Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/csslib/src/tokenizer_base.dart

+// Copyright (c) 2012, 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.
+// Generated by scripts/tokenizer_gen.py.
+
+part of csslib.parser;
+
+/** Tokenizer state to support look ahead for Less' nested selectors. */
+class TokenizerState {
+  final int index;
+  final int startIndex;
+  final bool inSelectorExpression;
+  final bool inSelector;
+
+  TokenizerState(TokenizerBase base) :
+      index = base._index,
+      startIndex = base._startIndex,
+      inSelectorExpression = base.inSelectorExpression,
+      inSelector = base.inSelector;
+}
+
+/**
+ * The base class for our tokenizer. The hand coded parts are in this file, with
+ * the generated parts in the subclass Tokenizer.
+ */
+abstract class TokenizerBase {
+  final SourceFile _file;
+  final String _text;
+
+  bool _skipWhitespace;
+
+  /**
+   * Changes tokenization when in a pseudo function expression.  If true then
+   * minus signs are handled as operators instead of identifiers.
+   */
+  bool inSelectorExpression = false;
+
+  /**
+   * Changes tokenization when in selectors. If true, it prevents identifiers
+   * from being treated as units. This would break things like ":lang(fr)" or
+   * the HTML (unknown) tag name "px", which is legal to use in a selector.
+   */
+  // TODO(jmesserly): is this a problem elsewhere? "fr" for example will be
+  // processed as a "fraction" unit token, preventing it from working in
+  // places where an identifier is expected. This was breaking selectors like:
+  //     :lang(fr)
+  // The assumption that "fr" always means fraction (and similar issue with
+  // other units) doesn't seem valid. We probably should defer this
+  // analysis until we reach places in the parser where units are expected.
+  // I'm not sure this is tokenizing as described in the specs:
+  //     http://dev.w3.org/csswg/css-syntax/
+  //     http://dev.w3.org/csswg/selectors4/
+  bool inSelector = false;
+
+  int _index;
+  int _startIndex;
+
+  static const String _CDATA_START = '<![CDATA[';
+  static const String _CDATA_END = ']]>';
+
+  TokenizerBase(this._file, this._text, this._skipWhitespace,
+      [this._index = 0]);
+
+  Token next();
+  int getIdentifierKind();
+
+  /** Snapshot of Tokenizer scanning state. */
+  TokenizerState get mark => new TokenizerState(this);
+
+  /** Restore Tokenizer scanning state. */
+  void restore(TokenizerState markedData) {
+    _index = markedData.index;
+    _startIndex = markedData.startIndex;
+    inSelectorExpression = markedData.inSelectorExpression;
+    inSelector = markedData.inSelector;
+  }
+
+  int _nextChar() {
+    if (_index < _text.length) {
+      return _text.codeUnitAt(_index++);
+    } else {
+      return 0;
+    }
+  }
+
+  int _peekChar() {
+    if (_index < _text.length) {
+      return _text.codeUnitAt(_index);
+    } else {
+      return 0;
+    }
+  }
+
+  bool _maybeEatChar(int ch) {
+    if (_index < _text.length) {
+      if (_text.codeUnitAt(_index) == ch) {
+        _index++;
+        return true;
+      } else {
+        return false;
+      }
+    } else {
+      return false;
+    }
+  }
+
+  String _tokenText() {
+    if (_index < _text.length) {
+      return _text.substring(_startIndex, _index);
+    } else {
+      return _text.substring(_startIndex, _text.length);
+    }
+  }
+
+  Token _finishToken(int kind) {
+    return new Token(kind, _file.span(_startIndex, _index));
+  }
+
+  Token _errorToken([String message = null]) {
+    return new ErrorToken(
+        TokenKind.ERROR, _file.span(_startIndex, _index), message);
+  }
+
+  Token finishWhitespace() {
+    _index--;
+    while (_index < _text.length) {
+      final ch = _text.codeUnitAt(_index++);
+      if (ch == TokenChar.SPACE ||
+          ch == TokenChar.TAB ||
+          ch == TokenChar.RETURN) {
+        // do nothing
+      } else if (ch == TokenChar.NEWLINE) {
+        if (!_skipWhitespace) {
+          return _finishToken(TokenKind.WHITESPACE); // note the newline?
+        }
+      } else {
+        _index--;
+        if (_skipWhitespace) {
+          return next();
+        } else {
+          return _finishToken(TokenKind.WHITESPACE);
+        }
+      }
+
+    }
+    return _finishToken(TokenKind.END_OF_FILE);
+  }
+
+  Token finishMultiLineComment() {
+    int nesting = 1;
+    do {
+      int ch = _nextChar();
+      if (ch == 0) {
+        return _errorToken();
+      } else if (ch == TokenChar.ASTERISK) {
+        if (_maybeEatChar(TokenChar.SLASH)) {
+          nesting--;
+        }
+      } else if (ch == TokenChar.SLASH) {
+        if (_maybeEatChar(TokenChar.ASTERISK)) {
+          nesting++;
+        }
+      }
+    } while (nesting > 0);
+
+    if (_skipWhitespace) {
+      return next();
+    } else {
+      return _finishToken(TokenKind.COMMENT);
+    }
+  }
+
+  void eatDigits() {
+    while (_index < _text.length) {
+      if (TokenizerHelpers.isDigit(_text.codeUnitAt(_index))) {
+        _index++;
+      } else {
+        return;
+      }
+    }
+  }
+
+  static int _hexDigit(int c) {
+    if(c >= 48/*0*/ && c <= 57/*9*/) {
+      return c - 48;
+    } else if (c >= 97/*a*/ && c <= 102/*f*/) {
+      return c - 87;
+    } else if (c >= 65/*A*/ && c <= 70/*F*/) {
+      return c - 55;
+    } else {
+      return -1;
+    }
+  }
+
+  int readHex([int hexLength]) {
+    int maxIndex;
+    if (hexLength == null) {
+      maxIndex = _text.length - 1;
+    } else {
+      // TODO(jimhug): What if this is too long?
+      maxIndex = _index + hexLength;
+      if (maxIndex >= _text.length) return -1;
+    }
+    var result = 0;
+    while (_index < maxIndex) {
+      final digit = _hexDigit(_text.codeUnitAt(_index));
+      if (digit == -1) {
+        if (hexLength == null) {
+          return result;
+        } else {
+          return -1;
+        }
+      }
+      _hexDigit(_text.codeUnitAt(_index));
+      // Multiply by 16 rather than shift by 4 since that will result in a
+      // correct value for numbers that exceed the 32 bit precision of JS
+      // 'integers'.
+      // TODO: Figure out a better solution to integer truncation. Issue 638.
+      result = (result * 16) + digit;
+      _index++;
+    }
+
+    return result;
+  }
+
+  Token finishNumber() {
+    eatDigits();
+
+    if (_peekChar() == TokenChar.DOT) {
+      // Handle the case of 1.toString().
+      _nextChar();
+      if (TokenizerHelpers.isDigit(_peekChar())) {
+        eatDigits();
+        return finishNumberExtra(TokenKind.DOUBLE);
+      } else {
+        _index--;
+      }
+    }
+
+    return finishNumberExtra(TokenKind.INTEGER);
+  }
+
+  Token finishNumberExtra(int kind) {
+    if (_maybeEatChar(101/*e*/) || _maybeEatChar(69/*E*/)) {
+      kind = TokenKind.DOUBLE;
+      _maybeEatChar(TokenKind.MINUS);
+      _maybeEatChar(TokenKind.PLUS);
+      eatDigits();
+    }
+    if (_peekChar() != 0 && TokenizerHelpers.isIdentifierStart(_peekChar())) {
+      _nextChar();
+      return _errorToken("illegal character in number");
+    }
+
+    return _finishToken(kind);
+  }
+
+  Token _makeStringToken(List<int> buf, bool isPart) {
+    final s = new String.fromCharCodes(buf);
+    final kind = isPart ? TokenKind.STRING_PART : TokenKind.STRING;
+    return new LiteralToken(kind, _file.span(_startIndex, _index), s);
+  }
+
+  Token makeIEFilter(int start, int end) {
+    var filter = _text.substring(start, end);
+    return new LiteralToken(TokenKind.STRING, _file.span(start, end), filter);
+  }
+
+  Token _makeRawStringToken(bool isMultiline) {
+    var s;
+    if (isMultiline) {
+      // Skip initial newline in multiline strings
+      int start = _startIndex + 4;
+      if (_text[start] == '\n') start++;
+      s = _text.substring(start, _index - 3);
+    } else {
+      s = _text.substring(_startIndex + 2, _index - 1);
+    }
+    return new LiteralToken(TokenKind.STRING,
+        _file.span(_startIndex, _index), s);
+  }
+
+  Token finishMultilineString(int quote) {
+    var buf = <int>[];
+    while (true) {
+      int ch = _nextChar();
+      if (ch == 0) {
+        return _errorToken();
+      } else if (ch == quote) {
+        if (_maybeEatChar(quote)) {
+          if (_maybeEatChar(quote)) {
+            return _makeStringToken(buf, false);
+          }
+          buf.add(quote);
+        }
+        buf.add(quote);
+      } else if (ch == TokenChar.BACKSLASH) {
+        var escapeVal = readEscapeSequence();
+        if (escapeVal == -1) {
+          return _errorToken("invalid hex escape sequence");
+        } else {
+          buf.add(escapeVal);
+        }
+      } else {
+        buf.add(ch);
+      }
+    }
+  }
+
+  Token _finishOpenBrace() {
+    return _finishToken(TokenKind.LBRACE);
+  }
+
+  Token _finishCloseBrace() {
+    return _finishToken(TokenKind.RBRACE);
+  }
+
+  Token finishString(int quote) {
+    if (_maybeEatChar(quote)) {
+      if (_maybeEatChar(quote)) {
+        // skip an initial newline
+        _maybeEatChar(TokenChar.NEWLINE);
+        return finishMultilineString(quote);
+      } else {
+        return _makeStringToken(new List<int>(), false);
+      }
+    }
+    return finishStringBody(quote);
+  }
+
+  Token finishRawString(int quote) {
+    if (_maybeEatChar(quote)) {
+      if (_maybeEatChar(quote)) {
+        return finishMultilineRawString(quote);
+      } else {
+        return _makeStringToken(<int>[], false);
+      }
+    }
+    while (true) {
+      int ch = _nextChar();
+      if (ch == quote) {
+        return _makeRawStringToken(false);
+      } else if (ch == 0) {
+        return _errorToken();
+      }
+    }
+  }
+
+  Token finishMultilineRawString(int quote) {
+    while (true) {
+      int ch = _nextChar();
+      if (ch == 0) {
+        return _errorToken();
+      } else if (ch == quote && _maybeEatChar(quote) && _maybeEatChar(quote)) {
+        return _makeRawStringToken(true);
+      }
+    }
+  }
+
+  Token finishStringBody(int quote) {
+    var buf = new List<int>();
+    while (true) {
+      int ch = _nextChar();
+      if (ch == quote) {
+        return _makeStringToken(buf, false);
+      } else if (ch == 0) {
+        return _errorToken();
+      } else if (ch == TokenChar.BACKSLASH) {
+        var escapeVal = readEscapeSequence();
+        if (escapeVal == -1) {
+          return _errorToken("invalid hex escape sequence");
+        } else {
+          buf.add(escapeVal);
+        }
+      } else {
+        buf.add(ch);
+      }
+    }
+  }
+
+  int readEscapeSequence() {
+    final ch = _nextChar();
+    int hexValue;
+    switch (ch) {
+      case 110/*n*/:
+        return TokenChar.NEWLINE;
+      case 114/*r*/:
+        return TokenChar.RETURN;
+      case 102/*f*/:
+        return TokenChar.FF;
+      case 98/*b*/:
+        return TokenChar.BACKSPACE;
+      case 116/*t*/:
+        return TokenChar.TAB;
+      case 118/*v*/:
+        return TokenChar.FF;
+      case 120/*x*/:
+        hexValue = readHex(2);
+        break;
+      case 117/*u*/:
+        if (_maybeEatChar(TokenChar.LBRACE)) {
+          hexValue = readHex();
+          if (!_maybeEatChar(TokenChar.RBRACE)) {
+            return -1;
+          }
+        } else {
+          hexValue = readHex(4);
+        }
+        break;
+      default: return ch;
+    }
+
+    if (hexValue == -1) return -1;
+
+    // According to the Unicode standard the high and low surrogate halves
+    // used by UTF-16 (U+D800 through U+DFFF) and values above U+10FFFF
+    // are not legal Unicode values.
+    if (hexValue < 0xD800 || hexValue > 0xDFFF && hexValue <= 0xFFFF) {
+      return hexValue;
+    } else if (hexValue <= 0x10FFFF){
+      messages.error('unicode values greater than 2 bytes not implemented yet',
+          _file.span(_startIndex, _startIndex + 1));
+      return -1;
+    } else {
+      return -1;
+    }
+  }
+
+  Token finishDot() {
+    if (TokenizerHelpers.isDigit(_peekChar())) {
+      eatDigits();
+      return finishNumberExtra(TokenKind.DOUBLE);
+    } else {
+      return _finishToken(TokenKind.DOT);
+    }
+  }
+}
+