Option<&syntax::Node>,
1869+ ctx: &mut ParseContext,
1870+ ) -> Result<Option<Vec<Node>>, ParseError> {
1871+ ctx.visited.insert(node.id);
1872+ if let Some(branch) = empty_branch {
1873+ ctx.visited.insert(branch.id);
1874+ }
1875+ ctx.enter(node);
1876+ // A malformed header is a syntax error, already reported
1877+ let Some(DirectiveArgs::Each(header)) = node.directive().map(|d| &d.args) else {
1878+ return Ok(None);
1879+ };
1880+ let body = &node.children;
1881+ let empty: &[syntax::Node] = empty_branch.map_or(&[], |b| &b.children);
1882+ let (item, index) = (header.item.as_str(), header.index.as_deref());
1883+ let list = &header.list;
1884+ // `[...]` is an attribute list or JSON elsewhere, not a list here
1885+ let bracketed = list.raw.starts_with('[') && list.raw.ends_with(']');
1886+ let (source, filled) = match bracketed {
1887+ true => (Value::empty(), false),
1888+ false => ctx.slot_value(&list.raw, list.span.line, Some(list.span.column)),
1889+ };
1890+ let not_a_list = |message: String, ctx: &ParseContext| {
1891+ let diagnostic = Diagnostic::error(code::INVALID_LOOP, list.span.line, message)
1892+ .column(list.span.column)
1893+ .subject(list.raw.as_str());
1894+ match &ctx.current_source {
1895+ (current, Some(text)) if *current == list.span.line => {
1896+ diagnostic.source(text.clone())
1897+ }
1898+ _ => diagnostic,
1899+ }
1900+ };
1901+ if bracketed {
1902+ let inner = list.raw[1..list.raw.len() - 1].trim().to_string();
1903+ let diagnostic = not_a_list(
1904+ format!(
1905+ "@each takes a list written without brackets, `@each ${} in {}`; \
1906+ JSON data goes in `@data`",
1907+ item, inner
1908+ ),
1909+ ctx,
1910+ )
1911+ .suggest(Some(inner));
1912+ ctx.push_once(diagnostic);
1913+ }
1914+ let items: Vec<Value> = match source {
1915+ Value::List(list) => list.items.to_vec(),
1916+ // Reported (an undefined `$name`, brackets): there is nothing
1917+ // to repeat
1918+ _ if !filled => Vec::new(),
1919+ Value::Record(_) => {
1920+ let diagnostic = not_a_list(
1921+ format!(
1922+ "@each repeats for the items of a list, and `{}` is a record: \
1923+ loop over a list of records, or use its fields",
1924+ list.raw
1925+ ),
1926+ ctx,
1927+ );
1928+ ctx.push_once(diagnostic);
1929+ Vec::new()
1930+ }
1931+ // Empty text (a field a record doesn't have) is no items; any
1932+ // other value is one
1933+ value if value.to_string().is_empty() => Vec::new(),
1934+ value => vec![value],
1935+ };
1936+
1937+ if body.iter().all(syntax::Node::is_trivia) {
1938+ return Ok(Some(Vec::new()));
1939+ }
1940+ if items.is_empty() {
1941+ return Ok(Some(self.eval_scoped(empty, ctx)));
1942+ }
1943+ let mut nodes = Vec::new();
1944+ for (i, value) in items.into_iter().enumerate() {
1945+ ctx.env.push();
1946+ ctx.bind(item, value);
1947+ if let Some(index) = index {
1948+ ctx.bind(index, Value::Num(i as f64));
1949+ }
1950+ nodes.extend(self.eval_block(body, ctx));
1951+ ctx.env.pop();
1952+ }
1953+ Ok(Some(nodes))
1954+ }
1955+
1956+ fn define_function(
1957+ &mut self,
1958+ name: &str,
1959+ params: &[syntax::Param],
1960+ node: &syntax::Node,
1961+ ctx: &mut ParseContext,
1962+ ) {
1963+ let line_num = node.span.line;
1964+ let body = &node.children;
1965+ // An @style block at the top of the body is scoped to the
1966+ // function: its rules apply inside a `.hl-fn-NAME-HASH` wrapper (a
1967+ // generated class never has a second `-`, so the two can't meet).
1968+ // The hash is the stylesheet's, so two functions of one name with
1969+ // two stylesheets, in two files, don't style each other's elements
1970+ // in a page that has both. It is written into the page when the
1971+ // function is called.
1972+ let (style, body): (Vec<&syntax::Node>, Vec<&syntax::Node>) =
1973+ body.iter().partition(|node| node.is_directive("style"));
1974+ let scoped = (!style.is_empty()).then(|| {
1975+ let css: String = style
1976+ .iter()
1977+ .map(|node| {
1978+ ctx.visited.insert(node.id);
1979+ verbatim_content(node)
1980+ })
1981+ .collect();
1982+ let digits = crate::codegen::CLASS_DIGITS;
1983+ let hash = crate::codegen::hash_digits(crate::codegen::stable_hash(&css), digits);
1984+ let class = format!("hl-fn-{}-{}", name, hash);
1985+ // Nested under the scope class, so any CSS works (multi-line
1986+ // rules, at-rules)
1987+ let css = if css.trim().is_empty() {
1988+ String::new()
1989+ } else {
1990+ format!(".{} {{\n{}}}", class, css)
1991+ };
1992+ (class, css)
1993+ });
1994+
1995+ // A default is filled in only when a call leaves its parameter
1996+ // out, so the names in it count as used here
1997+ for default in params.iter().filter_map(|p| p.default.as_ref()) {
1998+ track_var_refs(default, &mut ctx.used_variables);
1999+ }
2000+ ctx.fn_lines.entry(name.to_string()).or_insert(line_num);
2001+ let wraps_itself = ElementKind::from_name(name).is_some()
2002+ && body.iter().any(|node| calls_unguarded(node, name));
2003+ if wraps_itself {
2004+ ctx.push_once(
2005+ Diagnostic::error(
2006+ code::RECURSIVE_CALL,
2007+ line_num,
2008+ format!(
2009+ "@{0} in the body of `@let @{0}` calls the function itself, not the \
2010+ element @{0}, so it would never stop: give the function another name \
2011+ (such as @site-{0})",
2012+ name
2013+ ),
2014+ )
2015+ .subject(name),
2016+ );
2017+ }
2018+ for node in &body {
2019+ node.walk(&mut |node| {
2020+ if let Some(d) = marker_in_text(node) {
2021+ ctx.push_once(d);
2022+ }
2023+ });
2024+ }
2025+ let body: Vec<syntax::Node> = body.into_iter().cloned().collect();
2026+ let (slots, has_children) = declared_slots(&body, ctx);
2027+ let function = Rc::new(FnDef {
2028+ params: params.to_vec(),
2029+ line: line_num,
2030+ source: ctx.current_source.1.clone(),
2031+ node: node.id,
2032+ body,
2033+ file: ctx.current_file.clone(),
2034+ slots,
2035+ has_children,
2036+ scoped,
2037+ env: ctx.env.clone(),
2038+ wraps_itself,
2039+ });
2040+ ctx.defined_functions
2041+ .insert(name.to_string(), function.clone());
2042+ ctx.env.define(name, Binding::Function(function));
2043+ }
2044+
2045+ /// An element line: a chain of elements and function calls, the last of
2046+ /// which gets the indented children.
2047+ fn eval_element(
2048+ &mut self,
2049+ node: &syntax::Node,
2050+ element: &syntax::ElementLine,
2051+ ctx: &mut ParseContext,
2052+ ) -> Result<Vec<Node>, ParseError> {
2053+ // An unclosed attribute list is a syntax error, already reported
2054+ if element
2055+ .chain
2056+ .iter()
2057+ .any(|h| h.attrs.as_ref().is_some_and(|a| !a.closed))
2058+ {
2059+ return Ok(Vec::new());
2060+ }
2061+ let line_num = node.span.line;
2062+ let last = element.chain.len() - 1;
2063+ // Each head is read where it is written, left to right. The
2064+ // children belong to the last one, so the chain is built right to
2065+ // left, each link wrapping the next.
2066+ let mut links = Vec::new();
2067+ for (i, head) in element.chain.iter().enumerate() {
2068+ let text = if i == last {
2069+ element.text.as_ref()
2070+ } else {
2071+ None
2072+ };
2073+ links.push(resolve(head, text, line_num, &node.source, ctx)?);
2074+ }
2075+ let calls: Vec<Option<(String, Rc<FnDef>)>> = links
2076+ .iter()
2077+ .map(|link| match link {
2078+ Resolved::Call(call) => Some((call.name.clone(), call.function.clone())),
2079+ Resolved::Element(_) => None,
2080+ })
2081+ .collect();
2082+ let mut current = self.eval_scoped(&node.children, ctx);
2083+ // After the lines under the call ran, so the files they include
2084+ // are read
2085+ check_fillers(node, element, &calls, ctx);
2086+ for link in links.into_iter().rev() {
2087+ current = self.complete(link, current, ctx)?;
2088+ }
2089+ Ok(current)
2090+ }
2091+
2092+ /// Give a resolved `@name` its children: an element holds them, and a
2093+ /// function's body puts them where its `@children` is.
2094+ fn complete(
2095+ &mut self,
2096+ resolved: Resolved,
2097+ children: Vec<Node>,
2098+ ctx: &mut ParseContext,
2099+ ) -> Result<Vec<Node>, ParseError> {
2100+ match resolved {
2101+ Resolved::Element(mut element) => {
2102+ element.children.extend(children);
2103+ let line = element.line_num;
2104+ Ok(vec![inline_svg(Node::Element(element), line, ctx)])
2105+ }
2106+ Resolved::Call(call) => self.expand_fn_call(*call, children, ctx),
2107+ }
2108+ }
2109+
2110+ fn expand_fn_call(
2111+ &mut self,
2112+ call: Call,
2113+ all_caller_children: Vec<Node>,
2114+ ctx: &mut ParseContext,
2115+ ) -> Result<Vec<Node>, ParseError> {
2116+ let Call {
2117+ name,
2118+ function: fn_def,
2119+ args,
2120+ values,
2121+ text: trailing_text,
2122+ written_form,
2123+ written_keys,
2124+ line: line_num,
2125+ name_at,
2126+ source: content,
2127+ } = call;
2128+ let (name, content) = (name.as_str(), content.as_str());
2129+
2130+ // Separate the caller's `@slot NAME` blocks from its other
2131+ // children. A block for a slot the function doesn't declare was
2132+ // reported where it is written (see `check_fillers`), like one
2133+ // without a name.
2134+ let mut slot_contents: HashMap<String, Vec<Node>> = HashMap::new();
2135+ let mut caller_children = Vec::new();
2136+ for child in all_caller_children {
2137+ if let Node::Element(elem) = child {
2138+ match elem.kind {
2139+ ElementKind::Slot(slot_name) => {
2140+ slot_contents
2141+ .entry(slot_name)
2142+ .or_default()
2143+ .extend(elem.children);
2144+ }
2145+ kind => caller_children.push(Node::Element(Element { kind, ..elem })),
2146+ }
2147+ continue;
2148+ }
2149+ caller_children.push(child);
2150+ }
2151+ // Text after the call, as in `@card [color red] New`, is content:
2152+ // it goes first among the caller's children, and like them it is
2153+ // evaluated where the call is written.
2154+ if let Some(text) = &trailing_text {
2155+ caller_children.insert(0, Node::Text(text_segments(text, ctx)));
2156+ }
2157+ // Content goes where the body's `@children` is: without one, it
2158+ // would be dropped
2159+ if !fn_def.has_children && !caller_children.is_empty() {
2160+ let (column, text) = match &name_at {
2161+ Some((column, text)) => (Some(*column), text.as_str()),
2162+ None => (None, content),
2163+ };
2164+ ctx.push_once(no_children(name, line_num, column).source(text));
2165+ }
2166+
2167+ if fn_def.wraps_itself {
2168+ return Ok(Vec::new());
2169+ }
2170+ // Only the body is inside the call, so a function may appear in the
2171+ // content its caller passes it. A function may call itself, under
2172+ // a condition that stops it; one that doesn't stop goes too deep.
2173+ if ctx.too_deep {
2174+ return Ok(Vec::new());
2175+ }
2176+ if ctx.fn_call_stack.len() >= MAX_CALL_DEPTH {
2177+ ctx.too_deep = true;
2178+ return Err(too_deep(name, &ctx.fn_call_stack, line_num).source(content));
2179+ }
2180+ let caller = (
2181+ ctx.current_line,
2182+ ctx.current_source.clone(),
2183+ ctx.current_node,
2184+ );
2185+ ctx.fn_call_stack.push(name.to_string());
2186+
2187+ // The body runs where the function is defined: it sees what was
2188+ // visible there, the function itself (so it can call itself), and
2189+ // its parameters, bound by name in the order they are declared. A
2190+ // default is filled in at the call, seeing the same, with the
2191+ // parameters before it.
2192+ let caller_env = std::mem::replace(&mut ctx.env, fn_def.env.clone());
2193+ ctx.env.push();
2194+ ctx.env.define(name, Binding::Function(fn_def.clone()));
2195+ let mut consumed = vec![false; args.len()];
2196+ for param in &fn_def.params {
2197+ let mut passed = None;
2198+ for (j, arg) in args.iter().enumerate() {
2199+ if arg.key != param.name {
2200+ continue;
2201+ }
2202+ consumed[j] = true;
2203+ // The later one wins, as for any attribute: one written
2204+ // after a bundle overrides it, and only one written twice
2205+ // in the call's own list is reported
2206+ if passed.is_some() && written_keys.iter().filter(|k| **k == param.name).count() > 1
2207+ {
2208+ ctx.push_once(
2209+ Diagnostic::warning(
2210+ code::DUPLICATE_ATTRIBUTE,
2211+ line_num,
2212+ format!(
2213+ "parameter '{}' of @{} is passed twice: the later one wins",
2214+ param.name, name
2215+ ),
2216+ )
2217+ .source(content)
2218+ .subject(param.name.as_str()),
2219+ );
2220+ }
2221+ // Written `name=value` in the call's own list is reported
2222+ // as written; this is one from a bundle
2223+ if arg.html && !written_form.contains(&arg.key) {
2224+ let value = arg.value.as_deref().unwrap_or("");
2225+ ctx.push_once(parameter_form(name, &arg.key, value, line_num).source(content));
2226+ }
2227+ passed = Some(j);
2228+ }
2229+ let value = match passed {
2230+ // A parameter's name alone is true: `@post-card [featured]`
2231+ Some(j) if args[j].value.is_none() => Value::Bool(true),
2232+ // What the call passed, with its type: a record, a list,
2233+ // quoted text
2234+ Some(j) => values[j].clone().unwrap_or_else(|| {
2235+ let arg = &args[j];
2236+ match &arg.quoted {
2237+ Some(quoted) => Value::Quoted(quoted.clone()),
2238+ None => Value::Str(arg.value.clone().unwrap_or_default()),
2239+ }
2240+ }),
2241+ None => match ¶m.default {
2242+ Some(default) => {
2243+ let before = ctx.diagnostics.len();
2244+ let value = fill_default(&fn_def, param, default, ctx);
2245+ point_at_call(ctx, before, &fn_def, name, line_num, content);
2246+ value
2247+ }
2248+ None => {
2249+ let (column, text) = match &name_at {
2250+ Some((column, text)) => (Some(*column), text.as_str()),
2251+ None => (None, content),
2252+ };
2253+ ctx.push_once(
2254+ missing_parameter(name, ¶m.name, line_num, column).source(text),
2255+ );
2256+ Value::empty()
2257+ }
2258+ },
2259+ };
2260+ ctx.bind(¶m.name, value);
2261+ }
2262+ // Arguments that aren't parameters are attributes for the
2263+ // function's root element, so a function can be styled like an
2264+ // element: `@card [background red] New`.
2265+ let forwarded: Vec<Attribute> = args
2266+ .iter()
2267+ .zip(&consumed)
2268+ .filter(|&(_, &used)| !used)
2269+ .map(|(a, _)| a.clone())
2270+ .collect();
2271+
2272+ // Evaluate the body with the parameters in scope, as lines of the
2273+ // file that defines the function
2274+ let caller_file = std::mem::replace(&mut ctx.current_file, fn_def.file.clone());
2275+ let before = ctx.diagnostics.len();
2276+ let mut body_nodes = self.eval_block(&fn_def.body, ctx);
2277+ ctx.current_file = caller_file;
2278+ point_at_call(ctx, before, &fn_def, name, line_num, content);
2279+
2280+ // Back to the caller's names and call stack
2281+ ctx.env = caller_env;
2282+ ctx.fn_call_stack.pop();
2283+ if ctx.fn_call_stack.is_empty() {
2284+ ctx.too_deep = false;
2285+ }
2286+ (ctx.current_line, ctx.current_source, ctx.current_node) = caller;
2287+
2288+ // What the body wrote is the call's
2289+ belongs_to_call(&mut body_nodes, name, line_num);
2290+
2291+ // Replace @children with caller's children and @slot with slot content
2292+ let mut result_nodes =
2293+ replace_children_and_slots(body_nodes, &caller_children, &slot_contents);
2294+
2295+ // Attributes that aren't parameters style the function's root
2296+ // element, and a scoped @style's class goes on it too.
2297+ let scope_class = fn_def.scoped.as_ref().map(|(class, _)| class.clone());
2298+ if !forwarded.is_empty() || scope_class.is_some() {
2299+ let mut roots = result_nodes.iter_mut().filter_map(|n| match n {
2300+ Node::Element(e) => Some(e),
2301+ _ => None,
2302+ });
2303+ let root = match (roots.next(), roots.next()) {
2304+ (Some(root), None) => Some(root),
2305+ _ => None,
2306+ };
2307+ let mut problems = Vec::new();
2308+ match root {
2309+ Some(root) => {
2310+ // A call's `class=` adds to the root's own classes
2311+ for attr in forwarded {
2312+ let existing = (attr.html && attr.key == "class")
2313+ .then(|| root.attrs.iter_mut().find(|a| a.html && a.key == "class"))
2314+ .flatten();
2315+ match existing {
2316+ Some(class) => {
2317+ let mut value = class.value.take().unwrap_or_default();
2318+ for name in attr.value.as_deref().unwrap_or("").split_whitespace() {
2319+ if !value.split_whitespace().any(|c| c == name) {
2320+ value.push(' ');
2321+ value.push_str(name);
2322+ }
2323+ }
2324+ class.value = Some(value.trim().to_string());
2325+ }
2326+ None => root.attrs.push(attr),
2327+ }
2328+ }
2329+ // The scoped `@style` goes into the page once, when the
2330+ // function is first called
2331+ if let Some((_, css)) = &fn_def.scoped
2332+ && !css.is_empty()
2333+ && !ctx.scoped_css.contains(css)
2334+ {
2335+ ctx.scoped_css.push(css.clone());
2336+ }
2337+ if let Some(class) = scope_class {
2338+ match root.attrs.iter_mut().find(|a| a.html && a.key == "class") {
2339+ Some(attr) => {
2340+ let existing = attr.value.take().unwrap_or_default();
2341+ attr.value =
2342+ Some(format!("{} {}", existing, class).trim().to_string());
2343+ }
2344+ None => root.attrs.push(Attribute {
2345+ key: "class".to_string(),
2346+ value: Some(class),
2347+ html: true,
2348+ quoted: None,
2349+ }),
2350+ }
2351+ }
2352+ }
2353+ None => {
2354+ if !forwarded.is_empty() {
2355+ problems.push(format!(
2356+ "attributes {} on @{} are not parameters, and its body has no single \
2357+ root element to receive them",
2358+ forwarded
2359+ .iter()
2360+ .map(|a| format!("'{}'", a.key))
2361+ .collect::<Vec<_>>()
2362+ .join(", "),
2363+ name
2364+ ));
2365+ }
2366+ if scope_class.is_some() {
2367+ problems.push(format!(
2368+ "@{} has a scoped @style, but its body has no single root element \
2369+ to scope it to",
2370+ name
2371+ ));
2372+ }
2373+ }
2374+ }
2375+ for message in problems {
2376+ ctx.diagnostics.push(
2377+ Diagnostic::error(code::NO_SINGLE_ROOT, line_num, message)
2378+ .source(content)
2379+ .subject(name),
2380+ );
2381+ }
2382+ }
2383+
2384+ Ok(result_nodes)
2385+ }
2386+}
2387+
2388+/// A `@name` read where it is written: a built-in element, or a call.
2389+enum Resolved {
2390+ Element(Element),
2391+ Call(Box<Call>),
2392+}
2393+
2394+/// A call of a function, with its arguments evaluated where it is written.
2395+struct Call {
2396+ name: String,
2397+ function: Rc<FnDef>,
2398+ args: Vec<Attribute>,
2399+ /// The value of each argument that passes a parameter, with its type
2400+ /// (see [`ParseContext::slot_value`]), in the order of `args`.
2401+ values: Vec<Option<Value>>,
2402+ /// Text after the attributes, which is content.
2403+ text: Option<syntax::Text>,
2404+ /// Parameters written `name=value`, already reported.
2405+ written_form: Vec<String>,
2406+ /// The keys written in the call's own list, not from a bundle.
2407+ written_keys: Vec<String>,
2408+ line: usize,
2409+ /// The column of the call's name and the line it is on, for a missing
2410+ /// parameter.
2411+ name_at: Option<(usize, String)>,
2412+ /// The line as written, for diagnostics.
2413+ source: String,
2414+}
2415+
2416+/// What `@name` is where it is written: a call of the function `name`
2417+/// when one is defined, else the built-in element. A whole line, each link
2418+/// of a chain and an inline element in text all resolve here.
2419+fn resolve(
2420+ head: &syntax::Head,
2421+ text: Option<&syntax::Text>,
2422+ line: usize,
2423+ source: &str,
2424+ ctx: &mut ParseContext,
2425+) -> Result<Resolved, ParseError> {
2426+ let Some(function) = ctx.env.function(&head.name).cloned() else {
2427+ return parse_single_element(head, text, line, ctx).map(Resolved::Element);
2428+ };
2429+ ctx.used_functions.insert(head.name.clone());
2430+ let params: Vec<String> = function.params.iter().map(|p| p.name.clone()).collect();
2431+ let written = head.attrs.as_ref().map_or(&[][..], |list| &list.attrs[..]);
2432+ let written_form = written_parameter_forms(&head.name, &function, written, line, ctx);
2433+ let written_keys = written.iter().map(|a| a.key.clone()).collect();
2434+ // Parameters are bound by name; every other attribute goes to the
2435+ // root element, and is checked like any attribute
2436+ let (args, values) = parse_attrs(written, line, ctx, true, ¶ms)
2437+ .into_iter()
2438+ .unzip();
2439+ let name_at = name_column(head, line).zip(match &ctx.current_source {
2440+ (current, Some(text)) if *current == line => Some(text.clone()),
2441+ _ => None,
2442+ });
2443+ Ok(Resolved::Call(Box::new(Call {
2444+ name: head.name.clone(),
2445+ function,
2446+ args,
2447+ values,
2448+ text: text.cloned(),
2449+ written_form,
2450+ written_keys,
2451+ line,
2452+ name_at,
2453+ source: source.to_string(),
2454+ })))
2455+}
2456+
2457+/// A line of another file (the standard library, an included file) means
2458+/// nothing in this one: the problems reported since `before` while
2459+/// evaluating the function (its body, a default) are moved to the call.
2460+fn point_at_call(
2461+ ctx: &mut ParseContext,
2462+ before: usize,
2463+ function: &FnDef,
2464+ name: &str,
2465+ line: usize,
2466+ source: &str,
2467+) {
2468+ if function.file == ctx.current_file {
2469+ return;
2470+ }
2471+ let defined_in = function
2472+ .file
2473+ .as_deref()
2474+ .unwrap_or("the file being compiled");
2475+ for d in &mut ctx.diagnostics[before..] {
2476+ d.message = format!(
2477+ "{}\n in @{} (line {} of {})",
2478+ d.message, name, d.line, defined_in
2479+ );
2480+ d.line = line;
2481+ d.column = None;
2482+ d.subject = None;
2483+ d.suggestion = None;
2484+ d.source_line = Some(source.into());
2485+ }
2486+}
2487+
2488+/// A call nested deeper than [`MAX_CALL_DEPTH`].
2489+fn too_deep(name: &str, stack: &[String], line: usize) -> Diagnostic {
2490+ let message = if stack.iter().any(|n| n == name) {
2491+ format!(
2492+ "recursive function call to @{} goes more than {} calls deep: a function that \
2493+ calls itself needs a condition that stops it (`@if`)",
2494+ name, MAX_CALL_DEPTH
2495+ )
2496+ } else {
2497+ format!(
2498+ "function calls nest more than {} deep at @{} (starting with {})",
2499+ MAX_CALL_DEPTH,
2500+ name,
2501+ stack
2502+ .iter()
2503+ .take(3)
2504+ .map(|n| format!("@{}", n))
2505+ .collect::<Vec<_>>()
2506+ .join(" → ")
2507+ )
2508+ };
2509+ Diagnostic::error(code::RECURSIVE_CALL, line, message).subject(name)
2510+}
2511+
2512+/// Mark what a function's body wrote as the call's: it gets the call's
2513+/// line, so what is reported about it points at the call, and the name of
2514+/// the function, unless a call inside the body already claimed it.
2515+fn belongs_to_call(nodes: &mut [Node], function: &str, line: usize) {
2516+ fn claim(element: &mut Element, function: &str, line: usize) {
2517+ element.line_num = line;
2518+ element.function.get_or_insert_with(|| function.to_string());
2519+ belongs_to_call(&mut element.children, function, line);
2520+ }
2521+ for node in nodes {
2522+ match node {
2523+ Node::Element(element) => claim(element, function, line),
2524+ Node::Text(segments) => {
2525+ for segment in segments {
2526+ if let TextSegment::Inline(element) = segment {
2527+ claim(element, function, line);
2528+ }
2529+ }
2530+ }
2531+ Node::Raw(_) => {}
2532+ }
2533+ }
2534+}
2535+
2536+/// What an inline `{@name ...}` stands for in its line of text: an
2537+/// element; the text of a function whose body is text; or, for a body with
2538+/// several roots, its nodes as a fragment.
2539+fn inline_segments(mut nodes: Vec<Node>, line: usize) -> Vec<TextSegment> {
2540+ if let [Node::Element(_)] = nodes.as_slice()
2541+ && let Some(Node::Element(element)) = nodes.pop()
2542+ {
2543+ return vec![TextSegment::Inline(element)];
2544+ }
2545+ if nodes.iter().all(|n| matches!(n, Node::Text(_))) {
2546+ let mut segments = Vec::new();
2547+ for node in nodes {
2548+ if let Node::Text(run) = node {
2549+ if !segments.is_empty() {
2550+ segments.push(TextSegment::Plain(" ".to_string()));
2551+ }
2552+ segments.extend(run);
2553+ }
2554+ }
2555+ return segments;
2556+ }
2557+ vec![TextSegment::Inline(Element {
2558+ kind: ElementKind::Fragment,
2559+ attrs: Vec::new(),
2560+ argument: None,
2561+ children: nodes,
2562+ line_num: line,
2563+ function: None,
2564+ })]
2565+}
2566+
2567+/// Fill in the default of a parameter that a call leaves out, like the
2568+/// value of an attribute passed for it: variables are filled in, one
2569+/// `$name` keeps its type and one `"..."` is quoted text. It sees what the
2570+/// body sees: the names visible where the function is defined, and the
2571+/// parameters before it. Its problems are reported at the definition, once.
2572+fn fill_default(
2573+ fn_def: &FnDef,
2574+ param: &syntax::Param,
2575+ default: &str,
2576+ ctx: &mut ParseContext,
2577+) -> Value {
2578+ // A default that uses a later parameter is an error in the
2579+ // definition; the later one isn't bound yet, so don't report it again
2580+ let later = fn_def
2581+ .params
2582+ .iter()
2583+ .skip_while(|p| p.name != param.name)
2584+ .skip(1);
2585+ let names = interp::names(default);
2586+ if later.clone().any(|p| names.contains(&p.name.as_str())) {
2587+ return Value::empty();
2588+ }
2589+ let line = param.span.line;
2590+ let at_head = line == fn_def.line && fn_def.source.is_some();
2591+ let column =
2592+ at_head.then(|| param.span.column + (param.span.end - param.span.start) - default.len());
2593+ let caller = (
2594+ std::mem::replace(
2595+ &mut ctx.current_source,
2596+ (fn_def.line, fn_def.source.clone()),
2597+ ),
2598+ std::mem::replace(&mut ctx.current_node, fn_def.node),
2599+ );
2600+ let (value, _) = ctx.slot_value(default, line, column);
2601+ (ctx.current_source, ctx.current_node) = caller;
2602+ value
2603+}
2604+
2605+/// Read `@page`'s attribute list and title. The page is the root element,
2606+/// and its attributes are checked like any element's: `key=value` (and a
2607+/// bare boolean HTML attribute) go on `<html>`, styles on `<body>`, and
2608+/// `favicon FILE` is its one word of htmlang's own.
2609+fn read_page(
2610+ attrs: Option<&syntax::AttrList>,
2611+ title: Option<&syntax::Arg>,
2612+ line: usize,
2613+ ctx: &mut ParseContext,
2614+) -> Page {
2615+ let mut page = Page::default();
2616+ if let Some(list) = attrs {
2617+ let words: Vec<String> = crate::vocab::PAGE_WORDS
2618+ .iter()
2619+ .map(|w| w.to_string())
2620+ .collect();
2621+ ctx.in_page = true;
2622+ let read = parse_attr_list(&list.attrs, line, ctx, true, &words);
2623+ ctx.in_page = false;
2624+ // How many of each name have been read, to find where the next
2625+ // one is written
2626+ let mut seen: HashMap<String, usize> = HashMap::new();
2627+ for attr in read {
2628+ let boolean = attr.value.is_none() && crate::vocab::is_html_flag(&attr.key);
2629+ // Where it is written, when it is written in the list itself
2630+ let nth = seen.entry(attr.key.clone()).or_default();
2631+ let column = list
2632+ .attrs
2633+ .iter()
2634+ .filter(|token| token.key == attr.key)
2635+ .nth(*nth)
2636+ .map(|token| token.span.column);
2637+ *nth += 1;
2638+ let value = attr
2639+ .quoted
2640+ .as_ref()
2641+ .map(|q| q.text.clone())
2642+ .or(attr.value.clone());
2643+ if !check_page_attr(&attr.key, attr.html, value.as_deref(), line, column, ctx) {
2644+ continue;
2645+ }
2646+ if words.contains(&attr.key) {
2647+ if page.favicon.is_some() {
2648+ let diagnostic = Diagnostic::warning(
2649+ code::DUPLICATE_ATTRIBUTE,
2650+ line,
2651+ "duplicate attribute 'favicon': the later one wins".to_string(),
2652+ )
2653+ .subject("favicon");
2654+ ctx.diagnostics.push(at_attribute(diagnostic, column, ctx));
2655+ }
2656+ // The file itself goes into the page when it can be read
2657+ // (relative to the file); otherwise it is linked
2658+ page.favicon = value.map(|path| match std::fs::read(ctx.resolve(&path)) {
2659+ Ok(data) => crate::codegen::data_uri(&path, &data),
2660+ Err(_) => path,
2661+ });
2662+ } else if attr.html || boolean {
2663+ page.html_attrs.push(attr);
2664+ } else {
2665+ page.styles.push(attr);
2666+ }
2667+ }
2668+ }
2669+ page.title = match title {
2670+ Some(title) => ctx.interpolate_text(&title.raw, title.span.line, Some(title.span.column)),
2671+ None => String::new(),
2672+ };
2673+ page
2674+}
2675+
2676+/// `@page`'s own rules for one of its attributes, checked where the
2677+/// `@page` runs and where it doesn't (a layout that isn't called): its
2678+/// word is written `favicon FILE`, and `inline` belongs to `@image`.
2679+/// Returns whether the attribute can be used (a `favicon` with its file,
2680+/// or any other attribute but `inline`).
2681+fn check_page_attr(
2682+ key: &str,
2683+ html: bool,
2684+ value: Option<&str>,
2685+ line: usize,
2686+ column: Option<usize>,
2687+ ctx: &mut ParseContext,
2688+) -> bool {
2689+ let report = |ctx: &mut ParseContext, diagnostic: Diagnostic| {
2690+ let diagnostic = at_attribute(diagnostic, column, ctx);
2691+ ctx.diagnostics.push(diagnostic);
2692+ };
2693+ if crate::vocab::PAGE_WORDS.contains(&key) {
2694+ if html {
2695+ report(
2696+ ctx,
2697+ Diagnostic::error(
2698+ code::PARAMETER_FORM,
2699+ line,
2700+ format!(
2701+ "'{0}' is @page's own word, not an HTML attribute: write `{0} {1}`",
2702+ key,
2703+ value.filter(|v| !v.is_empty()).unwrap_or("FILE")
2704+ ),
2705+ )
2706+ .subject(format!("{}=", key))
2707+ .suggest(Some(format!("{} ", key))),
2708+ );
2709+ }
2710+ if value.is_none_or(|v| v.trim().is_empty()) {
2711+ report(
2712+ ctx,
2713+ Diagnostic::error(
2714+ code::MISSING_VALUE,
2715+ line,
2716+ format!("'{0}' needs its file: `{0} favicon.png`", key),
2717+ )
2718+ .subject(key),
2719+ );
2720+ return false;
2721+ }
2722+ return true;
2723+ }
2724+ if !html && crate::vocab::base_attribute(key) == "inline" {
2725+ report(
2726+ ctx,
2727+ Diagnostic::error(
2728+ code::UNEXPECTED_ARGUMENT,
2729+ line,
2730+ "`inline` puts an image's file into the page, and @page has none: it only \
2731+ goes on @image"
2732+ .to_string(),
2733+ )
2734+ .subject("inline"),
2735+ );
2736+ return false;
2737+ }
2738+ true
2739+}
2740+
2741+/// A parameter passed `name=value`, the form of an HTML attribute.
2742+fn parameter_form(function: &str, key: &str, value: &str, line: usize) -> Diagnostic {
2743+ Diagnostic::error(
2744+ code::PARAMETER_FORM,
2745+ line,
2746+ format!(
2747+ "'{}' is a parameter of @{}: parameters are written `name value`, so write `{} {}`",
2748+ key, function, key, value
2749+ ),
2750+ )
2751+ .subject(format!("{}=", key))
2752+ .suggest(Some(format!("{} ", key)))
2753+}
2754+
2755+/// A call that leaves out a parameter without a default.
2756+fn missing_parameter(
2757+ function: &str,
2758+ param: &str,
2759+ line: usize,
2760+ column: Option<usize>,
2761+) -> Diagnostic {
2762+ let diagnostic = Diagnostic::error(
2763+ code::MISSING_PARAMETER,
2764+ line,
2765+ format!(
2766+ "@{} needs '{}': the parameter has no default, so pass it as `{} VALUE`",
2767+ function, param, param
2768+ ),
2769+ )
2770+ .subject(param);
2771+ match column {
2772+ Some(column) => diagnostic.column(column),
2773+ None => diagnostic,
2774+ }
2775+}
2776+
2777+/// The column of a call's `@name`, when it is on the call's line.
2778+fn name_column(head: &syntax::Head, line: usize) -> Option<usize> {
2779+ (head.name_span.line == line).then_some(head.name_span.column)
2780+}
2781+
2782+/// Define `$name`, or, for `--name`, the CSS custom property on `:root`
2783+/// (which gets quoted text with its quotes, and is read with
2784+/// `var(--name)`, never as a variable). `@let name.field value` gives the
2785+/// record `$name` that field (or the list `$name` a new item at that
2786+/// index), as a new value in this block.
2787+fn set_variable(name: &str, value: Value, line_num: usize, ctx: &mut ParseContext) {
2788+ if name.starts_with("--") {
2789+ let css = value
2790+ .quoted_css()
2791+ .map_or_else(|| value.to_string(), str::to_string);
2792+ let at_line = |diagnostic: Diagnostic, ctx: &ParseContext| match &ctx.current_source {
2793+ (current, Some(text)) if *current == line_num => diagnostic.source(text.clone()),
2794+ _ => diagnostic,
2795+ };
2796+ // `:root` is one place for the whole page: a declaration inside a
2797+ // block (an element, a loop, a function's body) would not be
2798+ // kept to it, and each run would replace the last
2799+ if ctx.env.frames.len() > FILE_FRAMES {
2800+ let diagnostic = Diagnostic::error(
2801+ code::INVALID_DEFINITION,
2802+ line_num,
2803+ format!(
2804+ "`@let {name}` declares {name} on :root, for the whole page, so it goes at \
2805+ the top level of the file: to set it on an element and what is inside \
2806+ it, write `[{name} value]` on that element"
2807+ ),
2808+ )
2809+ .subject(name);
2810+ ctx.push_once(at_line(diagnostic, ctx));
2811+ return;
2812+ }
2813+ match css_breakout(&css) {
2814+ Some(reason) => {
2815+ let diagnostic = Diagnostic::error(
2816+ code::INVALID_VALUE,
2817+ line_num,
2818+ format!(
2819+ "the value of '{}' has {}: `{}` can't be written into the page's CSS",
2820+ name, reason, css
2821+ ),
2822+ )
2823+ .subject(css.as_str());
2824+ ctx.push_once(at_line(diagnostic, ctx));
2825+ }
2826+ None => match ctx.css_vars.iter_mut().find(|(n, _)| n == name) {
2827+ Some(declared) => {
2828+ let diagnostic = Diagnostic::warning(
2829+ code::DUPLICATE_ATTRIBUTE,
2830+ line_num,
2831+ format!(
2832+ "{name} is declared again: :root has one value for the whole page, \
2833+ so every element gets this one, also above this line (a theme \
2834+ redefines a token on an element: `[dark:{name} {css}]`)"
2835+ ),
2836+ )
2837+ .subject(name);
2838+ declared.1 = css;
2839+ ctx.push_once(at_line(diagnostic, ctx));
2840+ }
2841+ None => ctx.css_vars.push((name.to_string(), css)),
2842+ },
2843+ }
2844+ return;
2845+ }
2846+ let mut path = name.split('.');
2847+ let root = path.next().unwrap_or(name);
2848+ let fields: Vec<&str> = path.collect();
2849+ let value = match fields.is_empty() {
2850+ true => value,
2851+ false => match with_field(ctx.env.value(root).cloned(), root, &fields, value) {
2852+ Ok(value) => value,
2853+ Err(message) => {
2854+ let diagnostic =
2855+ Diagnostic::error(code::INVALID_DEFINITION, line_num, message).subject(name);
2856+ let diagnostic = match &ctx.current_source {
2857+ (current, Some(text)) if *current == line_num => {
2858+ diagnostic.source(text.clone())
2859+ }
2860+ _ => diagnostic,
2861+ };
2862+ ctx.push_once(diagnostic);
2863+ // Reported: the name keeps what it held
2864+ ctx.let_lines.entry(root.to_string()).or_insert(line_num);
2865+ return;
2866+ }
2867+ },
2868+ };
2869+ ctx.bind(root, value);
2870+ ctx.let_lines.entry(root.to_string()).or_insert(line_num);
2871+}
2872+
2873+/// `value` (the value of `$name`) with the field at `path` set to `new`:
2874+/// a record's field, or the item of a list at an index it has. A name
2875+/// without a value, or one whose value is empty (a field a record doesn't
2876+/// have), becomes a record; any other value has no fields to set.
2877+fn with_field(
2878+ value: Option<Value>,
2879+ name: &str,
2880+ path: &[&str],
2881+ new: Value,
2882+) -> Result<Value, String> {
2883+ let Some((field, rest)) = path.split_first() else {
2884+ return Ok(new);
2885+ };
2886+ let inner = format!("{}.{}", name, field);
2887+ match value {
2888+ Some(Value::Record(fields)) => {
2889+ let mut fields = fields.as_ref().clone();
2890+ match fields.iter().position(|(key, _)| key == field) {
2891+ Some(i) => {
2892+ let old = std::mem::replace(&mut fields[i].1, Value::empty());
2893+ fields[i].1 = with_field(Some(old), &inner, rest, new)?;
2894+ }
2895+ None => fields.push((field.to_string(), with_field(None, &inner, rest, new)?)),
2896+ }
2897+ Ok(Value::Record(Rc::new(fields)))
2898+ }
2899+ Some(Value::List(list)) => {
2900+ let count = list.items.len();
2901+ let Some(i) = field.parse::<usize>().ok().filter(|&i| i < count) else {
2902+ return Err(format!(
2903+ "`${}` is {}, so `.{}` isn't one of its items (they are `.0` to `.{}`)",
2904+ name,
2905+ Value::List(list).describe(),
2906+ field,
2907+ count.saturating_sub(1)
2908+ ));
2909+ };
2910+ let mut items = list.items.as_ref().clone();
2911+ let old = std::mem::replace(&mut items[i], Value::empty());
2912+ items[i] = with_field(Some(old), &inner, rest, new)?;
2913+ // Its items changed, so it no longer prints as written
2914+ Ok(Value::list(items))
2915+ }
2916+ None => Ok(Value::Record(Rc::new(vec![(
2917+ field.to_string(),
2918+ with_field(None, &inner, rest, new)?,
2919+ )]))),
2920+ Some(value) if value.to_string().is_empty() => with_field(None, name, path, new),
2921+ Some(value) => Err(format!(
2922+ "`@let {}.{}` sets a field of a record, but `${}` is {} (`{}`), which has no fields",
2923+ name,
2924+ path.join("."),
2925+ name,
2926+ value.describe(),
2927+ value
2928+ )),
2929+ }
2930+}
2931+
2932+/// What a verbatim directive holds (`@head`, `@style`, `@raw`): the rest
2933+/// of its line (`@style .a { color: red }`), or else its indented block.
2934+/// The two together are a syntax error, reported by the tree; the line
2935+/// wins.
2936+fn verbatim_content(node: &syntax::Node) -> String {
2937+ match node.directive().map(|d| &d.args) {
2938+ Some(DirectiveArgs::Text(Some(line))) => format!("{}\n", line.raw),
2939+ _ => verbatim_text(&node.children),
2940+ }
2941+}
2942+
2943+/// The text of a verbatim body (`@head`, `@style`, `@markdown`, `@raw`).
2944+fn verbatim_text(children: &[syntax::Node]) -> String {
2945+ let mut text = String::new();
2946+ for child in children {
2947+ if let NodeKind::Verbatim(body) = &child.kind {
2948+ text.push_str(&body.text);
2949+ text.push('\n');
2950+ }
2951+ }
2952+ text
2953+}
2954+
2955+// ---------------------------------------------------------------------------
2956+// @children replacement
2957+// ---------------------------------------------------------------------------
2958+
2959+fn replace_children_and_slots(
2960+ nodes: Vec<Node>,
2961+ caller_children: &[Node],
2962+ slot_contents: &HashMap<String, Vec<Node>>,
2963+) -> Vec<Node> {
2964+ let mut result = Vec::new();
2965+ for node in nodes {
2966+ match node {
2967+ Node::Element(elem) if elem.kind == ElementKind::Children => {
2968+ if caller_children.is_empty() && !elem.children.is_empty() {
2969+ // Use @children's own children as default/fallback content
2970+ result.extend(elem.children);
2971+ } else {
2972+ result.extend(caller_children.iter().cloned());
2973+ }
2974+ }
2975+ Node::Element(elem) if matches!(&elem.kind, ElementKind::Slot(name) if !name.is_empty()) =>
2976+ {
2977+ if let ElementKind::Slot(ref name) = elem.kind {
2978+ if let Some(content) = slot_contents.get(name) {
2979+ result.extend(content.iter().cloned());
2980+ }
2981+ // If no content provided for this slot, use the slot's own children as default
2982+ else if !elem.children.is_empty() {
2983+ result.extend(elem.children);
2984+ }
2985+ }
2986+ }
2987+ Node::Element(mut elem) => {
2988+ elem.children =
2989+ replace_children_and_slots(elem.children, caller_children, slot_contents);
2990+ result.push(Node::Element(elem));
2991+ }
2992+ other => result.push(other),
2993+ }
2994+ }
2995+ result
2996+}
2997+
2998+// ---------------------------------------------------------------------------
2999+// Where @slot and @children are written
3000+// ---------------------------------------------------------------------------
3001+
3002+/// The files each `@include` line brought in, by the line's node id, with
3003+/// the include chain that leads to each.
3004+type IncludedBy = HashMap<usize, Vec<(Rc<Tree>, String)>>;
3005+
3006+/// The lines of the files an `@include` line brings in, and the include
3007+/// chain of each (for diagnostics).
3008+type Included<'a, 'f> = &'f dyn Fn(&syntax::Node) -> Vec<(&'a [syntax::Node], Option<&'a str>)>;
3009+
3010+/// Whether `name` is a function here: defined so far, or anywhere in the
3011+/// file and the files it includes.
3012+fn is_function(name: &str, ctx: &ParseContext) -> bool {
3013+ ctx.env.function(name).is_some() || ctx.namespace.contains(name)
3014+}
3015+
3016+/// Whether `name` is one slot name: letters, digits, `-` and `_`,
3017+/// starting with a letter (like a function's name).
3018+fn is_slot_name(name: &str) -> bool {
3019+ name.chars().next().is_some_and(char::is_alphabetic)
3020+ && name
3021+ .chars()
3022+ .all(|c| c.is_alphanumeric() || c == '-' || c == '_')
3023+}
3024+
3025+/// What a `@slot` or `@children` line is written in.
3026+#[derive(Clone, Copy)]
3027+enum Place<'a> {
3028+ /// The top of a file or of a function's body, or a built-in element
3029+ /// (by its name).
3030+ Element(Option<&'a str>),
3031+ /// A call: its content.
3032+ Call,
3033+}
3034+
3035+/// Where a line is, for [`slot_uses`].
3036+#[derive(Clone, Copy)]
3037+struct At<'a> {
3038+ /// Inside a function's body.
3039+ body: bool,
3040+ place: Place<'a>,
3041+ /// Outside a body: the call (and its line) whose content it is in.
3042+ call: Option<(&'a str, usize)>,
3043+ /// The include chain of the file it is in, when that isn't the file
3044+ /// being compiled.
3045+ file: Option<&'a str>,
3046+}
3047+
3048+impl At<'_> {
3049+ /// The top of a file, or of a function's body.
3050+ fn top(body: bool) -> Self {
3051+ At {
3052+ body,
3053+ place: Place::Element(None),
3054+ call: None,
3055+ file: None,
3056+ }
3057+ }
3058+}
3059+
3060+/// What [`slot_uses`] knows about the names and files it walks.
3061+struct Scan<'a, 'f> {
3062+ is_function: &'f dyn Fn(&str) -> bool,
3063+ included: Included<'a, 'f>,
3064+ /// Visit the bodies of the functions defined in the lines too.
3065+ into_lets: bool,
3066+}
3067+
3068+/// A `@slot` or `@children` written in a file, and where.
3069+struct SlotUse<'a> {
3070+ node: &'a syntax::Node,
3071+ head: &'a syntax::Head,
3072+ /// The text after it, which is a slot's name; `None` when it isn't
3073+ /// the last head of its chain.
3074+ text: Option<&'a syntax::Text>,
3075+ /// Written inline in a line of text, `{@slot x}`.
3076+ inline: bool,
3077+ at: At<'a>,
3078+}
3079+
3080+impl SlotUse<'_> {
3081+ fn is_slot(&self) -> bool {
3082+ self.head.name == "slot"
3083+ }
3084+
3085+ /// The slot's name as written.
3086+ fn name(&self) -> &str {
3087+ self.text.map_or("", |t| t.raw.trim())
3088+ }
3089+
3090+ /// A `@slot NAME` that marks a place in a function's body (not one
3091+ /// that fills a slot of a call).
3092+ fn declares(&self) -> bool {
3093+ self.is_slot() && !self.inline && !matches!(self.at.place, Place::Call)
3094+ }
3095+}
3096+
3097+/// Where each `@slot` and `@children` in `block` is written. A `@slot`
3098+/// directly under a call (under its `@if`, `@else` and `@each` too) fills
3099+/// one of its slots; anywhere else in a function's body it declares one.
3100+/// An included file's lines are where its `@include` is.
3101+fn slot_uses<'a>(
3102+ block: &'a [syntax::Node],
3103+ at: At<'a>,
3104+ scan: &Scan<'a, '_>,
3105+ out: &mut Vec<SlotUse<'a>>,
3106+) {
3107+ fn inline<'a>(
3108+ text: &'a syntax::Text,
3109+ node: &'a syntax::Node,
3110+ at: At<'a>,
3111+ scan: &Scan<'a, '_>,
3112+ out: &mut Vec<SlotUse<'a>>,
3113+ ) {
3114+ for segment in &text.segments {
3115+ if let Segment::Inline(inline_element) = segment {
3116+ let head = &inline_element.head;
3117+ if matches!(head.name.as_str(), "slot" | "children")
3118+ && !(scan.is_function)(&head.name)
3119+ {
3120+ out.push(SlotUse {
3121+ node,
3122+ head,
3123+ text: inline_element.text.as_ref(),
3124+ inline: true,
3125+ at,
3126+ });
3127+ }
3128+ if let Some(text) = &inline_element.text {
3129+ inline(text, node, at, scan, out);
3130+ }
3131+ }
3132+ }
3133+ }
3134+ for node in block {
3135+ match &node.kind {
3136+ NodeKind::Directive(directive) => match &directive.args {
3137+ DirectiveArgs::Let(def) if matches!(def.form, LetForm::Function(_)) => {
3138+ if scan.into_lets {
3139+ let top = At {
3140+ file: at.file,
3141+ ..At::top(true)
3142+ };
3143+ slot_uses(&node.children, top, scan, out);
3144+ }
3145+ }
3146+ // A value's body is an error of its own
3147+ DirectiveArgs::Let(_) => {}
3148+ _ if directive.spec.body == BodyKind::Verbatim => {}
3149+ // `@if`, `@else` and `@each` put their lines in place, and
3150+ // `@include` its file's; the lines under a directive that
3151+ // takes no body are its siblings
3152+ _ => {
3153+ for (lines, file) in (scan.included)(node) {
3154+ slot_uses(lines, At { file, ..at }, scan, out);
3155+ }
3156+ slot_uses(&node.children, at, scan, out);
3157+ }
3158+ },
3159+ NodeKind::Element(line) => {
3160+ let mut at = at;
3161+ let last = line.chain.len() - 1;
3162+ for (i, head) in line.chain.iter().enumerate() {
3163+ let text = if i == last { line.text.as_ref() } else { None };
3164+ let function = (scan.is_function)(&head.name);
3165+ if !function && matches!(head.name.as_str(), "slot" | "children") {
3166+ out.push(SlotUse {
3167+ node,
3168+ head,
3169+ text,
3170+ inline: false,
3171+ at,
3172+ });
3173+ } else if let Some(text) = text {
3174+ inline(text, node, at, scan, out);
3175+ }
3176+ if function {
3177+ at.place = Place::Call;
3178+ if !at.body {
3179+ at.call = Some((&head.name, node.span.line));
3180+ }
3181+ } else {
3182+ at.place = Place::Element(Some(&head.name));
3183+ }
3184+ }
3185+ slot_uses(&node.children, at, scan, out);
3186+ }
3187+ NodeKind::Text(text) => {
3188+ inline(text, node, at, scan, out);
3189+ slot_uses(&node.children, at, scan, out);
3190+ }
3191+ NodeKind::Blank | NodeKind::Comment | NodeKind::Verbatim(_) => {}
3192+ }
3193+ }
3194+}
3195+
3196+/// The slots a function's body declares, and whether it has a
3197+/// `@children`, when it is defined. The files its `@include` lines bring
3198+/// in count too: they are read now, since they run only at a call.
3199+fn declared_slots(body: &[syntax::Node], ctx: &mut ParseContext) -> (Vec<String>, bool) {
3200+ let mut files = HashMap::new();
3201+ read_includes(
3202+ body,
3203+ ctx.base_path.clone(),
3204+ &mut Vec::new(),
3205+ ctx,
3206+ &mut files,
3207+ );
3208+ let included = |node: &syntax::Node| match files.get(&node.id) {
3209+ Some(tree) => vec![(&tree.nodes[..], None)],
3210+ None => Vec::new(),
3211+ };
3212+ let is_function = |name: &str| is_function(name, ctx);
3213+ slots_of(body, &is_function, &included)
3214+}
3215+
3216+/// Read and parse the files the `@include` lines in `nodes` bring in (by
3217+/// a literal path, relative to `base`), and the files those include, by
3218+/// the node id of each `@include` line.
3219+fn read_includes(
3220+ nodes: &[syntax::Node],
3221+ base: Option<PathBuf>,
3222+ stack: &mut Vec<PathBuf>,
3223+ ctx: &mut ParseContext,
3224+ files: &mut HashMap<usize, Rc<Tree>>,
3225+) {
3226+ let mut includes = Vec::new();
3227+ for node in nodes {
3228+ node.walk(&mut |node| {
3229+ if let Some(DirectiveArgs::Text(Some(path))) = node.directive().map(|d| &d.args)
3230+ && node.is_directive("include")
3231+ {
3232+ includes.push((node.id, path.raw.clone()));
3233+ }
3234+ });
3235+ }
3236+ for (id, path) in includes {
3237+ let path = path.trim_matches('"');
3238+ if path.contains('$') {
3239+ continue;
3240+ }
3241+ let resolved = match &base {
3242+ Some(base) => base.join(path),
3243+ None => PathBuf::from(path),
3244+ };
3245+ if stack.contains(&resolved) {
3246+ continue;
3247+ }
3248+ let Ok(text) = ctx.read_file(&resolved) else {
3249+ continue;
3250+ };
3251+ let tree = ctx.parse_tree(&text);
3252+ stack.push(resolved.clone());
3253+ let parent = resolved.parent().map(Path::to_path_buf);
3254+ read_includes(&tree.nodes, parent, stack, ctx, files);
3255+ stack.pop();
3256+ files.insert(id, tree);
3257+ }
3258+}
3259+
3260+/// The slots a function's body declares (`@slot NAME`, in order), and
3261+/// whether it has a `@children` for the content of a call. A `@slot`
3262+/// directly under a call in the body fills that call's slot instead, so
3263+/// `is_function` says which names are functions. The files the body
3264+/// includes aren't read.
3265+pub fn function_slots(
3266+ body: &[syntax::Node],
3267+ is_function: &dyn Fn(&str) -> bool,
3268+) -> (Vec<String>, bool) {
3269+ slots_of(body, is_function, &|_| Vec::new())
3270+}
3271+
3272+fn slots_of<'a>(
3273+ body: &'a [syntax::Node],
3274+ is_function: &dyn Fn(&str) -> bool,
3275+ included: Included<'a, '_>,
3276+) -> (Vec<String>, bool) {
3277+ let scan = Scan {
3278+ is_function,
3279+ included,
3280+ into_lets: false,
3281+ };
3282+ let mut uses = Vec::new();
3283+ slot_uses(body, At::top(true), &scan, &mut uses);
3284+ let mut slots: Vec<String> = Vec::new();
3285+ for slot in uses.iter().filter(|u| u.declares()) {
3286+ let name = slot.name();
3287+ if is_slot_name(name) && !slots.iter().any(|s| s == name) {
3288+ slots.push(name.to_string());
3289+ }
3290+ }
3291+ let has_children = uses.iter().any(|u| !u.is_slot() && !u.inline);
3292+ (slots, has_children)
3293+}
3294+
3295+/// The line as written, indented, when it is one physical line, so a
3296+/// column points into it.
3297+fn written_line(node: &syntax::Node) -> String {
3298+ match node.line_count <= 1 {
3299+ true => format!("{}{}", " ".repeat(node.indent), node.source),
3300+ false => node.source.clone(),
3301+ }
3302+}
3303+
3304+/// The lines of the files an `@include` line brought in when it ran, from
3305+/// `included_by`.
3306+fn ran_includes<'a>(
3307+ included_by: &'a IncludedBy,
3308+ node: &syntax::Node,
3309+) -> Vec<(&'a [syntax::Node], Option<&'a str>)> {
3310+ match included_by.get(&node.id) {
3311+ Some(files) => files
3312+ .iter()
3313+ .map(|(tree, chain)| (&tree.nodes[..], Some(chain.as_str())))
3314+ .collect(),
3315+ None => Vec::new(),
3316+ }
3317+}
3318+
3319+/// Check where every `@slot` and `@children` of the file and the files it
3320+/// includes is written, whether or not it runs: a slot has one name, a
3321+/// function's body marks places with them, and a call fills its slots
3322+/// with `@slot` blocks directly under it. An included file's lines are
3323+/// where its `@include` is (in a body, under a call), so an `@include`
3324+/// that never ran leaves its file unchecked.
3325+fn check_slot_places(ctx: &mut ParseContext) {
3326+ let trees = std::mem::take(&mut ctx.trees);
3327+ let included_by = ctx.included_by.clone();
3328+ let is_function = |name: &str| is_function(name, ctx);
3329+ let scan = Scan {
3330+ is_function: &is_function,
3331+ included: &|node| ran_includes(&included_by, node),
3332+ into_lets: true,
3333+ };
3334+ let mut uses = Vec::new();
3335+ for (tree, _) in trees.iter().filter(|(_, chain)| chain.is_none()) {
3336+ slot_uses(&tree.nodes, At::top(false), &scan, &mut uses);
3337+ }
3338+ let found: Vec<Diagnostic> = uses
3339+ .iter()
3340+ .filter_map(|slot| {
3341+ let mut d = slot_problem(slot)?;
3342+ if d.column.is_none() {
3343+ d = d.column(slot.head.name_span.column);
3344+ }
3345+ d = d.source(written_line(slot.node));
3346+ if let Some(file) = slot.at.file {
3347+ d.message = format!("{}\n in {}", d.message, file);
3348+ }
3349+ Some(d)
3350+ })
3351+ .collect();
3352+ ctx.diagnostics.extend(found);
3353+ ctx.trees = trees;
3354+}
3355+
3356+/// What is wrong with a `@slot` or `@children` where it is written.
3357+fn slot_problem(slot: &SlotUse) -> Option<Diagnostic> {
3358+ let line = slot.node.span.line;
3359+ let what = if slot.is_slot() {
3360+ match slot.name() {
3361+ "" => "@slot".to_string(),
3362+ name => format!("@slot {}", name),
3363+ }
3364+ } else {
3365+ "@children".to_string()
3366+ };
3367+ if slot.inline {
3368+ return Some(Diagnostic::error(
3369+ code::MISPLACED_SLOT,
3370+ line,
3371+ format!(
3372+ "{} goes on a line of its own: inline in text it marks and fills nothing",
3373+ what
3374+ ),
3375+ ));
3376+ }
3377+ if let Some(list) = &slot.head.attrs {
3378+ return Some(
3379+ Diagnostic::error(
3380+ code::UNEXPECTED_ARGUMENT,
3381+ line,
3382+ format!(
3383+ "{} takes no attributes: it is replaced by content, so style the \
3384+ element around it",
3385+ what
3386+ ),
3387+ )
3388+ .column(list.span.column),
3389+ );
3390+ }
3391+ if slot.is_slot() {
3392+ let name = slot.name();
3393+ if name.is_empty() {
3394+ return Some(Diagnostic::error(
3395+ code::MISSING_ARGUMENT,
3396+ line,
3397+ "@slot needs a name: `@slot footer` (the caller's content without a \
3398+ name goes where `@children` is)"
3399+ .to_string(),
3400+ ));
3401+ }
3402+ if !is_slot_name(name) {
3403+ let joined = name.split_whitespace().collect::<Vec<_>>().join("-");
3404+ let suggestion = is_slot_name(&joined).then_some(joined);
3405+ let column = slot.text.map(|t| t.span.column);
3406+ let d = Diagnostic::error(
3407+ code::INVALID_SLOT_NAME,
3408+ line,
3409+ format!(
3410+ "'{}' is not a slot name: a slot's name is one word of letters, digits, \
3411+ `-` and `_`, starting with a letter, and its content goes on the lines \
3412+ under it",
3413+ name
3414+ ),
3415+ )
3416+ .subject(name)
3417+ .suggest(suggestion);
3418+ return Some(match column {
3419+ Some(column) => d.column(column),
3420+ None => d,
3421+ });
3422+ }
3423+ if matches!(slot.at.place, Place::Call) || slot.at.body {
3424+ return None;
3425+ }
3426+ let message = match (slot.at.call, slot.at.place) {
3427+ (Some((call, call_line)), Place::Element(Some(element))) => format!(
3428+ "{} is inside @{}, so it fills nothing: a @slot block that fills a slot of \
3429+ @{} (line {}) goes directly under the call",
3430+ what, element, call, call_line
3431+ ),
3432+ _ => format!(
3433+ "{} is outside a function's body: `@slot NAME` marks a place in a body \
3434+ (`@let @name`), and directly under a call it fills one",
3435+ what
3436+ ),
3437+ };
3438+ return Some(Diagnostic::error(code::MISPLACED_SLOT, line, message));
3439+ }
3440+ if slot.at.body {
3441+ return None;
3442+ }
3443+ let message = match slot.at.call {
3444+ Some((call, _)) => format!(
3445+ "@children is outside a function's body, so it stands for nothing: the content \
3446+ for @{} is written directly under the call",
3447+ call
3448+ ),
3449+ None => "@children is outside a function's body: it marks where a body puts the \
3450+ content of each call"
3451+ .to_string(),
3452+ };
3453+ Some(Diagnostic::error(code::MISPLACED_SLOT, line, message))
3454+}
3455+
3456+/// A `@slot NAME` block that fills a slot of a call.
3457+struct Filler<'a> {
3458+ node: &'a syntax::Node,
3459+ text: &'a syntax::Text,
3460+ /// The include chain of the file it is in, when that isn't the file
3461+ /// being compiled.
3462+ file: Option<&'a str>,
3463+}
3464+
3465+/// Whether `@slot` is the built-in element here, and not a function
3466+/// defined so far that took its name.
3467+fn slot_is_built_in(ctx: &ParseContext) -> bool {
3468+ ctx.env.function("slot").is_none()
3469+}
3470+
3471+/// The `@slot NAME` blocks directly under a call, in `block` (under its
3472+/// `@if`, `@else` and `@each` too, and in the files its `@include` lines
3473+/// brought in).
3474+fn fillers<'a>(
3475+ block: &'a [syntax::Node],
3476+ file: Option<&'a str>,
3477+ included: &'a IncludedBy,
3478+ out: &mut Vec<Filler<'a>>,
3479+) {
3480+ for node in block {
3481+ match &node.kind {
3482+ NodeKind::Directive(directive)
3483+ if matches!(directive.name(), "if" | "else" | "each") =>
3484+ {
3485+ fillers(&node.children, file, included, out);
3486+ }
3487+ NodeKind::Directive(directive) if directive.name() == "include" => {
3488+ for (lines, file) in ran_includes(included, node) {
3489+ fillers(lines, file, included, out);
3490+ }
3491+ }
3492+ NodeKind::Element(line) if line.chain.len() == 1 && line.chain[0].name == "slot" => {
3493+ if let Some(text) = &line.text {
3494+ out.push(Filler { node, text, file });
3495+ }
3496+ }
3497+ _ => {}
3498+ }
3499+ }
3500+}
3501+
3502+/// Whether `block`, the lines under a call, holds content other than
3503+/// `@slot` blocks (under `@if`, `@else` and `@each` too): text, an
3504+/// element, raw HTML, Markdown or an included file. For code that doesn't
3505+/// run.
3506+fn holds_content(block: &[syntax::Node], ctx: &ParseContext) -> bool {
3507+ block.iter().any(|node| match &node.kind {
3508+ NodeKind::Directive(directive) => match directive.name() {
3509+ "if" | "else" | "each" => holds_content(&node.children, ctx),
3510+ name => matches!(name, "raw" | "markdown" | "include"),
3511+ },
3512+ NodeKind::Element(line) => {
3513+ line.chain[0].name != "slot" || !slot_is_built_in(ctx) || line.chain.len() > 1
3514+ }
3515+ NodeKind::Text(_) => true,
3516+ _ => false,
3517+ })
3518+}
3519+
3520+/// Check the `@slot NAME` blocks passed to each call of a line against
3521+/// the slots its function declares. `calls` has the function of each head
3522+/// of the chain that is a call.
3523+fn check_fillers(
3524+ node: &syntax::Node,
3525+ element: &syntax::ElementLine,
3526+ calls: &[Option<(String, Rc<FnDef>)>],
3527+ ctx: &mut ParseContext,
3528+) {
3529+ if !slot_is_built_in(ctx) {
3530+ return;
3531+ }
3532+ let included = ctx.included_by.clone();
3533+ let last = element.chain.len() - 1;
3534+ for (i, call) in calls.iter().enumerate() {
3535+ let Some((name, function)) = call else {
3536+ continue;
3537+ };
3538+ let mut found = Vec::new();
3539+ if i == last {
3540+ fillers(&node.children, None, &included, &mut found);
3541+ } else if i + 1 == last
3542+ && element.chain[last].name == "slot"
3543+ && let Some(text) = &element.text
3544+ {
3545+ // `@card > @slot footer`
3546+ found.push(Filler {
3547+ node,
3548+ text,
3549+ file: None,
3550+ });
3551+ }
3552+ for filler in found {
3553+ let slot = filler.text.raw.trim();
3554+ if !is_slot_name(slot) || function.slots.iter().any(|s| s == slot) {
3555+ continue;
3556+ }
3557+ let mut d = unknown_slot(name, slot, &function.slots, filler.text.span.line)
3558+ .column(filler.text.span.column)
3559+ .source(written_line(filler.node));
3560+ if let Some(file) = filler.file {
3561+ d.message = format!("{}\n in {}", d.message, file);
3562+ }
3563+ ctx.push_once(d);
3564+ }
3565+ }
3566+}
3567+
3568+/// A `@slot NAME` block for a slot the function doesn't declare.
3569+fn unknown_slot(function: &str, slot: &str, slots: &[String], line: usize) -> Diagnostic {
3570+ let candidates: Vec<&str> = slots.iter().map(String::as_str).collect();
3571+ let suggestion = suggest_closest(slot, &candidates);
3572+ let message = match (slots.is_empty(), suggestion) {
3573+ (true, _) => format!(
3574+ "@{} has no slot '{}': its body declares no slots (`@slot NAME`)",
3575+ function, slot
3576+ ),
3577+ (false, Some(close)) => format!(
3578+ "@{} has no slot '{}', did you mean '{}'? (its slots: {})",
3579+ function,
3580+ slot,
3581+ close,
3582+ slots.join(", ")
3583+ ),
3584+ (false, None) => format!(
3585+ "@{} has no slot '{}' (its slots: {})",
3586+ function,
3587+ slot,
3588+ slots.join(", ")
3589+ ),
3590+ };
3591+ Diagnostic::error(code::UNKNOWN_SLOT, line, message)
3592+ .subject(slot)
3593+ .suggest(suggestion)
3594+}
3595+
3596+/// Content passed to a function whose body has no `@children`.
3597+fn no_children(function: &str, line: usize, column: Option<usize>) -> Diagnostic {
3598+ let d = Diagnostic::error(
3599+ code::UNEXPECTED_CONTENT,
3600+ line,
3601+ format!(
3602+ "@{0} takes no content: its body has no `@children`, so the text and lines \
3603+ passed to it would be dropped (pass text as a parameter, `@{0} [name value]`, \
3604+ or add `@children` to the body)",
3605+ function
3606+ ),
3607+ )
3608+ .subject(function);
3609+ match column {
3610+ Some(column) => d.column(column),
3611+ None => d,
3612+ }
3613+}
3614+
3615+// ---------------------------------------------------------------------------
3616+// Element parsing
3617+// ---------------------------------------------------------------------------
3618+
3619+/// Build the element for `@name [attrs] text` (on its own line, in a chain,
3620+/// or inline in text).
3621+fn parse_single_element(
3622+ head: &syntax::Head,
3623+ text: Option<&syntax::Text>,
3624+ line_num: usize,
3625+ ctx: &mut ParseContext,
3626+) -> Result<Element, ParseError> {
3627+ let kind = parse_element_kind(&head.name, line_num, ctx)?;
3628+ let mut attrs = head.attrs.as_ref().map_or_else(Vec::new, |list| {
3629+ parse_attr_list(&list.attrs, line_num, ctx, true, &[])
3630+ });
3631+
3632+ // The leading argument: for an element whose row names a leading
3633+ // attribute (`@link`'s href, `@image`'s src, `@form`'s action, ...),
3634+ // the first token of the text fills it, split before anything is
3635+ // filled in, and the rest is content (an error on an element without
3636+ // content). `@slot`'s whole text is its name. Any other element's text
3637+ // is content, parsed like any line of text, as in `@el [padding 8]
3638+ // Hello` or `@h2 Meet {@text htmlang}`; its layout decides how it
3639+ // combines with the lines under it.
3640+ let mut children = Vec::new();
3641+ let mut argument = None;
3642+ let leading = kind.arg().attributes();
3643+ match text {
3644+ Some(text) if !leading.is_empty() => {
3645+ let (token, rest) = text.split_leading();
3646+ let given = attrs
3647+ .iter()
3648+ .find(|a| a.html && leading.contains(&a.key.as_str()))
3649+ .map(|a| (a.key.clone(), a.value.clone().unwrap_or_default()));
3650+ if let Some((key, value)) = given {
3651+ // The attribute wins; the text is content, as if the
3652+ // element had no leading argument
3653+ ctx.push_once(leading_twice(&kind, &token, &key, &value, text, ctx));
3654+ if !takes_no_text(&kind) {
3655+ children.push(Node::Text(text_segments(text, ctx)));
3656+ }
3657+ } else if let Some(d) = bad_leading_token(&kind, &token, &text.raw, ctx) {
3658+ // Nothing is taken as the argument; the line is content
3659+ ctx.push_once(d);
3660+ if !takes_no_text(&kind) {
3661+ children.push(Node::Text(text_segments(text, ctx)));
3662+ }
3663+ } else {
3664+ let column = Some(token.span.column);
3665+ if let Some(d) = text_as_url(&kind, &token, ctx) {
3666+ ctx.push_once(d);
3667+ }
3668+ argument = Some(
3669+ ctx.fill_value(&token.raw, text.span.line, column, Sink::Text)
3670+ .0,
3671+ );
3672+ if let Some(rest) = rest {
3673+ if let Some(d) = chain_after_argument(&kind, &token.raw, &rest, ctx) {
3674+ ctx.push_once(d);
3675+ }
3676+ if takes_no_text(&kind) {
3677+ let d = after_the_leading_argument(&kind, &token.raw, &rest);
3678+ let d = at_attribute(d, Some(rest.span.column), ctx);
3679+ ctx.push_once(d);
3680+ } else {
3681+ children.push(Node::Text(text_segments(&rest, ctx)));
3682+ }
3683+ }
3684+ }
3685+ }
3686+ Some(text) if matches!(kind, ElementKind::Slot(_)) => {
3687+ argument =
3688+ Some(ctx.interpolate_text(&text.raw, text.span.line, Some(text.span.column)));
3689+ }
3690+ Some(text) => children.push(Node::Text(text_segments(text, ctx))),
3691+ // `@link [href=/about]`: the attribute is the leading argument, so
3692+ // both forms compile the same (`@image [src=a.svg, inline]`). Not
3693+ // for `@source`, whose attribute depends on where it is.
3694+ None if leading.len() == 1 => {
3695+ if let Some(i) = attrs.iter().position(|a| a.html && a.key == leading[0]) {
3696+ argument = Some(attrs.remove(i).value.unwrap_or_default());
3697+ }
3698+ }
3699+ None => {}
3700+ }
3701+
3702+ // For @slot, the argument is the slot name
3703+ let kind = if let ElementKind::Slot(_) = kind {
3704+ ElementKind::Slot(argument.clone().unwrap_or_default())
3705+ } else {
3706+ kind
3707+ };
3708+
3709+ Ok(Element {
3710+ kind,
3711+ attrs,
3712+ argument,
3713+ children,
3714+ line_num,
3715+ function: None,
3716+ })
3717+}
3718+
3719+/// Whether `node` or a line inside it calls `@name` outside any `@if`
3720+/// (in a chain, or inline in text).
3721+fn calls_unguarded(node: &syntax::Node, name: &str) -> bool {
3722+ if node.is_directive("if") || node.is_directive("else") {
3723+ return false;
3724+ }
3725+ let text_calls = |text: &syntax::Text| {
3726+ text.segments
3727+ .iter()
3728+ .any(|s| matches!(s, Segment::Inline(inline) if inline.head.name == name))
3729+ };
3730+ let here = match &node.kind {
3731+ NodeKind::Element(element) => {
3732+ element.chain.iter().any(|head| head.name == name)
3733+ || element.text.as_ref().is_some_and(text_calls)
3734+ }
3735+ NodeKind::Text(text) => text_calls(text),
3736+ _ => false,
3737+ };
3738+ here || node
3739+ .children
3740+ .iter()
3741+ .any(|child| calls_unguarded(child, name))
3742+}
3743+
3744+/// `@td [padding 8] @children`: `@children` and `@slot NAME` mark where a
3745+/// call's content goes only on a line of their own; after an element's
3746+/// attributes, or in a verbatim body, they are text.
3747+fn marker_in_text(node: &syntax::Node) -> Option<Diagnostic> {
3748+ let is_marker = |text: &str| {
3749+ let text = text.trim();
3750+ text == "@children" || text == "@slot" || text.starts_with("@slot ")
3751+ };
3752+ let mut line = node.span.line;
3753+ let mut source = written_line(node);
3754+ let (marker, message) = match &node.kind {
3755+ NodeKind::Element(element) => {
3756+ let text = element.text.as_ref()?;
3757+ if !is_marker(&text.raw) {
3758+ return None;
3759+ }
3760+ let name = &element.chain.last()?.name;
3761+ let marker = text.raw.trim().to_string();
3762+ let message = format!(
3763+ "`{marker}` after @{name}'s attributes is text: it marks where a call's content \
3764+ goes only on a line of its own, so write it on the next line, indented under \
3765+ @{name}"
3766+ );
3767+ (marker, message)
3768+ }
3769+ NodeKind::Verbatim(verbatim) if verbatim.escaped => {
3770+ let (i, written) = verbatim
3771+ .text
3772+ .lines()
3773+ .enumerate()
3774+ .find(|(_, l)| is_marker(l))?;
3775+ let marker = written.trim().to_string();
3776+ line += i;
3777+ source = written.to_string();
3778+ let message = format!(
3779+ "`{marker}` in a verbatim body is text: the body is written as it is, so it can't \
3780+ hold a call's content (pass the text as a parameter instead)"
3781+ );
3782+ (marker, message)
3783+ }
3784+ _ => return None,
3785+ };
3786+ Some(
3787+ Diagnostic::error(code::MISPLACED_SLOT, line, message)
3788+ .subject(marker)
3789+ .source(source),
3790+ )
3791+}
3792+
3793+/// A first word that can't be a leading argument: an inline element
3794+/// (`@link {@b x} y`), or a quote that isn't closed (`@link "a b`).
3795+fn bad_leading_token(
3796+ kind: &ElementKind,
3797+ token: &syntax::Arg,
3798+ text: &str,
3799+ ctx: &ParseContext,
3800+) -> Option<Diagnostic> {
3801+ let what = leading_name(kind);
3802+ let name = kind.name();
3803+ let message = if token.raw.starts_with("{@") {
3804+ format!(
3805+ "@{0} takes its {1} first, before any text: write `@{0} VALUE {2}`, or give it as \
3806+ `[{1}=VALUE]`",
3807+ name,
3808+ what,
3809+ text.trim()
3810+ )
3811+ } else if token.raw.starts_with('"') && syntax::quoted_string(&token.raw).is_none() {
3812+ format!(
3813+ "@{}'s {} starts with a `\"` that isn't closed: close it (`\"...\"`), or write \
3814+ `\\\"` for a quote in the value",
3815+ name, what
3816+ )
3817+ } else {
3818+ return None;
3819+ };
3820+ let d = Diagnostic::error(code::UNEXPECTED_ARGUMENT, token.span.line, message)
3821+ .subject(token.raw.clone());
3822+ Some(at_attribute(d, Some(token.span.column), ctx))
3823+}
3824+
3825+/// A first word taken as a URL that reads as text: a word with a capital
3826+/// and nothing a URL or a file name has, as in `@link [hx-get=/panel] Open
3827+/// panel`, whose href would be `Open`. It still is (a relative URL can be
3828+/// such a word), with a warning.
3829+fn text_as_url(kind: &ElementKind, token: &syntax::Arg, ctx: &ParseContext) -> Option<Diagnostic> {
3830+ const URLS: &[&str] = &["href", "src", "srcset", "action", "data"];
3831+ let word = token.raw.as_str();
3832+ let reads_as_text = word.starts_with(char::is_uppercase)
3833+ && !word.contains([
3834+ '/', '.', ':', '#', '?', '=', '&', '%', '~', '$', '{', '\\', '"',
3835+ ]);
3836+ if !reads_as_text || !kind.arg().attributes().iter().any(|a| URLS.contains(a)) {
3837+ return None;
3838+ }
3839+ let name = kind.name();
3840+ let attr = leading_name(kind);
3841+ let text = if takes_no_text(kind) {
3842+ String::new()
3843+ } else {
3844+ format!(": write the {attr} before the text, or put the text on the lines under it")
3845+ };
3846+ let message = format!(
3847+ "@{name} takes '{word}', its first word, as its {attr}{text}. A relative URL that \
3848+ starts with a capital is written `./{word}`"
3849+ );
3850+ let d = Diagnostic::warning(code::TEXT_AS_URL, token.span.line, message).subject(word);
3851+ Some(at_attribute(d, Some(token.span.column), ctx))
3852+}
3853+
3854+/// `@link /a > @image logo.png`: a `>` chains only after an element's
3855+/// name or its `[attributes]`, so after a leading argument it is text.
3856+/// Said when what follows names an element or a function.
3857+fn chain_after_argument(
3858+ kind: &ElementKind,
3859+ token: &str,
3860+ rest: &syntax::Text,
3861+ ctx: &ParseContext,
3862+) -> Option<Diagnostic> {
3863+ let after = rest.raw.strip_prefix('>')?;
3864+ let name_start = after.trim_start().strip_prefix('@')?;
3865+ if after.len() == after.trim_start().len() {
3866+ return None;
3867+ }
3868+ let name: String = name_start
3869+ .chars()
3870+ .take_while(|c| c.is_ascii_alphanumeric() || *c == '-')
3871+ .collect();
3872+ if ElementKind::from_name(&name).is_none() && ctx.env.function(&name).is_none() {
3873+ return None;
3874+ }
3875+ let attr = leading_name(kind);
3876+ let d = Diagnostic::warning(
3877+ code::UNEXPECTED_ARGUMENT,
3878+ rest.span.line,
3879+ format!(
3880+ "`{}` after @{}'s {} is text, not a chain: `>` chains after an element's name or \
3881+ its [attributes], so write `@{} [{}={}] {}`",
3882+ rest.raw.trim_end(),
3883+ kind.name(),
3884+ attr,
3885+ kind.name(),
3886+ attr,
3887+ token,
3888+ rest.raw.trim_end()
3889+ ),
3890+ )
3891+ .subject(rest.raw.trim_end());
3892+ Some(at_attribute(d, Some(rest.span.column), ctx))
3893+}
3894+
3895+/// A leading argument given twice, as the first token and as its
3896+/// attribute: `@link [href=/a] About`.
3897+fn leading_twice(
3898+ kind: &ElementKind,
3899+ token: &syntax::Arg,
3900+ key: &str,
3901+ value: &str,
3902+ text: &syntax::Text,
3903+ ctx: &ParseContext,
3904+) -> Diagnostic {
3905+ let name = kind.name();
3906+ let what = leading_name(kind);
3907+ // The value as one token: quoted when it is empty or has a space in it
3908+ let value = if !value.is_empty() && syntax::leading_token_len(value) == value.len() {
3909+ value.to_string()
3910+ } else {
3911+ format!("\"{}\"", value.replace('\\', "\\\\").replace('"', "\\\""))
3912+ };
3913+ let written = if takes_no_text(kind) {
3914+ format!("@{} {}", name, value)
3915+ } else {
3916+ format!("@{} {} {}", name, value, text.raw)
3917+ };
3918+ let d = Diagnostic::error(
3919+ code::DUPLICATE_ATTRIBUTE,
3920+ text.span.line,
3921+ format!(
3922+ "@{} takes its first word '{}' as its {}, and it also has {}=: give it once, \
3923+ as `{}`",
3924+ name, token.raw, what, key, written
3925+ ),
3926+ )
3927+ .subject(token.raw.clone());
3928+ at_attribute(d, Some(token.span.column), ctx)
3929+}
3930+
3931+/// The attribute an element's leading argument fills, for messages.
3932+fn leading_name(kind: &ElementKind) -> &'static str {
3933+ match kind.arg() {
3934+ TagArg::Source => "srcset in @picture or src elsewhere",
3935+ arg => arg.attribute(false).unwrap_or("argument"),
3936+ }
3937+}
3938+
3939+/// Whether text after an element's leading argument has nowhere to go:
3940+/// an element without content (`@image`, `@source`, ...), or `@optgroup`,
3941+/// which holds only `@option` lines, so `@optgroup Citrus fruits` would
3942+/// otherwise make `Citrus` the label and drop `fruits`.
3943+fn takes_no_text(kind: &ElementKind) -> bool {
3944+ kind.layout() == Layout::Void || kind.is_tag("optgroup")
3945+}
3946+
3947+/// Text after the leading argument of an element without content:
3948+/// `@image logo.png Our logo`.
3949+fn after_the_leading_argument(kind: &ElementKind, token: &str, rest: &syntax::Text) -> Diagnostic {
3950+ let name = kind.name();
3951+ let attr = leading_name(kind);
3952+ let alt = if matches!(kind, ElementKind::Image) || kind.is_tag("area") {
3953+ " For a text alternative, write `alt=...`."
3954+ } else {
3955+ ""
3956+ };
3957+ let holds = if kind.layout() == Layout::Void {
3958+ "it has no content"
3959+ } else {
3960+ "it holds only the elements on the lines under it"
3961+ };
3962+ let bare = syntax::quoted_string(token).unwrap_or(token);
3963+ Diagnostic::error(
3964+ code::UNEXPECTED_ARGUMENT,
3965+ rest.span.line,
3966+ format!(
3967+ "@{0} takes one word after its attributes, its {1} ('{2}'), and {5}, so '{3}' \
3968+ would go nowhere. A value with a space in it is quoted: `\"{6} {3}\"`.{4}",
3969+ name, attr, token, rest.raw, alt, holds, bare
3970+ ),
3971+ )
3972+ .subject(rest.raw.clone())
3973+}
3974+
3975+/// The element named `name`, or an "unknown element" error that suggests
3976+/// the closest element, directive or function.
3977+fn parse_element_kind(
3978+ name: &str,
3979+ line_num: usize,
3980+ ctx: &mut ParseContext,
3981+) -> Result<ElementKind, ParseError> {
3982+ if let Some(kind) = ElementKind::from_name(name) {
3983+ return Ok(kind);
3984+ }
3985+ // A known name in a place it can't go: say why instead of suggesting
3986+ // the name itself.
3987+ let misplaced = if crate::ast::directive(name).is_some() {
3988+ Some(format!(
3989+ "unknown element @{}: @{} is a directive, which goes at the start of its own line",
3990+ name, name
3991+ ))
3992+ } else if ctx.env.bundle(name).is_some() {
3993+ Some(format!(
3994+ "unknown element @{}: '{}' is an attribute bundle, used as `[${}]` \
3995+ (a function is defined with `@let @{}`)",
3996+ name, name, name, name
3997+ ))
3998+ } else if ctx.env.value(name).is_some() {
3999+ Some(format!(
4000+ "unknown element @{}: '{}' is a value, used as `${}` \
4001+ (a function is defined with `@let @{}`)",
4002+ name, name, name, name
4003+ ))
4004+ } else if ctx.namespace.contains(name) {
4005+ ctx.used_functions.insert(name.to_string());
4006+ Some(format!(
4007+ "unknown element @{}: the function @{} isn't visible here. A definition is \
4008+ visible from its line to the end of its block, and a function's body sees what \
4009+ is defined above the function, so define @{} above this line, outside the block \
4010+ it is in",
4011+ name, name, name
4012+ ))
4013+ } else if matches!(name, "svg" | "math" | "template") {
4014+ Some(format!(
4015+ "unknown element @{}: htmlang doesn't write <{}>; put its markup in the page with \
4016+ @raw{}",
4017+ name,
4018+ name,
4019+ if name == "svg" {
4020+ " (or an SVG file with `@image [inline] file.svg`)"
4021+ } else {
4022+ ""
4023+ }
4024+ ))
4025+ } else {
4026+ None
4027+ };
4028+ if let Some(message) = misplaced {
4029+ return Err(Diagnostic::error(code::UNKNOWN_ELEMENT, line_num, message).subject(name));
4030+ }
4031+ let all_known: Vec<&str> = ElementKind::all_names()
4032+ .chain(DIRECTIVES.iter().map(|d| d.name))
4033+ .collect();
4034+ // An HTML element htmlang writes under its own name (`@a` is `@link`).
4035+ let written_otherwise = crate::ast::HTML_NAMES_WRITTEN_OTHERWISE
4036+ .iter()
4037+ .find(|(html, _)| *html == name)
4038+ .map(|(_, htmlang)| *htmlang);
4039+ let closest = written_otherwise.or_else(|| suggest_closest(name, &all_known));
4040+ let mut message = match (closest, written_otherwise) {
4041+ (Some(closest), Some(_)) => format!(
4042+ "unknown element @{}, did you mean @{}? (@{} writes <{}>)",
4043+ name, closest, closest, name
4044+ ),
4045+ (Some(closest), None) => format!("unknown element @{}, did you mean @{}?", name, closest),
4046+ (None, _) => format!("unknown element @{}", name),
4047+ };
4048+ let function = suggest_fn_name(name, ctx);
4049+ if let Some(function) = &function {
4050+ message = format!("{}, or did you mean @{}?", message, function);
4051+ }
4052+ Err(Diagnostic::error(code::UNKNOWN_ELEMENT, line_num, message)
4053+ .subject(name)
4054+ .suggest(closest.map(str::to_string).or(function)))
4055+}
4056+
4057+/// Format include/import stack as a readable chain for error messages.
4058+fn format_include_chain(stack: &[PathBuf]) -> String {
4059+ stack
4060+ .iter()
4061+ .map(|p| {
4062+ p.file_name()
4063+ .unwrap_or_default()
4064+ .to_string_lossy()
4065+ .to_string()
4066+ })
4067+ .collect::<Vec<_>>()
4068+ .join(" → ")
4069+}
4070+
4071+/// Levenshtein distance with a rolling two-row buffer (O(min(a,b)) memory) and an
4072+/// early-exit cutoff: if every cell in a row exceeds `cutoff`, no further cell can
4073+/// be <= `cutoff`, so we return `cutoff + 1` immediately. Used for typo-suggestion
4074+/// hot paths where we only care about distances <= 2.
4075+fn levenshtein_bounded(a: &[char], b: &[char], cutoff: usize) -> usize {
4076+ let (a, b) = if a.len() > b.len() { (b, a) } else { (a, b) };
4077+ if b.len() - a.len() > cutoff {
4078+ return cutoff + 1;
4079+ }
4080+ if a.is_empty() {
4081+ return b.len();
4082+ }
4083+
4084+ let mut prev: Vec<usize> = (0..=a.len()).collect();
4085+ let mut curr: Vec<usize> = vec![0; a.len() + 1];
4086+
4087+ for (j, &bc) in b.iter().enumerate() {
4088+ curr[0] = j + 1;
4089+ let mut row_min = curr[0];
4090+ for (i, &ac) in a.iter().enumerate() {
4091+ let cost = if ac == bc { 0 } else { 1 };
4092+ curr[i + 1] = (prev[i + 1] + 1).min(curr[i] + 1).min(prev[i] + cost);
4093+ row_min = row_min.min(curr[i + 1]);
4094+ }
4095+ if row_min > cutoff {
4096+ return cutoff + 1;
4097+ }
4098+ std::mem::swap(&mut prev, &mut curr);
4099+ }
4100+ prev[a.len()]
4101+}
4102+
4103+fn suggest_closest<'a>(input: &str, candidates: &[&'a str]) -> Option<&'a str> {
4104+ let input_chars: Vec<char> = input.chars().collect();
4105+ let max_allowed = 2usize.min(input_chars.len().saturating_sub(1));
4106+ let mut best = None;
4107+ let mut best_dist = usize::MAX;
4108+ for &candidate in candidates {
4109+ // Cheap length-based prune before allocating chars.
4110+ let clen = candidate.chars().count();
4111+ let diff = clen.abs_diff(input_chars.len());
4112+ if diff > max_allowed {
4113+ continue;
4114+ }
4115+ let cand_chars: Vec<char> = candidate.chars().collect();
4116+ let dist = levenshtein_bounded(&input_chars, &cand_chars, max_allowed);
4117+ if dist < best_dist && dist <= max_allowed {
4118+ best_dist = dist;
4119+ best = Some(candidate);
4120+ }
4121+ }
4122+ best
4123+}
4124+
4125+/// Suggest the closest user-defined function name for typos, from the
4126+/// functions defined so far and those defined anywhere in the file.
4127+fn suggest_fn_name(input: &str, ctx: &ParseContext) -> Option<String> {
4128+ let input_chars: Vec<char> = input.chars().collect();
4129+ let max_allowed = 2usize.min(input_chars.len().saturating_sub(1));
4130+ let mut best: Option<(usize, &String)> = None;
4131+ let visible: Vec<&String> = ctx.defined_functions.keys().collect();
4132+ for name in visible.into_iter().chain(ctx.namespace.iter()) {
4133+ let nlen = name.chars().count();
4134+ if nlen.abs_diff(input_chars.len()) > max_allowed {
4135+ continue;
4136+ }
4137+ let name_chars: Vec<char> = name.chars().collect();
4138+ let dist = levenshtein_bounded(&input_chars, &name_chars, max_allowed);
4139+ if dist <= max_allowed && best.is_none_or(|b| (dist, name) < b) {
4140+ best = Some((dist, name));
4141+ }
4142+ }
4143+ best.map(|(_, name)| name.clone())
4144+}
4145+
4146+/// Suggest the closest variable name for undefined `$var` references.
4147+fn suggest_var_name(input: &str, vars: &[&str]) -> Option<String> {
4148+ let input_chars: Vec<char> = input.chars().collect();
4149+ let max_allowed = 2usize.min(input_chars.len().saturating_sub(1));
4150+ let mut best: Option<String> = None;
4151+ let mut best_dist = usize::MAX;
4152+ let mut vars = vars.to_vec();
4153+ // The same answer every time, whatever the order of the names
4154+ vars.sort_unstable();
4155+ for name in vars {
4156+ let nlen = name.chars().count();
4157+ if nlen.abs_diff(input_chars.len()) > max_allowed {
4158+ continue;
4159+ }
4160+ let name_chars: Vec<char> = name.chars().collect();
4161+ let dist = levenshtein_bounded(&input_chars, &name_chars, max_allowed);
4162+ if dist < best_dist && dist <= max_allowed {
4163+ best_dist = dist;
4164+ best = Some(name.to_string());
4165+ }
4166+ }
4167+ best
4168+}
4169+
4170+// ---------------------------------------------------------------------------
4171+// Attribute parsing
4172+// ---------------------------------------------------------------------------
4173+
4174+/// The quoted strings of a CSS value, without their quotes.
4175+fn css_strings(value: &str) -> Vec<&str> {
4176+ let mut strings = Vec::new();
4177+ let mut start = None;
4178+ let mut escaped = false;
4179+ for (i, c) in value.char_indices() {
4180+ match (c, start) {
4181+ _ if escaped => escaped = false,
4182+ ('\\', Some(_)) => escaped = true,
4183+ ('"', None) => start = Some(i + 1),
4184+ ('"', Some(from)) => {
4185+ strings.push(&value[from..i]);
4186+ start = None;
4187+ }
4188+ _ => {}
4189+ }
4190+ }
4191+ strings
4192+}
4193+
4194+/// An `if(...)` in a CSS value that isn't CSS's if(): CSS writes each
4195+/// branch `CONDITION: VALUE`, so an if() without a `:` is something else.
4196+/// Quoted CSS strings are text, not calls.
4197+fn not_css_if(value: &str) -> Option<&str> {
4198+ let mut quote = None;
4199+ let mut prev = None;
4200+ let mut chars = value.char_indices();
4201+ while let Some((at, c)) = chars.next() {
4202+ match quote {
4203+ Some(_) if c == '\\' => {
4204+ chars.next();
4205+ }
4206+ Some(q) if c == q => quote = None,
4207+ Some(_) => {}
4208+ None if matches!(c, '"' | '\'') => quote = Some(c),
4209+ None => {
4210+ let word_before =
4211+ prev.is_some_and(|p: char| p.is_alphanumeric() || matches!(p, '-' | '_'));
4212+ if !word_before && value[at..].starts_with("if(") {
4213+ let mut depth = 0;
4214+ let close = value[at + 2..].char_indices().find_map(|(i, c)| {
4215+ match c {
4216+ '(' => depth += 1,
4217+ ')' => depth -= 1,
4218+ _ => {}
4219+ }
4220+ (depth == 0).then_some(at + 2 + i)
4221+ });
4222+ let end = close.map_or(value.len(), |c| c + 1);
4223+ if !value[at + 3..end].contains(':') {
4224+ return Some(&value[at..end]);
4225+ }
4226+ }
4227+ }
4228+ }
4229+ prev = Some(c);
4230+ }
4231+ None
4232+}
4233+
4234+/// Why a CSS value can't be written into a rule as it is, whatever it
4235+/// means: a `;` (outside parentheses, where CSS's own `if()` uses it), a
4236+/// `{` or a `}` would end the declaration or the rule, and an unclosed
4237+/// quote or parenthesis would run on into the rules after it. Quoted
4238+/// strings are text, and a backslash escapes the character after it, as
4239+/// in CSS. A `</style` anywhere, even in a string, would end the page's
4240+/// `<style>` element and start HTML.
4241+fn css_breakout(value: &str) -> Option<&'static str> {
4242+ if value.to_ascii_lowercase().contains("</style") {
4243+ return Some("a `</style`, which would end the page's style element");
4244+ }
4245+ let mut quote = None;
4246+ let mut depth = 0usize;
4247+ let mut chars = value.chars();
4248+ while let Some(c) = chars.next() {
4249+ match (quote, c) {
4250+ (_, '\\') => {
4251+ chars.next();
4252+ }
4253+ (Some(q), c) if c == q => quote = None,
4254+ (Some(_), _) => {}
4255+ (None, '"' | '\'') => quote = Some(c),
4256+ (None, '(') => depth += 1,
4257+ (None, ')') if depth == 0 => return Some("a `)` that closes nothing"),
4258+ (None, ')') => depth -= 1,
4259+ (None, ';') if depth == 0 => return Some("a `;`, which would end the declaration"),
4260+ (None, '{' | '}') => return Some("a `{` or `}`, which would end the CSS rule"),
4261+ _ => {}
4262+ }
4263+ }
4264+ match (quote, depth) {
4265+ (Some('"'), _) => Some("a `\"` that isn't closed"),
4266+ (Some(_), _) => Some("a `'` that isn't closed"),
4267+ (None, 0) => None,
4268+ (None, _) => Some("a `(` that isn't closed"),
4269+ }
4270+}
4271+
4272+/// The hex colors of a CSS value that don't have 3, 4, 6 or 8 hex
4273+/// digits. A `#` word in a CSS value is a color, except inside `url(...)`
4274+/// and quoted strings.
4275+fn bad_hex_colors(value: &str) -> Vec<&str> {
4276+ let mut bad = Vec::new();
4277+ let mut quote = None;
4278+ let mut in_url = 0usize;
4279+ let mut depth = 0usize;
4280+ let mut chars = value.char_indices().peekable();
4281+ while let Some((at, c)) = chars.next() {
4282+ match (quote, c) {
4283+ (_, '\\') => {
4284+ chars.next();
4285+ }
4286+ (Some(q), c) if c == q => quote = None,
4287+ (Some(_), _) => {}
4288+ (None, '"' | '\'') => quote = Some(c),
4289+ (None, '(') => {
4290+ depth += 1;
4291+ if value[..at].ends_with("url") && in_url == 0 {
4292+ in_url = depth;
4293+ }
4294+ }
4295+ (None, ')') => {
4296+ if in_url == depth {
4297+ in_url = 0;
4298+ }
4299+ depth = depth.saturating_sub(1);
4300+ }
4301+ (None, '#') if in_url == 0 => {
4302+ let end = value[at + 1..]
4303+ .find(|c: char| !(c.is_alphanumeric() || c == '-' || c == '_'))
4304+ .map_or(value.len(), |n| at + 1 + n);
4305+ let hex = &value[at + 1..end];
4306+ if !(matches!(hex.len(), 3 | 4 | 6 | 8)
4307+ && hex.chars().all(|c| c.is_ascii_hexdigit()))
4308+ {
4309+ bad.push(&value[at..end]);
4310+ }
4311+ }
4312+ _ => {}
4313+ }
4314+ }
4315+ bad
4316+}
4317+
4318+/// A diagnostic about an attribute, with its column and source line when
4319+/// it is on the line being evaluated.
4320+fn at_attribute(diagnostic: Diagnostic, column: Option<usize>, ctx: &ParseContext) -> Diagnostic {
4321+ match (&ctx.current_source, column) {
4322+ ((current, Some(text)), Some(column)) if *current == diagnostic.line => {
4323+ diagnostic.column(column).source(text.clone())
4324+ }
4325+ _ => diagnostic,
4326+ }
4327+}
4328+
4329+/// Check a style's value. Values go to the CSS as written, so only what
4330+/// can't be wrong in any CSS is checked: a value that would break out of
4331+/// its rule is an error (and it is left out); a hex color without 3, 4, 6
4332+/// or 8 digits, an `if()` that isn't CSS's and a quoted font stack are
4333+/// warnings. Returns whether the value can be written.
4334+fn check_css_value(
4335+ attr: &Attribute,
4336+ base: &str,
4337+ line: usize,
4338+ column: Option<usize>,
4339+ ctx: &mut ParseContext,
4340+) -> bool {
4341+ let Some(value) = &attr.value else {
4342+ return true;
4343+ };
4344+ if let Some(reason) = css_breakout(value) {
4345+ let diagnostic = Diagnostic::error(
4346+ code::INVALID_VALUE,
4347+ line,
4348+ format!(
4349+ "the value of '{}' has {}: `{}` can't be written into the page's CSS",
4350+ attr.key, reason, value
4351+ ),
4352+ )
4353+ .subject(value.as_str());
4354+ ctx.diagnostics.push(at_attribute(diagnostic, column, ctx));
4355+ return false;
4356+ }
4357+ if crate::vocab::is_custom_property(base) {
4358+ return true;
4359+ }
4360+
4361+ let warn = |ctx: &mut ParseContext, diagnostic: Diagnostic| {
4362+ let diagnostic = at_attribute(diagnostic, column, ctx);
4363+ ctx.diagnostics.push(diagnostic);
4364+ };
4365+ // In CSS, a quoted font-family is one family, commas and all
4366+ if base == "font-family"
4367+ && let Some(family) = css_strings(value).into_iter().find(|s| s.contains(','))
4368+ {
4369+ let stack = family
4370+ .split(',')
4371+ .map(str::trim)
4372+ .collect::<Vec<_>>()
4373+ .join("\\, ");
4374+ warn(
4375+ ctx,
4376+ Diagnostic::warning(
4377+ code::INVALID_VALUE,
4378+ line,
4379+ format!(
4380+ "font-family \"{}\" is one family, whose name has a comma in it: \
4381+ for a font stack, write `font-family {}`",
4382+ family, stack
4383+ ),
4384+ )
4385+ .subject(format!("\"{}\"", family))
4386+ .suggest(Some(stack)),
4387+ );
4388+ }
4389+ if let Some(call) = not_css_if(value) {
4390+ warn(
4391+ ctx,
4392+ Diagnostic::warning(
4393+ code::INVALID_VALUE,
4394+ line,
4395+ format!(
4396+ "'{}' is not CSS's if(), whose branches are written \
4397+ `if(CONDITION: VALUE; else: VALUE)`",
4398+ call
4399+ ),
4400+ )
4401+ .subject(call),
4402+ );
4403+ }
4404+ for color in bad_hex_colors(value) {
4405+ warn(
4406+ ctx,
4407+ Diagnostic::warning(
4408+ code::INVALID_COLOR,
4409+ line,
4410+ format!(
4411+ "invalid hex color '{}': a hex color has 3, 4, 6 or 8 hex digits",
4412+ color
4413+ ),
4414+ )
4415+ .subject(color),
4416+ );
4417+ }
4418+ true
4419+}
4420+
4421+/// An unknown prefix: the message, the text it is about, and what to write
4422+/// instead, when something is close enough.
4423+struct PrefixProblem {
4424+ message: String,
4425+ subject: String,
4426+ suggestion: Option<String>,
4427+}
4428+
4429+/// What is wrong with the prefix `rest` starts with, when the known
4430+/// prefixes are already split off it and what is left still starts with
4431+/// one: a word and a `:` (`hovr:`), or a word and a parenthesised argument
4432+/// and a `:` (`nth-chld(2):`). Selector prefixes are CSS's pseudo-classes
4433+/// and pseudo-elements under their CSS names, so an unknown one gets the
4434+/// closest name as a suggestion. Only names with the same first letter are
4435+/// suggested: `odd:` is two edits from `md:`, which it doesn't mean.
4436+fn unknown_prefix(rest: &str) -> Option<PrefixProblem> {
4437+ use crate::vocab::{self, Pseudo};
4438+ let name_len = rest.find(|c: char| !(c.is_ascii_alphanumeric() || c == '-'))?;
4439+ let name = &rest[..name_len];
4440+ if name.is_empty() {
4441+ return None;
4442+ }
4443+ if rest[name_len..].starts_with('(') {
4444+ // `name(...):`: a pseudo-class with an argument
4445+ let close = vocab::closing_paren(rest, name_len)?;
4446+ if !rest[close + 1..].starts_with(':') {
4447+ return None;
4448+ }
4449+ let written = &rest[..close + 2];
4450+ if matches!(vocab::pseudo(name), Some(Pseudo::Class | Pseudo::Element)) {
4451+ let bare = format!("{}:", name);
4452+ return Some(PrefixProblem {
4453+ message: format!(
4454+ "'{}': `{}` takes no argument: write `{}`",
4455+ written,
4456+ vocab::pseudo_selector(&bare).unwrap_or_default(),
4457+ bare
4458+ ),
4459+ subject: written.to_string(),
4460+ suggestion: Some(bare),
4461+ });
4462+ }
4463+ let functional: Vec<&str> = vocab::functional_pseudos()
4464+ .into_iter()
4465+ .filter(|p| p.chars().next() == name.chars().next())
4466+ .collect();
4467+ let suggestion = suggest_closest(name, &functional)
4468+ .filter(|&closest| closest != name)
4469+ .map(|closest| format!("{}(", closest));
4470+ let written = format!("{}(", name);
4471+ let message = match &suggestion {
4472+ Some(closest) => format!("unknown prefix '{}', did you mean '{}'?", written, closest),
4473+ None => format!("unknown prefix '{}'", written),
4474+ };
4475+ return Some(PrefixProblem {
4476+ message,
4477+ subject: written,
4478+ suggestion,
4479+ });
4480+ }
4481+ if !rest[name_len..].starts_with(':') {
4482+ return None;
4483+ }
4484+ let written = &rest[..name_len + 1];
4485+ // `has:`: its argument is missing
4486+ if vocab::pseudo(name) == Some(Pseudo::Function) {
4487+ return Some(PrefixProblem {
4488+ message: format!(
4489+ "'{}': `:{}()` takes an argument, in parentheses, as in CSS: `{}(...):`",
4490+ written, name, name
4491+ ),
4492+ subject: written.to_string(),
4493+ suggestion: None,
4494+ });
4495+ }
4496+ let prefixes = vocab::all_prefixes();
4497+ let candidates: Vec<&str> = prefixes
4498+ .iter()
4499+ .map(String::as_str)
4500+ .filter(|p| p.chars().next() == written.chars().next())
4501+ .collect();
4502+ // The closest name that starts with the same letter (`hvoer:` →
4503+ // `hover:`), else the first that starts with the word written and a `-`
4504+ // (`first:` → `first-child:`)
4505+ let suggestion = suggest_closest(written, &candidates)
4506+ .or_else(|| {
4507+ let longer = format!("{}-", name);
4508+ candidates.iter().copied().find(|p| p.starts_with(&longer))
4509+ })
4510+ .filter(|&closest| closest != written)
4511+ .map(str::to_string);
4512+ let message = match &suggestion {
4513+ Some(closest) => format!("unknown prefix '{}', did you mean '{}'?", written, closest),
4514+ None => format!("unknown prefix '{}'", written),
4515+ };
4516+ Some(PrefixProblem {
4517+ message,
4518+ subject: written.to_string(),
4519+ suggestion,
4520+ })
4521+}
4522+
4523+/// Check an attribute's element prefix (`@td:padding 8`), when it has one:
4524+/// it names a built-in element that has an HTML tag of its own (not a
4525+/// function, and not `@el`, whose `<div>` other elements write too), there
4526+/// is one, not with `children:`, and what it styles is a CSS property, not
4527+/// one of htmlang's words, which compile against each element's layout and
4528+/// its parent's. Returns false, after reporting, when the attribute can't
4529+/// be written.
4530+fn check_element_prefixes(
4531+ attr: &Attribute,
4532+ prefixes: &[&str],
4533+ base: &str,
4534+ line: usize,
4535+ column: Option<usize>,
4536+ ctx: &mut ParseContext,
4537+) -> bool {
4538+ use crate::ast::ElementKind;
4539+ use crate::vocab;
4540+ let elements: Vec<&str> = prefixes
4541+ .iter()
4542+ .copied()
4543+ .filter(|p| vocab::element_prefix(p).is_some())
4544+ .collect();
4545+ let Some(&prefix) = elements.first() else {
4546+ return true;
4547+ };
4548+ let fail = |ctx: &mut ParseContext,
4549+ code: &'static str,
4550+ message: String,
4551+ subject: &str,
4552+ suggestion: Option<String>| {
4553+ let diagnostic = Diagnostic::error(code, line, message)
4554+ .subject(subject)
4555+ .suggest(suggestion);
4556+ let diagnostic = at_attribute(diagnostic, column, ctx);
4557+ ctx.diagnostics.push(diagnostic);
4558+ false
4559+ };
4560+ let name = vocab::element_prefix(prefix).unwrap_or_default();
4561+ if is_function(name, ctx) {
4562+ return fail(
4563+ ctx,
4564+ code::INVALID_PREFIX,
4565+ format!(
4566+ "'{}': @{} is a function, and `{}` would pick elements out by their HTML tag, \
4567+ which a function doesn't have: style what @{} writes in its body, or pass it \
4568+ attributes",
4569+ attr.key, name, prefix, name
4570+ ),
4571+ prefix,
4572+ None,
4573+ );
4574+ }
4575+ match ElementKind::from_name(name) {
4576+ None => {
4577+ let own: Vec<&str> = ElementKind::all_names()
4578+ .filter(|n| ElementKind::from_name(n).is_some_and(|k| k.own_tag().is_some()))
4579+ .collect();
4580+ // An HTML name htmlang writes under another (`@a:` is `@link:`)
4581+ let (written_otherwise, shared) = match crate::ast::HTML_NAMES_WRITTEN_OTHERWISE
4582+ .iter()
4583+ .find(|(html, _)| *html == name)
4584+ {
4585+ Some((_, htmlang)) if own.contains(htmlang) => (Some(*htmlang), false),
4586+ Some(_) => (None, true),
4587+ None => (None, false),
4588+ };
4589+ // `@each:`, `@markdown:`: a directive, which is no element
4590+ if crate::ast::directive(name).is_some() {
4591+ return fail(
4592+ ctx,
4593+ code::UNKNOWN_PREFIX,
4594+ format!(
4595+ "unknown element @{} in '{}': @{} is a directive, and an element \
4596+ prefix names an element with an HTML tag of its own, such as `@td:`",
4597+ name, prefix, name
4598+ ),
4599+ prefix,
4600+ None,
4601+ );
4602+ }
4603+ // `@div:`, `@span:`: several elements write it
4604+ if shared {
4605+ return fail(
4606+ ctx,
4607+ code::UNKNOWN_PREFIX,
4608+ format!(
4609+ "unknown element @{} in '{}': htmlang writes <{}> for several \
4610+ elements, so no element prefix picks it out",
4611+ name, prefix, name
4612+ ),
4613+ prefix,
4614+ None,
4615+ );
4616+ }
4617+ // A name with the same first letter first (`@tdd:` is `@td:`)
4618+ let same_letter: Vec<&str> = own
4619+ .iter()
4620+ .copied()
4621+ .filter(|n| n.chars().next() == name.chars().next())
4622+ .collect();
4623+ let closest = written_otherwise
4624+ .or_else(|| suggest_closest(name, &same_letter))
4625+ .or_else(|| suggest_closest(name, &own));
4626+ let message = match (closest, written_otherwise) {
4627+ (Some(closest), Some(_)) => format!(
4628+ "unknown element @{} in '{}', did you mean '@{}:'? (@{} writes <{}>)",
4629+ name, prefix, closest, closest, name
4630+ ),
4631+ (Some(closest), None) => format!(
4632+ "unknown element @{} in '{}', did you mean '@{}:'?",
4633+ name, prefix, closest
4634+ ),
4635+ (None, _) => format!("unknown element @{} in '{}'", name, prefix),
4636+ };
4637+ let suggestion = closest.map(|c| format!("@{}:", c));
4638+ fail(ctx, code::UNKNOWN_PREFIX, message, prefix, suggestion)
4639+ }
4640+ Some(kind) if kind.own_tag().is_none() => {
4641+ let reason = match kind.tag() {
4642+ None => format!(
4643+ "@{} writes no element of its own, so there is nothing for `{}` to style",
4644+ name, prefix
4645+ ),
4646+ Some(_) if kind.is_verbatim() => {
4647+ format!("@{} isn't shown, so there is nothing to style", name)
4648+ }
4649+ Some("span") => format!(
4650+ "@{} writes a <span>, as every line of text in a row or column does, so \
4651+ `{}` can't pick it out",
4652+ name, prefix
4653+ ),
4654+ Some(tag) => {
4655+ let others: Vec<String> = ElementKind::all_names()
4656+ .filter(|n| {
4657+ *n != name
4658+ && ElementKind::from_name(n).and_then(|k| k.tag()) == Some(tag)
4659+ })
4660+ .map(|n| format!("@{}", n))
4661+ .collect();
4662+ let others = match others.split_last() {
4663+ Some((last, [])) => last.clone(),
4664+ Some((last, rest)) => format!("{} and {}", rest.join(", "), last),
4665+ None => String::new(),
4666+ };
4667+ format!(
4668+ "@{} writes a <{}>, as {} do, so `{}` can't pick it out",
4669+ name, tag, others, prefix
4670+ )
4671+ }
4672+ };
4673+ fail(
4674+ ctx,
4675+ code::INVALID_PREFIX,
4676+ format!(
4677+ "'{}': {}. Give those elements their styles themselves, or a bundle \
4678+ (`@let name [...]`, used as `[$name]`)",
4679+ attr.key, reason
4680+ ),
4681+ prefix,
4682+ None,
4683+ )
4684+ }
4685+ Some(_) if elements.len() > 1 => fail(
4686+ ctx,
4687+ code::INVALID_PREFIX,
4688+ format!(
4689+ "'{}': a style takes one element prefix, which styles every such element \
4690+ inside this one, at any depth",
4691+ attr.key
4692+ ),
4693+ &attr.key,
4694+ None,
4695+ ),
4696+ Some(_) if prefixes.contains(&vocab::CHILDREN) => fail(
4697+ ctx,
4698+ code::INVALID_PREFIX,
4699+ format!(
4700+ "'{}': `children:` and `{}` each say which elements the style is for: write \
4701+ one of them",
4702+ attr.key, prefix
4703+ ),
4704+ &attr.key,
4705+ None,
4706+ ),
4707+ Some(_) if vocab::is_htmlang_word(base, attr.value.as_deref()) => {
4708+ let value = attr.value.as_deref().map(str::trim);
4709+ let css = match (base, value) {
4710+ ("spacing", _) => " (`gap`)",
4711+ ("wrap", _) => " (`flex-wrap wrap`)",
4712+ ("grid-cols", _) => " (`grid-template-columns`)",
4713+ ("grid-rows", _) => " (`grid-template-rows`)",
4714+ ("col-span", _) => " (`grid-column span N`)",
4715+ ("row-span", _) => " (`grid-row span N`)",
4716+ ("width", Some("fill")) => " (`flex 1` in a row, `width 100%` otherwise)",
4717+ ("height", Some("fill")) => " (`flex 1` in a column, `height 100%` otherwise)",
4718+ ("width", _) => " (`flex-shrink 0` in a row, `width fit-content` otherwise)",
4719+ ("height", _) => " (`flex-shrink 0` in a column, `height fit-content` otherwise)",
4720+ ("center-x", _) => " (`margin-inline auto`)",
4721+ ("center-y", _) => " (`margin-block auto`)",
4722+ _ => "",
4723+ };
4724+ let word = match value {
4725+ Some(v) if matches!(base, "width" | "height") => format!("{} {}", base, v),
4726+ _ => base.to_string(),
4727+ };
4728+ fail(
4729+ ctx,
4730+ code::INVALID_PREFIX,
4731+ format!(
4732+ "'{}': `{}` is one of htmlang's layout words, which compile against each \
4733+ element's layout and its parent's, and `{}` styles elements whose \
4734+ parents it doesn't know: write `{}` on the elements themselves, or the \
4735+ CSS you mean{}",
4736+ attr.key, word, prefix, word, css
4737+ ),
4738+ &attr.key,
4739+ None,
4740+ )
4741+ }
4742+ Some(_) => true,
4743+ }
4744+}
4745+
4746+/// Check an attribute's prefixes: each is known, their selector prefixes
4747+/// read left to right with a pseudo-element (`before:`) last, the argument
4748+/// of `has(...)` or `nth-child(...)` can be written into the CSS, and a word that
4749+/// places an element in its parent (`width fill`, `center-x`, `align-*`)
4750+/// isn't under `children:`, whose styles go on the children. Media,
4751+/// container and width prefixes go anywhere. Returns false, after
4752+/// reporting, when the attribute can't be written.
4753+fn check_prefixes(
4754+ attr: &Attribute,
4755+ line: usize,
4756+ column: Option<usize>,
4757+ ctx: &mut ParseContext,
4758+) -> bool {
4759+ use crate::vocab;
4760+ let (prefixes, base) = vocab::split_prefixes(&attr.key);
4761+ let fail =
4762+ |ctx: &mut ParseContext, message: String, subject: &str, suggestion: Option<String>| {
4763+ let diagnostic = Diagnostic::error(code::INVALID_PREFIX, line, message)
4764+ .subject(subject)
4765+ .suggest(suggestion);
4766+ let diagnostic = at_attribute(diagnostic, column, ctx);
4767+ ctx.diagnostics.push(diagnostic);
4768+ false
4769+ };
4770+
4771+ if let Some(problem) = unknown_prefix(base) {
4772+ let diagnostic = Diagnostic::error(code::UNKNOWN_PREFIX, line, problem.message)
4773+ .subject(problem.subject)
4774+ .suggest(problem.suggestion);
4775+ let diagnostic = at_attribute(diagnostic, column, ctx);
4776+ ctx.diagnostics.push(diagnostic);
4777+ return false;
4778+ }
4779+ if !check_element_prefixes(attr, &prefixes, base, line, column, ctx) {
4780+ return false;
4781+ }
4782+ // The argument of `has(...)` or `nth-child(...)` goes into the CSS as
4783+ // written
4784+ for prefix in &prefixes {
4785+ if let Some(reason) = css_breakout(prefix.trim_end_matches(':')) {
4786+ return fail(
4787+ ctx,
4788+ format!(
4789+ "the prefix '{}' has {}: it can't be written into the page's CSS",
4790+ prefix, reason
4791+ ),
4792+ prefix,
4793+ None,
4794+ );
4795+ }
4796+ }
4797+ // `nth-child():` or `has( ):`: CSS has no pseudo-class with an empty
4798+ // argument
4799+ let empty_argument = |prefix: &str| {
4800+ prefix
4801+ .strip_suffix("):")
4802+ .and_then(|p| p.split_once('('))
4803+ .is_some_and(|(_, argument)| argument.trim().is_empty())
4804+ };
4805+ if let Some(empty) = prefixes.iter().find(|p| empty_argument(p)) {
4806+ return fail(
4807+ ctx,
4808+ format!(
4809+ "'{}': `:{}()` takes an argument between its parentheses, as in CSS",
4810+ attr.key,
4811+ vocab::pseudo_name(empty)
4812+ ),
4813+ empty,
4814+ None,
4815+ );
4816+ }
4817+ // A pseudo-element is the last selector prefix: CSS has no
4818+ // `::before:hover`
4819+ let selectors: Vec<&str> = prefixes
4820+ .iter()
4821+ .copied()
4822+ .filter(|p| vocab::at_rule_rank(p).is_none())
4823+ .collect();
4824+ // Only one: an element has one `::before`, which has no `::after`
4825+ let elements: Vec<&str> = selectors
4826+ .iter()
4827+ .copied()
4828+ .filter(|p| vocab::is_pseudo_element(p))
4829+ .collect();
4830+ if elements.len() > 1 {
4831+ return fail(
4832+ ctx,
4833+ format!(
4834+ "'{}': `{}` and `{}` each select a pseudo-element, and a style applies to one \
4835+ of them",
4836+ attr.key, elements[0], elements[1]
4837+ ),
4838+ &attr.key,
4839+ None,
4840+ );
4841+ }
4842+ if let Some(at) = selectors.iter().position(|p| vocab::is_pseudo_element(p))
4843+ && at + 1 < selectors.len()
4844+ {
4845+ let element = selectors[at];
4846+ // The same prefixes, with the pseudo-element moved after the other
4847+ // selector prefixes
4848+ let mut order: Vec<&str> = prefixes.iter().copied().filter(|p| *p != element).collect();
4849+ let last_selector = order
4850+ .iter()
4851+ .rposition(|p| vocab::at_rule_rank(p).is_none())
4852+ .map_or(order.len(), |i| i + 1);
4853+ order.insert(last_selector, element);
4854+ let fixed = format!("{}{}", order.concat(), base);
4855+ return fail(
4856+ ctx,
4857+ format!(
4858+ "'{}': `{}` selects a pseudo-element, which comes after the other selector \
4859+ prefixes, as in CSS: write `{}`",
4860+ attr.key, element, fixed
4861+ ),
4862+ &attr.key,
4863+ Some(fixed),
4864+ );
4865+ }
4866+ // Under `children:` the styles go on the children, whose parent is this
4867+ // element: a word that places an element in its parent can't say where
4868+ if prefixes.contains(&"children:") && vocab::places_in_parent(base, attr.value.as_deref()) {
4869+ // The CSS of `fill` and `shrink` depends on the direction: along
4870+ // it, they are flex properties
4871+ let (word, css) = match (base, attr.value.as_deref().map(str::trim)) {
4872+ ("width", Some("fill")) => (
4873+ "width fill",
4874+ " (`children:flex 1` in a row, `children:width 100%` otherwise)",
4875+ ),
4876+ ("height", Some("fill")) => (
4877+ "height fill",
4878+ " (`children:flex 1` in a column, `children:height 100%` otherwise)",
4879+ ),
4880+ ("width", Some(_)) => (
4881+ "width shrink",
4882+ " (`children:flex-shrink 0` in a row, `children:width fit-content` otherwise)",
4883+ ),
4884+ ("height", Some(_)) => (
4885+ "height shrink",
4886+ " (`children:flex-shrink 0` in a column, `children:height fit-content` \
4887+ otherwise)",
4888+ ),
4889+ _ => (base, ""),
4890+ };
4891+ return fail(
4892+ ctx,
4893+ format!(
4894+ "'{}{}': `{}` places an element in its parent, and under `children:` that \
4895+ parent is this element: write `{}` on the children themselves, or the CSS \
4896+ you mean{}",
4897+ attr.key,
4898+ attr.value
4899+ .as_deref()
4900+ .map_or(String::new(), |v| format!(" {}", v.trim())),
4901+ word,
4902+ word,
4903+ css
4904+ ),
4905+ &attr.key,
4906+ None,
4907+ );
4908+ }
4909+ true
4910+}
4911+
4912+/// Check an attribute written as a style or a flag (not `key=value`): its
4913+/// prefix, its name, and, for a style, its value. A name htmlang doesn't
4914+/// know but CSS could have (`corner-shape`) is passed to the CSS as written,
4915+/// with a warning; custom properties (`--brand`) and vendor-prefixed ones
4916+/// (`-webkit-...`) without one. Anything that can't be written into the
4917+/// page is an error; returns false then, and the attribute is left out.
4918+fn check_attribute(
4919+ attr: &Attribute,
4920+ line: usize,
4921+ column: Option<usize>,
4922+ before: Option<&Attribute>,
4923+ ctx: &mut ParseContext,
4924+) -> bool {
4925+ use crate::vocab;
4926+ let (prefixes, base) = vocab::split_prefixes(&attr.key);
4927+ let fail = |ctx: &mut ParseContext, code: &'static str, message: String, subject: &str| {
4928+ let diagnostic = Diagnostic::error(code, line, message).subject(subject);
4929+ let diagnostic = at_attribute(diagnostic, column, ctx);
4930+ ctx.diagnostics.push(diagnostic);
4931+ false
4932+ };
4933+
4934+ if !check_prefixes(attr, line, column, ctx) {
4935+ return false;
4936+ }
4937+ let prefixed = !prefixes.is_empty();
4938+ // `md:id=x`: `=` makes an HTML attribute, which has no states
4939+ if prefixed && let Some((name, _)) = base.split_once('=') {
4940+ return fail(
4941+ ctx,
4942+ code::INVALID_PREFIX,
4943+ format!(
4944+ "'{}': a prefix applies to a style, and `{}=` is an HTML attribute",
4945+ attr.key, name
4946+ ),
4947+ &attr.key,
4948+ );
4949+ }
4950+ let Some(value) = &attr.value else {
4951+ // `inline` puts a file into the page as it compiles, which no
4952+ // state or media condition can undo
4953+ if base == "inline" && prefixed {
4954+ return fail(
4955+ ctx,
4956+ code::INVALID_PREFIX,
4957+ format!(
4958+ "'{}': `inline` puts the image's file into the page, which can't depend \
4959+ on a prefix",
4960+ attr.key
4961+ ),
4962+ &attr.key,
4963+ );
4964+ }
4965+ if vocab::HTMLANG_FLAGS.contains(&base) {
4966+ return true;
4967+ }
4968+ if vocab::is_html_flag(base) {
4969+ if !prefixed {
4970+ return true;
4971+ }
4972+ return fail(
4973+ ctx,
4974+ code::INVALID_PREFIX,
4975+ format!(
4976+ "'{}': a prefix applies to a style, and '{}' is an HTML attribute",
4977+ attr.key, base
4978+ ),
4979+ &attr.key,
4980+ );
4981+ }
4982+ if vocab::is_style_attribute(base)
4983+ || vocab::is_custom_property(base)
4984+ || vocab::is_vendor_property(base)
4985+ {
4986+ return fail(
4987+ ctx,
4988+ code::MISSING_VALUE,
4989+ format!("'{}' needs a value: `{} VALUE`", attr.key, attr.key),
4990+ &attr.key,
4991+ );
4992+ }
4993+ if vocab::is_html_attribute(base) && !prefixed {
4994+ return fail(
4995+ ctx,
4996+ code::HTML_ATTRIBUTE_FORM,
4997+ format!(
4998+ "'{}' is an HTML attribute that isn't a flag: write `{}=VALUE`",
4999+ base, base
5000+ ),
5001+ base,
5002+ );
5003+ }
5004+ return unknown_attribute(attr, base, line, column, before, true, ctx);
5005+ };
5006+
5007+ if vocab::HTMLANG_FLAGS.contains(&base) {
5008+ return fail(
5009+ ctx,
5010+ code::INVALID_VALUE,
5011+ format!(
5012+ "'{}' is a flag and takes no value: write `{}` alone",
5013+ base, attr.key
5014+ ),
5015+ &attr.key,
5016+ );
5017+ }
5018+ if vocab::is_style_attribute(base)
5019+ || vocab::is_custom_property(base)
5020+ || vocab::is_vendor_property(base)
5021+ {
5022+ return check_css_value(attr, base, line, column, ctx);
5023+ }
5024+ if vocab::is_html_attribute(base) && !prefixed {
5025+ let diagnostic = Diagnostic::error(
5026+ code::HTML_ATTRIBUTE_FORM,
5027+ line,
5028+ format!(
5029+ "'{}' is an HTML attribute: write `{}={}`",
5030+ attr.key, attr.key, value
5031+ ),
5032+ )
5033+ .subject(attr.key.as_str());
5034+ let diagnostic = at_attribute(diagnostic, column, ctx);
5035+ ctx.diagnostics.push(diagnostic);
5036+ return false;
5037+ }
5038+ let passes = vocab::is_property_name(base);
5039+ unknown_attribute(attr, base, line, column, before, !passes, ctx)
5040+ && check_css_value(attr, base, line, column, ctx)
5041+}
5042+
5043+/// Whether an attribute of a bundle could pass a parameter to a function
5044+/// it is spliced into (`@let t [title Hello]`): a name without a prefix
5045+/// that isn't a style or a flag. Such a name is checked where the bundle is
5046+/// used.
5047+fn could_be_parameter(attr: &Attribute) -> bool {
5048+ use crate::vocab;
5049+ let key = attr.key.as_str();
5050+ let flag =
5051+ attr.value.is_none() && (vocab::HTMLANG_FLAGS.contains(&key) || vocab::is_html_flag(key));
5052+ !attr.html
5053+ && !flag
5054+ && !vocab::is_style_attribute(key)
5055+ && key.starts_with(|c: char| c.is_alphabetic())
5056+ && key
5057+ .chars()
5058+ .all(|c| c.is_alphanumeric() || matches!(c, '-' | '_'))
5059+}
5060+
5061+/// At a call, a name close to one of the function's parameters is a
5062+/// misspelled parameter, not an attribute for its root: report it, and
5063+/// return true (it is left out).
5064+fn misspelled_parameter(
5065+ attr: &Attribute,
5066+ text_keys: &[String],
5067+ line: usize,
5068+ column: Option<usize>,
5069+ ctx: &mut ParseContext,
5070+) -> bool {
5071+ if text_keys.is_empty() || !could_be_parameter(attr) {
5072+ return false;
5073+ }
5074+ let params: Vec<&str> = text_keys.iter().map(String::as_str).collect();
5075+ let Some(closest) = suggest_closest(&attr.key, ¶ms) else {
5076+ return false;
5077+ };
5078+ let what = if ctx.in_page {
5079+ "@page word"
5080+ } else {
5081+ "parameter"
5082+ };
5083+ let diagnostic = Diagnostic::error(
5084+ code::UNKNOWN_ATTRIBUTE,
5085+ line,
5086+ format!(
5087+ "unknown {} '{}', did you mean '{}'?",
5088+ what, attr.key, closest
5089+ ),
5090+ )
5091+ .subject(attr.key.as_str())
5092+ .suggest(Some(closest));
5093+ let diagnostic = at_attribute(diagnostic, column, ctx);
5094+ ctx.diagnostics.push(diagnostic);
5095+ true
5096+}
5097+
5098+/// An attribute name htmlang doesn't know. A style whose name CSS could
5099+/// have goes to the CSS as written, with a warning; anything else (a flag,
5100+/// a name that isn't a word) is an error. Returns whether it is kept.
5101+fn unknown_attribute(
5102+ attr: &Attribute,
5103+ base: &str,
5104+ line: usize,
5105+ column: Option<usize>,
5106+ before: Option<&Attribute>,
5107+ error: bool,
5108+ ctx: &mut ParseContext,
5109+) -> bool {
5110+ // `@td padding 8`: an element prefix without its colon
5111+ if let Some(name) = base.strip_prefix('@')
5112+ && crate::ast::ElementKind::from_name(name).is_some()
5113+ {
5114+ let example = match attr.value.as_deref() {
5115+ Some(value) => format!("{}:{}", attr.key, value.trim()),
5116+ None => format!("{}:padding 8", attr.key),
5117+ };
5118+ let diagnostic = Diagnostic::error(
5119+ code::UNKNOWN_ATTRIBUTE,
5120+ line,
5121+ format!(
5122+ "unknown attribute '{}': an element prefix ends in a colon, as in `{}`",
5123+ attr.key, example
5124+ ),
5125+ )
5126+ .subject(base);
5127+ let diagnostic = at_attribute(diagnostic, column, ctx);
5128+ ctx.diagnostics.push(diagnostic);
5129+ return false;
5130+ }
5131+ // `[card]` where `card` is a bundle: it is used as `$card`
5132+ if attr.value.is_none() && ctx.env.bundle(base).is_some() && base == attr.key {
5133+ ctx.used_defines.insert(base.to_string());
5134+ let diagnostic = Diagnostic::error(
5135+ code::UNKNOWN_ATTRIBUTE,
5136+ line,
5137+ format!(
5138+ "unknown attribute '{}': '{}' is an attribute bundle, used as `${}`",
5139+ base, base, base
5140+ ),
5141+ )
5142+ .subject(base)
5143+ .suggest(Some(format!("${}", base)));
5144+ let diagnostic = at_attribute(diagnostic, column, ctx);
5145+ ctx.diagnostics.push(diagnostic);
5146+ return false;
5147+ }
5148+ // `hover:title x`: an HTML attribute's name is not a suggestion for
5149+ // itself
5150+ let suggestion =
5151+ suggest_closest(base, &crate::vocab::all_attributes()).filter(|&closest| closest != base);
5152+ // `hx-trigger=load, every 2s`: right after a `key=value`, a name that
5153+ // isn't close to one htmlang knows is the rest of that value, which
5154+ // the comma ended. It is left out.
5155+ let cut = before.filter(|b| b.html && b.value.is_some());
5156+ let rest = match &attr.value {
5157+ Some(value) => format!("{} {}", attr.key, value),
5158+ None => attr.key.clone(),
5159+ };
5160+ let joined = cut.map(|cut| {
5161+ let value = cut.value.as_deref().unwrap_or("");
5162+ (
5163+ format!("{}={}", cut.key, value),
5164+ format!("{}={}\\, {}", cut.key, value, rest),
5165+ )
5166+ });
5167+ if let (Some((cut, joined)), None) = (&joined, suggestion) {
5168+ let diagnostic = Diagnostic::error(
5169+ code::SPLIT_VALUE,
5170+ line,
5171+ format!(
5172+ "unknown attribute '{}' after `{}`: if '{}' is the rest of its value, the comma \
5173+ ended it. To keep a comma in a value, write `\\,`: `{}`",
5174+ base, cut, rest, joined
5175+ ),
5176+ )
5177+ .subject(base);
5178+ let diagnostic = at_attribute(diagnostic, column, ctx);
5179+ ctx.diagnostics.push(diagnostic);
5180+ return false;
5181+ }
5182+ let mut message = match (&suggestion, error) {
5183+ (Some(closest), true) => {
5184+ format!(
5185+ "unknown attribute '{}', did you mean '{}'?",
5186+ attr.key, closest
5187+ )
5188+ }
5189+ (None, true) => format!("unknown attribute '{}'", attr.key),
5190+ (Some(closest), false) => format!(
5191+ "unknown CSS property '{}', did you mean '{}'? It is written to the CSS as it is",
5192+ base, closest
5193+ ),
5194+ (None, false) => format!(
5195+ "unknown CSS property '{}': it is written to the CSS as it is",
5196+ base
5197+ ),
5198+ };
5199+ // `box-shadow 0 1px red, 0 2px blue` or `font-family Inter,
5200+ // sans-serif`: the comma ended the attribute, and the rest of the
5201+ // value became one
5202+ let rest_of_a_value = !base.starts_with(|c: char| c.is_ascii_alphabetic() || c == '-')
5203+ || (suggestion.is_none() && attr.value.is_none() && before.is_some());
5204+ if joined.is_some() || (rest_of_a_value && error) {
5205+ if !message.ends_with('?') {
5206+ message.push('.');
5207+ }
5208+ match &joined {
5209+ Some((cut, joined)) => message.push_str(&format!(
5210+ " If it is the rest of `{}`, the comma ended it: write `{}`",
5211+ cut, joined
5212+ )),
5213+ None => message
5214+ .push_str(" A comma separates attributes: to keep one in a value, write `\\,`"),
5215+ }
5216+ }
5217+ let severity = if error {
5218+ Severity::Error
5219+ } else {
5220+ Severity::Warning
5221+ };
5222+ let diagnostic = Diagnostic::new(code::UNKNOWN_ATTRIBUTE, severity, line, message)
5223+ .subject(base)
5224+ .suggest(suggestion);
5225+ let diagnostic = at_attribute(diagnostic, column, ctx);
5226+ ctx.diagnostics.push(diagnostic);
5227+ !error
5228+}
5229+
5230+/// Evaluate the attributes of a list: bundles are spliced in, `if()`
5231+/// chooses, and variables fill values. A variable fills only the value it
5232+/// is written in: attributes come from bundles, never from text. With
5233+/// `validate`, unknown names and invalid values are reported. `text_keys`
5234+/// are a called function's parameters: their values are text rather than
5235+/// CSS, and they aren't checked as attributes.
5236+fn parse_attr_list(
5237+ tokens: &[syntax::Attr],
5238+ line_num: usize,
5239+ ctx: &mut ParseContext,
5240+ validate: bool,
5241+ text_keys: &[String],
5242+) -> Vec<Attribute> {
5243+ parse_attrs(tokens, line_num, ctx, validate, text_keys)
5244+ .into_iter()
5245+ .map(|(attr, _)| attr)
5246+ .collect()
5247+}
5248+
5249+/// [`parse_attr_list`], with the value of each attribute whose key is one
5250+/// of `text_keys` (a call's parameters) as a value with its type (see
5251+/// [`ParseContext::slot_value`]), so a parameter can get a list or a
5252+/// record.
5253+fn parse_attrs(
5254+ tokens: &[syntax::Attr],
5255+ line_num: usize,
5256+ ctx: &mut ParseContext,
5257+ validate: bool,
5258+ text_keys: &[String],
5259+) -> Vec<(Attribute, Option<Value>)> {
5260+ let mut read = ReadAttrs::default();
5261+ read_attrs(tokens, "", line_num, ctx, validate, text_keys, &mut read);
5262+ read.attrs
5263+}
5264+
5265+/// The attributes of a list read so far, and the keys written (for the
5266+/// duplicate check).
5267+#[derive(Default)]
5268+struct ReadAttrs {
5269+ attrs: Vec<(Attribute, Option<Value>)>,
5270+ seen_keys: Vec<(String, bool)>,
5271+}
5272+
5273+/// [`parse_attrs`] for the attributes of `tokens`, each under the prefixes
5274+/// `prefix` (`md:` for those of `md:[...]`), which distribute over a
5275+/// group, a bundle and the branch an `if()` takes. Only styles take a
5276+/// prefix, so an HTML attribute there is an error.
5277+fn read_attrs(
5278+ tokens: &[syntax::Attr],
5279+ prefix: &str,
5280+ line_num: usize,
5281+ ctx: &mut ParseContext,
5282+ validate: bool,
5283+ text_keys: &[String],
5284+ out: &mut ReadAttrs,
5285+) {
5286+ let mut chosen = Vec::new();
5287+ choose_attrs(
5288+ tokens,
5289+ prefix,
5290+ line_num,
5291+ ctx,
5292+ validate,
5293+ text_keys,
5294+ &mut chosen,
5295+ );
5296+
5297+ for token in &chosen {
5298+ let line = if token.span.line == 0 {
5299+ line_num
5300+ } else {
5301+ token.span.line
5302+ };
5303+ let (key, value, html) = (token.key.clone(), token.value.clone(), token.html);
5304+ let column = |at: usize| Some(token.span.column + at);
5305+
5306+ // `md:[...]`, `md:$card`, `md:if(...)`: the prefixes apply to each
5307+ // attribute there, and a prefix a parameter can't have
5308+ if let Some(prefixed) = &token.prefixed {
5309+ if let Some(inner) = group_prefix(token, prefixed, prefix, line, ctx) {
5310+ read_attrs(
5311+ prefixed.target.attrs(),
5312+ &inner,
5313+ line_num,
5314+ ctx,
5315+ validate,
5316+ text_keys,
5317+ out,
5318+ );
5319+ }
5320+ continue;
5321+ }
5322+
5323+ // `$name` (or `${name}`) alone: an attribute bundle, spliced in
5324+ let bundle = key.strip_prefix('$').filter(|_| value.is_none() && !html);
5325+ let bundle = bundle.and_then(|after| match interp::reference(after, &ctx.env)? {
5326+ (interp::Reference::Var(name), len) if len == after.len() => Some(name),
5327+ _ => None,
5328+ });
5329+ if let Some(name) = bundle {
5330+ if let Some(define_attrs) = ctx.env.bundle(&name).cloned() {
5331+ ctx.used_defines.insert(name.clone());
5332+ for attr in define_attrs.iter() {
5333+ if !prefix.is_empty() {
5334+ let prefixed = Attribute {
5335+ key: format!("{}{}", prefix, attr.key),
5336+ ..attr.clone()
5337+ };
5338+ if prefixed_parameter(&prefixed, text_keys, line, column(0), validate, ctx)
5339+ {
5340+ continue;
5341+ }
5342+ if let Some(attr) =
5343+ prefixed_member(attr, prefix, &name, line, column(0), validate, ctx)
5344+ {
5345+ out.attrs.push((attr, None));
5346+ }
5347+ continue;
5348+ }
5349+ let attrs = &out.attrs;
5350+ // Checked here, where it is either a parameter or not
5351+ let checked_here = validate
5352+ && !ctx.in_bundle
5353+ && could_be_parameter(attr)
5354+ && !text_keys.contains(&attr.key);
5355+ if checked_here
5356+ && (misspelled_parameter(attr, text_keys, line, column(0), ctx)
5357+ || !check_attribute(
5358+ attr,
5359+ line,
5360+ column(0),
5361+ attrs.last().map(|(a, _)| a),
5362+ ctx,
5363+ ))
5364+ {
5365+ continue;
5366+ }
5367+ out.attrs.push((attr.clone(), None));
5368+ }
5369+ } else {
5370+ not_a_bundle(&name, line, column(0), ctx);
5371+ }
5372+ continue;
5373+ }
5374+ // A name never comes from a variable
5375+ if key.contains('$') {
5376+ track_var_refs(&key, &mut ctx.used_variables);
5377+ ctx.diagnostics.push(
5378+ Diagnostic::error(
5379+ code::ATTRIBUTE_FROM_VARIABLE,
5380+ line,
5381+ format!(
5382+ "'{}': an attribute's name can't come from a variable. A variable \
5383+ fills a value (`padding $size`), and whole attributes come from a \
5384+ bundle (`@let name [padding 8]`, used as `[$name]`)",
5385+ key
5386+ ),
5387+ )
5388+ .subject(key.as_str()),
5389+ );
5390+ continue;
5391+ }
5392+
5393+ // Only a style has states: `md:[id=x]`, `md:id=x`
5394+ if html && (!prefix.is_empty() || !crate::vocab::split_prefixes(&key).0.is_empty()) {
5395+ let written = format!("{}{}", prefix, key);
5396+ let (name, _) = crate::vocab::split_prefixes(&written);
5397+ let diagnostic = Diagnostic::error(
5398+ code::INVALID_PREFIX,
5399+ line,
5400+ format!(
5401+ "'{}=': a prefix applies to a style, and `{}=` is an HTML attribute, \
5402+ which has no states",
5403+ written,
5404+ &written[name.concat().len()..]
5405+ ),
5406+ )
5407+ .subject(token.key.as_str());
5408+ let diagnostic = at_attribute(diagnostic, column(0), ctx);
5409+ ctx.diagnostics.push(diagnostic);
5410+ continue;
5411+ }
5412+ let key = if prefix.is_empty() {
5413+ key
5414+ } else {
5415+ format!("{}{}", prefix, key)
5416+ };
5417+
5418+ // A value's variables are filled in. A style's value is CSS, where
5419+ // quoted text keeps its quotes; an HTML attribute's (and a
5420+ // parameter's) is text, where it loses them.
5421+ let sink = if html || text_keys.contains(&key) {
5422+ Sink::Text
5423+ } else {
5424+ Sink::Css
5425+ };
5426+ let mut filled = true;
5427+ let mut quoted = None;
5428+ let mut typed = None;
5429+ let value = match value {
5430+ None => None,
5431+ // A parameter's value keeps its type
5432+ Some(value) if !html && text_keys.contains(&key) => {
5433+ let at = column(token.raw.len() - value.len());
5434+ let (value, ok) = ctx.slot_value(&value, line, at);
5435+ filled = ok;
5436+ if let Value::Quoted(q) = &value {
5437+ quoted = Some(q.clone());
5438+ }
5439+ let text = value.to_string();
5440+ typed = Some(value);
5441+ Some(text)
5442+ }
5443+ Some(value) => {
5444+ let at = column(token.raw.len() - value.len());
5445+ let (text, is_quoted, ok) = ctx.fill_value(&value, line, at, sink);
5446+ filled = ok;
5447+ quoted = is_quoted;
5448+ Some(text)
5449+ }
5450+ };
5451+ let attr = Attribute {
5452+ key,
5453+ value,
5454+ html,
5455+ quoted,
5456+ };
5457+ // A value that couldn't be filled in is already reported, and a
5458+ // parameter's value is text for the function
5459+ let validate = validate && filled && !text_keys.contains(&attr.key);
5460+
5461+ // A duplicate is reported (compare the full key, so `border` and
5462+ // `hover:border` differ, and the form, so `width=800` and
5463+ // `width 200` do too), and the later one wins
5464+ if validate {
5465+ let seen = (normal_key(&attr.key), attr.html);
5466+ if out.seen_keys.contains(&seen) {
5467+ let written = if attr.html { "=" } else { "" };
5468+ let message = format!(
5469+ "duplicate attribute '{}{}': the later one wins",
5470+ attr.key, written
5471+ );
5472+ let diagnostic = Diagnostic::warning(code::DUPLICATE_ATTRIBUTE, line, message)
5473+ .subject(attr.key.as_str());
5474+ let diagnostic = at_attribute(diagnostic, column(0), ctx);
5475+ ctx.diagnostics.push(diagnostic);
5476+ } else {
5477+ out.seen_keys.push(seen);
5478+ }
5479+ }
5480+
5481+ if validate && misspelled_parameter(&attr, text_keys, line, column(0), ctx) {
5482+ continue;
5483+ }
5484+ if prefixed_parameter(&attr, text_keys, line, column(0), validate, ctx) {
5485+ continue;
5486+ }
5487+ if validate && attr.html && attr.key == "class" {
5488+ reserved_class(&attr, line, column(0), ctx);
5489+ }
5490+ // `padding=4`: a style written as an HTML attribute, which the
5491+ // browser ignores (`width=` and `height=` are real on some
5492+ // elements, see `validate_tree`)
5493+ if validate
5494+ && attr.html
5495+ && crate::vocab::is_style_attribute(&attr.key)
5496+ && !crate::vocab::HTML_ATTRIBUTES.contains(&attr.key.as_str())
5497+ {
5498+ let value = token.value.as_deref().unwrap_or("").trim();
5499+ let diagnostic = Diagnostic::warning(
5500+ code::HTML_ATTRIBUTE_FORM,
5501+ line,
5502+ format!(
5503+ "'{0}={1}' is an HTML attribute, but {0} is a style: write `{0} {1}`",
5504+ attr.key, value
5505+ ),
5506+ )
5507+ .subject(token.raw.as_str())
5508+ .suggest(Some(format!("{} {}", attr.key, value)));
5509+ let diagnostic = at_attribute(diagnostic, column(0), ctx);
5510+ ctx.diagnostics.push(diagnostic);
5511+ }
5512+
5513+ // A style or a flag: its name is checked, and what can't be
5514+ // written into the page is an error and left out
5515+ let checked = validate && !attr.html && !(ctx.in_bundle && could_be_parameter(&attr));
5516+ let before = out.attrs.last().map(|(a, _)| a);
5517+ if checked && !check_attribute(&attr, line, column(0), before, ctx) {
5518+ continue;
5519+ }
5520+
5521+ out.attrs.push((attr, typed));
5522+ }
5523+}
5524+
5525+/// At a call, a parameter under prefixes (`md:title x`, `md:[title x]`):
5526+/// a parameter has one value, with no states, so it is reported (with
5527+/// `validate`) and left out; returns true then. A parameter named like a
5528+/// style (`color`) is a style under a prefix, for the root element.
5529+fn prefixed_parameter(
5530+ attr: &Attribute,
5531+ text_keys: &[String],
5532+ line: usize,
5533+ column: Option<usize>,
5534+ validate: bool,
5535+ ctx: &mut ParseContext,
5536+) -> bool {
5537+ let (prefixes, name) = crate::vocab::split_prefixes(&attr.key);
5538+ if attr.html
5539+ || prefixes.is_empty()
5540+ || !text_keys.iter().any(|k| k == name)
5541+ || crate::vocab::is_style_attribute(name)
5542+ {
5543+ return false;
5544+ }
5545+ if validate {
5546+ let what = if ctx.in_page {
5547+ "@page's own word"
5548+ } else {
5549+ "a parameter"
5550+ };
5551+ let diagnostic = Diagnostic::error(
5552+ code::INVALID_PREFIX,
5553+ line,
5554+ format!(
5555+ "'{}': `{}` is {}, which has one value, and a prefix applies to a style, \
5556+ which has states",
5557+ attr.key, name, what
5558+ ),
5559+ )
5560+ .subject(attr.key.as_str());
5561+ let diagnostic = at_attribute(diagnostic, column, ctx);
5562+ ctx.diagnostics.push(diagnostic);
5563+ }
5564+ true
5565+}
5566+
5567+/// The prefixes of a prefixed group, bundle or `if()` inside `outer` (the
5568+/// prefixes of the groups it is in), when they are all known; else the
5569+/// unknown one is reported. Text after a group's `]` is an error too.
5570+fn group_prefix(
5571+ token: &syntax::Attr,
5572+ prefixed: &syntax::Prefixed,
5573+ outer: &str,
5574+ line: usize,
5575+ ctx: &mut ParseContext,
5576+) -> Option<String> {
5577+ let at = |ctx: &ParseContext, diagnostic: Diagnostic, span: syntax::Span| match &ctx
5578+ .current_source
5579+ {
5580+ (current, Some(text)) if span.line != 0 && *current == span.line => {
5581+ diagnostic.column(span.column).source(text.clone())
5582+ }
5583+ _ => diagnostic,
5584+ };
5585+ if let syntax::Branch::Group {
5586+ trailing: Some(trailing),
5587+ ..
5588+ } = &prefixed.target
5589+ {
5590+ let diagnostic = Diagnostic::error(
5591+ code::UNEXPECTED_ARGUMENT,
5592+ line,
5593+ format!(
5594+ "'{}' after the `]` of `{}[...]`: the prefixes apply to the attributes in the \
5595+ group, so it goes inside it",
5596+ trailing.raw, prefixed.prefix
5597+ ),
5598+ )
5599+ .subject(trailing.raw.as_str());
5600+ let diagnostic = at(ctx, diagnostic, trailing.span);
5601+ ctx.push_once(diagnostic);
5602+ }
5603+ let (known, rest) = crate::vocab::split_prefixes(&prefixed.prefix);
5604+ if !rest.is_empty() {
5605+ let problem = unknown_prefix(rest).unwrap_or_else(|| {
5606+ let written = rest.split_inclusive(':').next().unwrap_or(rest);
5607+ PrefixProblem {
5608+ message: format!("unknown prefix '{}'", written),
5609+ subject: written.to_string(),
5610+ suggestion: None,
5611+ }
5612+ });
5613+ let diagnostic = Diagnostic::error(code::UNKNOWN_PREFIX, line, problem.message)
5614+ .subject(problem.subject)
5615+ .suggest(problem.suggestion);
5616+ let diagnostic = at(ctx, diagnostic, token.span);
5617+ ctx.push_once(diagnostic);
5618+ return None;
5619+ }
5620+ Some(format!("{}{}", outer, known.concat()))
5621+}
5622+
5623+/// An attribute of the bundle `bundle`, spliced in under `prefix`
5624+/// (`md:$card`): the same attribute with the prefixes in front, when it can
5625+/// take them. An HTML attribute can't; a style's prefixes are checked, as
5626+/// is a flag or a name that isn't a style (a bundle's parameter), which
5627+/// under a prefix are attributes like any other.
5628+fn prefixed_member(
5629+ attr: &Attribute,
5630+ prefix: &str,
5631+ bundle: &str,
5632+ line: usize,
5633+ column: Option<usize>,
5634+ validate: bool,
5635+ ctx: &mut ParseContext,
5636+) -> Option<Attribute> {
5637+ let key = format!("{}{}", prefix, attr.key);
5638+ if attr.html {
5639+ if validate {
5640+ let diagnostic = Diagnostic::error(
5641+ code::INVALID_PREFIX,
5642+ line,
5643+ format!(
5644+ "'{}${}': the bundle has `{}=`, an HTML attribute, and a prefix applies to \
5645+ styles, which have states",
5646+ prefix, bundle, attr.key
5647+ ),
5648+ )
5649+ .subject(format!("{}${}", prefix, bundle));
5650+ let diagnostic = at_attribute(diagnostic, column, ctx);
5651+ ctx.diagnostics.push(diagnostic);
5652+ }
5653+ return None;
5654+ }
5655+ let prefixed = Attribute {
5656+ key,
5657+ ..attr.clone()
5658+ };
5659+ if validate {
5660+ let fine = if attr.value.is_none() || could_be_parameter(attr) {
5661+ check_attribute(&prefixed, line, column, None, ctx)
5662+ } else {
5663+ check_prefixes(&prefixed, line, column, ctx)
5664+ };
5665+ if !fine {
5666+ return None;
5667+ }
5668+ }
5669+ Some(prefixed)
5670+}
5671+
5672+/// `class=hl-x`: the `hl-` prefix is htmlang's, for its generated classes,
5673+/// whose rules would then apply to the element too. It goes into the page
5674+/// as written, so this is a warning.
5675+fn reserved_class(attr: &Attribute, line: usize, column: Option<usize>, ctx: &mut ParseContext) {
5676+ let classes = attr.value.as_deref().unwrap_or_default();
5677+ for class in classes.split_whitespace() {
5678+ if class.starts_with(crate::codegen::CLASS_PREFIX) {
5679+ let diagnostic = Diagnostic::warning(
5680+ code::INVALID_VALUE,
5681+ line,
5682+ format!(
5683+ "class '{}' starts with `{}`, which htmlang keeps for the classes it \
5684+ generates, so their styles could apply to this element: give it \
5685+ another name",
5686+ class,
5687+ crate::codegen::CLASS_PREFIX
5688+ ),
5689+ )
5690+ .subject(class);
5691+ let diagnostic = at_attribute(diagnostic, column, ctx);
5692+ ctx.diagnostics.push(diagnostic);
5693+ }
5694+ }
5695+}
5696+
5697+/// A style's key as the CSS reads it, for finding duplicates: its at-rule
5698+/// prefixes in one order (`dark:md:` is `md:dark:`), then its selector
5699+/// prefixes as written, whose order is the selector's.
5700+fn normal_key(key: &str) -> String {
5701+ let (prefixes, name) = crate::vocab::split_prefixes(key);
5702+ let mut at: Vec<(usize, &str)> = prefixes
5703+ .iter()
5704+ .filter_map(|p| crate::vocab::at_rule_rank(p).map(|rank| (rank, *p)))
5705+ .collect();
5706+ at.sort_unstable();
5707+ at.dedup();
5708+ let mut normal: String = at.iter().map(|(_, p)| *p).collect();
5709+ for prefix in prefixes
5710+ .iter()
5711+ .filter(|p| crate::vocab::at_rule_rank(p).is_none())
5712+ {
5713+ normal.push_str(prefix);
5714+ }
5715+ normal.push_str(name);
5716+ normal
5717+}
5718+
5719+/// `[$name]` where `$name` isn't an attribute bundle.
5720+fn not_a_bundle(name: &str, line: usize, column: Option<usize>, ctx: &mut ParseContext) {
5721+ track_var_refs(&format!("${}", name), &mut ctx.used_variables);
5722+ let is_value = interp::name_len(name) > 0 && interp::resolve(name, &ctx.env).is_some();
5723+ let diagnostic = if is_value {
5724+ Diagnostic::error(
5725+ code::ATTRIBUTE_FROM_VARIABLE,
5726+ line,
5727+ format!(
5728+ "'${}' is a value, not an attribute: attributes come from a bundle \
5729+ (`@let name [padding 8]`, used as `[$name]`), and a value fills an \
5730+ attribute's value (`padding ${}`)",
5731+ name, name
5732+ ),
5733+ )
5734+ .subject(name)
5735+ } else if ctx.env.function(name).is_some() {
5736+ ctx.used_functions.insert(name.to_string());
5737+ Diagnostic::error(
5738+ code::UNDEFINED_VARIABLE,
5739+ line,
5740+ format!(
5741+ "'${}' is a function, not an attribute bundle: it is called as an element, \
5742+ `@{}`",
5743+ name, name
5744+ ),
5745+ )
5746+ .subject(name)
5747+ } else {
5748+ let mut bundles = ctx.env.bundle_names();
5749+ bundles.sort_unstable();
5750+ let suggestion = suggest_closest(name, &bundles);
5751+ let message = match suggestion {
5752+ Some(closest) => format!(
5753+ "undefined attribute bundle '${}', did you mean '${}'?",
5754+ name, closest
5755+ ),
5756+ None => format!("undefined attribute bundle '${}'", name),
5757+ };
5758+ Diagnostic::error(code::UNDEFINED_VARIABLE, line, message)
5759+ .subject(name)
5760+ .suggest(suggestion)
5761+ };
5762+ let diagnostic = match (&ctx.current_source, column) {
5763+ ((current, Some(text)), Some(column)) if *current == line => {
5764+ diagnostic.column(column).source(text.clone())
5765+ }
5766+ _ => diagnostic,
5767+ };
5768+ ctx.diagnostics.push(diagnostic);
5769+}
5770+
5771+// ---------------------------------------------------------------------------
5772+// Text segment parsing (inline {...} elements)
5773+// ---------------------------------------------------------------------------
5774+
5775+/// While a slot is filled in, each escape (see [`syntax::ESCAPES`]) is a
5776+/// private-use placeholder, U+E000 plus its place in the table, so it
5777+/// can't start a variable, a quote or an inline element. Afterwards it
5778+/// becomes what it stands for.
5779+fn protect_escapes(text: &str) -> String {
5780+ if !text.contains('\\') {
5781+ return text.to_string();
5782+ }
5783+ let mut out = String::with_capacity(text.len());
5784+ let mut i = 0;
5785+ while let Some(c) = text[i..].chars().next() {
5786+ let len = syntax::escape_len(&text[i..]);
5787+ if len == 0 {
5788+ out.push(c);
5789+ i += c.len_utf8();
5790+ continue;
5791+ }
5792+ let escape = &text[i..i + len];
5793+ let index = syntax::ESCAPES.iter().position(|e| *e == escape);
5794+ out.extend(index.and_then(|n| char::from_u32(0xE000 + n as u32)));
5795+ i += len;
5796+ }
5797+ out
5798+}
5799+
5800+/// The escape a placeholder stands for, as written (`\,`).
5801+fn escape_of(c: char) -> Option<&'static str> {
5802+ let index = (c as u32).checked_sub(0xE000)?;
5803+ syntax::ESCAPES.get(index as usize).copied()
5804+}
5805+
5806+fn restore_escapes(text: &str) -> String {
5807+ text.chars()
5808+ .fold(String::with_capacity(text.len()), |mut out, c| {
5809+ match escape_of(c) {
5810+ // What the escape stands for: what follows the backslash
5811+ Some(escape) => out.push_str(&escape[1..]),
5812+ None => out.push(c),
5813+ }
5814+ out
5815+ })
5816+}
5817+
5818+/// Inside the quoted strings of a CSS value, `\"` and `\\` mean in CSS what
5819+/// they mean in htmlang, so they stay as written there.
5820+fn keep_css_string_escapes(protected: &str) -> String {
5821+ let mut out = String::with_capacity(protected.len());
5822+ let mut inside = false;
5823+ for c in protected.chars() {
5824+ match escape_of(c) {
5825+ Some(escape @ ("\\\"" | "\\\\")) if inside => out.push_str(escape),
5826+ _ => {
5827+ if c == '"' {
5828+ inside = !inside;
5829+ }
5830+ out.push(c);
5831+ }
5832+ }
5833+ }
5834+ out
5835+}
5836+
5837+/// Evaluate text: fill in the variables of its plain runs and build its
5838+/// inline elements. Each run is one slot, so a value can't make markup.
5839+fn text_segments(text: &syntax::Text, ctx: &mut ParseContext) -> Vec<TextSegment> {
5840+ let mut segments = Vec::new();
5841+ // The plain text so far, and where it starts
5842+ let mut plain = String::new();
5843+ let mut start: Option<syntax::Span> = None;
5844+ let flush = |plain: &mut String,
5845+ start: &mut Option<syntax::Span>,
5846+ segments: &mut Vec<TextSegment>,
5847+ ctx: &mut ParseContext| {
5848+ if !plain.is_empty() {
5849+ let at = start.unwrap_or(text.span);
5850+ let filled = ctx.interpolate_text(plain, at.line, Some(at.column));
5851+ segments.push(TextSegment::Plain(filled));
5852+ plain.clear();
5853+ }
5854+ *start = None;
5855+ };
5856+ for segment in &text.segments {
5857+ match segment {
5858+ Segment::Plain { raw, span } => {
5859+ start.get_or_insert(*span);
5860+ plain.push_str(raw);
5861+ }
5862+ Segment::Inline(inline) => {
5863+ let line = ctx.current_line;
5864+ match resolve(&inline.head, inline.text.as_ref(), line, &text.raw, ctx) {
5865+ Ok(resolved) => {
5866+ if !inline.closed {
5867+ let d = Diagnostic::warning(
5868+ code::UNCLOSED_BRACKET,
5869+ inline.span.line,
5870+ format!(
5871+ "unclosed `{{`: the inline @{} runs to the end of the line. \
5872+ An inline element ends with `}}` (a brace that is text is \
5873+ written `\\{{`)",
5874+ inline.head.name
5875+ ),
5876+ );
5877+ let d = at_attribute(d, Some(inline.span.column), ctx);
5878+ ctx.push_once(d);
5879+ }
5880+ flush(&mut plain, &mut start, &mut segments, ctx);
5881+ // A function called inline gets no children: its
5882+ // content is the text after its attributes
5883+ match Evaluator.complete(resolved, Vec::new(), ctx) {
5884+ Ok(nodes) => segments.extend(inline_segments(nodes, line)),
5885+ Err(mut e) => {
5886+ e.source_line
5887+ .get_or_insert_with(|| text.raw.as_str().into());
5888+ ctx.diagnostics.push(e);
5889+ }
5890+ }
5891+ }
5892+ Err(mut e) => {
5893+ // A misspelled element is an error inline too (a
5894+ // brace that is text is written `\{`); the braces
5895+ // stay as written
5896+ e.source_line = Some(text.raw.as_str().into());
5897+ ctx.diagnostics.push(e);
5898+ start.get_or_insert(inline.span);
5899+ plain.push('{');
5900+ plain.push_str(&inline.raw);
5901+ if inline.closed {
5902+ plain.push('}');
5903+ }
5904+ }
5905+ }
5906+ }
5907+ }
5908+ }
5909+ flush(&mut plain, &mut start, &mut segments, ctx);
5910+ segments
5911+}
5912+
5913+/// The variable `raw` is, when it is exactly one `$name` or `${name}`.
5914+fn whole_reference(raw: &str, env: &Env) -> Option<String> {
5915+ let after = raw.trim().strip_prefix('$')?;
5916+ match interp::reference(after, env)? {
5917+ (interp::Reference::Var(path), len) if len == after.len() => Some(path),
5918+ _ => None,
5919+ }
5920+}
5921+
5922+/// The attributes of `tokens` after each whole-attribute `if()` has
5923+/// chosen (see [`syntax::Choice`]), in order, into `out`. The branch not
5924+/// taken isn't evaluated; with `validate`, its attribute names are checked
5925+/// like code that doesn't run, under the prefixes `prefix` the `if()` is
5926+/// under (`hover:if(...)`).
5927+fn choose_attrs(
5928+ tokens: &[syntax::Attr],
5929+ prefix: &str,
5930+ line_num: usize,
5931+ ctx: &mut ParseContext,
5932+ validate: bool,
5933+ text_keys: &[String],
5934+ out: &mut Vec<syntax::Attr>,
5935+) {
5936+ for token in tokens {
5937+ let Some(choice) = &token.choice else {
5938+ out.push(token.clone());
5939+ continue;
5940+ };
5941+ let Some(condition) = choice_shape(token, choice, line_num, ctx) else {
5942+ continue;
5943+ };
5944+ let taken = match condition.span.line {
5945+ 0 => ctx.condition(&condition.raw, line_num, None),
5946+ line => ctx.condition(&condition.raw, line, Some(condition.span.column)),
5947+ };
5948+ let (chosen, other) = match taken {
5949+ true => (choice.branches.first(), choice.branches.get(1)),
5950+ false => (choice.branches.get(1), choice.branches.first()),
5951+ };
5952+ if let Some(other) = other {
5953+ track_var_refs(&branch_text(other), &mut ctx.used_variables);
5954+ if validate {
5955+ check_branch(token, other, prefix, line_num, ctx, text_keys);
5956+ }
5957+ }
5958+ if let Some(branch) = chosen {
5959+ choose_attrs(
5960+ branch.attrs(),
5961+ prefix,
5962+ line_num,
5963+ ctx,
5964+ validate,
5965+ text_keys,
5966+ out,
5967+ );
5968+ }
5969+ }
5970+}
5971+
5972+/// Report what is wrong with the shape of `if()`: an empty condition, a
5973+/// number of branches other than one or two, text after a group's `]`.
5974+/// Returns the condition when the `if()` can be evaluated.
5975+fn choice_shape<'a>(
5976+ token: &syntax::Attr,
5977+ choice: &'a syntax::Choice,
5978+ line_num: usize,
5979+ ctx: &mut ParseContext,
5980+) -> Option<&'a syntax::Arg> {
5981+ let line = if token.span.line == 0 {
5982+ line_num
5983+ } else {
5984+ token.span.line
5985+ };
5986+ // The line the column points into, when it is the one being evaluated
5987+ let source = |ctx: &ParseContext, diagnostic: Diagnostic, at: usize| match &ctx.current_source {
5988+ (current, Some(text)) if *current == at => diagnostic.source(text.clone()),
5989+ _ => diagnostic,
5990+ };
5991+ for branch in &choice.branches {
5992+ if let syntax::Branch::Group {
5993+ trailing: Some(trailing),
5994+ ..
5995+ } = branch
5996+ {
5997+ let diagnostic = source(
5998+ ctx,
5999+ Diagnostic::error(
6000+ code::UNEXPECTED_ARGUMENT,
6001+ trailing.span.line,
6002+ format!(
6003+ "'{}' after the `]` of a group in if(): a branch is one attribute, \
6004+ one `[group]` of attributes or one `$bundle`",
6005+ trailing.raw
6006+ ),
6007+ )
6008+ .column(trailing.span.column)
6009+ .subject(trailing.raw.as_str()),
6010+ trailing.span.line,
6011+ );
6012+ ctx.push_once(diagnostic);
6013+ }
6014+ }
6015+ match &choice.condition {
6016+ Some(condition) if (1..=2).contains(&choice.branches.len()) => Some(condition),
6017+ _ => {
6018+ let diagnostic = source(
6019+ ctx,
6020+ Diagnostic::error(
6021+ code::INVALID_EXPRESSION,
6022+ line,
6023+ format!(
6024+ "`{}`: if() takes a condition and one or two branches, \
6025+ `if(CONDITION, A, B)`",
6026+ token.raw
6027+ ),
6028+ )
6029+ .column(token.span.column),
6030+ line,
6031+ );
6032+ ctx.push_once(diagnostic);
6033+ None
6034+ }
6035+ }
6036+}
6037+
6038+/// A branch's text, for the names it uses.
6039+fn branch_text(branch: &syntax::Branch) -> String {
6040+ let raws: Vec<&str> = branch.attrs().iter().map(|a| a.raw.as_str()).collect();
6041+ raws.join(", ")
6042+}
6043+
6044+/// Check attributes that are never evaluated (in code that doesn't run,
6045+/// or the branch an `if()` didn't take), as far as they can be checked:
6046+/// names are, and literal values; a value with a variable depends on what
6047+/// the variable holds. Each branch of an `if()` is checked on its own.
6048+fn check_attrs(tokens: &[syntax::Attr], line: usize, ctx: &mut ParseContext, text_keys: &[String]) {
6049+ parse_attr_list(&literal_attrs(tokens), line, ctx, true, text_keys);
6050+ check_choices(tokens, "", line, ctx, text_keys);
6051+}
6052+
6053+/// [`check_attrs`] for a branch of the `if()` `token`, under the prefixes
6054+/// `prefix` it is under: `hover:if($on, color red, [id=x])` checks
6055+/// `hover:[id=x]`, an error whichever branch is taken.
6056+fn check_branch(
6057+ token: &syntax::Attr,
6058+ branch: &syntax::Branch,
6059+ prefix: &str,
6060+ line: usize,
6061+ ctx: &mut ParseContext,
6062+ text_keys: &[String],
6063+) {
6064+ if prefix.is_empty() {
6065+ check_attrs(branch.attrs(), line, ctx, text_keys);
6066+ return;
6067+ }
6068+ let list = syntax::AttrList {
6069+ attrs: branch.attrs().to_vec(),
6070+ span: token.span,
6071+ closed: true,
6072+ quoted_close: None,
6073+ };
6074+ let grouped = syntax::Attr {
6075+ key: prefix.to_string(),
6076+ value: None,
6077+ html: false,
6078+ raw: token.raw.clone(),
6079+ span: token.span,
6080+ choice: None,
6081+ prefixed: Some(Box::new(syntax::Prefixed {
6082+ prefix: prefix.to_string(),
6083+ prefix_span: token.span,
6084+ target: syntax::Branch::Group {
6085+ list,
6086+ trailing: None,
6087+ },
6088+ })),
6089+ };
6090+ check_attrs(std::slice::from_ref(&grouped), line, ctx, text_keys);
6091+}
6092+
6093+/// [`check_attrs`] for the branches of each `if()` of `tokens`, which are
6094+/// under the prefixes `prefix`, also inside a prefixed group or as a
6095+/// prefixed `if()`.
6096+fn check_choices(
6097+ tokens: &[syntax::Attr],
6098+ prefix: &str,
6099+ line: usize,
6100+ ctx: &mut ParseContext,
6101+ text_keys: &[String],
6102+) {
6103+ for token in tokens {
6104+ if let Some(choice) = &token.choice
6105+ && choice_shape(token, choice, line, ctx).is_some()
6106+ {
6107+ for branch in &choice.branches {
6108+ check_branch(token, branch, prefix, line, ctx, text_keys);
6109+ }
6110+ }
6111+ if let Some(prefixed) = &token.prefixed {
6112+ let inner = format!("{}{}", prefix, prefixed.prefix);
6113+ check_choices(prefixed.target.attrs(), &inner, line, ctx, text_keys);
6114+ }
6115+ }
6116+}
6117+
6118+// ---------------------------------------------------------------------------
6119+// Post-parse validation (context-dependent warnings)
6120+// ---------------------------------------------------------------------------
6121+
6122+fn element_kind_name(kind: &ElementKind) -> String {
6123+ format!("@{}", kind.name())
6124+}
6125+
6126+/// HTML elements whose start tag ends an open `<p>`: written inside a
6127+/// `@paragraph`, the browser moves them out of it. (`div` isn't here:
6128+/// inside text, htmlang writes its `<div>`s as `<span>`s.)
6129+#[rustfmt::skip]
6130+const ENDS_A_PARAGRAPH: &[&str] = &[
6131+ "address", "article", "aside", "blockquote", "dd", "details", "dialog", "dl", "dt",
6132+ "fieldset", "figcaption", "figure", "footer", "form", "h1", "h2", "h3", "h4", "h5", "h6",
6133+ "header", "hgroup", "hr", "li", "main", "menu", "nav", "ol", "p", "pre", "search",
6134+ "section", "summary", "table", "ul",
6135+];
6136+
6137+/// The HTML element `kind` is written as, if the browser would take it out
6138+/// of a `<p>`.
6139+fn ends_a_paragraph(kind: &ElementKind) -> Option<&'static str> {
6140+ let html = match kind {
6141+ ElementKind::Paragraph => "p",
6142+ ElementKind::Tag(spec) => spec.html,
6143+ _ => return None,
6144+ };
6145+ ENDS_A_PARAGRAPH.contains(&html).then_some(html)
6146+}
6147+
6148+/// Stricter checks for `htmlang lint`, on top of the diagnostics every
6149+/// compile reports: deep nesting, empty layout containers, and buttons
6150+/// without an explicit `type`.
6151+pub fn lint(nodes: &[Node]) -> Vec<Diagnostic> {
6152+ fn walk(nodes: &[Node], depth: usize, out: &mut Vec<Diagnostic>) {
6153+ for node in nodes {
6154+ let Node::Element(elem) = node else { continue };
6155+ let start = out.len();
6156+ let mut warn = |code: &'static str, message: String| {
6157+ out.push(Diagnostic::warning(code, elem.line_num, message))
6158+ };
6159+ if depth > 10 {
6160+ warn(
6161+ code::DEEP_NESTING,
6162+ format!(
6163+ "deeply nested element ({} levels): consider simplifying",
6164+ depth
6165+ ),
6166+ );
6167+ }
6168+ // A function's body may draw with an empty element (a spacer,
6169+ // a dot): only one written in the page is flagged
6170+ if elem.kind.layout().is_container()
6171+ && elem.children.is_empty()
6172+ && elem.function.is_none()
6173+ {
6174+ warn(
6175+ code::EMPTY_CONTAINER,
6176+ format!("empty container (@{}) has no children", elem.kind.name()),
6177+ );
6178+ }
6179+ if elem.kind.is_tag("button") && !elem.attrs.iter().any(|a| a.key == "type") {
6180+ warn(
6181+ code::MISSING_BUTTON_TYPE,
6182+ "@button missing 'type' attribute (defaults to submit)".to_string(),
6183+ );
6184+ }
6185+ in_function_body(elem, &mut out[start..]);
6186+ walk(&elem.children, depth + 1, out);
6187+ }
6188+ }
6189+ let mut out = Vec::new();
6190+ walk(nodes, 0, &mut out);
6191+ dedupe(&mut out);
6192+ out
6193+}
6194+
6195+/// `in_paragraph`: the nodes are inside a `@paragraph` (and not inside a
6196+/// `@button` in it, which the browser keeps whole).
6197+fn validate_tree(
6198+ nodes: &[Node],
6199+ parent_kind: Option<&ElementKind>,
6200+ in_paragraph: bool,
6201+ diagnostics: &mut Vec<Diagnostic>,
6202+) {
6203+ for node in nodes {
6204+ // An element inside a line of text (`{@kbd ...}`, an inline call)
6205+ // is checked like one on a line of its own
6206+ if let Node::Text(segments) = node {
6207+ let inline: Vec<Node> = segments
6208+ .iter()
6209+ .filter_map(|segment| match segment {
6210+ TextSegment::Inline(elem) => Some(Node::Element(elem.clone())),
6211+ _ => None,
6212+ })
6213+ .collect();
6214+ validate_tree(&inline, parent_kind, in_paragraph, diagnostics);
6215+ }
6216+ if let Node::Element(elem) = node {
6217+ let start = diagnostics.len();
6218+ dropped_by_the_element(elem, diagnostics);
6219+ if in_paragraph && let Some(html) = ends_a_paragraph(&elem.kind) {
6220+ diagnostics.push(
6221+ Diagnostic::warning(
6222+ code::BLOCK_IN_PARAGRAPH,
6223+ elem.line_num,
6224+ format!(
6225+ "{0} inside @paragraph: HTML ends a <p> before a <{1}>, so the \
6226+ browser moves the <{1}> out of the paragraph. Put {0} after the \
6227+ paragraph, or use @el, @row or @grid, which are laid out inline \
6228+ in text",
6229+ element_kind_name(&elem.kind),
6230+ html
6231+ ),
6232+ )
6233+ .subject(elem.kind.name()),
6234+ );
6235+ }
6236+ for attr in &elem.attrs {
6237+ let base = crate::vocab::base_attribute(&attr.key);
6238+
6239+ // htmlang's words for laying out children, on an element
6240+ // that doesn't lay out its children: left out (codegen)
6241+ if !attr.html
6242+ && crate::vocab::CONTAINER_ATTRIBUTES.contains(&base)
6243+ && !elem.kind.layout().is_container()
6244+ && !has_no_element(&elem.kind)
6245+ && !crate::vocab::split_prefixes(&attr.key)
6246+ .0
6247+ .contains(&"children:")
6248+ {
6249+ diagnostics.push(not_a_container(&elem.kind, elem.line_num, base));
6250+ }
6251+
6252+ // Form-specific: placeholder only on @input/@textarea
6253+ if base == "placeholder"
6254+ && !(elem.kind.is_tag("input") || elem.kind.is_tag("textarea"))
6255+ {
6256+ diagnostics.push(Diagnostic::new(
6257+ code::NO_EFFECT,
6258+ Severity::Warning,
6259+ elem.line_num,
6260+ format!(
6261+ "'placeholder' has no effect on {} (only works on @input, @textarea)",
6262+ element_kind_name(&elem.kind)
6263+ ),
6264+ ));
6265+ }
6266+
6267+ // 'for' only on @label and @output
6268+ if base == "for" && !(elem.kind.is_tag("label") || elem.kind.is_tag("output")) {
6269+ diagnostics.push(Diagnostic::new(
6270+ code::NO_EFFECT,
6271+ Severity::Warning,
6272+ elem.line_num,
6273+ format!(
6274+ "'for' has no effect on {} (only works on @label and @output)",
6275+ element_kind_name(&elem.kind)
6276+ ),
6277+ ));
6278+ }
6279+
6280+ // `width=` and `height=` are HTML attributes of media and
6281+ // embedded content only; elsewhere they are styles
6282+ if attr.html
6283+ && (base == "width" || base == "height")
6284+ && !matches!(elem.kind, ElementKind::Image)
6285+ && ![
6286+ "video", "canvas", "iframe", "embed", "object", "input", "source",
6287+ ]
6288+ .iter()
6289+ .any(|tag| elem.kind.is_tag(tag))
6290+ {
6291+ let value = attr.value.as_deref().unwrap_or("");
6292+ diagnostics.push(
6293+ Diagnostic::warning(
6294+ code::HTML_ATTRIBUTE_FORM,
6295+ elem.line_num,
6296+ format!(
6297+ "'{0}={1}' has no effect on {2}, which has no {0} attribute: \
6298+ the style is written `{0} {1}`",
6299+ base,
6300+ value,
6301+ element_kind_name(&elem.kind)
6302+ ),
6303+ )
6304+ .subject(format!("{}={}", base, value)),
6305+ );
6306+ }
6307+
6308+ // 'rows'/'cols' only on @textarea
6309+ if (base == "rows" || base == "cols") && !elem.kind.is_tag("textarea") {
6310+ diagnostics.push(Diagnostic::new(
6311+ code::NO_EFFECT,
6312+ Severity::Warning,
6313+ elem.line_num,
6314+ format!(
6315+ "'{}' has no effect on {} (only works on @textarea)",
6316+ base,
6317+ element_kind_name(&elem.kind)
6318+ ),
6319+ ));
6320+ }
6321+
6322+ // Media-specific attributes only on @video/@audio
6323+ if matches!(
6324+ base,
6325+ "controls"
6326+ | "autoplay"
6327+ | "loop"
6328+ | "muted"
6329+ | "playsinline"
6330+ | "poster"
6331+ | "preload"
6332+ ) && !matches!(elem.kind.name(), "video" | "audio")
6333+ {
6334+ diagnostics.push(Diagnostic::new(
6335+ code::NO_EFFECT,
6336+ Severity::Warning,
6337+ elem.line_num,
6338+ format!(
6339+ "'{}' has no effect on {} (only works on @video, @audio)",
6340+ base,
6341+ element_kind_name(&elem.kind)
6342+ ),
6343+ ));
6344+ }
6345+ }
6346+ // Missing alt text on @image
6347+ if matches!(elem.kind, ElementKind::Image) && !elem.attrs.iter().any(|a| a.key == "alt")
6348+ {
6349+ diagnostics.push(Diagnostic::new(
6350+ code::MISSING_ALT,
6351+ Severity::Warning,
6352+ elem.line_num,
6353+ "@image missing 'alt' attribute (accessibility)".to_string(),
6354+ ));
6355+ }
6356+ if elem.kind.is_tag("input") && !elem.attrs.iter().any(|a| a.key == "type") {
6357+ diagnostics.push(Diagnostic::new(
6358+ code::MISSING_INPUT_TYPE,
6359+ Severity::Warning,
6360+ elem.line_num,
6361+ "@input missing 'type' attribute (defaults to 'text')".to_string(),
6362+ ));
6363+ }
6364+ if matches!(elem.kind, ElementKind::Link) {
6365+ // For @link, argument is the URL, not text content
6366+ let has_text = !elem.children.is_empty();
6367+ if !has_text
6368+ && !elem
6369+ .attrs
6370+ .iter()
6371+ .any(|a| a.key == "aria-label" || a.key == "title")
6372+ {
6373+ diagnostics.push(Diagnostic::new(
6374+ code::MISSING_LINK_TEXT,
6375+ Severity::Warning,
6376+ elem.line_num,
6377+ "@link has no visible text or aria-label (accessibility)".to_string(),
6378+ ));
6379+ }
6380+ }
6381+
6382+ // Contrast ratio check for hex color pairs, each pair on the
6383+ // same elements: the element's own, or those an element prefix
6384+ // (`@td:`) picks out inside it
6385+ let inside = |key: &str| {
6386+ crate::vocab::split_prefixes(key)
6387+ .0
6388+ .into_iter()
6389+ .find_map(crate::vocab::element_prefix)
6390+ .map(str::to_string)
6391+ };
6392+ let mut targets: Vec<Option<String>> = Vec::new();
6393+ for attr in elem.attrs.iter().filter(|a| !a.html) {
6394+ let target = inside(&attr.key);
6395+ if !targets.contains(&target) {
6396+ targets.push(target);
6397+ }
6398+ }
6399+ for target in targets {
6400+ let color = |property: &str| {
6401+ elem.attrs
6402+ .iter()
6403+ .filter(|a| !a.html && inside(&a.key) == target)
6404+ .find(|a| crate::vocab::base_attribute(&a.key) == property)
6405+ .and_then(|a| a.value.as_deref())
6406+ };
6407+ let (bg_color, fg_color) = (color("background"), color("color"));
6408+ if let (Some(bg), Some(fg)) = (bg_color, fg_color)
6409+ && let (Some(bg_rgb), Some(fg_rgb)) = (parse_hex_rgb(bg), parse_hex_rgb(fg))
6410+ {
6411+ let ratio = contrast_ratio(bg_rgb, fg_rgb);
6412+ if ratio < 4.5 {
6413+ diagnostics.push(Diagnostic::new(code::LOW_CONTRAST, Severity::Warning, elem.line_num, format!(
6414+ "low contrast ratio {:.1}:1 between '{}' and '{}' (WCAG AA requires 4.5:1)",
6415+ ratio, fg, bg
6416+ )));
6417+ }
6418+ }
6419+ }
6420+
6421+ // @form inputs should have associated @label
6422+ if matches!(elem.kind.name(), "input" | "select" | "textarea") {
6423+ let has_id = elem.attrs.iter().any(|a| a.key == "id");
6424+ let has_aria_label = elem
6425+ .attrs
6426+ .iter()
6427+ .any(|a| a.key == "aria-label" || a.key == "aria-labelledby");
6428+ let has_title = elem.attrs.iter().any(|a| a.key == "title");
6429+ let in_label = parent_kind.is_some_and(|k| k.is_tag("label"));
6430+ if !has_id && !has_aria_label && !has_title && !in_label {
6431+ diagnostics.push(Diagnostic::new(code::MISSING_LABEL, Severity::Warning, elem.line_num, format!(
6432+ "{} should have an 'id' (with matching @label[for]), 'aria-label', or be wrapped in @label (accessibility)",
6433+ element_kind_name(&elem.kind)
6434+ )));
6435+ }
6436+ }
6437+
6438+ // @iframe should have title attribute
6439+ if elem.kind.is_tag("iframe") && !elem.attrs.iter().any(|a| a.key == "title") {
6440+ diagnostics.push(Diagnostic::new(
6441+ code::MISSING_TITLE,
6442+ Severity::Warning,
6443+ elem.line_num,
6444+ "@iframe missing 'title' attribute (accessibility)".to_string(),
6445+ ));
6446+ }
6447+
6448+ // @button should have accessible text
6449+ if elem.kind.is_tag("button") {
6450+ let has_text = !elem.children.is_empty();
6451+ let has_aria = elem.attrs.iter().any(|a| a.key == "aria-label");
6452+ if !has_text && !has_aria {
6453+ diagnostics.push(Diagnostic::new(
6454+ code::MISSING_BUTTON_TEXT,
6455+ Severity::Warning,
6456+ elem.line_num,
6457+ "@button has no text content or aria-label (accessibility)".to_string(),
6458+ ));
6459+ }
6460+ }
6461+
6462+ // @video should have captions or aria-label
6463+ if elem.kind.is_tag("video") {
6464+ let has_aria = elem
6465+ .attrs
6466+ .iter()
6467+ .any(|a| a.key == "aria-label" || a.key == "aria-describedby");
6468+ let has_track = elem
6469+ .children
6470+ .iter()
6471+ .any(|c| matches!(c, Node::Element(e) if e.kind.is_tag("track")));
6472+ if !has_aria && !has_track {
6473+ diagnostics.push(Diagnostic::new(
6474+ code::MISSING_CAPTIONS,
6475+ Severity::Warning,
6476+ elem.line_num,
6477+ "@video should have aria-label or a captions @track for accessibility"
6478+ .to_string(),
6479+ ));
6480+ }
6481+ }
6482+
6483+ // Tabindex > 0 is an anti-pattern
6484+ if let Some(tabindex_attr) = elem.attrs.iter().find(|a| a.key == "tabindex")
6485+ && let Some(ref val) = tabindex_attr.value
6486+ && let Ok(n) = val.parse::<i32>()
6487+ && n > 0
6488+ {
6489+ diagnostics.push(Diagnostic::new(code::POSITIVE_TABINDEX, Severity::Warning, elem.line_num, format!("tabindex {} is positive — avoid positive tabindex values as they disrupt natural tab order", n)));
6490+ }
6491+ in_function_body(elem, &mut diagnostics[start..]);
6492+
6493+ // An element that ends the <p> takes what is inside it out of
6494+ // the paragraph too, so only it is reported
6495+ let in_paragraph = elem.kind == ElementKind::Paragraph
6496+ || (in_paragraph
6497+ && ends_a_paragraph(&elem.kind).is_none()
6498+ && !elem.kind.is_tag("button"));
6499+ validate_tree(&elem.children, Some(&elem.kind), in_paragraph, diagnostics);
6500+ }
6501+ }
6502+}
6503+
6504+/// What an element has no place for in HTML, which would otherwise be
6505+/// left out of the page: attributes on `@fragment` (which has no element
6506+/// of its own), styles on `@script` (which isn't shown), a body under a
6507+/// `@script` that has a src (which the browser doesn't run), an element
6508+/// under a `@script` (whose body is code), and content in a void element
6509+/// such as `@input`.
6510+fn dropped_by_the_element(elem: &Element, diagnostics: &mut Vec<Diagnostic>) {
6511+ let name = elem.kind.name();
6512+ let keys = |attrs: Vec<&Attribute>| {
6513+ attrs
6514+ .iter()
6515+ .map(|a| format!("'{}'", a.key))
6516+ .collect::<Vec<_>>()
6517+ .join(", ")
6518+ };
6519+ let mut error = |code: &'static str, message: String| {
6520+ diagnostics.push(Diagnostic::error(code, elem.line_num, message).subject(name))
6521+ };
6522+ if elem.kind == ElementKind::Fragment && !elem.attrs.is_empty() {
6523+ error(
6524+ code::UNEXPECTED_ARGUMENT,
6525+ format!(
6526+ "@fragment has no element of its own to put attributes on, so {} would go \
6527+ nowhere: put them on its children, or use @el",
6528+ keys(elem.attrs.iter().collect())
6529+ ),
6530+ );
6531+ }
6532+ // The leading argument given twice: an attribute passed to the root
6533+ // of a function whose body gives the argument (written on one line,
6534+ // it is reported where it is read, and the attribute wins there)
6535+ if let Some(argument) = &elem.argument
6536+ && let Some(attr) = elem
6537+ .attrs
6538+ .iter()
6539+ .find(|a| a.html && elem.kind.arg().attributes().contains(&a.key.as_str()))
6540+ {
6541+ error(
6542+ code::DUPLICATE_ATTRIBUTE,
6543+ format!(
6544+ "@{} takes '{}' as its {}, and it also has {}={}: give it once",
6545+ name,
6546+ argument,
6547+ leading_name(&elem.kind),
6548+ attr.key,
6549+ attr.value.as_deref().unwrap_or("")
6550+ ),
6551+ );
6552+ }
6553+ if elem.kind.is_verbatim() {
6554+ let styles: Vec<&Attribute> = elem
6555+ .attrs
6556+ .iter()
6557+ .filter(|a| !a.html && !crate::vocab::is_html_flag(&a.key))
6558+ .collect();
6559+ if !styles.is_empty() {
6560+ error(
6561+ code::UNEXPECTED_ARGUMENT,
6562+ format!(
6563+ "@{} isn't shown on the page, so its styles {} would go nowhere",
6564+ name,
6565+ keys(styles)
6566+ ),
6567+ );
6568+ }
6569+ let src = elem.argument.clone().or_else(|| {
6570+ elem.attrs
6571+ .iter()
6572+ .find(|a| a.html && a.key == "src")
6573+ .map(|a| a.value.clone().unwrap_or_default())
6574+ });
6575+ if let Some(src) = src
6576+ && !elem.children.is_empty()
6577+ {
6578+ error(
6579+ code::UNEXPECTED_CONTENT,
6580+ format!(
6581+ "@{0} has both a src ('{1}') and a body: the browser runs only the file, \
6582+ so the body would go nowhere. Put the code in {1}, or leave out the src",
6583+ name, src
6584+ ),
6585+ );
6586+ } else if let Some(Node::Element(child)) = elem
6587+ .children
6588+ .iter()
6589+ .find(|child| matches!(child, Node::Element(_)))
6590+ {
6591+ // `@script > @b x`: its body is code, not elements
6592+ error(
6593+ code::UNEXPECTED_CONTENT,
6594+ format!(
6595+ "@{} holds its code as the lines under it, kept as written, so @{} would \
6596+ go nowhere",
6597+ name,
6598+ child.kind.name()
6599+ ),
6600+ );
6601+ }
6602+ }
6603+ if elem.kind != ElementKind::Image && elem.attrs.iter().any(|a| !a.html && a.key == "inline") {
6604+ error(
6605+ code::UNEXPECTED_ARGUMENT,
6606+ format!(
6607+ "`inline` puts an image's file into the page, and @{} has none: it only \
6608+ works on @image",
6609+ name
6610+ ),
6611+ );
6612+ }
6613+ if elem.kind.layout() == Layout::Void && !elem.children.is_empty() {
6614+ error(
6615+ code::UNEXPECTED_CONTENT,
6616+ format!(
6617+ "@{} takes no content: it is an element without a closing tag, so its text \
6618+ and indented lines would go nowhere",
6619+ name
6620+ ),
6621+ );
6622+ }
6623+}
6624+
6625+/// `@fragment`, `@script`, `@children` and `@slot`, whose attributes are
6626+/// reported on their own (see `dropped_by_the_element`).
6627+fn has_no_element(kind: &ElementKind) -> bool {
6628+ matches!(
6629+ kind,
6630+ ElementKind::Fragment | ElementKind::Children | ElementKind::Slot(_)
6631+ ) || kind.is_verbatim()
6632+}
6633+
6634+/// htmlang's word `word` for laying out children (`spacing`, `wrap`,
6635+/// `grid-cols`, `grid-rows`) on an element that doesn't lay out its
6636+/// children: an error, and the word is left out.
6637+fn not_a_container(kind: &ElementKind, line: usize, word: &str) -> Diagnostic {
6638+ let name = element_kind_name(kind);
6639+ let (what, instead) = match kind.layout() {
6640+ Layout::Text => (
6641+ "is text, whose lines and children flow together with no gap between them",
6642+ "; to space the children out, put them in an @el or @row",
6643+ ),
6644+ Layout::Void => ("has no content to lay out", ""),
6645+ _ => (
6646+ "keeps HTML's own layout",
6647+ "; for a flex layout of your own, write CSS, such as `display flex, gap 8`",
6648+ ),
6649+ };
6650+ Diagnostic::error(
6651+ code::NO_EFFECT,
6652+ line,
6653+ format!(
6654+ "'{0}' can't go on {1}: {1} {2}. `{0}` works on a row, column or grid \
6655+ (@el, @row, @grid, @section, ...){3}",
6656+ word, name, what, instead
6657+ ),
6658+ )
6659+ .subject(word)
6660+}
6661+
6662+/// Diagnostics about an element a function's body wrote are reported at
6663+/// the call (see `belongs_to_call`); say which body the element is in.
6664+fn in_function_body(elem: &Element, diagnostics: &mut [Diagnostic]) {
6665+ if let Some(function) = &elem.function {
6666+ for d in diagnostics {
6667+ d.message = format!("{}\n in the body of @{}", d.message, function);
6668+ }
6669+ }
6670+}
6671+
6672+/// Report each diagnostic once: a line that runs many times (in a loop, in
6673+/// a function called from one place many times) reports its problems once.
6674+fn dedupe(diagnostics: &mut Vec<Diagnostic>) {
6675+ let mut seen = HashSet::new();
6676+ diagnostics.retain(|d| {
6677+ seen.insert((
6678+ d.code,
6679+ d.line,
6680+ d.column,
6681+ d.message.clone(),
6682+ d.severity as u8,
6683+ ))
6684+ });
6685+}
6686+
6687+fn relative_luminance(r: u8, g: u8, b: u8) -> f64 {
6688+ fn linearize(c: u8) -> f64 {
6689+ let s = c as f64 / 255.0;
6690+ if s <= 0.03928 {
6691+ s / 12.92
6692+ } else {
6693+ ((s + 0.055) / 1.055).powf(2.4)
6694+ }
6695+ }
6696+ 0.2126 * linearize(r) + 0.7152 * linearize(g) + 0.0722 * linearize(b)
6697+}
6698+
6699+/// The red, green and blue of a `#rgb` or `#rrggbb` colour.
6700+fn parse_hex_rgb(s: &str) -> Option<(u8, u8, u8)> {
6701+ let s = s.strip_prefix('#')?;
6702+ if !s.bytes().all(|b| b.is_ascii_hexdigit()) {
6703+ return None;
6704+ }
6705+ let channel = |i: usize, len: usize| u8::from_str_radix(&s[i..i + len], 16).ok();
6706+ match s.len() {
6707+ 3 => Some((
6708+ channel(0, 1)? * 17,
6709+ channel(1, 1)? * 17,
6710+ channel(2, 1)? * 17,
6711+ )),
6712+ 6 => Some((channel(0, 2)?, channel(2, 2)?, channel(4, 2)?)),
6713+ _ => None,
6714+ }
6715+}
6716+
6717+fn contrast_ratio(c1: (u8, u8, u8), c2: (u8, u8, u8)) -> f64 {
6718+ let l1 = relative_luminance(c1.0, c1.1, c1.2);
6719+ let l2 = relative_luminance(c2.0, c2.1, c2.2);
6720+ let (lighter, darker) = if l1 > l2 { (l1, l2) } else { (l2, l1) };
6721+ (lighter + 0.05) / (darker + 0.05)
6722+}
6723+
6724+/// `@image [inline] icon.svg` becomes the SVG's markup, with `width`,
6725+/// `height`, `color` / `fill` and the HTML attributes (`class=`, `id=`,
6726+/// `aria-label=`, ...) applied to the `<svg>` tag; any other attribute is
6727+/// an error. Other nodes are returned unchanged.
6728+fn inline_svg(node: Node, line_num: usize, ctx: &mut ParseContext) -> Node {
6729+ let Node::Element(elem) = &node else {
6730+ return node;
6731+ };
6732+ let inline = elem.kind == ElementKind::Image
6733+ && elem.attrs.iter().any(|a| a.key == "inline" && !a.html)
6734+ && elem.argument.as_deref().is_some_and(|src| !src.is_empty());
6735+ if !inline {
6736+ return node;
6737+ }
6738+ // A raster image: its file, read relative to this one, as a `data:` URI
6739+ if !elem
6740+ .argument
6741+ .as_deref()
6742+ .is_some_and(|src| src.ends_with(".svg"))
6743+ {
6744+ let Node::Element(mut elem) = node else {
6745+ return node;
6746+ };
6747+ let filename = elem.argument.clone().unwrap_or_default();
6748+ let resolved = ctx.resolve(&filename);
6749+ match std::fs::read(&resolved) {
6750+ Ok(data) => {
6751+ elem.argument = Some(crate::codegen::data_uri(&filename, &data));
6752+ ctx.included_files.push(resolved);
6753+ }
6754+ Err(e) => ctx.diagnostics.push(Diagnostic::new(
6755+ code::UNREADABLE_FILE,
6756+ Severity::Error,
6757+ line_num,
6758+ format!(
6759+ "cannot load image '{}' to put it into the page: {}",
6760+ filename, e
6761+ ),
6762+ )),
6763+ }
6764+ return Node::Element(elem);
6765+ }
6766+ let filename = elem.argument.clone().unwrap_or_default();
6767+ let resolved = match &ctx.base_path {
6768+ Some(base) => base.join(&filename),
6769+ None => PathBuf::from(&filename),
6770+ };
6771+ let mut svg = match std::fs::read_to_string(&resolved) {
6772+ Ok(text) => text.trim().to_string(),
6773+ Err(e) => {
6774+ ctx.diagnostics.push(Diagnostic::new(
6775+ code::UNREADABLE_FILE,
6776+ Severity::Error,
6777+ line_num,
6778+ format!("cannot load SVG '{}': {}", filename, e),
6779+ ));
6780+ return node;
6781+ }
6782+ };
6783+ ctx.included_files.push(resolved);
6784+ // The file's markup has no class of its own, so a style reaches it only
6785+ // as one of the root's attributes: anything else is reported, never
6786+ // left out silently
6787+ let mut left_out: Vec<String> = Vec::new();
6788+ // The styles go in the root's `style=`, where a length takes its unit
6789+ // and `var(--name)` works, as in any CSS
6790+ let mut style: Vec<String> = Vec::new();
6791+ for attr in &elem.attrs {
6792+ let target = match (attr.key.as_str(), attr.html, &attr.value) {
6793+ ("inline", false, None) | ("src", true, _) => continue,
6794+ // `fill` and `shrink` are layout words, which need a class
6795+ ("width" | "height", false, Some(value))
6796+ if matches!(value.as_str(), "fill" | "shrink") =>
6797+ {
6798+ left_out.push(format!("{} {}", attr.key, value));
6799+ continue;
6800+ }
6801+ ("width" | "height", false, Some(value)) => {
6802+ let value = crate::vocab::with_px(&attr.key, value);
6803+ style.push(format!("{}:{}", attr.key, value));
6804+ continue;
6805+ }
6806+ ("color" | "fill", false, Some(value)) => {
6807+ style.push(format!("fill:{}", value));
6808+ continue;
6809+ }
6810+ ("style", true, Some(value)) => {
6811+ style.insert(0, value.trim().trim_end_matches(';').to_string());
6812+ continue;
6813+ }
6814+ ("alt", true, _) => {
6815+ left_out.push("alt".to_string());
6816+ continue;
6817+ }
6818+ (key, true, Some(_)) => key,
6819+ (key, false, None) if crate::vocab::is_html_flag(key) => key,
6820+ _ => {
6821+ left_out.push(attr.key.clone());
6822+ continue;
6823+ }
6824+ };
6825+ let value = attr.value.as_deref().unwrap_or("");
6826+ svg = set_svg_attr(&svg, target, &html_escape_md(value));
6827+ }
6828+ if !style.is_empty() {
6829+ // After the file's own `style=`, which stays: these come later, so
6830+ // they win where both set a property
6831+ let mut value = html_escape_md(&style.join(";"));
6832+ if let Some(own) = svg_attr_value(&svg, "style")
6833+ .map(|range| svg[range].trim().trim_end_matches(';').to_string())
6834+ .filter(|own| !own.is_empty())
6835+ {
6836+ value = format!("{};{}", own, value);
6837+ }
6838+ svg = set_svg_attr(&svg, "style", &value);
6839+ }
6840+ if !left_out.is_empty() {
6841+ let alt = left_out.iter().any(|name| name == "alt");
6842+ let names = left_out
6843+ .iter()
6844+ .map(|name| format!("'{}'", name))
6845+ .collect::<Vec<_>>()
6846+ .join(", ");
6847+ let mut message = format!(
6848+ "{} can't go on an inline SVG: `@image [inline]` puts the file's own markup into the page, which takes `width` and `height` as lengths, `color` or `fill` (as its fill) and HTML attributes (`class=`, `aria-label=`, ...)",
6849+ names
6850+ );
6851+ if alt {
6852+ message.push_str("; an SVG has no alt text: name it with `aria-label=` and `role=img`");
6853+ }
6854+ ctx.diagnostics.push(Diagnostic::new(
6855+ code::UNEXPECTED_ARGUMENT,
6856+ Severity::Error,
6857+ line_num,
6858+ message,
6859+ ));
6860+ }
6861+ Node::Raw(svg)
6862+}
6863+
6864+// ---------------------------------------------------------------------------
6865+// Variable usage tracking
6866+// ---------------------------------------------------------------------------
6867+
6868+/// Record the names a string refers to (by syntax) as used.
6869+fn track_var_refs(input: &str, used: &mut HashSet<String>) {
6870+ if input.contains('$') {
6871+ used.extend(interp::names(input).into_iter().map(String::from));
6872+ }
6873+}
6874+
6875+// ---------------------------------------------------------------------------
6876+// Unused definition warnings
6877+// ---------------------------------------------------------------------------
6878+
6879+/// Warn about definitions nothing uses, except `exported` ones (the
6880+/// definitions of a library, for the files that include it).
6881+fn check_unused(ctx: &mut ParseContext, exported: &HashSet<String>) {
6882+ // Check unused @let variables
6883+ for (name, &line) in &ctx.let_lines {
6884+ if exported.contains(name) {
6885+ // A library's names are for other files (a custom property
6886+ // isn't a variable, so it is never listed here)
6887+ continue;
6888+ }
6889+ if !ctx.used_variables.contains(name) {
6890+ ctx.diagnostics.push(
6891+ Diagnostic::new(
6892+ code::UNUSED_VARIABLE,
6893+ Severity::Warning,
6894+ line,
6895+ format!("unused variable '${}' (defined but never referenced)", name),
6896+ )
6897+ .subject(name.as_str()),
6898+ );
6899+ }
6900+ }
6901+
6902+ // Check unused attribute bundles (@let name [...]). A `$name` in code
6903+ // that doesn't run (an `if()` branch or `@if` not taken) counts too.
6904+ for (name, &line) in &ctx.define_lines {
6905+ if !ctx.used_defines.contains(name)
6906+ && !ctx.used_variables.contains(name)
6907+ && !exported.contains(name)
6908+ {
6909+ ctx.diagnostics.push(
6910+ Diagnostic::new(
6911+ code::UNUSED_BUNDLE,
6912+ Severity::Warning,
6913+ line,
6914+ format!(
6915+ "unused attribute bundle '${}' (defined but never referenced)",
6916+ name
6917+ ),
6918+ )
6919+ .subject(name.as_str()),
6920+ );
6921+ }
6922+ }
6923+
6924+ // Check unused functions (@let name ... with body)
6925+ for (name, &line) in &ctx.fn_lines {
6926+ if !ctx.used_functions.contains(name) && !exported.contains(name) {
6927+ ctx.diagnostics.push(
6928+ Diagnostic::new(
6929+ code::UNUSED_FUNCTION,
6930+ Severity::Warning,
6931+ line,
6932+ format!("unused function '@{}' (defined but never called)", name),
6933+ )
6934+ .subject(name.as_str()),
6935+ );
6936+ }
6937+ }
6938+}
6939+
6940+// ---------------------------------------------------------------------------
6941+// Minimal JSON parser for @data directive
6942+// ---------------------------------------------------------------------------
6943+
6944+#[derive(Debug, Clone)]
6945+enum JsonValue {
6946+ Null,
6947+ Bool(bool),
6948+ Number(String),
6949+ Str(String),
6950+ Array(Vec<JsonValue>),
6951+ Object(Vec<(String, JsonValue)>),
6952+}
6953+
6954+/// Parse JSON with an error message indicating where parsing failed.
6955+fn parse_json_with_error(input: &str) -> Result<JsonValue, String> {
6956+ let trimmed = input.trim();
6957+ if trimmed.is_empty() {
6958+ return Err("empty input".to_string());
6959+ }
6960+ let chars: Vec<char> = trimmed.chars().collect();
6961+ match parse_json_value(&chars, 0) {
6962+ Some((val, _)) => Ok(val),
6963+ None => {
6964+ // Find approximate error position by parsing as far as possible
6965+ let mut deepest = 0usize;
6966+ fn probe(chars: &[char], pos: usize, deepest: &mut usize) {
6967+ let mut p = pos;
6968+ while p < chars.len() {
6969+ if p > *deepest {
6970+ *deepest = p;
6971+ }
6972+ match chars[p] {
6973+ '{' | '[' => {
6974+ p += 1;
6975+ probe(chars, p, deepest);
6976+ return;
6977+ }
6978+ '"' => {
6979+ p += 1;
6980+ while p < chars.len() && chars[p] != '"' {
6981+ if chars[p] == '\\' {
6982+ p += 1;
6983+ }
6984+ p += 1;
6985+ }
6986+ if p < chars.len() {
6987+ p += 1;
6988+ }
6989+ if p > *deepest {
6990+ *deepest = p;
6991+ }
6992+ return;
6993+ }
6994+ _ => {
6995+ p += 1;
6996+ }
6997+ }
6998+ }
6999+ }
7000+ probe(&chars, 0, &mut deepest);
7001+ // Convert char position to line:col
7002+ let prefix: String = chars[..deepest.min(chars.len())].iter().collect();
7003+ let line = prefix.chars().filter(|&c| c == '\n').count() + 1;
7004+ let col = prefix
7005+ .rfind('\n')
7006+ .map_or(prefix.len(), |p| prefix.len() - p - 1)
7007+ + 1;
7008+ let context: String = chars[deepest.saturating_sub(20)..deepest.min(chars.len())]
7009+ .iter()
7010+ .collect();
7011+ Err(format!(
7012+ "at line {}:{} near \"{}\"",
7013+ line,
7014+ col,
7015+ context.trim()
7016+ ))
7017+ }
7018+ }
7019+}
7020+
7021+fn parse_json_value(chars: &[char], mut pos: usize) -> Option<(JsonValue, usize)> {
7022+ pos = skip_ws(chars, pos);
7023+ if pos >= chars.len() {
7024+ return None;
7025+ }
7026+ match chars[pos] {
7027+ '"' => {
7028+ let (s, p) = parse_json_string(chars, pos)?;
7029+ Some((JsonValue::Str(s), p))
7030+ }
7031+ '{' => parse_json_object(chars, pos),
7032+ '[' => parse_json_array(chars, pos),
7033+ 't' => {
7034+ if chars.get(pos..pos + 4)?.iter().collect::<String>() == "true" {
7035+ Some((JsonValue::Bool(true), pos + 4))
7036+ } else {
7037+ None
7038+ }
7039+ }
7040+ 'f' => {
7041+ if chars.get(pos..pos + 5)?.iter().collect::<String>() == "false" {
7042+ Some((JsonValue::Bool(false), pos + 5))
7043+ } else {
7044+ None
7045+ }
7046+ }
7047+ 'n' => {
7048+ if chars.get(pos..pos + 4)?.iter().collect::<String>() == "null" {
7049+ Some((JsonValue::Null, pos + 4))
7050+ } else {
7051+ None
7052+ }
7053+ }
7054+ c if c == '-' || c.is_ascii_digit() => {
7055+ let start = pos;
7056+ if chars[pos] == '-' {
7057+ pos += 1;
7058+ }
7059+ while pos < chars.len()
7060+ && (chars[pos].is_ascii_digit()
7061+ || chars[pos] == '.'
7062+ || chars[pos] == 'e'
7063+ || chars[pos] == 'E'
7064+ || chars[pos] == '+'
7065+ || chars[pos] == '-')
7066+ {
7067+ if (chars[pos] == '+' || chars[pos] == '-')
7068+ && pos > start + 1
7069+ && chars[pos - 1] != 'e'
7070+ && chars[pos - 1] != 'E'
7071+ {
7072+ break;
7073+ }
7074+ pos += 1;
7075+ }
7076+ let num: String = chars[start..pos].iter().collect();
7077+ Some((JsonValue::Number(num), pos))
7078+ }
7079+ _ => None,
7080+ }
7081+}
7082+
7083+fn parse_json_string(chars: &[char], mut pos: usize) -> Option<(String, usize)> {
7084+ if chars.get(pos) != Some(&'"') {
7085+ return None;
7086+ }
7087+ pos += 1;
7088+ let mut s = String::new();
7089+ while pos < chars.len() && chars[pos] != '"' {
7090+ if chars[pos] == '\\' && pos + 1 < chars.len() {
7091+ pos += 1;
7092+ match chars[pos] {
7093+ '"' | '\\' | '/' => s.push(chars[pos]),
7094+ 'n' => s.push('\n'),
7095+ 't' => s.push('\t'),
7096+ 'r' => s.push('\r'),
7097+ 'b' => s.push('\u{8}'),
7098+ 'f' => s.push('\u{c}'),
7099+ 'u' => {
7100+ let hex4 = |at: usize| -> Option<u32> {
7101+ let digits: String = chars.get(at..at + 4)?.iter().collect();
7102+ u32::from_str_radix(&digits, 16).ok()
7103+ };
7104+ let hi = hex4(pos + 1)?;
7105+ pos += 4;
7106+ let code = if (0xD800..0xDC00).contains(&hi)
7107+ && chars.get(pos + 1) == Some(&'\\')
7108+ && chars.get(pos + 2) == Some(&'u')
7109+ && let Some(lo) = hex4(pos + 3)
7110+ && (0xDC00..0xE000).contains(&lo)
7111+ {
7112+ pos += 6;
7113+ 0x10000 + ((hi - 0xD800) << 10) + (lo - 0xDC00)
7114+ } else {
7115+ hi
7116+ };
7117+ s.push(char::from_u32(code).unwrap_or('\u{FFFD}'));
7118+ }
7119+ _ => {
7120+ s.push('\\');
7121+ s.push(chars[pos]);
7122+ }
7123+ }
7124+ } else {
7125+ s.push(chars[pos]);
7126+ }
7127+ pos += 1;
7128+ }
7129+ if pos < chars.len() {
7130+ pos += 1; // closing quote
7131+ }
7132+ Some((s, pos))
7133+}
7134+
7135+fn parse_json_object(chars: &[char], mut pos: usize) -> Option<(JsonValue, usize)> {
7136+ pos += 1; // skip '{'
7137+ pos = skip_ws(chars, pos);
7138+ let mut pairs = Vec::new();
7139+ if pos < chars.len() && chars[pos] == '}' {
7140+ return Some((JsonValue::Object(pairs), pos + 1));
7141+ }
7142+ loop {
7143+ pos = skip_ws(chars, pos);
7144+ let (key, p) = parse_json_string(chars, pos)?;
7145+ pos = skip_ws(chars, p);
7146+ if pos >= chars.len() || chars[pos] != ':' {
7147+ return None;
7148+ }
7149+ pos += 1;
7150+ let (val, p) = parse_json_value(chars, pos)?;
7151+ pos = p;
7152+ pairs.push((key, val));
7153+ pos = skip_ws(chars, pos);
7154+ if pos >= chars.len() {
7155+ break;
7156+ }
7157+ if chars[pos] == '}' {
7158+ pos += 1;
7159+ break;
7160+ }
7161+ if chars[pos] == ',' {
7162+ pos += 1;
7163+ }
7164+ }
7165+ Some((JsonValue::Object(pairs), pos))
7166+}
7167+
7168+fn parse_json_array(chars: &[char], mut pos: usize) -> Option<(JsonValue, usize)> {
7169+ pos += 1; // skip '['
7170+ pos = skip_ws(chars, pos);
7171+ let mut items = Vec::new();
7172+ if pos < chars.len() && chars[pos] == ']' {
7173+ return Some((JsonValue::Array(items), pos + 1));
7174+ }
7175+ loop {
7176+ let (val, p) = parse_json_value(chars, pos)?;
7177+ pos = p;
7178+ items.push(val);
7179+ pos = skip_ws(chars, pos);
7180+ if pos >= chars.len() {
7181+ break;
7182+ }
7183+ if chars[pos] == ']' {
7184+ pos += 1;
7185+ break;
7186+ }
7187+ if chars[pos] == ',' {
7188+ pos += 1;
7189+ }
7190+ }
7191+ Some((JsonValue::Array(items), pos))
7192+}
7193+
7194+fn skip_ws(chars: &[char], mut pos: usize) -> usize {
7195+ while pos < chars.len() && chars[pos].is_ascii_whitespace() {
7196+ pos += 1;
7197+ }
7198+ pos
7199+}
7200+
7201+/// A JSON value as an htmlang value: an object is a record, an array a
7202+/// list, a string text (never quoted text), `null` empty. A number keeps
7203+/// the text it is written with (`1.50`), and reads as a number.
7204+fn json_value(json: JsonValue) -> Value {
7205+ match json {
7206+ JsonValue::Null => Value::empty(),
7207+ JsonValue::Bool(b) => Value::Bool(b),
7208+ JsonValue::Number(n) | JsonValue::Str(n) => Value::Str(n),
7209+ JsonValue::Array(items) => Value::list(items.into_iter().map(json_value).collect()),
7210+ JsonValue::Object(pairs) => Value::Record(Rc::new(
7211+ pairs
7212+ .into_iter()
7213+ .map(|(key, value)| (key, json_value(value)))
7214+ .collect(),
7215+ )),
7216+ }
7217+}
7218+
7219+// ---------------------------------------------------------------------------
7220+// SVG attribute injection helper
7221+// ---------------------------------------------------------------------------
7222+
7223+/// Where the root `<svg ...>` tag's `attr_name="..."` value is, as a byte
7224+/// range of `svg`. Only the opening tag is read, so a child's attribute is
7225+/// never found, and the name must follow whitespace, so `width` doesn't
7226+/// match `stroke-width`.
7227+fn svg_attr_value(svg: &str, attr_name: &str) -> Option<std::ops::Range<usize>> {
7228+ let tag_start = svg.find("<svg")?;
7229+ let tag_end = svg[tag_start..]
7230+ .find('>')
7231+ .map(|p| tag_start + p)
7232+ .unwrap_or(svg.len());
7233+ let tag = &svg[tag_start..tag_end];
7234+ let pattern = format!("{}=\"", attr_name);
7235+ let (pos, _) = tag.match_indices(&pattern).find(|(pos, _)| {
7236+ tag[..*pos]
7237+ .chars()
7238+ .next_back()
7239+ .is_some_and(char::is_whitespace)
7240+ })?;
7241+ let value_start = tag_start + pos + pattern.len();
7242+ let end = svg[value_start..tag_end].find('"')?;
7243+ Some(value_start..value_start + end)
7244+}
7245+
7246+fn set_svg_attr(svg: &str, attr_name: &str, value: &str) -> String {
7247+ // Only the opening <svg ...> tag is touched, so child attributes such as
7248+ // `stroke-width` are left alone.
7249+ let Some(tag_start) = svg.find("<svg") else {
7250+ return svg.to_string();
7251+ };
7252+ let tag_end = svg[tag_start..]
7253+ .find('>')
7254+ .map(|p| tag_start + p)
7255+ .unwrap_or(svg.len());
7256+
7257+ // Replace an existing attribute
7258+ if let Some(existing) = svg_attr_value(svg, attr_name) {
7259+ let mut result = String::with_capacity(svg.len());
7260+ result.push_str(&svg[..existing.start]);
7261+ result.push_str(value);
7262+ result.push_str(&svg[existing.end..]);
7263+ return result;
7264+ }
7265+
7266+ // Otherwise inject it into the opening tag (before a self-closing `/`).
7267+ let insert_at = if svg[..tag_end].ends_with('/') {
7268+ tag_end - 1
7269+ } else {
7270+ tag_end
7271+ };
7272+ let mut result = String::with_capacity(svg.len() + attr_name.len() + value.len() + 4);
7273+ result.push_str(svg[..insert_at].trim_end());
7274+ result.push(' ');
7275+ result.push_str(attr_name);
7276+ result.push_str("=\"");
7277+ result.push_str(value);
7278+ result.push('"');
7279+ result.push_str(&svg[insert_at..]);
7280+ result
7281+}
7282+
7283+// ---------------------------------------------------------------------------
7284+// Markdown → HTML conversion (minimal subset)
7285+// ---------------------------------------------------------------------------
7286+
7287+fn markdown_to_html(lines: &[String]) -> String {
7288+ let mut html = String::new();
7289+ // Tag of the list currently open ("ul" or "ol"), if any.
7290+ let mut list: Option<&'static str> = None;
7291+ let mut in_code_block = false;
7292+ let mut code_lang = String::new();
7293+ let mut code_buf = String::new();
7294+ let mut para_buf = String::new();
7295+
7296+ let flush_para = |para: &mut String, out: &mut String| {
7297+ let trimmed = para.trim();
7298+ if !trimmed.is_empty() {
7299+ out.push_str("<p>");
7300+ out.push_str(&md_inline(trimmed));
7301+ out.push_str("</p>\n");
7302+ }
7303+ para.clear();
7304+ };
7305+ let close_list = |list: &mut Option<&'static str>, out: &mut String| {
7306+ if let Some(tag) = list.take() {
7307+ out.push_str(&format!("</{}>\n", tag));
7308+ }
7309+ };
7310+ let open_list = |list: &mut Option<&'static str>, tag: &'static str, out: &mut String| {
7311+ if *list != Some(tag) {
7312+ if let Some(prev) = list.take() {
7313+ out.push_str(&format!("</{}>\n", prev));
7314+ }
7315+ out.push_str(&format!("<{}>\n", tag));
7316+ *list = Some(tag);
7317+ }
7318+ };
7319+
7320+ for line in lines {
7321+ let trimmed = line.trim();
7322+
7323+ // Fenced code blocks
7324+ if let Some(after_fence) = trimmed.strip_prefix("```") {
7325+ if in_code_block {
7326+ html.push_str("<pre><code");
7327+ if !code_lang.is_empty() {
7328+ html.push_str(&format!(" class=\"language-{}\"", code_lang));
7329+ }
7330+ html.push('>');
7331+ html.push_str(&html_escape_md(&code_buf));
7332+ html.push_str("</code></pre>\n");
7333+ code_buf.clear();
7334+ code_lang.clear();
7335+ in_code_block = false;
7336+ } else {
7337+ flush_para(&mut para_buf, &mut html);
7338+ close_list(&mut list, &mut html);
7339+ code_lang = after_fence.trim().to_string();
7340+ in_code_block = true;
7341+ }
7342+ continue;
7343+ }
7344+ if in_code_block {
7345+ if !code_buf.is_empty() {
7346+ code_buf.push('\n');
7347+ }
7348+ // Keep indentation inside code blocks.
7349+ code_buf.push_str(line.trim_end());
7350+ continue;
7351+ }
7352+
7353+ // Blank line ends paragraph
7354+ if trimmed.is_empty() {
7355+ flush_para(&mut para_buf, &mut html);
7356+ close_list(&mut list, &mut html);
7357+ continue;
7358+ }
7359+
7360+ // Headings
7361+ let heading_level = trimmed.bytes().take_while(|&b| b == b'#').count();
7362+ if (1..=6).contains(&heading_level) && trimmed.as_bytes().get(heading_level) == Some(&b' ')
7363+ {
7364+ flush_para(&mut para_buf, &mut html);
7365+ close_list(&mut list, &mut html);
7366+ let text = &trimmed[heading_level + 1..];
7367+ html.push_str(&format!(
7368+ "<h{}>{}</h{}>\n",
7369+ heading_level,
7370+ md_inline(text),
7371+ heading_level
7372+ ));
7373+ continue;
7374+ }
7375+
7376+ // Horizontal rule (checked before list items so `---`/`***` aren't
7377+ // mistaken for bullets)
7378+ if trimmed == "---" || trimmed == "***" || trimmed == "___" {
7379+ flush_para(&mut para_buf, &mut html);
7380+ close_list(&mut list, &mut html);
7381+ html.push_str("<hr>\n");
7382+ continue;
7383+ }
7384+
7385+ // Unordered list items
7386+ if (trimmed.starts_with("- ") || trimmed.starts_with("* ")) && trimmed.len() > 2 {
7387+ flush_para(&mut para_buf, &mut html);
7388+ open_list(&mut list, "ul", &mut html);
7389+ html.push_str(&format!("<li>{}</li>\n", md_inline(&trimmed[2..])));
7390+ continue;
7391+ }
7392+
7393+ // Ordered list items
7394+ if let Some(dot_pos) = trimmed.find(". ")
7395+ && (1..=3).contains(&dot_pos)
7396+ && trimmed[..dot_pos].chars().all(|c| c.is_ascii_digit())
7397+ {
7398+ flush_para(&mut para_buf, &mut html);
7399+ open_list(&mut list, "ol", &mut html);
7400+ html.push_str(&format!(
7401+ "<li>{}</li>\n",
7402+ md_inline(&trimmed[dot_pos + 2..])
7403+ ));
7404+ continue;
7405+ }
7406+
7407+ // Blockquote
7408+ if let Some(quote_content) = trimmed.strip_prefix("> ") {
7409+ flush_para(&mut para_buf, &mut html);
7410+ close_list(&mut list, &mut html);
7411+ html.push_str(&format!(
7412+ "<blockquote><p>{}</p></blockquote>\n",
7413+ md_inline(quote_content)
7414+ ));
7415+ continue;
7416+ }
7417+
7418+ // Otherwise, accumulate paragraph text
7419+ close_list(&mut list, &mut html);
7420+ if !para_buf.is_empty() {
7421+ para_buf.push(' ');
7422+ }
7423+ para_buf.push_str(trimmed);
7424+ }
7425+
7426+ // Flush remaining
7427+ close_list(&mut list, &mut html);
7428+ flush_para(&mut para_buf, &mut html);
7429+
7430+ html
7431+}
7432+
7433+fn md_inline(text: &str) -> String {
7434+ let mut result = String::new();
7435+ let chars: Vec<char> = text.chars().collect();
7436+ let mut i = 0;
7437+
7438+ while i < chars.len() {
7439+ // Bold: **text** or __text__
7440+ if i + 1 < chars.len()
7441+ && ((chars[i] == '*' && chars[i + 1] == '*')
7442+ || (chars[i] == '_' && chars[i + 1] == '_'))
7443+ {
7444+ let marker = chars[i];
7445+ if let Some(end) = find_closing_double(&chars, i + 2, marker) {
7446+ let inner: String = chars[i + 2..end].iter().collect();
7447+ result.push_str("<strong>");
7448+ result.push_str(&md_inline(&inner));
7449+ result.push_str("</strong>");
7450+ i = end + 2;
7451+ continue;
7452+ }
7453+ }
7454+ // Italic: *text* or _text_
7455+ if (chars[i] == '*' || chars[i] == '_') && i + 1 < chars.len() && chars[i + 1] != chars[i] {
7456+ let marker = chars[i];
7457+ if let Some(end) = find_closing_single(&chars, i + 1, marker) {
7458+ let inner: String = chars[i + 1..end].iter().collect();
7459+ result.push_str("<em>");
7460+ result.push_str(&md_inline(&inner));
7461+ result.push_str("</em>");
7462+ i = end + 1;
7463+ continue;
7464+ }
7465+ }
7466+ // Inline code: `text`
7467+ if chars[i] == '`'
7468+ && let Some(end) = chars[i + 1..].iter().position(|&c| c == '`')
7469+ {
7470+ let inner: String = chars[i + 1..i + 1 + end].iter().collect();
7471+ result.push_str("<code>");
7472+ result.push_str(&html_escape_md(&inner));
7473+ result.push_str("</code>");
7474+ i = i + 2 + end;
7475+ continue;
7476+ }
7477+ // Links: [text](url)
7478+ if chars[i] == '['
7479+ && let Some(close_bracket) = chars[i + 1..].iter().position(|&c| c == ']')
7480+ {
7481+ let after = i + 1 + close_bracket + 1;
7482+ if after < chars.len()
7483+ && chars[after] == '('
7484+ && let Some(close_paren) = chars[after + 1..].iter().position(|&c| c == ')')
7485+ {
7486+ let text: String = chars[i + 1..i + 1 + close_bracket].iter().collect();
7487+ let url: String = chars[after + 1..after + 1 + close_paren].iter().collect();
7488+ result.push_str(&format!(
7489+ "<a href=\"{}\">{}</a>",
7490+ html_escape_md(&url),
7491+ md_inline(&text)
7492+ ));
7493+ i = after + 2 + close_paren;
7494+ continue;
7495+ }
7496+ }
7497+ result.push(chars[i]);
7498+ i += 1;
7499+ }
7500+
7501+ result
7502+}
7503+
7504+fn find_closing_double(chars: &[char], start: usize, marker: char) -> Option<usize> {
7505+ let mut i = start;
7506+ while i + 1 < chars.len() {
7507+ if chars[i] == marker && chars[i + 1] == marker {
7508+ return Some(i);
7509+ }
7510+ i += 1;
7511+ }
7512+ None
7513+}
7514+
7515+fn find_closing_single(chars: &[char], start: usize, marker: char) -> Option<usize> {
7516+ (start..chars.len()).find(|&i| chars[i] == marker)
7517+}
7518+
7519+/// Simple glob matching supporting `*` as wildcard for any characters and `?` for a single character.
7520+fn glob_match(pattern: &str, text: &str) -> bool {
7521+ let mut pi = 0;
7522+ let mut ti = 0;
7523+ let pb = pattern.as_bytes();
7524+ let tb = text.as_bytes();
7525+ let mut star_pi = usize::MAX;
7526+ let mut star_ti = 0;
7527+ while ti < tb.len() {
7528+ if pi < pb.len() && (pb[pi] == b'?' || pb[pi] == tb[ti]) {
7529+ pi += 1;
7530+ ti += 1;
7531+ } else if pi < pb.len() && pb[pi] == b'*' {
7532+ star_pi = pi;
7533+ star_ti = ti;
7534+ pi += 1;
7535+ } else if star_pi != usize::MAX {
7536+ pi = star_pi + 1;
7537+ star_ti += 1;
7538+ ti = star_ti;
7539+ } else {
7540+ return false;
7541+ }
7542+ }
7543+ while pi < pb.len() && pb[pi] == b'*' {
7544+ pi += 1;
7545+ }
7546+ pi == pb.len()
7547+}
7548+
7549+fn html_escape_md(s: &str) -> String {
7550+ s.replace('&', "&")
7551+ .replace('<', "<")
7552+ .replace('>', ">")
7553+ .replace('"', """)
7554+}
7555+
7556+#[cfg(test)]
7557+mod tests {
7558+ use super::*;
7559+
7560+ fn parse_ok(src: &str) -> ParseResult {
7561+ let r = parse(src);
7562+ assert!(
7563+ r.diagnostics.iter().all(|d| d.severity != Severity::Error),
7564+ "unexpected error diagnostics: {:?}",
7565+ r.diagnostics,
7566+ );
7567+ r
7568+ }
7569+
7570+ #[test]
7571+ fn parses_empty_input() {
7572+ let r = parse("");
7573+ assert!(r.document.nodes.is_empty());
7574+ assert!(r.diagnostics.is_empty());
7575+ }
7576+
7577+ #[test]
7578+ fn parses_bare_text_node() {
7579+ let r = parse_ok("Hello world\n");
7580+ assert_eq!(r.document.nodes.len(), 1);
7581+ }
7582+
7583+ #[test]
7584+ fn parses_page_directive() {
7585+ let r = parse_ok("@page My Title\n");
7586+ assert_eq!(
7587+ r.document.page.map(|p| p.title).as_deref(),
7588+ Some("My Title")
7589+ );
7590+ }
7591+
7592+ #[test]
7593+ fn let_variable_substitution() {
7594+ let r = parse_ok("@let color red\n@text [color $color] hi\n");
7595+ assert_eq!(
7596+ r.document.variables.get("color").map(|s| s.as_str()),
7597+ Some("red")
7598+ );
7599+ }
7600+
7601+ #[test]
7602+ fn error_recovery_continues_after_unknown_element() {
7603+ // Intentionally malformed line followed by a valid one — recovery must
7604+ // let us still see the good line in diagnostics / output.
7605+ let r = parse("@notareal\n@text hi\n");
7606+ let has_error = r.diagnostics.iter().any(|d| d.severity == Severity::Error);
7607+ assert!(has_error, "expected at least one error for @notareal");
7608+ }
7609+
7610+ #[test]
7611+ fn undefined_fn_is_reported_not_panics() {
7612+ // Prior to the unwrap fix this panicked.
7613+ let r = parse("@missing\n");
7614+ assert!(r.diagnostics.iter().any(|d| d.severity == Severity::Error));
7615+ }
7616+
7617+ #[test]
7618+ fn scope_without_selector_does_not_panic() {
7619+ let r = parse("@scope\n body { background red; }\n");
7620+ // Should parse — may or may not emit diagnostics, but must not panic.
7621+ let _ = r;
7622+ }
7623+
7624+ #[test]
7625+ fn levenshtein_bounded_respects_cutoff() {
7626+ let a: Vec<char> = "hello".chars().collect();
7627+ let b: Vec<char> = "world".chars().collect();
7628+ // Full distance is 4, but asking for cutoff 2 should early-exit.
7629+ let d = levenshtein_bounded(&a, &b, 2);
7630+ assert!(d > 2, "expected early exit above cutoff, got {}", d);
7631+ }
7632+
7633+ #[test]
7634+ fn severity_has_all_variants() {
7635+ // This compiles only if Severity has Error, Warning, Info, Help.
7636+ let all = [
7637+ Severity::Error,
7638+ Severity::Warning,
7639+ Severity::Info,
7640+ Severity::Help,
7641+ ];
7642+ assert_eq!(all.len(), 4);
7643+ }
7644+
7645+ #[test]
7646+ fn arithmetic_empty_operator_does_not_panic() {
7647+ // Guards the `op.trim().chars().next().unwrap()` fix.
7648+ let r = parse("@let x = 1 + 2\n");
7649+ assert_eq!(r.document.variables.get("x").map(|s| s.as_str()), Some("3"));
7650+ }
7651+}