Beginning of CSS parser using frog parsering infrastructure.

utils/css/tokenizer.dart

+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Tokenizer extends lang.TokenizerBase {
+  TokenKind cssTokens;
+
+  Tokenizer(lang.SourceFile source, bool skipWhitespace, [int index = 0])
+    : super(source, skipWhitespace, index) {
+    cssTokens = new TokenKind();
+  }
+
+  lang.Token next() {
+    // keep track of our starting position
+    _startIndex = _index;
+
+    if (_interpStack != null && _interpStack.depth == 0) {
+      var istack = _interpStack;
+      _interpStack = _interpStack.pop();
+
+      /* TODO(terry): Enable for variable and string interpolation.
+       * if (istack.isMultiline) {
+       *   return finishMultilineStringBody(istack.quote);
+       * } else {
+       *   return finishStringBody(istack.quote);
+       * }
+       */
+    }
+
+    int ch;
+    ch = _nextChar();
+    switch(ch) {
+      case 0:
+        return _finishToken(TokenKind.END_OF_FILE);
+      case cssTokens.tokens[TokenKind.SPACE]:
+      case cssTokens.tokens[TokenKind.TAB]:
+      case cssTokens.tokens[TokenKind.NEWLINE]:
+      case cssTokens.tokens[TokenKind.RETURN]:
+        return finishWhitespace();
+      case cssTokens.tokens[TokenKind.END_OF_FILE]:
+        return _finishToken(TokenKind.END_OF_FILE);
+      case cssTokens.tokens[TokenKind.AT]:
+        return _finishToken(TokenKind.AT);
+      case cssTokens.tokens[TokenKind.DOT]:
+        return _finishToken(TokenKind.DOT);
+      case cssTokens.tokens[TokenKind.LBRACE]:
+        return _finishToken(TokenKind.LBRACE);
+      case cssTokens.tokens[TokenKind.RBRACE]:
+        return _finishToken(TokenKind.RBRACE);
+      case cssTokens.tokens[TokenKind.HASH]:
+        return _finishToken(TokenKind.HASH);
+      case cssTokens.tokens[TokenKind.COMBINATOR_PLUS]:
+        return _finishToken(TokenKind.COMBINATOR_PLUS);
+      case cssTokens.tokens[TokenKind.COMBINATOR_GREATER]:
+        return _finishToken(TokenKind.COMBINATOR_GREATER);
+      case cssTokens.tokens[TokenKind.COMBINATOR_TILDE]:
+        return _finishToken(TokenKind.COMBINATOR_TILDE);
+      case cssTokens.tokens[TokenKind.ASTERISK]:
+        return _finishToken(TokenKind.ASTERISK);
+      case cssTokens.tokens[TokenKind.NAMESPACE]:
+        return _finishToken(TokenKind.NAMESPACE);
+      case cssTokens.tokens[TokenKind.PSEUDO]:
+        return _finishToken(TokenKind.PSEUDO);
+      case cssTokens.tokens[TokenKind.COMMA]:
+        return _finishToken(TokenKind.COMMA);
+
+      default:
+        if (isIdentifierStart(ch)) {
+          return this.finishIdentifier();
+        } else if (isDigit(ch)) {
+          return this.finishNumber();
+        } else {
+          return _errorToken();
+        }
+    }
+  }
+
+  // TODO(jmesserly): we need a way to emit human readable error messages from
+  // the tokenizer.
+  lang.Token _errorToken() {
+    return _finishToken(TokenKind.ERROR);
+  }
+
+  int getIdentifierKind() {
+    return TokenKind.IDENTIFIER;
+  }
+
+  // Need to override so CSS version of isIdentifierPart is used.
+  lang.Token finishIdentifier() {
+    while (_index < _text.length) {
+      if (!TokenizerHelpers.isIdentifierPart(_text.charCodeAt(_index++))) {
+        _index--;
+        break;
+      }
+    }
+    int kind = getIdentifierKind();
+    if (_interpStack != null && _interpStack.depth == -1) {
+      _interpStack.depth = 0;
+    }
+    if (kind == TokenKind.IDENTIFIER) {
+      return _finishToken(TokenKind.IDENTIFIER);
+    } else {
+      return _finishToken(kind);
+    }
+  }
+
+}
+
+/** Static helper methods. */
+class TokenizerHelpers {
+  static bool isIdentifierStart(int c) =>
+      lang.TokenizerHelpers.isIdentifierStart(c) || c == 95 /*_*/;
+
+  static bool isDigit(int c) => lang.TokenizerHelpers.isDigit(c);
+
+  static bool isHexDigit(int c) => lang.TokenizerHelpers.isHexDigit(c);
+
+  static bool isWhitespace(int c) => lang.TokenizerHelpers.isWhitespace(c);
+
+  static bool isIdentifierPart(int c) =>
+      lang.TokenizerHelpers.isIdentifierPart(c) || c == 45 /*-*/;
+}