[Indented syntax improvements] Dart implementation

lib/src/parse/at_root_query.dart

@@ -14,17 +14,17 @@ class AtRootQueryParser extends Parser {
   AtRootQuery parse() {
     return wrapSpanFormatException(() {
       scanner.expectChar($lparen);
-      whitespace();
+      whitespace(allowNewlines: true);
       var include = scanIdentifier("with");
       if (!include) expectIdentifier("without", name: '"with" or "without"');
-      whitespace();
+      whitespace(allowNewlines: true);
       scanner.expectChar($colon);
-      whitespace();
+      whitespace(allowNewlines: true);
 
       var atRules = <String>{};
       do {
         atRules.add(identifier().toLowerCase());
-        whitespace();
+        whitespace(allowNewlines: true);
       } while (lookingAtIdentifier());
       scanner.expectChar($rparen);
       scanner.expectDone();

lib/src/parse/css.dart

@@ -49,7 +49,7 @@ class CssParser extends ScssParser {
     var start = scanner.state;
     scanner.expectChar($at);
     var name = interpolatedIdentifier();
-    whitespace();
+    whitespace(allowNewlines: true);
 
     return switch (name.asPlain) {
       "at-root" ||
@@ -113,7 +113,7 @@ class CssParser extends ScssParser {
           .text
     };
 
-    whitespace();
+    whitespace(allowNewlines: true);
     var modifiers = tryImportModifiers();
     expectStatementSeparator("@import rule");
     return ImportRule(
@@ -126,7 +126,7 @@ class CssParser extends ScssParser {
     // evaluation time.
     var start = scanner.state;
     scanner.expectChar($lparen);
-    whitespace();
+    whitespace(allowNewlines: true);
     var expression = expressionUntilComma();
     scanner.expectChar($rparen);
     return ParenthesizedExpression(expression, scanner.spanFrom(start));
@@ -151,7 +151,7 @@ class CssParser extends ScssParser {
     var arguments = <Expression>[];
     if (!scanner.scanChar($rparen)) {
       do {
-        whitespace();
+        whitespace(allowNewlines: true);
         if (allowEmptySecondArg &&
             arguments.length == 1 &&
             scanner.peekChar() == $rparen) {
@@ -160,7 +160,7 @@ class CssParser extends ScssParser {
         }
 
         arguments.add(expressionUntilComma(singleEquals: true));
-        whitespace();
+        whitespace(allowNewlines: true);
       } while (scanner.scanChar($comma));
       scanner.expectChar($rparen);
     }

lib/src/parse/keyframe_selector.dart

@@ -15,7 +15,7 @@ class KeyframeSelectorParser extends Parser {
     return wrapSpanFormatException(() {
       var selectors = <String>[];
       do {
-        whitespace();
+        whitespace(allowNewlines: false);
         if (lookingAtIdentifier()) {
           if (scanIdentifier("from")) {
             selectors.add("from");
@@ -26,7 +26,7 @@ class KeyframeSelectorParser extends Parser {
         } else {
           selectors.add(_percentage());
         }
-        whitespace();
+        whitespace(allowNewlines: false);
       } while (scanner.scanChar($comma));
       scanner.expectDone();
 

lib/src/parse/media_query.dart

@@ -16,9 +16,9 @@ class MediaQueryParser extends Parser {
     return wrapSpanFormatException(() {
       var queries = <CssMediaQuery>[];
       do {
-        whitespace();
+        whitespace(allowNewlines: true);
         queries.add(_mediaQuery());
-        whitespace();
+        whitespace(allowNewlines: true);
       } while (scanner.scanChar($comma));
       scanner.expectDone();
       return queries;
@@ -30,7 +30,7 @@ class MediaQueryParser extends Parser {
     // This is somewhat duplicated in StylesheetParser._mediaQuery.
     if (scanner.peekChar() == $lparen) {
       var conditions = [_mediaInParens()];
-      whitespace();
+      whitespace(allowNewlines: true);
 
       var conjunction = true;
       if (scanIdentifier("and")) {
@@ -57,7 +57,7 @@ class MediaQueryParser extends Parser {
       }
     }
 
-    whitespace();
+    whitespace(allowNewlines: true);
     if (!lookingAtIdentifier()) {
       // For example, "@media screen {"
       return CssMediaQuery.type(identifier1);
@@ -70,7 +70,7 @@ class MediaQueryParser extends Parser {
       // For example, "@media screen and ..."
       type = identifier1;
     } else {
-      whitespace();
+      whitespace(allowNewlines: true);
       modifier = identifier1;
       type = identifier2;
       if (scanIdentifier("and")) {
@@ -102,7 +102,7 @@ class MediaQueryParser extends Parser {
     var result = <String>[];
     while (true) {
       result.add(_mediaInParens());
-      whitespace();
+      whitespace(allowNewlines: true);
 
       if (!scanIdentifier(operator)) return result;
       expectWhitespace();

lib/src/parse/parser.dart

@@ -67,23 +67,29 @@ class Parser {
     if (!scanner.scanChar($dollar)) return false;
     if (!lookingAtIdentifier()) return false;
     identifier();
-    whitespace();
+    whitespace(allowNewlines: false);
     return scanner.scanChar($colon);
   }
 
   // ## Tokens
 
   /// Consumes whitespace, including any comments.
+  ///
+  /// If [allowNewlines] is true, the indented syntax will consume newlines as
+  /// whitespace, in positions when a statement can not end.
   @protected
-  void whitespace() {
+  void whitespace({required bool allowNewlines}) {
     do {
-      whitespaceWithoutComments();
+      whitespaceWithoutComments(allowNewlines: allowNewlines);
     } while (scanComment());
   }
 
   /// Consumes whitespace, but not comments.
+  ///
+  /// If [allowNewlines] is true, the indented syntax will consume newlines as
+  /// whitespace, in positions when a statement can not end.
   @protected
-  void whitespaceWithoutComments() {
+  void whitespaceWithoutComments({required bool allowNewlines}) {
     while (!scanner.isDone && scanner.peekChar().isWhitespace) {
       scanner.readChar();
     }
@@ -116,13 +122,15 @@ class Parser {
   }
 
   /// Like [whitespace], but throws an error if no whitespace is consumed.
+  ///
+  /// If [allowNewlines] is true, the indented syntax will consume newlines as
+  /// whitespace, in positions when a statement can not end.
   @protected
-  void expectWhitespace() {
+  void expectWhitespace({bool allowNewlines = false}) {
     if (scanner.isDone || !(scanner.peekChar().isWhitespace || scanComment())) {
       scanner.error("Expected whitespace.");
     }
-
-    whitespace();
+    whitespace(allowNewlines: allowNewlines);
   }
 
   /// Consumes and ignores a single silent (Sass-style) comment, not including
@@ -386,7 +394,7 @@ class Parser {
       return null;
     }
 
-    whitespace();
+    whitespace(allowNewlines: true);
 
     // Match Ruby Sass's behavior: parse a raw URL() if possible, and if not
     // backtrack and re-parse as a function expression.
@@ -407,7 +415,7 @@ class Parser {
               >= 0x0080:
           buffer.writeCharCode(scanner.readChar());
         case int(isWhitespace: true):
-          whitespace();
+          whitespace(allowNewlines: true);
           if (scanner.peekChar() != $rparen) break loop;
         case $rparen:
           buffer.writeCharCode(scanner.readChar());

lib/src/parse/sass.dart

@@ -54,14 +54,19 @@ class SassParser extends StylesheetParser {
   }
 
   void expectStatementSeparator([String? name]) {
-    if (!atEndOfStatement()) _expectNewline();
+    if (!atEndOfStatement()) _expectNewline(canEndInSemicolon: true);
     if (_peekIndentation() <= currentIndentation) return;
     scanner.error(
         "Nothing may be indented ${name == null ? 'here' : 'beneath a $name'}.",
         position: _nextIndentationEnd!.position);
   }
 
-  bool atEndOfStatement() => scanner.peekChar()?.isNewline ?? true;
+  bool atEndOfStatement() {
+    var next = scanner.peekChar();
+    return next.isNewline ||
+        next == null ||
+        (next == $semicolon && scanner.peekChar(1).isNewline);
+  }
 
   bool lookingAtChildren() =>
       atEndOfStatement() && _peekIndentation() > currentIndentation;
@@ -259,7 +264,7 @@ class SassParser extends StylesheetParser {
               buffer.writeCharCode(scanner.readChar());
               buffer.writeCharCode(scanner.readChar());
               var span = scanner.spanFrom(start);
-              whitespace();
+              whitespace(allowNewlines: false);
 
               // For backwards compatibility, allow additional comments after
               // the initial comment is closed.
@@ -269,7 +274,7 @@ class SassParser extends StylesheetParser {
                   _expectNewline();
                 }
                 _readIndentation();
-                whitespace();
+                whitespace(allowNewlines: false);
               }
 
               if (!scanner.isDone && !scanner.peekChar().isNewline) {
@@ -309,37 +314,39 @@ class SassParser extends StylesheetParser {
     return LoudComment(buffer.interpolation(scanner.spanFrom(start)));
   }
 
-  void whitespaceWithoutComments() {
+  void whitespaceWithoutComments({required bool allowNewlines}) {
     // This overrides whitespace consumption so that it doesn't consume
-    // newlines.
+    // newlines where that would cause a statement to end.
     while (!scanner.isDone) {
       var next = scanner.peekChar();
-      if (next != $tab && next != $space) break;
+      if (!allowNewlines && !next.isSpaceOrTab) {
+        break;
+      } else if (allowNewlines && !next.isWhitespace) {
+        break;
+      }
       scanner.readChar();
     }
   }
 
-  void loudComment() {
-    // This overrides loud comment consumption so that it doesn't consume
-    // multi-line comments.
-    scanner.expect("/*");
-    while (true) {
-      var next = scanner.readChar();
-      if (next.isNewline) scanner.error("expected */.");
-      if (next != $asterisk) continue;
-
-      do {
-        next = scanner.readChar();
-      } while (next == $asterisk);
-      if (next == $slash) break;
-    }
-  }
-
-  /// Expect and consume a single newline character.
-  void _expectNewline() {
+  /// Expect and consume a single newline.
+  ///
+  /// If [canEndInSemicolon] is true, this will also consume a `;` before the
+  /// newline if present.
+  void _expectNewline({bool canEndInSemicolon = false}) {
     switch (scanner.peekChar()) {
+      case $semicolon
+          when canEndInSemicolon && [$lf, $ff].contains(scanner.peekChar(1)):
+        scanner.readChar();
+        scanner.readChar();
+        return;
+      case $semicolon when canEndInSemicolon && scanner.peekChar(1) == $cr:
+        scanner.readChar();
+        scanner.readChar();
+        if (scanner.peekChar() == $lf) scanner.readChar();
+        return;
       case $semicolon:
-        scanner.error("semicolons aren't allowed in the indented syntax.");
+        scanner.error(
+            "multiple statements on one line are not supported in the indented syntax.");
       case $cr:
         scanner.readChar();
         if (scanner.peekChar() == $lf) scanner.readChar();
@@ -404,7 +411,14 @@ class SassParser extends StylesheetParser {
     }
 
     var start = scanner.state;
-    if (!scanCharIf((char) => char.isNewline)) {
+
+    if (scanner.peekChar().isNewline) {
+      scanner.readChar();
+    } else if (scanner.peekChar() == $semicolon &&
+        scanner.peekChar(1).isNewline) {
+      scanner.readChar();
+      scanner.readChar();
+    } else {
       scanner.error("Expected newline.", position: scanner.position);
     }
 

lib/src/parse/scss.dart

@@ -20,7 +20,7 @@ class ScssParser extends StylesheetParser {
   Interpolation styleRuleSelector() => almostAnyValue();
 
   void expectStatementSeparator([String? name]) {
-    whitespaceWithoutComments();
+    whitespaceWithoutComments(allowNewlines: true);
     if (scanner.isDone) return;
     if (scanner.peekChar() case $semicolon || $rbrace) return;
     scanner.expectChar($semicolon);
@@ -38,7 +38,7 @@ class ScssParser extends StylesheetParser {
 
   bool scanElse(int ifIndentation) {
     var start = scanner.state;
-    whitespace();
+    whitespace(allowNewlines: true);
     var beforeAt = scanner.state;
     if (scanner.scanChar($at)) {
       if (scanIdentifier('else', caseSensitive: true)) return true;
@@ -62,7 +62,7 @@ class ScssParser extends StylesheetParser {
 
   List<Statement> children(Statement child()) {
     scanner.expectChar($lbrace);
-    whitespaceWithoutComments();
+    whitespaceWithoutComments(allowNewlines: true);
     var children = <Statement>[];
     while (true) {
       switch (scanner.peekChar()) {
@@ -73,17 +73,17 @@ class ScssParser extends StylesheetParser {
           switch (scanner.peekChar(1)) {
             case $slash:
               children.add(_silentComment());
-              whitespaceWithoutComments();
+              whitespaceWithoutComments(allowNewlines: true);
             case $asterisk:
               children.add(_loudComment());
-              whitespaceWithoutComments();
+              whitespaceWithoutComments(allowNewlines: true);
             default:
               children.add(child());
           }
 
         case $semicolon:
           scanner.readChar();
-          whitespaceWithoutComments();
+          whitespaceWithoutComments(allowNewlines: true);
 
         case $rbrace:
           scanner.expectChar($rbrace);
@@ -97,7 +97,7 @@ class ScssParser extends StylesheetParser {
 
   List<Statement> statements(Statement? statement()) {
     var statements = <Statement>[];
-    whitespaceWithoutComments();
+    whitespaceWithoutComments(allowNewlines: true);
     while (!scanner.isDone) {
       switch (scanner.peekChar()) {
         case $dollar:
@@ -107,17 +107,17 @@ class ScssParser extends StylesheetParser {
           switch (scanner.peekChar(1)) {
             case $slash:
               statements.add(_silentComment());
-              whitespaceWithoutComments();
+              whitespaceWithoutComments(allowNewlines: true);
             case $asterisk:
               statements.add(_loudComment());
-              whitespaceWithoutComments();
+              whitespaceWithoutComments(allowNewlines: true);
             default:
               if (statement() case var child?) statements.add(child);
           }
 
         case $semicolon:
           scanner.readChar();
-          whitespaceWithoutComments();
+          whitespaceWithoutComments(allowNewlines: true);
 
         default:
           if (statement() case var child?) statements.add(child);