Enhance error recovery for incomplete syntax

crates/syntax/src/parser.rs

@@ -153,30 +153,42 @@ impl<'i> Parser<'i> {
     }
 
     /// Consumes a token if the next token matches the expected one, or does nothing if not.
-    fn want(&mut self, expect: SyntaxKind) {
+    /// Return whether the expected token is consumed.
+    fn want(&mut self, expect: SyntaxKind) -> bool {
         if self.peek_non_ws() == Some(expect) {
             self.bump();
+            true
         } else {
             self.error(ErrorKind::MissingToken(expect));
+            false
         }
     }
 
-    /// Consumes tokens until it matches the expected one.
+    /// Expect the termination of an experssion by a followed `guard` token.
-    fn require(&mut self, expect: SyntaxKind) {
+    /// Return whether the expected token is consumed.
+    fn require_expr_end(&mut self, guard: SyntaxKind) -> bool {
+        if matches!(self.peek_non_ws(), Some(k) if k == guard) {
+            self.bump();
+            return true;
+        }
+        self.error(ErrorKind::MissingToken(guard));
+
+        // Try to consume more experssions as recovery.
         loop {
             match self.peek_non_ws() {
-                Some(k) if k == expect => {
+                Some(k) if k == guard => {
                     self.bump();
-                    break;
+                    return true;
                 }
-                Some(_) => {
+                Some(k) if !k.is_separator() => {
-                    self.error(ErrorKind::UnexpectedToken);
+                    let prev = self.tokens.len();
+                    self.expr_function_opt();
+                    // Don't stuck!
+                    if self.tokens.len() == prev {
                         self.bump();
                     }
-                None => {
-                    self.error(ErrorKind::MissingToken(expect));
-                    break;
                 }
+                _ => return false,
             }
         }
     }
@@ -235,10 +247,13 @@ impl<'i> Parser<'i> {
                 self.start_node(IF_THEN_ELSE);
                 self.bump(); // if
                 self.expr_function_opt();
-                self.require(T![then]);
+                // If the separator is not found, stop early.
+                if self.require_expr_end(T![then]) {
                     self.expr_function_opt();
-                self.require(T![else]);
+                    if self.require_expr_end(T![else]) {
                         self.expr_function_opt();
+                    }
+                }
                 self.finish_node();
             }
             Some(T!['{']) => {
@@ -454,7 +469,7 @@ impl<'i> Parser<'i> {
                 self.start_node(PAREN);
                 self.bump(); // '('
                 self.expr_function_opt();
-                self.require(T![')']);
+                self.require_expr_end(T![')']);
                 self.finish_node();
             }
             Some(T![rec] | T![let]) => {
@@ -491,11 +506,11 @@ impl<'i> Parser<'i> {
                             self.expr_select_opt();
                             continue;
                         }
-                        Some(_) => {
+                        Some(k) if !k.is_separator() => {
                             self.error(ErrorKind::UnexpectedToken);
                             self.bump();
                         }
-                        None => {
+                        _ => {
                             self.error(ErrorKind::MissingToken(T![']']));
                             break;
                         }
@@ -638,7 +653,7 @@ impl<'i> Parser<'i> {
                         self.start_node(PAREN);
                         self.bump(); // '('
                         self.expr_function_opt();
-                        self.require(T![')']);
+                        self.require_expr_end(T![')']);
                         self.finish_node();
                     }
                     // Use lookahead for ending condition, since `;` might not be typed yet.
@@ -652,7 +667,32 @@ impl<'i> Parser<'i> {
                 Some(k) if k.can_start_attr() => {
                     self.start_node(ATTR_PATH_VALUE);
                     self.attrpath_opt();
-                    self.want(T![=]);
+                    // If there is no `=`, we assume this binding is to be typed.
+                    // Stop parsing RHS and try the next binding.
+                    // ```
+                    // {
+                    //   b.|    # Typing...
+                    //   a = 1; # Valid binding follows.
+                    // }
+                    // ```
+                    if self.want(T![=]) {
+                        self.expr_function_opt();
+                    }
+                    self.want(T![;]);
+                    self.finish_node();
+                }
+                // Recover for missing attrpath. This happens when the previous binding is not
+                // terminated by `;`.
+                // ```
+                // {
+                //   a = 1   # => `a = 1 b <missing semicolon>`
+                //   b = 2;  # => `= 2;` <- We are here.
+                // }
+                // ```
+                Some(T![=]) => {
+                    self.error(ErrorKind::MissingAttr);
+                    self.start_node(ATTR_PATH_VALUE);
+                    self.bump(); // =
                     self.expr_function_opt();
                     self.want(T![;]);
                     self.finish_node();
@@ -699,7 +739,7 @@ impl<'i> Parser<'i> {
         self.start_node(DYNAMIC);
         self.bump(); // "${"
         self.expr_function_opt();
-        self.require(T!['}']);
+        self.require_expr_end(T!['}']);
         self.finish_node();
     }
 
@@ -762,6 +802,15 @@ impl SyntaxKind {
         )
     }
 
+    /// Whether this token is a separator in some syntax.
+    /// We should stop at these tokens during error recovery.
+    fn is_separator(self) -> bool {
+        matches!(
+            self,
+            T![then] | T![else] | T![')'] | T![']'] | T!['}'] | T![=] | T![;] | T![,]
+        )
+    }
+
     #[rustfmt::skip]
     fn prefix_bp(self) -> Option<u8> {
         // See `infix_bp`.

crates/syntax/test_data/parser/err/broken-states.ast

@@ -1,41 +1,36 @@
 Unexpected token at 16..17
-Unexpected token at 16..17
+Missing R_CURLY at 16..17
-Unexpected token at 18..20
-Unexpected token at 21..22
-Unexpected token at 25..28
-Unexpected token at 29..30
-Unexpected token at 31..32
-Unexpected token at 32..34
-Unexpected token at 34..36
-Unexpected token at 36..37
-Unexpected token at 41..42
-Missing KW_IN at 43..43
-Missing expression at 43..43
 SOURCE_FILE@0..43
   LET_IN@0..43
     KW_LET@0..3 "let"
     SPACE@3..6 "\n  "
-    INHERIT@6..40
+    INHERIT@6..17
       KW_INHERIT@6..13 "inherit"
       SPACE@13..14 " "
-      DYNAMIC@14..38
+      DYNAMIC@14..16
         DOLLAR_L_CURLY@14..16 "${"
       SEMICOLON@16..17 ";"
     SPACE@17..18 "\n"
     KW_IN@18..20 "in"
     SPACE@20..21 " "
+    ATTR_SET@21..42
       L_CURLY@21..22 "{"
       SPACE@22..25 "\n  "
+      ATTR_PATH_VALUE@25..40
+        ATTR_PATH@25..29
+          NAME@25..28
             IDENT@25..28 "foo"
           SPACE@28..29 " "
         EQ@29..30 "="
         SPACE@30..31 " "
+        STRING@31..39
           DQUOTE@31..32 "\""
           STRING_FRAGMENT@32..34 "a-"
+          DYNAMIC@34..38
             DOLLAR_L_CURLY@34..36 "${"
+            REF@36..37
               IDENT@36..37 "b"
             R_CURLY@37..38 "}"
-      STRING@38..39
           DQUOTE@38..39 "\""
         SEMICOLON@39..40 ";"
       SPACE@40..41 "\n"

crates/syntax/test_data/parser/err/incomplete-attrset.ast

@@ -1,45 +1,28 @@
-Missing SEMICOLON at 14..15
+Missing EQ at 4..5
-Unexpected token at 14..15
+Missing SEMICOLON at 4..5
-Unexpected token at 16..18
+Unexpected token at 12..13
-Unexpected token at 18..19
+Missing SEMICOLON at 12..13
-Missing attribute at 27..28
+SOURCE_FILE@0..14
-Unexpected token at 29..30
+  APPLY@0..14
-Missing SEMICOLON at 29..30
+    ATTR_SET@0..5
-Missing EQ at 38..39
-Unexpected token at 38..39
-Missing SEMICOLON at 38..39
-SOURCE_FILE@0..40
-  BINARY_OP@0..40
-    ATTR_SET@0..30
       L_CURLY@0..1 "{"
-      SPACE@1..4 "\n  "
+      SPACE@1..2 " "
-      INHERIT@4..14
+      ATTR_PATH_VALUE@2..4
-        KW_INHERIT@4..11 "inherit"
+        ATTR_PATH@2..4
-        SPACE@11..14 "\n  "
+          NAME@2..3
-      EQ@14..15 "="
+            IDENT@2..3 "x"
-      SPACE@15..16 " "
+          SPACE@3..4 " "
-      INT@16..18 "42"
+      R_CURLY@4..5 "}"
-      SEMICOLON@18..19 ";"
+    SPACE@5..6 " "
-      SPACE@19..22 "\n  "
+    ATTR_SET@6..13
-      ATTR_PATH_VALUE@22..29
+      L_CURLY@6..7 "{"
-        ATTR_PATH@22..27
+      SPACE@7..8 " "
-          NAME@22..25
+      ATTR_PATH_VALUE@8..12
-            IDENT@22..25 "bar"
+        ATTR_PATH@8..10
-          DOT@25..26 "."
+          NAME@8..9
-          SPACE@26..27 " "
+            IDENT@8..9 "x"
-        EQ@27..28 "="
+          SPACE@9..10 " "
-        SPACE@28..29 "\n"
+        EQ@10..11 "="
-      R_CURLY@29..30 "}"
+        SPACE@11..12 " "
-    SPACE@30..31 " "
+      R_CURLY@12..13 "}"
-    SLASH2@31..33 "//"
+    SPACE@13..14 "\n"
-    SPACE@33..34 " "
-    ATTR_SET@34..39
-      L_CURLY@34..35 "{"
-      SPACE@35..36 " "
-      ATTR_PATH_VALUE@36..38
-        ATTR_PATH@36..38
-          NAME@36..37
-            IDENT@36..37 "x"
-          SPACE@37..38 " "
-      R_CURLY@38..39 "}"
-    SPACE@39..40 "\n"

crates/syntax/test_data/parser/err/incomplete-attrset.nix

@@ -1,5 +1 @@
-{
+{ x } { x = }
-  inherit
-  = 42;
-  bar. =
-} // { x }

crates/syntax/test_data/parser/err/incomplete-binding.ast

@@ -0,0 +1,119 @@
+Missing EQ at 17..18
+Missing SEMICOLON at 17..18
+Missing EQ at 46..47
+Missing SEMICOLON at 46..47
+Missing SEMICOLON at 65..66
+Missing attribute at 65..66
+Missing SEMICOLON at 84..85
+Missing attribute at 84..85
+SOURCE_FILE@0..91
+  ATTR_SET@0..90
+    L_CURLY@0..1 "{"
+    SPACE@1..4 "\n  "
+    ATTR_PATH_VALUE@4..10
+      ATTR_PATH@4..6
+        NAME@4..5
+          IDENT@4..5 "a"
+        SPACE@5..6 " "
+      EQ@6..7 "="
+      SPACE@7..8 " "
+      LITERAL@8..9
+        INT@8..9 "1"
+      SEMICOLON@9..10 ";"
+    SPACE@10..13 "\n  "
+    ATTR_PATH_VALUE@13..17
+      ATTR_PATH@13..17
+        NAME@13..14
+          IDENT@13..14 "x"
+        SPACE@14..17 "\n  "
+    ATTR_PATH_VALUE@17..23
+      ATTR_PATH@17..19
+        NAME@17..18
+          IDENT@17..18 "b"
+        SPACE@18..19 " "
+      EQ@19..20 "="
+      SPACE@20..21 " "
+      LITERAL@21..22
+        INT@21..22 "1"
+      SEMICOLON@22..23 ";"
+    SPACE@23..26 "\n  "
+    ATTR_PATH_VALUE@26..37
+      ATTR_PATH@26..33
+        NAME@26..27
+          IDENT@26..27 "x"
+        DOT@27..28 "."
+        SPACE@28..31 "\n  "
+        NAME@31..32
+          IDENT@31..32 "c"
+        SPACE@32..33 " "
+      EQ@33..34 "="
+      SPACE@34..35 " "
+      LITERAL@35..36
+        INT@35..36 "1"
+      SEMICOLON@36..37 ";"
+    SPACE@37..40 "\n  "
+    ATTR_PATH_VALUE@40..46
+      ATTR_PATH@40..46
+        NAME@40..41
+          IDENT@40..41 "x"
+        DOT@41..42 "."
+        NAME@42..43
+          IDENT@42..43 "y"
+        SPACE@43..46 "\n  "
+    ATTR_PATH_VALUE@46..52
+      ATTR_PATH@46..48
+        NAME@46..47
+          IDENT@46..47 "d"
+        SPACE@47..48 " "
+      EQ@48..49 "="
+      SPACE@49..50 " "
+      LITERAL@50..51
+        INT@50..51 "1"
+      SEMICOLON@51..52 ";"
+    SPACE@52..55 "\n  "
+    ATTR_PATH_VALUE@55..65
+      ATTR_PATH@55..59
+        NAME@55..56
+          IDENT@55..56 "x"
+        DOT@56..57 "."
+        NAME@57..58
+          IDENT@57..58 "y"
+        SPACE@58..59 " "
+      EQ@59..60 "="
+      SPACE@60..63 "\n  "
+      REF@63..64
+        IDENT@63..64 "e"
+      SPACE@64..65 " "
+    ATTR_PATH_VALUE@65..69
+      EQ@65..66 "="
+      SPACE@66..67 " "
+      LITERAL@67..68
+        INT@67..68 "1"
+      SEMICOLON@68..69 ";"
+    SPACE@69..72 "\n  "
+    ATTR_PATH_VALUE@72..84
+      ATTR_PATH@72..76
+        NAME@72..73
+          IDENT@72..73 "x"
+        DOT@73..74 "."
+        NAME@74..75
+          IDENT@74..75 "y"
+        SPACE@75..76 " "
+      EQ@76..77 "="
+      SPACE@77..78 " "
+      APPLY@78..84
+        LITERAL@78..79
+          INT@78..79 "1"
+        SPACE@79..82 "\n  "
+        REF@82..83
+          IDENT@82..83 "f"
+        SPACE@83..84 " "
+    ATTR_PATH_VALUE@84..88
+      EQ@84..85 "="
+      SPACE@85..86 " "
+      LITERAL@86..87
+        INT@86..87 "1"
+      SEMICOLON@87..88 ";"
+    SPACE@88..89 "\n"
+    R_CURLY@89..90 "}"
+  SPACE@90..91 "\n"

crates/syntax/test_data/parser/err/incomplete-binding.nix

@@ -0,0 +1,13 @@
+{
+  a = 1;
+  x
+  b = 1;
+  x.
+  c = 1;
+  x.y
+  d = 1;
+  x.y =
+  e = 1;
+  x.y = 1
+  f = 1;
+}

crates/syntax/test_data/parser/err/incomplete-if.ast

@@ -0,0 +1,105 @@
+Unexpected token at 10..11
+Missing KW_THEN at 10..11
+Missing KW_THEN at 22..23
+Unexpected token at 39..40
+Missing KW_ELSE at 39..40
+Missing KW_ELSE at 58..59
+Unexpected token at 82..83
+SOURCE_FILE@0..95
+  ATTR_SET@0..94
+    L_CURLY@0..1 "{"
+    SPACE@1..4 "\n  "
+    ATTR_PATH_VALUE@4..11
+      ATTR_PATH@4..6
+        NAME@4..5
+          IDENT@4..5 "a"
+        SPACE@5..6 " "
+      EQ@6..7 "="
+      SPACE@7..8 " "
+      IF_THEN_ELSE@8..10
+        KW_IF@8..10 "if"
+      SEMICOLON@10..11 ";"
+    SPACE@11..14 "\n  "
+    ATTR_PATH_VALUE@14..23
+      ATTR_PATH@14..16
+        NAME@14..15
+          IDENT@14..15 "b"
+        SPACE@15..16 " "
+      EQ@16..17 "="
+      SPACE@17..18 " "
+      IF_THEN_ELSE@18..22
+        KW_IF@18..20 "if"
+        SPACE@20..21 " "
+        LITERAL@21..22
+          INT@21..22 "1"
+      SEMICOLON@22..23 ";"
+    SPACE@23..26 "\n  "
+    ATTR_PATH_VALUE@26..40
+      ATTR_PATH@26..28
+        NAME@26..27
+          IDENT@26..27 "c"
+        SPACE@27..28 " "
+      EQ@28..29 "="
+      SPACE@29..30 " "
+      IF_THEN_ELSE@30..39
+        KW_IF@30..32 "if"
+        SPACE@32..33 " "
+        LITERAL@33..34
+          INT@33..34 "1"
+        SPACE@34..35 " "
+        KW_THEN@35..39 "then"
+      SEMICOLON@39..40 ";"
+    SPACE@40..43 "\n  "
+    ATTR_PATH_VALUE@43..59
+      ATTR_PATH@43..45
+        NAME@43..44
+          IDENT@43..44 "d"
+        SPACE@44..45 " "
+      EQ@45..46 "="
+      SPACE@46..47 " "
+      IF_THEN_ELSE@47..58
+        KW_IF@47..49 "if"
+        SPACE@49..50 " "
+        LITERAL@50..51
+          INT@50..51 "1"
+        SPACE@51..52 " "
+        KW_THEN@52..56 "then"
+        SPACE@56..57 " "
+        LITERAL@57..58
+          INT@57..58 "2"
+      SEMICOLON@58..59 ";"
+    SPACE@59..62 "\n  "
+    ATTR_PATH_VALUE@62..83
+      ATTR_PATH@62..64
+        NAME@62..63
+          IDENT@62..63 "e"
+        SPACE@63..64 " "
+      EQ@64..65 "="
+      SPACE@65..66 " "
+      IF_THEN_ELSE@66..82
+        KW_IF@66..68 "if"
+        SPACE@68..69 " "
+        LITERAL@69..70
+          INT@69..70 "1"
+        SPACE@70..71 " "
+        KW_THEN@71..75 "then"
+        SPACE@75..76 " "
+        LITERAL@76..77
+          INT@76..77 "2"
+        SPACE@77..78 " "
+        KW_ELSE@78..82 "else"
+      SEMICOLON@82..83 ";"
+    SPACE@83..86 "\n  "
+    ATTR_PATH_VALUE@86..92
+      ATTR_PATH@86..88
+        NAME@86..87
+          IDENT@86..87 "f"
+        SPACE@87..88 " "
+      EQ@88..89 "="
+      SPACE@89..90 " "
+      LITERAL@90..91
+        INT@90..91 "1"
+      SEMICOLON@91..92 ";"
+    SPACE@92..93 "\n"
+    R_CURLY@93..94 "}"
+  SPACE@94..95 "\n"

crates/syntax/test_data/parser/err/incomplete-if.nix

@@ -0,0 +1,8 @@
+{
+  a = if;
+  b = if 1;
+  c = if 1 then;
+  d = if 1 then 2;
+  e = if 1 then 2 else;
+  f = 1;
+}

crates/syntax/test_data/parser/err/incomplete-list.ast

@@ -0,0 +1,64 @@
+Missing R_BRACK at 23..24
+Missing SEMICOLON at 23..24
+Missing attribute at 23..24
+Missing R_BRACK at 36..37
+SOURCE_FILE@0..49
+  ATTR_SET@0..48
+    L_CURLY@0..1 "{"
+    SPACE@1..4 "\n  "
+    ATTR_PATH_VALUE@4..10
+      ATTR_PATH@4..6
+        NAME@4..5
+          IDENT@4..5 "a"
+        SPACE@5..6 " "
+      EQ@6..7 "="
+      SPACE@7..8 " "
+      LITERAL@8..9
+        INT@8..9 "1"
+      SEMICOLON@9..10 ";"
+    SPACE@10..13 "\n  "
+    ATTR_PATH_VALUE@13..23
+      ATTR_PATH@13..15
+        NAME@13..14
+          IDENT@13..14 "x"
+        SPACE@14..15 " "
+      EQ@15..16 "="
+      SPACE@16..17 " "
+      LIST@17..23
+        L_BRACK@17..18 "["
+        SPACE@18..21 "\n  "
+        REF@21..22
+          IDENT@21..22 "b"
+        SPACE@22..23 " "
+    ATTR_PATH_VALUE@23..27
+      EQ@23..24 "="
+      SPACE@24..25 " "
+      LITERAL@25..26
+        INT@25..26 "2"
+      SEMICOLON@26..27 ";"
+    SPACE@27..30 "\n  "
+    ATTR_PATH_VALUE@30..37
+      ATTR_PATH@30..32
+        NAME@30..31
+          IDENT@30..31 "x"
+        SPACE@31..32 " "
+      EQ@32..33 "="
+      SPACE@33..34 " "
+      LIST@34..36
+        L_BRACK@34..35 "["
+        SPACE@35..36 " "
+      SEMICOLON@36..37 ";"
+    SPACE@37..40 "\n  "
+    ATTR_PATH_VALUE@40..46
+      ATTR_PATH@40..42
+        NAME@40..41
+          IDENT@40..41 "c"
+        SPACE@41..42 " "
+      EQ@42..43 "="
+      SPACE@43..44 " "
+      LITERAL@44..45
+        INT@44..45 "3"
+      SEMICOLON@45..46 ";"
+    SPACE@46..47 "\n"
+    R_CURLY@47..48 "}"
+  SPACE@48..49 "\n"

crates/syntax/test_data/parser/err/incomplete-list.nix

@@ -0,0 +1,7 @@
+{
+  a = 1;
+  x = [
+  b = 2;
+  x = [ ;
+  c = 3;
+}

crates/syntax/test_data/parser/err/incomplete-pat.ast

@@ -0,0 +1,40 @@
+Unexpected token at 6..7
+Unexpected token at 16..17
+SOURCE_FILE@0..25
+  LAMBDA@0..25
+    PARAM@0..21
+      PAT@0..21
+        L_CURLY@0..1 "{"
+        SPACE@1..2 " "
+        PAT_FIELD@2..4
+          NAME@2..3
+            IDENT@2..3 "a"
+          SPACE@3..4 "\n"
+        COMMA@4..5 ","
+        SPACE@5..6 "\n"
+        COMMA@6..7 ","
+        SPACE@7..8 " "
+        PAT_FIELD@8..10
+          NAME@8..9
+            IDENT@8..9 "b"
+          SPACE@9..10 "\n"
+        COMMA@10..11 ","
+        SPACE@11..12 " "
+        PAT_FIELD@12..16
+          NAME@12..13
+            IDENT@12..13 "x"
+          SPACE@13..14 " "
+          QUESTION@14..15 "?"
+          SPACE@15..16 "\n"
+        COMMA@16..17 ","
+        SPACE@17..18 " "
+        PAT_FIELD@18..20
+          NAME@18..19
+            IDENT@18..19 "c"
+          SPACE@19..20 "\n"
+        R_CURLY@20..21 "}"
+    COLON@21..22 ":"
+    SPACE@22..23 " "
+    LITERAL@23..24
+      INT@23..24 "1"
+    SPACE@24..25 "\n"

crates/syntax/test_data/parser/err/incomplete-pat.nix

@@ -0,0 +1,6 @@
+{ a
+,
+, b
+, x ?
+, c
+}: 1

crates/syntax/test_data/parser/err/multiple-or.ast

@@ -1,3 +1,4 @@
+Missing R_PAREN at 6..8
 Unexpected token at 6..8
 Unexpected token at 17..19
 SOURCE_FILE@0..24
@@ -11,7 +12,9 @@ SOURCE_FILE@0..24
         REF@3..5
           IDENT@3..5 "or"
       SPACE@5..6 " "
-      KW_OR@6..8 "or"
+      APPLY@6..8
+        REF@6..8
+          IDENT@6..8 "or"
       R_PAREN@8..9 ")"
     SPACE@9..10 " "
     LIST@10..23

crates/syntax/test_data/parser/fuzz/0002.ast

@@ -7,6 +7,7 @@ Multiple root expressions at 19..20
 Unexpected token at 20..21
 Unexpected token at 21..22
 Unexpected token at 22..23
+Missing R_CURLY at 50..51
 Unexpected token at 50..51
 Unexpected token at 51..52
 Unexpected token at 52..53
@@ -75,26 +76,28 @@ Unexpected token at 114..115
 Unexpected token at 115..116
 Unexpected token at 116..117
 Unexpected token at 117..118
-Unexpected token at 118..122
 Unexpected token at 122..123
 Unexpected token at 123..124
 Unexpected token at 124..125
 Unexpected token at 125..126
 Unexpected token at 126..127
 Unexpected token at 127..128
-Unexpected token at 128..129
+Missing R_BRACK at 129..130
+Missing R_BRACK at 129..130
+Multiple root expressions at 129..130
 Unexpected token at 129..130
+Multiple root expressions at 130..131
 Unexpected token at 130..131
+Multiple root expressions at 131..132
 Unexpected token at 131..132
+Multiple root expressions at 132..133
 Unexpected token at 132..133
-Unexpected token at 133..133
+Multiple root expressions at 133..133
-Unexpected token at 133..134
+Missing R_CURLY at 141..142
-Unexpected token at 134..136
-Unexpected token at 136..141
 Unexpected token at 141..142
 Unexpected token at 142..143
-Unexpected token at 143..144
+Missing EQ at 146..147
-Unexpected token at 144..146
+Missing SEMICOLON at 146..147
 Unexpected token at 146..147
 Unexpected token at 147..148
 Unexpected token at 148..149
@@ -104,53 +107,82 @@ Unexpected token at 151..152
 Unexpected token at 152..153
 Unexpected token at 153..154
 Unexpected token at 154..155
-Unexpected token at 156..157
+Multiple root expressions at 157..158
 Unexpected token at 157..158
+Multiple root expressions at 158..159
 Unexpected token at 158..159
+Multiple root expressions at 159..160
 Unexpected token at 159..160
+Multiple root expressions at 160..161
 Unexpected token at 160..161
+Multiple root expressions at 161..162
 Unexpected token at 161..162
+Multiple root expressions at 162..163
 Unexpected token at 162..163
+Multiple root expressions at 163..164
 Unexpected token at 163..164
+Multiple root expressions at 164..165
 Unexpected token at 164..165
+Multiple root expressions at 165..166
+Missing R_BRACK at 169..170
+Multiple root expressions at 169..170
 Unexpected token at 169..170
+Multiple root expressions at 170..170
 Unexpected token at 170..170
-Unexpected token at 172..173
+Multiple root expressions at 170..171
 Unexpected token at 173..174
+Multiple root expressions at 173..174
+Unexpected token at 173..174
+Multiple root expressions at 174..174
 Unexpected token at 174..174
+Multiple root expressions at 174..175
 Unexpected token at 174..175
+Multiple root expressions at 175..176
 Unexpected token at 175..176
+Multiple root expressions at 176..177
 Unexpected token at 176..177
+Multiple root expressions at 177..178
 Unexpected token at 177..178
+Multiple root expressions at 178..179
+Missing R_BRACK at 182..183
+Multiple root expressions at 182..183
 Unexpected token at 182..183
+Multiple root expressions at 183..184
 Unexpected token at 184..185
+Multiple root expressions at 186..187
 Unexpected token at 186..187
-Unexpected token at 189..190
+Multiple root expressions at 187..188
 Unexpected token at 190..191
+Multiple root expressions at 190..191
+Unexpected token at 190..191
+Multiple root expressions at 191..210
+Multiple root expressions at 210..211
 Unexpected token at 210..211
+Multiple root expressions at 211..212
 Unexpected token at 211..212
+Multiple root expressions at 212..213
 Unexpected token at 212..213
+Multiple root expressions at 213..214
 Unexpected token at 213..214
+Multiple root expressions at 214..215
 Unexpected token at 214..215
+Multiple root expressions at 215..216
 Unexpected token at 215..216
+Multiple root expressions at 216..217
 Unexpected token at 217..218
 Unexpected token at 218..219
 Unexpected token at 219..220
 Unexpected token at 220..221
+Missing R_CURLY at 232..233
 Unexpected token at 232..233
 Unexpected token at 233..234
-Unexpected token at 234..235
 Unexpected token at 235..236
 Unexpected token at 236..237
 Unexpected token at 237..238
-Unexpected token at 238..238
+Missing expression at 241..241
-Unexpected token at 238..239
-Unexpected token at 239..241
 Missing R_CURLY at 241..241
 Missing R_BRACK at 241..241
 Missing R_BRACK at 241..241
-Missing R_BRACK at 241..241
-Missing R_BRACK at 241..241
 SOURCE_FILE@0..241
   REF@0..7
     IDENT@0..7 "KKKKKKK"
@@ -160,15 +192,15 @@ SOURCE_FILE@0..241
       IDENT@8..17 "KKKKKKKKK"
   ERROR@17..18 "%"
   ERROR@18..19 "$"
-  LIST@19..241
+  LIST@19..129
     L_BRACK@19..20 "["
     ERROR@20..21 "^"
     ERROR@21..22 "'"
     ERROR@22..23 "$"
-    PATH_INTERPOLATION@23..156
+    PATH_INTERPOLATION@23..129
       PATH_START@23..23 ""
       PATH_FRAGMENT@23..24 "/"
-      DYNAMIC@24..156
+      DYNAMIC@24..129
         DOLLAR_L_CURLY@24..26 "${"
         REF@26..50
           IDENT@26..50 "KKKKKKKKKKKKKKKcKKkKKKKK"
@@ -240,6 +272,7 @@ SOURCE_FILE@0..241
         ERROR@115..116 "\u{11}"
         ERROR@116..117 "\u{11}"
         ERROR@117..118 "\u{11}"
+        REF@118..122
           IDENT@118..122 "KKKK"
         ERROR@122..123 "%"
         ERROR@123..124 "\0"
@@ -247,18 +280,26 @@ SOURCE_FILE@0..241
         ERROR@125..126 "\0"
         ERROR@126..127 "\u{14}"
         ERROR@127..128 "$"
+        LIST@128..129
           L_BRACK@128..129 "["
   R_PAREN@129..130 ")"
   ERROR@130..131 "^"
   ERROR@131..132 "'"
   ERROR@132..133 "$"
+  PATH_INTERPOLATION@133..157
     PATH_START@133..133 ""
     PATH_FRAGMENT@133..134 "/"
+    DYNAMIC@134..157
       DOLLAR_L_CURLY@134..136 "${"
+      REF@136..141
         IDENT@136..141 "KKKKK"
       ERROR@141..142 "\u{6}"
       ERROR@142..143 "\u{6}"
+      ATTR_SET@143..156
         L_CURLY@143..144 "{"
+        ATTR_PATH_VALUE@144..146
+          ATTR_PATH@144..146
+            NAME@144..146
               IDENT@144..146 "YY"
         L_CURLY@146..147 "{"
         ERROR@147..148 "'"
@@ -279,7 +320,7 @@ SOURCE_FILE@0..241
   ERROR@162..163 "\0"
   ERROR@163..164 "\0"
   ERROR@164..165 "\0"
-    LIST@165..241
+  LIST@165..169
     L_BRACK@165..166 "["
     REF@166..167
       IDENT@166..167 "a"
@@ -288,7 +329,9 @@ SOURCE_FILE@0..241
       R_CURLY@168..169 "}"
   R_CURLY@169..170 "}"
   PATH_END@170..170 ""
-      ATTR_SET@170..172
+  LAMBDA@170..173
+    PARAM@170..172
+      PAT@170..172
         L_CURLY@170..171 "{"
         R_CURLY@171..172 "}"
     COLON@172..173 ":"
@@ -298,7 +341,7 @@ SOURCE_FILE@0..241
   ERROR@175..176 "\0"
   ERROR@176..177 "\0"
   R_PAREN@177..178 ")"
-      LIST@178..241
+  LIST@178..182
     L_BRACK@178..179 "["
     REF@179..180
       IDENT@179..180 "a"
@@ -311,7 +354,9 @@ SOURCE_FILE@0..241
     L_CURLY@184..185 "{"
     R_CURLY@185..186 "}"
   R_CURLY@186..187 "}"
-        ATTR_SET@187..189
+  LAMBDA@187..190
+    PARAM@187..189
+      PAT@187..189
         L_CURLY@187..188 "{"
         R_CURLY@188..189 "}"
     COLON@189..190 ":"
@@ -339,10 +384,13 @@ SOURCE_FILE@0..241
           IDENT@224..232 "KKKKKKKK"
         ERROR@232..233 "%"
         ERROR@233..234 "$"
+        LIST@234..241
           L_BRACK@234..235 "["
           ERROR@235..236 "^"
           ERROR@236..237 "'"
           ERROR@237..238 "$"
+          PATH_INTERPOLATION@238..241
             PATH_START@238..238 ""
             PATH_FRAGMENT@238..239 "/"
+            DYNAMIC@239..241
               DOLLAR_L_CURLY@239..241 "${"