Autoscope syntax (#9372)

Add autoscope syntax (`..Ident`).

# Important Notes
- Also rename previous `Tree.Autoscope` to `SuspendedDefaultArguments`.

engine/runtime-parser/src/main/java/org/enso/compiler/core/TreeToIr.java

@@ -615,7 +615,7 @@ final class TreeToIr {
     var tree = ast;
     for (;;) {
       switch (tree) {
-        case Tree.App app when app.getArg() instanceof Tree.AutoScope -> {
+        case Tree.App app when app.getArg() instanceof Tree.SuspendedDefaultArguments -> {
           hasDefaultsSuspended = true;
           tree = app.getFunc();
         }
@@ -670,16 +670,6 @@ final class TreeToIr {
               var loc = getIdentifiedLocation(oprApp.getLhs());
               args.add(new CallArgument.Specified(Option.empty(), self, loc, meta(), diag()));
             }
-          } else if (tree instanceof Tree.OprApp oprApp
-                  && isDotDotOperator(oprApp.getOpr().getRight())
-                  && oprApp.getRhs() instanceof Tree.Ident ident) {
-              var methodName = buildName(ident);
-              func = new Name.MethodReference(
-                Option.empty(),
-                methodName,
-                methodName.location(),
-                meta(), diag()
-              );
           } else if (args.isEmpty()) {
             return null;
           } else {
@@ -1064,12 +1054,21 @@ final class TreeToIr {
       case Tree.App app -> {
           var fn = translateExpression(app.getFunc(), isMethod);
           var loc = getIdentifiedLocation(app);
-          if (app.getArg() instanceof Tree.AutoScope) {
+          if (app.getArg() instanceof Tree.SuspendedDefaultArguments) {
               yield new Application.Prefix(fn, nil(), true, loc, meta(), diag());
           } else {
               yield fn.setLocation(loc);
           }
       }
+      case Tree.AutoscopedIdentifier autoscopedIdentifier -> {
+        var methodName = buildName(autoscopedIdentifier.getIdent());
+        yield new Name.MethodReference(
+                Option.empty(),
+                methodName,
+                methodName.location(),
+                meta(), diag()
+        );
+      }
       case Tree.Invalid __ -> translateSyntaxError(tree, Syntax.UnexpectedExpression$.MODULE$);
       default -> translateSyntaxError(tree, new Syntax.UnsupportedSyntax("translateExpression"));
     };
@@ -1103,7 +1102,7 @@ final class TreeToIr {
         case Tree.BodyBlock ignored -> null;
         case Tree.Number ignored -> null;
         case Tree.Wildcard ignored -> null;
-        case Tree.AutoScope ignored -> null;
+        case Tree.SuspendedDefaultArguments ignored -> null;
         case Tree.ForeignFunction ignored -> null;
         case Tree.Import ignored -> null;
         case Tree.Export ignored -> null;
@@ -1880,10 +1879,6 @@ final class TreeToIr {
     return op != null && ".".equals(op.codeRepr());
   }
 
-  private static boolean isDotDotOperator(Token.Operator op) {
-    return op != null && "..".equals(op.codeRepr());
-  }
-
   private static Tree maybeManyParensed(Tree t) {
     for (;;) {
       switch (t) {

engine/runtime-parser/src/test/java/org/enso/compiler/core/EnsoParserTest.java

@@ -934,7 +934,7 @@ public class EnsoParserTest {
   }
 
   @Test
-  public void testAutoScope() throws Exception {
+  public void testSuspendedDefaultArguments() throws Exception {
     parseTest("""
     fn that_meta =
         c_2 = that_meta.constructor ...
@@ -942,7 +942,7 @@ public class EnsoParserTest {
   }
 
   @Test
-  public void testAutoScope2() throws Exception {
+  public void testSuspendedDefaultArguments2() throws Exception {
     parseTest("""
     fn1 = fn ...
     fn2 = fn 1 ...

lib/rust/parser/debug/src/lib.rs

@@ -49,7 +49,7 @@ where T: serde::Serialize + Reflect {
         vec![Digits::reflect(), NumberBase::reflect(), Operator::reflect(), TextSection::reflect()];
     let stringish_tokens = stringish_tokens.into_iter().map(|t| rust_to_meta[&t.id]);
     let skip_tokens = vec![
-        AutoScope::reflect(),
+        SuspendedDefaultArguments::reflect(),
         CloseSymbol::reflect(),
         Newline::reflect(),
         OpenSymbol::reflect(),

lib/rust/parser/debug/tests/parse.rs

@@ -865,6 +865,25 @@ fn method_app_in_minus_unary() {
         (UnaryOprApp "-" (OprApp (Ident Number) (Ok ".") (Ident positive_infinity))));
 }
 
+#[test]
+fn autoscope_operator() {
+    test!("x : ..True", (TypeSignature (Ident x) ":" (AutoscopedIdentifier ".." True)));
+    test!("x = ..True", (Assignment (Ident x) "=" (AutoscopedIdentifier ".." True)));
+    test!("x = f ..True",
+        (Assignment (Ident x) "=" (App (Ident f) (AutoscopedIdentifier ".." True))));
+    expect_invalid_node("x = ..not_a_constructor");
+    expect_invalid_node("x = case a of ..True -> True");
+    expect_invalid_node("x = ..4");
+    expect_invalid_node("x = ..Foo.Bar");
+    expect_invalid_node("x = f .. True");
+    expect_invalid_node("x = f(.. ..)");
+    expect_invalid_node("x = f(.. *)");
+    expect_invalid_node("x = f(.. True)");
+    expect_multiple_operator_error("x = ..");
+    expect_multiple_operator_error("x = .. True");
+    expect_multiple_operator_error("x : .. True");
+}
+
 
 // === Import/Export ===
 
@@ -1005,7 +1024,10 @@ fn type_annotations() {
              (App (Ident foo)
               (Group (TypeAnnotated (Ident x) ":" (Ident Int)))))]),
         ("(x : My_Type _)", block![
-            (Group (TypeAnnotated (Ident x) ":" (App (Ident My_Type) (Wildcard -1))))]),
+            (Group
+             (TypeAnnotated (Ident x)
+                            ":"
+                            (App (Ident My_Type) (TemplateFunction 1 (Wildcard 0)))))]),
         ("x : List Int -> Int", block![
             (TypeSignature (Ident x) ":"
              (OprApp (App (Ident List) (Ident Int)) (Ok "->") (Ident Int)))]),
@@ -1219,8 +1241,13 @@ fn case_expression() {
         (CaseOf (Ident foo) #(
          ((() (TypeAnnotated (Ident v) ":" (Ident My_Type)) "->" (Ident x)))
          ((() (TypeAnnotated (Ident v) ":"
-            (Group (App (App (Ident My_Type) (Wildcard -1)) (Wildcard -1))))
-           "->" (Ident x)))))];
+          (Group (App
+                  (App
+                   (Ident My_Type)
+                   (TemplateFunction 1 (Wildcard 0)))
+                  (TemplateFunction 1 (Wildcard 0)))))
+          "->" (Ident x)))))
+    ];
     test(&code.join("\n"), expected);
 }
 
@@ -1269,7 +1296,7 @@ fn case_by_type() {
 }
 
 #[test]
-fn pattern_match_auto_scope() {
+fn pattern_match_suspended_default_arguments() {
     #[rustfmt::skip]
     let code = [
         "case self of",
@@ -1277,7 +1304,7 @@ fn pattern_match_auto_scope() {
     ];
     #[rustfmt::skip]
     let expected = block![
-        (CaseOf (Ident self) #(((() (App (Ident Vector_2d) (AutoScope)) "->" (Ident x)))))];
+        (CaseOf (Ident self) #(((() (App (Ident Vector_2d) (SuspendedDefaultArguments)) "->" (Ident x)))))];
     test(&code.join("\n"), expected);
 }
 

lib/rust/parser/src/lexer.rs

@@ -652,7 +652,7 @@ impl<'s> Lexer<'s> {
                 }
                 // Composed of operator characters, but not an operator node.
                 "..." => {
-                    let token = token.with_variant(token::Variant::auto_scope());
+                    let token = token.with_variant(token::Variant::suspended_default_arguments());
                     self.submit_token(token);
                 }
                 // Decimal vs. method-application must be distinguished before parsing because they
@@ -714,6 +714,11 @@ fn analyze_operator(token: &str) -> token::OperatorProperties {
                 .with_unary_prefix_mode(token::Precedence::max())
                 .as_compile_time_operation()
                 .as_suspension(),
+        ".." =>
+            return operator
+                .with_unary_prefix_mode(token::Precedence::min_valid())
+                .as_compile_time_operation()
+                .as_autoscope(),
         "@" =>
             return operator
                 .with_unary_prefix_mode(token::Precedence::max())

lib/rust/parser/src/lib.rs

@@ -300,26 +300,6 @@ fn is_qualified_name(tree: &syntax::Tree) -> bool {
     }
 }
 
-fn expression_to_type(mut input: syntax::Tree<'_>) -> syntax::Tree<'_> {
-    use syntax::tree::*;
-    if let Variant::Wildcard(wildcard) = &mut *input.variant {
-        wildcard.de_bruijn_index = None;
-        return input;
-    }
-    let mut out = match input.variant {
-        box Variant::TemplateFunction(TemplateFunction { ast, .. }) => expression_to_type(ast),
-        box Variant::Group(Group { open, body: Some(body), close }) =>
-            Tree::group(open, Some(expression_to_type(body)), close),
-        box Variant::OprApp(OprApp { lhs, opr, rhs }) =>
-            Tree::opr_app(lhs.map(expression_to_type), opr, rhs.map(expression_to_type)),
-        box Variant::App(App { func, arg }) =>
-            Tree::app(expression_to_type(func), expression_to_type(arg)),
-        _ => return input,
-    };
-    out.span.left_offset += input.span.left_offset;
-    out
-}
-
 fn expression_to_pattern(mut input: syntax::Tree<'_>) -> syntax::Tree<'_> {
     use syntax::tree::*;
     if let Variant::Wildcard(wildcard) = &mut *input.variant {
@@ -334,6 +314,8 @@ fn expression_to_pattern(mut input: syntax::Tree<'_>) -> syntax::Tree<'_> {
             Tree::app(expression_to_pattern(func), expression_to_pattern(arg)),
         box Variant::TypeAnnotated(TypeAnnotated { expression, operator, type_ }) =>
             Tree::type_annotated(expression_to_pattern(expression), operator, type_),
+        box Variant::AutoscopedIdentifier(_) =>
+            return input.with_error("The autoscope operator (..) cannot be used in a pattern."),
         _ => return input,
     };
     out.span.left_offset += input.span.left_offset;

lib/rust/parser/src/syntax/token.rs

@@ -259,7 +259,7 @@ macro_rules! with_token_definition { ($f:ident ($($args:tt)*)) => { $f! { $($arg
         Wildcard {
             pub lift_level: u32
         },
-        AutoScope,
+        SuspendedDefaultArguments,
         Ident {
             pub is_free:               bool,
             pub lift_level:            u32,
@@ -340,6 +340,7 @@ pub struct OperatorProperties {
     is_arrow:                  bool,
     is_sequence:               bool,
     is_suspension:             bool,
+    is_autoscope:              bool,
     is_annotation:             bool,
     is_dot:                    bool,
     is_special:                bool,
@@ -427,6 +428,11 @@ impl OperatorProperties {
         Self { is_suspension: true, ..self }
     }
 
+    /// Return a copy of this operator, modified to be flagged as the autoscope operator.
+    pub fn as_autoscope(self) -> Self {
+        Self { is_autoscope: true, ..self }
+    }
+
     /// Return a copy of this operator, modified to be flagged as the dot operator.
     pub fn as_dot(self) -> Self {
         Self { is_dot: true, ..self }
@@ -492,6 +498,11 @@ impl OperatorProperties {
         self.is_suspension
     }
 
+    /// Return whether this operator is the autoscope operator.
+    pub fn is_autoscope(&self) -> bool {
+        self.is_autoscope
+    }
+
     /// Return whether this operator is the annotation operator.
     pub fn is_annotation(&self) -> bool {
         self.is_annotation

lib/rust/parser/src/syntax/tree.rs

@@ -118,9 +118,9 @@ macro_rules! with_ast_definition { ($f:ident ($($args:tt)*)) => { $f! { $($args)
             #[reflect(as = "i32")]
             pub de_bruijn_index: Option<u32>,
         },
-        /// The auto-scoping marker, `...`.
-        AutoScope {
-            pub token: token::AutoScope<'s>,
+        /// The suspended-default-arguments marker, `...`.
+        SuspendedDefaultArguments {
+            pub token: token::SuspendedDefaultArguments<'s>,
         },
         TextLiteral {
             pub open:     Option<token::TextStart<'s>>,
@@ -162,6 +162,11 @@ macro_rules! with_ast_definition { ($f:ident ($($args:tt)*)) => { $f! { $($args)
             pub opr: token::Operator<'s>,
             pub rhs: Option<Tree<'s>>,
         },
+        /// Application of the autoscope operator to an identifier, e.g. `..True`.
+        AutoscopedIdentifier {
+            pub opr: token::Operator<'s>,
+            pub ident: token::Ident<'s>,
+        },
         /// Defines the point where operator sections should be expanded to lambdas. Let's consider
         /// the expression `map (.sum 1)`. It should be desugared to `map (x -> x.sum 1)`, not to
         /// `map ((x -> x.sum) 1)`. The expression `.sum` will be parsed as operator section
@@ -897,10 +902,7 @@ pub fn apply_operator<'s>(
     }
     if let Ok(opr_) = &opr && opr_.properties.is_type_annotation() {
         return match (lhs, rhs) {
-            (Some(lhs), Some(rhs)) => {
-                let rhs = crate::expression_to_type(rhs);
-                Tree::type_annotated(lhs, opr.unwrap(), rhs)
-            },
+            (Some(lhs), Some(rhs)) => Tree::type_annotated(lhs, opr.unwrap(), rhs),
             (lhs, rhs) => {
                 let invalid = Tree::opr_app(lhs, opr, rhs);
                 invalid.with_error("`:` operator must be applied to two operands.")
@@ -951,6 +953,21 @@ pub fn apply_unary_operator<'s>(opr: token::Operator<'s>, rhs: Option<Tree<'s>>)
             false => Tree::annotated(opr, token, None, vec![], None),
         };
     }
+    if opr.properties.is_autoscope() && let Some(rhs) = rhs {
+        return if let box Variant::Ident(Ident { mut token }) = rhs.variant {
+            let applied_to_type = token.variant.is_type;
+            token.left_offset = rhs.span.left_offset;
+            let autoscope_application = Tree::autoscoped_identifier(opr, token);
+            return if applied_to_type {
+                autoscope_application
+            } else {
+                autoscope_application
+                    .with_error("The auto-scope operator may only be applied to a capitalized identifier.")
+            }
+        } else {
+            Tree::unary_opr_app(opr, Some(rhs)).with_error("The auto-scope operator (..) may only be applied to an identifier.")
+        }
+    }
     if !opr.properties.can_form_section() && rhs.is_none() {
         let error = format!("Operator `{opr:?}` must be applied to an operand.");
         let invalid = Tree::unary_opr_app(opr, rhs);
@@ -990,7 +1007,7 @@ pub fn to_ast(token: Token) -> Tree {
             Tree::text_literal(default(), default(), vec![newline], default(), default())
         }
         token::Variant::Wildcard(wildcard) => Tree::wildcard(token.with_variant(wildcard), default()),
-        token::Variant::AutoScope(t) => Tree::auto_scope(token.with_variant(t)),
+        token::Variant::SuspendedDefaultArguments(t) => Tree::suspended_default_arguments(token.with_variant(t)),
         token::Variant::OpenSymbol(s) =>
             Tree::group(Some(token.with_variant(s)), default(), default()).with_error("Unmatched delimiter"),
         token::Variant::CloseSymbol(s) =>