Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/analyzer/lib/src/generated/scanner.dart

+// Copyright (c) 2014, 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.
+
+library engine.scanner;
+
+import 'dart:collection';
+
+import 'error.dart';
+import 'java_engine.dart';
+import 'source.dart';
+
+/**
+ * The opening half of a grouping pair of tokens. This is used for curly
+ * brackets ('{'), parentheses ('('), and square brackets ('[').
+ */
+class BeginToken extends Token {
+  /**
+   * The token that corresponds to this token.
+   */
+  Token endToken;
+
+  /**
+   * Initialize a newly created token to have the given [type] at the given
+   * [offset].
+   */
+  BeginToken(TokenType type, int offset) : super(type, offset) {
+    assert(type == TokenType.OPEN_CURLY_BRACKET ||
+        type == TokenType.OPEN_PAREN ||
+        type == TokenType.OPEN_SQUARE_BRACKET ||
+        type == TokenType.STRING_INTERPOLATION_EXPRESSION);
+  }
+
+  @override
+  Token copy() => new BeginToken(type, offset);
+}
+
+/**
+ * A begin token that is preceded by comments.
+ */
+class BeginTokenWithComment extends BeginToken {
+  /**
+   * The first comment in the list of comments that precede this token.
+   */
+  CommentToken _precedingComment;
+
+  /**
+   * Initialize a newly created token to have the given [type] at the given
+   * [offset] and to be preceded by the comments reachable from the given
+   * [comment].
+   */
+  BeginTokenWithComment(TokenType type, int offset, this._precedingComment)
+      : super(type, offset) {
+    _setCommentParent(_precedingComment);
+  }
+
+  CommentToken get precedingComments => _precedingComment;
+
+  void set precedingComments(CommentToken comment) {
+    _precedingComment = comment;
+    _setCommentParent(_precedingComment);
+  }
+
+  @override
+  void applyDelta(int delta) {
+    super.applyDelta(delta);
+    Token token = precedingComments;
+    while (token != null) {
+      token.applyDelta(delta);
+      token = token.next;
+    }
+  }
+
+  @override
+  Token copy() =>
+      new BeginTokenWithComment(type, offset, copyComments(precedingComments));
+}
+
+/**
+ * A [CharacterReader] that reads a range of characters from another character
+ * reader.
+ */
+class CharacterRangeReader extends CharacterReader {
+  /**
+   * The reader from which the characters are actually being read.
+   */
+  final CharacterReader baseReader;
+
+  /**
+   * The last character to be read.
+   */
+  final int endIndex;
+
+  /**
+   * Initialize a newly created reader to read the characters from the given
+   * [baseReader] between the [startIndex] inclusive to [endIndex] exclusive.
+   */
+  CharacterRangeReader(this.baseReader, int startIndex, this.endIndex) {
+    baseReader.offset = startIndex - 1;
+  }
+
+  @override
+  int get offset => baseReader.offset;
+
+  @override
+  void set offset(int offset) {
+    baseReader.offset = offset;
+  }
+
+  @override
+  int advance() {
+    if (baseReader.offset + 1 >= endIndex) {
+      return -1;
+    }
+    return baseReader.advance();
+  }
+
+  @override
+  String getString(int start, int endDelta) =>
+      baseReader.getString(start, endDelta);
+
+  @override
+  int peek() {
+    if (baseReader.offset + 1 >= endIndex) {
+      return -1;
+    }
+    return baseReader.peek();
+  }
+}
+
+/**
+ * An object used by the scanner to read the characters to be scanned.
+ */
+abstract class CharacterReader {
+  /**
+   * The current offset relative to the beginning of the source. Return the
+   * initial offset if the scanner has not yet scanned the source code, and one
+   * (1) past the end of the source code if the entire source code has been
+   * scanned.
+   */
+  int get offset;
+
+  /**
+   * Set the current offset relative to the beginning of the source to the given
+   * [offset]. The new offset must be between the initial offset and one (1)
+   * past the end of the source code.
+   */
+  void set offset(int offset);
+
+  /**
+   * Advance the current position and return the character at the new current
+   * position.
+   */
+  int advance();
+
+  /**
+   * Return the substring of the source code between the [start] offset and the
+   * modified current position. The current position is modified by adding the
+   * [endDelta], which is the number of characters after the current location to
+   * be included in the string, or the number of characters before the current
+   * location to be excluded if the offset is negative.
+   */
+  String getString(int start, int endDelta);
+
+  /**
+   * Return the character at the current position without changing the current
+   * position.
+   */
+  int peek();
+}
+
+/**
+ * A [CharacterReader] that reads characters from a character sequence.
+ */
+class CharSequenceReader implements CharacterReader {
+  /**
+   * The sequence from which characters will be read.
+   */
+  final String _sequence;
+
+  /**
+   * The number of characters in the string.
+   */
+  int _stringLength = 0;
+
+  /**
+   * The index, relative to the string, of the last character that was read.
+   */
+  int _charOffset = 0;
+
+  /**
+   * Initialize a newly created reader to read the characters in the given
+   * [_sequence].
+   */
+  CharSequenceReader(this._sequence) {
+    this._stringLength = _sequence.length;
+    this._charOffset = -1;
+  }
+
+  @override
+  int get offset => _charOffset;
+
+  @override
+  void set offset(int offset) {
+    _charOffset = offset;
+  }
+
+  @override
+  int advance() {
+    if (_charOffset + 1 >= _stringLength) {
+      return -1;
+    }
+    return _sequence.codeUnitAt(++_charOffset);
+  }
+
+  @override
+  String getString(int start, int endDelta) =>
+      _sequence.substring(start, _charOffset + 1 + endDelta).toString();
+
+  @override
+  int peek() {
+    if (_charOffset + 1 >= _stringLength) {
+      return -1;
+    }
+    return _sequence.codeUnitAt(_charOffset + 1);
+  }
+}
+
+/**
+ * A token representing a comment.
+ */
+class CommentToken extends StringToken {
+  /**
+   * The [Token] that contains this comment.
+   */
+  Token parent;
+
+  /**
+   * Initialize a newly created token to represent a token of the given [type]
+   * with the given [value] at the given [offset].
+   */
+  CommentToken(TokenType type, String value, int offset)
+      : super(type, value, offset);
+
+  @override
+  CommentToken copy() => new CommentToken(type, _value, offset);
+}
+
+/**
+ * A documentation comment token.
+ */
+class DocumentationCommentToken extends CommentToken {
+  /**
+   * The references embedded within the documentation comment.
+   * This list will be empty unless this is a documentation comment that has
+   * references embedded within it.
+   */
+  final List<Token> references = <Token>[];
+
+  /**
+   * Initialize a newly created token to represent a token of the given [type]
+   * with the given [value] at the given [offset].
+   */
+  DocumentationCommentToken(TokenType type, String value, int offset)
+      : super(type, value, offset);
+
+  @override
+  CommentToken copy() => new DocumentationCommentToken(type, _value, offset);
+}
+
+/**
+ * The keywords in the Dart programming language.
+ */
+class Keyword {
+  static const Keyword ASSERT = const Keyword('ASSERT', "assert");
+
+  static const Keyword BREAK = const Keyword('BREAK', "break");
+
+  static const Keyword CASE = const Keyword('CASE', "case");
+
+  static const Keyword CATCH = const Keyword('CATCH', "catch");
+
+  static const Keyword CLASS = const Keyword('CLASS', "class");
+
+  static const Keyword CONST = const Keyword('CONST', "const");
+
+  static const Keyword CONTINUE = const Keyword('CONTINUE', "continue");
+
+  static const Keyword DEFAULT = const Keyword('DEFAULT', "default");
+
+  static const Keyword DO = const Keyword('DO', "do");
+
+  static const Keyword ELSE = const Keyword('ELSE', "else");
+
+  static const Keyword ENUM = const Keyword('ENUM', "enum");
+
+  static const Keyword EXTENDS = const Keyword('EXTENDS', "extends");
+
+  static const Keyword FALSE = const Keyword('FALSE', "false");
+
+  static const Keyword FINAL = const Keyword('FINAL', "final");
+
+  static const Keyword FINALLY = const Keyword('FINALLY', "finally");
+
+  static const Keyword FOR = const Keyword('FOR', "for");
+
+  static const Keyword IF = const Keyword('IF', "if");
+
+  static const Keyword IN = const Keyword('IN', "in");
+
+  static const Keyword IS = const Keyword('IS', "is");
+
+  static const Keyword NEW = const Keyword('NEW', "new");
+
+  static const Keyword NULL = const Keyword('NULL', "null");
+
+  static const Keyword RETHROW = const Keyword('RETHROW', "rethrow");
+
+  static const Keyword RETURN = const Keyword('RETURN', "return");
+
+  static const Keyword SUPER = const Keyword('SUPER', "super");
+
+  static const Keyword SWITCH = const Keyword('SWITCH', "switch");
+
+  static const Keyword THIS = const Keyword('THIS', "this");
+
+  static const Keyword THROW = const Keyword('THROW', "throw");
+
+  static const Keyword TRUE = const Keyword('TRUE', "true");
+
+  static const Keyword TRY = const Keyword('TRY', "try");
+
+  static const Keyword VAR = const Keyword('VAR', "var");
+
+  static const Keyword VOID = const Keyword('VOID', "void");
+
+  static const Keyword WHILE = const Keyword('WHILE', "while");
+
+  static const Keyword WITH = const Keyword('WITH', "with");
+
+  static const Keyword ABSTRACT = const Keyword('ABSTRACT', "abstract", true);
+
+  static const Keyword AS = const Keyword('AS', "as", true);
+
+  static const Keyword DEFERRED = const Keyword('DEFERRED', "deferred", true);
+
+  static const Keyword DYNAMIC = const Keyword('DYNAMIC', "dynamic", true);
+
+  static const Keyword EXPORT = const Keyword('EXPORT', "export", true);
+
+  static const Keyword EXTERNAL = const Keyword('EXTERNAL', "external", true);
+
+  static const Keyword FACTORY = const Keyword('FACTORY', "factory", true);
+
+  static const Keyword GET = const Keyword('GET', "get", true);
+
+  static const Keyword IMPLEMENTS =
+      const Keyword('IMPLEMENTS', "implements", true);
+
+  static const Keyword IMPORT = const Keyword('IMPORT', "import", true);
+
+  static const Keyword LIBRARY = const Keyword('LIBRARY', "library", true);
+
+  static const Keyword OPERATOR = const Keyword('OPERATOR', "operator", true);
+
+  static const Keyword PART = const Keyword('PART', "part", true);
+
+  static const Keyword SET = const Keyword('SET', "set", true);
+
+  static const Keyword STATIC = const Keyword('STATIC', "static", true);
+
+  static const Keyword TYPEDEF = const Keyword('TYPEDEF', "typedef", true);
+
+  static const List<Keyword> values = const [
+    ASSERT,
+    BREAK,
+    CASE,
+    CATCH,
+    CLASS,
+    CONST,
+    CONTINUE,
+    DEFAULT,
+    DO,
+    ELSE,
+    ENUM,
+    EXTENDS,
+    FALSE,
+    FINAL,
+    FINALLY,
+    FOR,
+    IF,
+    IN,
+    IS,
+    NEW,
+    NULL,
+    RETHROW,
+    RETURN,
+    SUPER,
+    SWITCH,
+    THIS,
+    THROW,
+    TRUE,
+    TRY,
+    VAR,
+    VOID,
+    WHILE,
+    WITH,
+    ABSTRACT,
+    AS,
+    DEFERRED,
+    DYNAMIC,
+    EXPORT,
+    EXTERNAL,
+    FACTORY,
+    GET,
+    IMPLEMENTS,
+    IMPORT,
+    LIBRARY,
+    OPERATOR,
+    PART,
+    SET,
+    STATIC,
+    TYPEDEF
+  ];
+
+  /**
+   * A table mapping the lexemes of keywords to the corresponding keyword.
+   */
+  static final Map<String, Keyword> keywords = _createKeywordMap();
+
+  /**
+   * The name of the keyword type.
+   */
+  final String name;
+
+  /**
+   * The lexeme for the keyword.
+   */
+  final String syntax;
+
+  /**
+   * A flag indicating whether the keyword is a pseudo-keyword. Pseudo keywords
+   * can be used as identifiers.
+   */
+  final bool isPseudoKeyword;
+
+  /**
+   * Initialize a newly created keyword to have the given [name] and [syntax].
+   * The keyword is a pseudo-keyword if the [isPseudoKeyword] flag is `true`.
+   */
+  const Keyword(this.name, this.syntax, [this.isPseudoKeyword = false]);
+
+  @override
+  String toString() => name;
+
+  /**
+   * Create a table mapping the lexemes of keywords to the corresponding keyword
+   * and return the table that was created.
+   */
+  static Map<String, Keyword> _createKeywordMap() {
+    LinkedHashMap<String, Keyword> result =
+        new LinkedHashMap<String, Keyword>();
+    for (Keyword keyword in values) {
+      result[keyword.syntax] = keyword;
+    }
+    return result;
+  }
+}
+
+/**
+ * A state in a state machine used to scan keywords.
+ */
+class KeywordState {
+  /**
+   * An empty transition table used by leaf states.
+   */
+  static List<KeywordState> _EMPTY_TABLE = new List<KeywordState>(26);
+
+  /**
+   * The initial state in the state machine.
+   */
+  static final KeywordState KEYWORD_STATE = _createKeywordStateTable();
+
+  /**
+   * A table mapping characters to the states to which those characters will
+   * transition. (The index into the array is the offset from the character
+   * `'a'` to the transitioning character.)
+   */
+  final List<KeywordState> _table;
+
+  /**
+   * The keyword that is recognized by this state, or `null` if this state is
+   * not a terminal state.
+   */
+  Keyword _keyword;
+
+  /**
+   * Initialize a newly created state to have the given transitions and to
+   * recognize the keyword with the given [syntax].
+   */
+  KeywordState(this._table, String syntax) {
+    this._keyword = (syntax == null) ? null : Keyword.keywords[syntax];
+  }
+
+  /**
+   * Return the keyword that was recognized by this state, or `null` if this
+   * state does not recognized a keyword.
+   */
+  Keyword keyword() => _keyword;
+
+  /**
+   * Return the state that follows this state on a transition of the given
+   * [character], or `null` if there is no valid state reachable from this state
+   * with such a transition.
+   */
+  KeywordState next(int character) => _table[character - 0x61];
+
+  /**
+   * Create the next state in the state machine where we have already recognized
+   * the subset of strings in the given array of [strings] starting at the given
+   * [offset] and having the given [length]. All of these strings have a common
+   * prefix and the next character is at the given [start] index.
+   */
+  static KeywordState _computeKeywordStateTable(
+      int start, List<String> strings, int offset, int length) {
+    List<KeywordState> result = new List<KeywordState>(26);
+    assert(length != 0);
+    int chunk = 0x0;
+    int chunkStart = -1;
+    bool isLeaf = false;
+    for (int i = offset; i < offset + length; i++) {
+      if (strings[i].length == start) {
+        isLeaf = true;
+      }
+      if (strings[i].length > start) {
+        int c = strings[i].codeUnitAt(start);
+        if (chunk != c) {
+          if (chunkStart != -1) {
+            result[chunk - 0x61] = _computeKeywordStateTable(
+                start + 1, strings, chunkStart, i - chunkStart);
+          }
+          chunkStart = i;
+          chunk = c;
+        }
+      }
+    }
+    if (chunkStart != -1) {
+      assert(result[chunk - 0x61] == null);
+      result[chunk - 0x61] = _computeKeywordStateTable(
+          start + 1, strings, chunkStart, offset + length - chunkStart);
+    } else {
+      assert(length == 1);
+      return new KeywordState(_EMPTY_TABLE, strings[offset]);
+    }
+    if (isLeaf) {
+      return new KeywordState(result, strings[offset]);
+    } else {
+      return new KeywordState(result, null);
+    }
+  }
+
+  /**
+   * Create and return the initial state in the state machine.
+   */
+  static KeywordState _createKeywordStateTable() {
+    List<Keyword> values = Keyword.values;
+    List<String> strings = new List<String>(values.length);
+    for (int i = 0; i < values.length; i++) {
+      strings[i] = values[i].syntax;
+    }
+    strings.sort();
+    return _computeKeywordStateTable(0, strings, 0, strings.length);
+  }
+}
+
+/**
+ * A token representing a keyword in the language.
+ */
+class KeywordToken extends Token {
+  /**
+   * The keyword being represented by this token.
+   */
+  final Keyword keyword;
+
+  /**
+   * Initialize a newly created token to represent the given [keyword] at the
+   * given [offset].
+   */
+  KeywordToken(this.keyword, int offset) : super(TokenType.KEYWORD, offset);
+
+  @override
+  String get lexeme => keyword.syntax;
+
+  @override
+  Token copy() => new KeywordToken(keyword, offset);
+
+  @override
+  Keyword value() => keyword;
+}
+
+/**
+ * A keyword token that is preceded by comments.
+ */
+class KeywordTokenWithComment extends KeywordToken {
+  /**
+   * The first comment in the list of comments that precede this token.
+   */
+  CommentToken _precedingComment;
+
+  /**
+   * Initialize a newly created token to to represent the given [keyword] at the
+   * given [offset] and to be preceded by the comments reachable from the given
+   * [comment].
+   */
+  KeywordTokenWithComment(Keyword keyword, int offset, this._precedingComment)
+      : super(keyword, offset) {
+    _setCommentParent(_precedingComment);
+  }
+
+  CommentToken get precedingComments => _precedingComment;
+
+  void set precedingComments(CommentToken comment) {
+    _precedingComment = comment;
+    _setCommentParent(_precedingComment);
+  }
+
+  @override
+  void applyDelta(int delta) {
+    super.applyDelta(delta);
+    Token token = precedingComments;
+    while (token != null) {
+      token.applyDelta(delta);
+      token = token.next;
+    }
+  }
+
+  @override
+  Token copy() => new KeywordTokenWithComment(
+      keyword, offset, copyComments(precedingComments));
+}
+
+/**
+ * The class `Scanner` implements a scanner for Dart code.
+ *
+ * The lexical structure of Dart is ambiguous without knowledge of the context
+ * in which a token is being scanned. For example, without context we cannot
+ * determine whether source of the form "<<" should be scanned as a single
+ * left-shift operator or as two left angle brackets. This scanner does not have
+ * any context, so it always resolves such conflicts by scanning the longest
+ * possible token.
+ */
+class Scanner {
+  /**
+   * The source being scanned.
+   */
+  final Source source;
+
+  /**
+   * The reader used to access the characters in the source.
+   */
+  final CharacterReader _reader;
+
+  /**
+   * The error listener that will be informed of any errors that are found
+   * during the scan.
+   */
+  final AnalysisErrorListener _errorListener;
+
+  /**
+   * The flag specifying whether documentation comments should be parsed.
+   */
+  bool _preserveComments = true;
+
+  /**
+   * The token pointing to the head of the linked list of tokens.
+   */
+  Token _tokens;
+
+  /**
+   * The last token that was scanned.
+   */
+  Token _tail;
+
+  /**
+   * The first token in the list of comment tokens found since the last
+   * non-comment token.
+   */
+  Token _firstComment;
+
+  /**
+   * The last token in the list of comment tokens found since the last
+   * non-comment token.
+   */
+  Token _lastComment;
+
+  /**
+   * The index of the first character of the current token.
+   */
+  int _tokenStart = 0;
+
+  /**
+   * A list containing the offsets of the first character of each line in the
+   * source code.
+   */
+  List<int> _lineStarts = new List<int>();
+
+  /**
+   * A list, treated something like a stack, of tokens representing the
+   * beginning of a matched pair. It is used to pair the end tokens with the
+   * begin tokens.
+   */
+  List<BeginToken> _groupingStack = new List<BeginToken>();
+
+  /**
+   * The index of the last item in the [_groupingStack], or `-1` if the stack is
+   * empty.
+   */
+  int _stackEnd = -1;
+
+  /**
+   * A flag indicating whether any unmatched groups were found during the parse.
+   */
+  bool _hasUnmatchedGroups = false;
+
+  /**
+   * Initialize a newly created scanner to scan characters from the given
+   * [source]. The given character [_reader] will be used to read the characters
+   * in the source. The given [_errorListener] will be informed of any errors
+   * that are found.
+   */
+  Scanner(this.source, this._reader, this._errorListener) {
+    _tokens = new Token(TokenType.EOF, -1);
+    _tokens.setNext(_tokens);
+    _tail = _tokens;
+    _tokenStart = -1;
+    _lineStarts.add(0);
+  }
+
+  /**
+   * Return the first token in the token stream that was scanned.
+   */
+  Token get firstToken => _tokens.next;
+
+  /**
+   * Return `true` if any unmatched groups were found during the parse.
+   */
+  bool get hasUnmatchedGroups => _hasUnmatchedGroups;
+
+  /**
+   * Return an array containing the offsets of the first character of each line
+   * in the source code.
+   */
+  List<int> get lineStarts => _lineStarts;
+
+  /**
+   * Set whether documentation tokens should be preserved.
+   */
+  void set preserveComments(bool preserveComments) {
+    this._preserveComments = preserveComments;
+  }
+
+  /**
+   * Return the last token that was scanned.
+   */
+  Token get tail => _tail;
+
+  /**
+   * Append the given [token] to the end of the token stream being scanned. This
+   * method is intended to be used by subclasses that copy existing tokens and
+   * should not normally be used because it will fail to correctly associate any
+   * comments with the token being passed in.
+   */
+  void appendToken(Token token) {
+    _tail = _tail.setNext(token);
+  }
+
+  int bigSwitch(int next) {
+    _beginToken();
+    if (next == 0xD) {
+      // '\r'
+      next = _reader.advance();
+      if (next == 0xA) {
+        // '\n'
+        next = _reader.advance();
+      }
+      recordStartOfLine();
+      return next;
+    } else if (next == 0xA) {
+      // '\n'
+      next = _reader.advance();
+      recordStartOfLine();
+      return next;
+    } else if (next == 0x9 || next == 0x20) {
+      // '\t' || ' '
+      return _reader.advance();
+    }
+    if (next == 0x72) {
+      // 'r'
+      int peek = _reader.peek();
+      if (peek == 0x22 || peek == 0x27) {
+        // '"' || "'"
+        int start = _reader.offset;
+        return _tokenizeString(_reader.advance(), start, true);
+      }
+    }
+    if (0x61 <= next && next <= 0x7A) {
+      // 'a'-'z'
+      return _tokenizeKeywordOrIdentifier(next, true);
+    }
+    if ((0x41 <= next && next <= 0x5A) || next == 0x5F || next == 0x24) {
+      // 'A'-'Z' || '_' || '$'
+      return _tokenizeIdentifier(next, _reader.offset, true);
+    }
+    if (next == 0x3C) {
+      // '<'
+      return _tokenizeLessThan(next);
+    }
+    if (next == 0x3E) {
+      // '>'
+      return _tokenizeGreaterThan(next);
+    }
+    if (next == 0x3D) {
+      // '='
+      return _tokenizeEquals(next);
+    }
+    if (next == 0x21) {
+      // '!'
+      return _tokenizeExclamation(next);
+    }
+    if (next == 0x2B) {
+      // '+'
+      return _tokenizePlus(next);
+    }
+    if (next == 0x2D) {
+      // '-'
+      return _tokenizeMinus(next);
+    }
+    if (next == 0x2A) {
+      // '*'
+      return _tokenizeMultiply(next);
+    }
+    if (next == 0x25) {
+      // '%'
+      return _tokenizePercent(next);
+    }
+    if (next == 0x26) {
+      // '&'
+      return _tokenizeAmpersand(next);
+    }
+    if (next == 0x7C) {
+      // '|'
+      return _tokenizeBar(next);
+    }
+    if (next == 0x5E) {
+      // '^'
+      return _tokenizeCaret(next);
+    }
+    if (next == 0x5B) {
+      // '['
+      return _tokenizeOpenSquareBracket(next);
+    }
+    if (next == 0x7E) {
+      // '~'
+      return _tokenizeTilde(next);
+    }
+    if (next == 0x5C) {
+      // '\\'
+      _appendTokenOfType(TokenType.BACKSLASH);
+      return _reader.advance();
+    }
+    if (next == 0x23) {
+      // '#'
+      return _tokenizeTag(next);
+    }
+    if (next == 0x28) {
+      // '('
+      _appendBeginToken(TokenType.OPEN_PAREN);
+      return _reader.advance();
+    }
+    if (next == 0x29) {
+      // ')'
+      _appendEndToken(TokenType.CLOSE_PAREN, TokenType.OPEN_PAREN);
+      return _reader.advance();
+    }
+    if (next == 0x2C) {
+      // ','
+      _appendTokenOfType(TokenType.COMMA);
+      return _reader.advance();
+    }
+    if (next == 0x3A) {
+      // ':'
+      _appendTokenOfType(TokenType.COLON);
+      return _reader.advance();
+    }
+    if (next == 0x3B) {
+      // ';'
+      _appendTokenOfType(TokenType.SEMICOLON);
+      return _reader.advance();
+    }
+    if (next == 0x3F) {
+      // '?'
+      return _tokenizeQuestion();
+    }
+    if (next == 0x5D) {
+      // ']'
+      _appendEndToken(
+          TokenType.CLOSE_SQUARE_BRACKET, TokenType.OPEN_SQUARE_BRACKET);
+      return _reader.advance();
+    }
+    if (next == 0x60) {
+      // '`'
+      _appendTokenOfType(TokenType.BACKPING);
+      return _reader.advance();
+    }
+    if (next == 0x7B) {
+      // '{'
+      _appendBeginToken(TokenType.OPEN_CURLY_BRACKET);
+      return _reader.advance();
+    }
+    if (next == 0x7D) {
+      // '}'
+      _appendEndToken(
+          TokenType.CLOSE_CURLY_BRACKET, TokenType.OPEN_CURLY_BRACKET);
+      return _reader.advance();
+    }
+    if (next == 0x2F) {
+      // '/'
+      return _tokenizeSlashOrComment(next);
+    }
+    if (next == 0x40) {
+      // '@'
+      _appendTokenOfType(TokenType.AT);
+      return _reader.advance();
+    }
+    if (next == 0x22 || next == 0x27) {
+      // '"' || "'"
+      return _tokenizeString(next, _reader.offset, false);
+    }
+    if (next == 0x2E) {
+      // '.'
+      return _tokenizeDotOrNumber(next);
+    }
+    if (next == 0x30) {
+      // '0'
+      return _tokenizeHexOrNumber(next);
+    }
+    if (0x31 <= next && next <= 0x39) {
+      // '1'-'9'
+      return _tokenizeNumber(next);
+    }
+    if (next == -1) {
+      // EOF
+      return -1;
+    }
+    _reportError(ScannerErrorCode.ILLEGAL_CHARACTER, [next]);
+    return _reader.advance();
+  }
+
+  /**
+   * Record the fact that we are at the beginning of a new line in the source.
+   */
+  void recordStartOfLine() {
+    _lineStarts.add(_reader.offset);
+  }
+
+  /**
+   * Record that the source begins on the given [line] and [column] at the
+   * current offset as given by the reader. Both the line and the column are
+   * one-based indexes. The line starts for lines before the given line will not
+   * be correct.
+   *
+   * This method must be invoked at most one time and must be invoked before
+   * scanning begins. The values provided must be sensible. The results are
+   * undefined if these conditions are violated.
+   */
+  void setSourceStart(int line, int column) {
+    int offset = _reader.offset;
+    if (line < 1 || column < 1 || offset < 0 || (line + column - 2) >= offset) {
+      return;
+    }
+    for (int i = 2; i < line; i++) {
+      _lineStarts.add(1);
+    }
+    _lineStarts.add(offset - column + 1);
+  }
+
+  /**
+   * Scan the source code to produce a list of tokens representing the source,
+   * and return the first token in the list of tokens that were produced.
+   */
+  Token tokenize() {
+    int next = _reader.advance();
+    while (next != -1) {
+      next = bigSwitch(next);
+    }
+    _appendEofToken();
+    return firstToken;
+  }
+
+  void _appendBeginToken(TokenType type) {
+    BeginToken token;
+    if (_firstComment == null) {
+      token = new BeginToken(type, _tokenStart);
+    } else {
+      token = new BeginTokenWithComment(type, _tokenStart, _firstComment);
+      _firstComment = null;
+      _lastComment = null;
+    }
+    _tail = _tail.setNext(token);
+    _groupingStack.add(token);
+    _stackEnd++;
+  }
+
+  void _appendCommentToken(TokenType type, String value) {
+    // Ignore comment tokens if client specified that it doesn't need them.
+    if (!_preserveComments) {
+      return;
+    }
+    // OK, remember comment tokens.
+    CommentToken token;
+    if (_isDocumentationComment(value)) {
+      token = new DocumentationCommentToken(type, value, _tokenStart);
+    } else {
+      token = new CommentToken(type, value, _tokenStart);
+    }
+    if (_firstComment == null) {
+      _firstComment = token;
+      _lastComment = _firstComment;
+    } else {
+      _lastComment = _lastComment.setNext(token);
+    }
+  }
+
+  void _appendEndToken(TokenType type, TokenType beginType) {
+    Token token;
+    if (_firstComment == null) {
+      token = new Token(type, _tokenStart);
+    } else {
+      token = new TokenWithComment(type, _tokenStart, _firstComment);
+      _firstComment = null;
+      _lastComment = null;
+    }
+    _tail = _tail.setNext(token);
+    if (_stackEnd >= 0) {
+      BeginToken begin = _groupingStack[_stackEnd];
+      if (begin.type == beginType) {
+        begin.endToken = token;
+        _groupingStack.removeAt(_stackEnd--);
+      }
+    }
+  }
+
+  void _appendEofToken() {
+    Token eofToken;
+    if (_firstComment == null) {
+      eofToken = new Token(TokenType.EOF, _reader.offset + 1);
+    } else {
+      eofToken = new TokenWithComment(
+          TokenType.EOF, _reader.offset + 1, _firstComment);
+      _firstComment = null;
+      _lastComment = null;
+    }
+    // The EOF token points to itself so that there is always infinite
+    // look-ahead.
+    eofToken.setNext(eofToken);
+    _tail = _tail.setNext(eofToken);
+    if (_stackEnd >= 0) {
+      _hasUnmatchedGroups = true;
+      // TODO(brianwilkerson) Fix the ungrouped tokens?
+    }
+  }
+
+  void _appendKeywordToken(Keyword keyword) {
+    if (_firstComment == null) {
+      _tail = _tail.setNext(new KeywordToken(keyword, _tokenStart));
+    } else {
+      _tail = _tail.setNext(
+          new KeywordTokenWithComment(keyword, _tokenStart, _firstComment));
+      _firstComment = null;
+      _lastComment = null;
+    }
+  }
+
+  void _appendStringToken(TokenType type, String value) {
+    if (_firstComment == null) {
+      _tail = _tail.setNext(new StringToken(type, value, _tokenStart));
+    } else {
+      _tail = _tail.setNext(
+          new StringTokenWithComment(type, value, _tokenStart, _firstComment));
+      _firstComment = null;
+      _lastComment = null;
+    }
+  }
+
+  void _appendStringTokenWithOffset(TokenType type, String value, int offset) {
+    if (_firstComment == null) {
+      _tail = _tail.setNext(new StringToken(type, value, _tokenStart + offset));
+    } else {
+      _tail = _tail.setNext(new StringTokenWithComment(
+          type, value, _tokenStart + offset, _firstComment));
+      _firstComment = null;
+      _lastComment = null;
+    }
+  }
+
+  void _appendTokenOfType(TokenType type) {
+    if (_firstComment == null) {
+      _tail = _tail.setNext(new Token(type, _tokenStart));
+    } else {
+      _tail =
+          _tail.setNext(new TokenWithComment(type, _tokenStart, _firstComment));
+      _firstComment = null;
+      _lastComment = null;
+    }
+  }
+
+  void _appendTokenOfTypeWithOffset(TokenType type, int offset) {
+    if (_firstComment == null) {
+      _tail = _tail.setNext(new Token(type, offset));
+    } else {
+      _tail = _tail.setNext(new TokenWithComment(type, offset, _firstComment));
+      _firstComment = null;
+      _lastComment = null;
+    }
+  }
+
+  void _beginToken() {
+    _tokenStart = _reader.offset;
+  }
+
+  /**
+   * Return the beginning token corresponding to a closing brace that was found
+   * while scanning inside a string interpolation expression. Tokens that cannot
+   * be matched with the closing brace will be dropped from the stack.
+   */
+  BeginToken _findTokenMatchingClosingBraceInInterpolationExpression() {
+    while (_stackEnd >= 0) {
+      BeginToken begin = _groupingStack[_stackEnd];
+      if (begin.type == TokenType.OPEN_CURLY_BRACKET ||
+          begin.type == TokenType.STRING_INTERPOLATION_EXPRESSION) {
+        return begin;
+      }
+      _hasUnmatchedGroups = true;
+      _groupingStack.removeAt(_stackEnd--);
+    }
+    //
+    // We should never get to this point because we wouldn't be inside a string
+    // interpolation expression unless we had previously found the start of the
+    // expression.
+    //
+    return null;
+  }
+
+  /**
+   * Report an error at the current offset. The [errorCode] is the error code
+   * indicating the nature of the error. The [arguments] are any arguments
+   * needed to complete the error message
+   */
+  void _reportError(ScannerErrorCode errorCode, [List<Object> arguments]) {
+    _errorListener.onError(
+        new AnalysisError(source, _reader.offset, 1, errorCode, arguments));
+  }
+
+  int _select(int choice, TokenType yesType, TokenType noType) {
+    int next = _reader.advance();
+    if (next == choice) {
+      _appendTokenOfType(yesType);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(noType);
+      return next;
+    }
+  }
+
+  int _selectWithOffset(
+      int choice, TokenType yesType, TokenType noType, int offset) {
+    int next = _reader.advance();
+    if (next == choice) {
+      _appendTokenOfTypeWithOffset(yesType, offset);
+      return _reader.advance();
+    } else {
+      _appendTokenOfTypeWithOffset(noType, offset);
+      return next;
+    }
+  }
+
+  int _tokenizeAmpersand(int next) {
+    // && &= &
+    next = _reader.advance();
+    if (next == 0x26) {
+      _appendTokenOfType(TokenType.AMPERSAND_AMPERSAND);
+      return _reader.advance();
+    } else if (next == 0x3D) {
+      _appendTokenOfType(TokenType.AMPERSAND_EQ);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(TokenType.AMPERSAND);
+      return next;
+    }
+  }
+
+  int _tokenizeBar(int next) {
+    // | || |=
+    next = _reader.advance();
+    if (next == 0x7C) {
+      _appendTokenOfType(TokenType.BAR_BAR);
+      return _reader.advance();
+    } else if (next == 0x3D) {
+      _appendTokenOfType(TokenType.BAR_EQ);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(TokenType.BAR);
+      return next;
+    }
+  }
+
+  int _tokenizeCaret(int next) =>
+      _select(0x3D, TokenType.CARET_EQ, TokenType.CARET);
+
+  int _tokenizeDotOrNumber(int next) {
+    int start = _reader.offset;
+    next = _reader.advance();
+    if (0x30 <= next && next <= 0x39) {
+      return _tokenizeFractionPart(next, start);
+    } else if (0x2E == next) {
+      return _select(
+          0x2E, TokenType.PERIOD_PERIOD_PERIOD, TokenType.PERIOD_PERIOD);
+    } else {
+      _appendTokenOfType(TokenType.PERIOD);
+      return next;
+    }
+  }
+
+  int _tokenizeEquals(int next) {
+    // = == =>
+    next = _reader.advance();
+    if (next == 0x3D) {
+      _appendTokenOfType(TokenType.EQ_EQ);
+      return _reader.advance();
+    } else if (next == 0x3E) {
+      _appendTokenOfType(TokenType.FUNCTION);
+      return _reader.advance();
+    }
+    _appendTokenOfType(TokenType.EQ);
+    return next;
+  }
+
+  int _tokenizeExclamation(int next) {
+    // ! !=
+    next = _reader.advance();
+    if (next == 0x3D) {
+      _appendTokenOfType(TokenType.BANG_EQ);
+      return _reader.advance();
+    }
+    _appendTokenOfType(TokenType.BANG);
+    return next;
+  }
+
+  int _tokenizeExponent(int next) {
+    if (next == 0x2B || next == 0x2D) {
+      next = _reader.advance();
+    }
+    bool hasDigits = false;
+    while (true) {
+      if (0x30 <= next && next <= 0x39) {
+        hasDigits = true;
+      } else {
+        if (!hasDigits) {
+          _reportError(ScannerErrorCode.MISSING_DIGIT);
+        }
+        return next;
+      }
+      next = _reader.advance();
+    }
+  }
+
+  int _tokenizeFractionPart(int next, int start) {
+    bool done = false;
+    bool hasDigit = false;
+    LOOP: while (!done) {
+      if (0x30 <= next && next <= 0x39) {
+        hasDigit = true;
+      } else if (0x65 == next || 0x45 == next) {
+        hasDigit = true;
+        next = _tokenizeExponent(_reader.advance());
+        done = true;
+        continue LOOP;
+      } else {
+        done = true;
+        continue LOOP;
+      }
+      next = _reader.advance();
+    }
+    if (!hasDigit) {
+      _appendStringToken(TokenType.INT, _reader.getString(start, -2));
+      if (0x2E == next) {
+        return _selectWithOffset(0x2E, TokenType.PERIOD_PERIOD_PERIOD,
+            TokenType.PERIOD_PERIOD, _reader.offset - 1);
+      }
+      _appendTokenOfTypeWithOffset(TokenType.PERIOD, _reader.offset - 1);
+      return bigSwitch(next);
+    }
+    _appendStringToken(
+        TokenType.DOUBLE, _reader.getString(start, next < 0 ? 0 : -1));
+    return next;
+  }
+
+  int _tokenizeGreaterThan(int next) {
+    // > >= >> >>=
+    next = _reader.advance();
+    if (0x3D == next) {
+      _appendTokenOfType(TokenType.GT_EQ);
+      return _reader.advance();
+    } else if (0x3E == next) {
+      next = _reader.advance();
+      if (0x3D == next) {
+        _appendTokenOfType(TokenType.GT_GT_EQ);
+        return _reader.advance();
+      } else {
+        _appendTokenOfType(TokenType.GT_GT);
+        return next;
+      }
+    } else {
+      _appendTokenOfType(TokenType.GT);
+      return next;
+    }
+  }
+
+  int _tokenizeHex(int next) {
+    int start = _reader.offset - 1;
+    bool hasDigits = false;
+    while (true) {
+      next = _reader.advance();
+      if ((0x30 <= next && next <= 0x39) ||
+          (0x41 <= next && next <= 0x46) ||
+          (0x61 <= next && next <= 0x66)) {
+        hasDigits = true;
+      } else {
+        if (!hasDigits) {
+          _reportError(ScannerErrorCode.MISSING_HEX_DIGIT);
+        }
+        _appendStringToken(
+            TokenType.HEXADECIMAL, _reader.getString(start, next < 0 ? 0 : -1));
+        return next;
+      }
+    }
+  }
+
+  int _tokenizeHexOrNumber(int next) {
+    int x = _reader.peek();
+    if (x == 0x78 || x == 0x58) {
+      _reader.advance();
+      return _tokenizeHex(x);
+    }
+    return _tokenizeNumber(next);
+  }
+
+  int _tokenizeIdentifier(int next, int start, bool allowDollar) {
+    while ((0x61 <= next && next <= 0x7A) ||
+        (0x41 <= next && next <= 0x5A) ||
+        (0x30 <= next && next <= 0x39) ||
+        next == 0x5F ||
+        (next == 0x24 && allowDollar)) {
+      next = _reader.advance();
+    }
+    _appendStringToken(
+        TokenType.IDENTIFIER, _reader.getString(start, next < 0 ? 0 : -1));
+    return next;
+  }
+
+  int _tokenizeInterpolatedExpression(int next, int start) {
+    _appendBeginToken(TokenType.STRING_INTERPOLATION_EXPRESSION);
+    next = _reader.advance();
+    while (next != -1) {
+      if (next == 0x7D) {
+        BeginToken begin =
+            _findTokenMatchingClosingBraceInInterpolationExpression();
+        if (begin == null) {
+          _beginToken();
+          _appendTokenOfType(TokenType.CLOSE_CURLY_BRACKET);
+          next = _reader.advance();
+          _beginToken();
+          return next;
+        } else if (begin.type == TokenType.OPEN_CURLY_BRACKET) {
+          _beginToken();
+          _appendEndToken(
+              TokenType.CLOSE_CURLY_BRACKET, TokenType.OPEN_CURLY_BRACKET);
+          next = _reader.advance();
+          _beginToken();
+        } else if (begin.type == TokenType.STRING_INTERPOLATION_EXPRESSION) {
+          _beginToken();
+          _appendEndToken(TokenType.CLOSE_CURLY_BRACKET,
+              TokenType.STRING_INTERPOLATION_EXPRESSION);
+          next = _reader.advance();
+          _beginToken();
+          return next;
+        }
+      } else {
+        next = bigSwitch(next);
+      }
+    }
+    return next;
+  }
+
+  int _tokenizeInterpolatedIdentifier(int next, int start) {
+    _appendStringTokenWithOffset(
+        TokenType.STRING_INTERPOLATION_IDENTIFIER, "\$", 0);
+    if ((0x41 <= next && next <= 0x5A) ||
+        (0x61 <= next && next <= 0x7A) ||
+        next == 0x5F) {
+      _beginToken();
+      next = _tokenizeKeywordOrIdentifier(next, false);
+    }
+    _beginToken();
+    return next;
+  }
+
+  int _tokenizeKeywordOrIdentifier(int next, bool allowDollar) {
+    KeywordState state = KeywordState.KEYWORD_STATE;
+    int start = _reader.offset;
+    while (state != null && 0x61 <= next && next <= 0x7A) {
+      state = state.next(next);
+      next = _reader.advance();
+    }
+    if (state == null || state.keyword() == null) {
+      return _tokenizeIdentifier(next, start, allowDollar);
+    }
+    if ((0x41 <= next && next <= 0x5A) ||
+        (0x30 <= next && next <= 0x39) ||
+        next == 0x5F ||
+        next == 0x24) {
+      return _tokenizeIdentifier(next, start, allowDollar);
+    } else if (next < 128) {
+      _appendKeywordToken(state.keyword());
+      return next;
+    } else {
+      return _tokenizeIdentifier(next, start, allowDollar);
+    }
+  }
+
+  int _tokenizeLessThan(int next) {
+    // < <= << <<=
+    next = _reader.advance();
+    if (0x3D == next) {
+      _appendTokenOfType(TokenType.LT_EQ);
+      return _reader.advance();
+    } else if (0x3C == next) {
+      return _select(0x3D, TokenType.LT_LT_EQ, TokenType.LT_LT);
+    } else {
+      _appendTokenOfType(TokenType.LT);
+      return next;
+    }
+  }
+
+  int _tokenizeMinus(int next) {
+    // - -- -=
+    next = _reader.advance();
+    if (next == 0x2D) {
+      _appendTokenOfType(TokenType.MINUS_MINUS);
+      return _reader.advance();
+    } else if (next == 0x3D) {
+      _appendTokenOfType(TokenType.MINUS_EQ);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(TokenType.MINUS);
+      return next;
+    }
+  }
+
+  int _tokenizeMultiLineComment(int next) {
+    int nesting = 1;
+    next = _reader.advance();
+    while (true) {
+      if (-1 == next) {
+        _reportError(ScannerErrorCode.UNTERMINATED_MULTI_LINE_COMMENT);
+        _appendCommentToken(
+            TokenType.MULTI_LINE_COMMENT, _reader.getString(_tokenStart, 0));
+        return next;
+      } else if (0x2A == next) {
+        next = _reader.advance();
+        if (0x2F == next) {
+          --nesting;
+          if (0 == nesting) {
+            _appendCommentToken(TokenType.MULTI_LINE_COMMENT,
+                _reader.getString(_tokenStart, 0));
+            return _reader.advance();
+          } else {
+            next = _reader.advance();
+          }
+        }
+      } else if (0x2F == next) {
+        next = _reader.advance();
+        if (0x2A == next) {
+          next = _reader.advance();
+          ++nesting;
+        }
+      } else if (next == 0xD) {
+        next = _reader.advance();
+        if (next == 0xA) {
+          next = _reader.advance();
+        }
+        recordStartOfLine();
+      } else if (next == 0xA) {
+        next = _reader.advance();
+        recordStartOfLine();
+      } else {
+        next = _reader.advance();
+      }
+    }
+  }
+
+  int _tokenizeMultiLineRawString(int quoteChar, int start) {
+    int next = _reader.advance();
+    outer: while (next != -1) {
+      while (next != quoteChar) {
+        if (next == -1) {
+          break outer;
+        } else if (next == 0xD) {
+          next = _reader.advance();
+          if (next == 0xA) {
+            next = _reader.advance();
+          }
+          recordStartOfLine();
+        } else if (next == 0xA) {
+          next = _reader.advance();
+          recordStartOfLine();
+        } else {
+          next = _reader.advance();
+        }
+      }
+      next = _reader.advance();
+      if (next == quoteChar) {
+        next = _reader.advance();
+        if (next == quoteChar) {
+          _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+          return _reader.advance();
+        }
+      }
+    }
+    _reportError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+    _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+    return _reader.advance();
+  }
+
+  int _tokenizeMultiLineString(int quoteChar, int start, bool raw) {
+    if (raw) {
+      return _tokenizeMultiLineRawString(quoteChar, start);
+    }
+    int next = _reader.advance();
+    while (next != -1) {
+      if (next == 0x24) {
+        _appendStringToken(TokenType.STRING, _reader.getString(start, -1));
+        next = _tokenizeStringInterpolation(start);
+        _beginToken();
+        start = _reader.offset;
+        continue;
+      }
+      if (next == quoteChar) {
+        next = _reader.advance();
+        if (next == quoteChar) {
+          next = _reader.advance();
+          if (next == quoteChar) {
+            _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+            return _reader.advance();
+          }
+        }
+        continue;
+      }
+      if (next == 0x5C) {
+        next = _reader.advance();
+        if (next == -1) {
+          break;
+        }
+        if (next == 0xD) {
+          next = _reader.advance();
+          if (next == 0xA) {
+            next = _reader.advance();
+          }
+          recordStartOfLine();
+        } else if (next == 0xA) {
+          recordStartOfLine();
+          next = _reader.advance();
+        } else {
+          next = _reader.advance();
+        }
+      } else if (next == 0xD) {
+        next = _reader.advance();
+        if (next == 0xA) {
+          next = _reader.advance();
+        }
+        recordStartOfLine();
+      } else if (next == 0xA) {
+        recordStartOfLine();
+        next = _reader.advance();
+      } else {
+        next = _reader.advance();
+      }
+    }
+    _reportError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+    if (start == _reader.offset) {
+      _appendStringTokenWithOffset(TokenType.STRING, "", 1);
+    } else {
+      _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+    }
+    return _reader.advance();
+  }
+
+  int _tokenizeMultiply(int next) =>
+      _select(0x3D, TokenType.STAR_EQ, TokenType.STAR);
+
+  int _tokenizeNumber(int next) {
+    int start = _reader.offset;
+    while (true) {
+      next = _reader.advance();
+      if (0x30 <= next && next <= 0x39) {
+        continue;
+      } else if (next == 0x2E) {
+        return _tokenizeFractionPart(_reader.advance(), start);
+      } else if (next == 0x65 || next == 0x45) {
+        return _tokenizeFractionPart(next, start);
+      } else {
+        _appendStringToken(
+            TokenType.INT, _reader.getString(start, next < 0 ? 0 : -1));
+        return next;
+      }
+    }
+  }
+
+  int _tokenizeOpenSquareBracket(int next) {
+    // [ []  []=
+    next = _reader.advance();
+    if (next == 0x5D) {
+      return _select(0x3D, TokenType.INDEX_EQ, TokenType.INDEX);
+    } else {
+      _appendBeginToken(TokenType.OPEN_SQUARE_BRACKET);
+      return next;
+    }
+  }
+
+  int _tokenizePercent(int next) =>
+      _select(0x3D, TokenType.PERCENT_EQ, TokenType.PERCENT);
+
+  int _tokenizePlus(int next) {
+    // + ++ +=
+    next = _reader.advance();
+    if (0x2B == next) {
+      _appendTokenOfType(TokenType.PLUS_PLUS);
+      return _reader.advance();
+    } else if (0x3D == next) {
+      _appendTokenOfType(TokenType.PLUS_EQ);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(TokenType.PLUS);
+      return next;
+    }
+  }
+
+  int _tokenizeQuestion() {
+    // ? ?. ?? ??=
+    int next = _reader.advance();
+    if (next == 0x2E) {
+      // '.'
+      _appendTokenOfType(TokenType.QUESTION_PERIOD);
+      return _reader.advance();
+    } else if (next == 0x3F) {
+      // '?'
+      next = _reader.advance();
+      if (next == 0x3D) {
+        // '='
+        _appendTokenOfType(TokenType.QUESTION_QUESTION_EQ);
+        return _reader.advance();
+      } else {
+        _appendTokenOfType(TokenType.QUESTION_QUESTION);
+        return next;
+      }
+    } else {
+      _appendTokenOfType(TokenType.QUESTION);
+      return next;
+    }
+  }
+
+  int _tokenizeSingleLineComment(int next) {
+    while (true) {
+      next = _reader.advance();
+      if (-1 == next) {
+        _appendCommentToken(
+            TokenType.SINGLE_LINE_COMMENT, _reader.getString(_tokenStart, 0));
+        return next;
+      } else if (0xA == next || 0xD == next) {
+        _appendCommentToken(
+            TokenType.SINGLE_LINE_COMMENT, _reader.getString(_tokenStart, -1));
+        return next;
+      }
+    }
+  }
+
+  int _tokenizeSingleLineRawString(int next, int quoteChar, int start) {
+    next = _reader.advance();
+    while (next != -1) {
+      if (next == quoteChar) {
+        _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+        return _reader.advance();
+      } else if (next == 0xD || next == 0xA) {
+        _reportError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+        _appendStringToken(TokenType.STRING, _reader.getString(start, -1));
+        return _reader.advance();
+      }
+      next = _reader.advance();
+    }
+    _reportError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+    _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+    return _reader.advance();
+  }
+
+  int _tokenizeSingleLineString(int next, int quoteChar, int start) {
+    while (next != quoteChar) {
+      if (next == 0x5C) {
+        next = _reader.advance();
+      } else if (next == 0x24) {
+        _appendStringToken(TokenType.STRING, _reader.getString(start, -1));
+        next = _tokenizeStringInterpolation(start);
+        _beginToken();
+        start = _reader.offset;
+        continue;
+      }
+      if (next <= 0xD && (next == 0xA || next == 0xD || next == -1)) {
+        _reportError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL);
+        if (start == _reader.offset) {
+          _appendStringTokenWithOffset(TokenType.STRING, "", 1);
+        } else if (next == -1) {
+          _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+        } else {
+          _appendStringToken(TokenType.STRING, _reader.getString(start, -1));
+        }
+        return _reader.advance();
+      }
+      next = _reader.advance();
+    }
+    _appendStringToken(TokenType.STRING, _reader.getString(start, 0));
+    return _reader.advance();
+  }
+
+  int _tokenizeSlashOrComment(int next) {
+    next = _reader.advance();
+    if (0x2A == next) {
+      return _tokenizeMultiLineComment(next);
+    } else if (0x2F == next) {
+      return _tokenizeSingleLineComment(next);
+    } else if (0x3D == next) {
+      _appendTokenOfType(TokenType.SLASH_EQ);
+      return _reader.advance();
+    } else {
+      _appendTokenOfType(TokenType.SLASH);
+      return next;
+    }
+  }
+
+  int _tokenizeString(int next, int start, bool raw) {
+    int quoteChar = next;
+    next = _reader.advance();
+    if (quoteChar == next) {
+      next = _reader.advance();
+      if (quoteChar == next) {
+        // Multiline string.
+        return _tokenizeMultiLineString(quoteChar, start, raw);
+      } else {
+        // Empty string.
+        _appendStringToken(TokenType.STRING, _reader.getString(start, -1));
+        return next;
+      }
+    }
+    if (raw) {
+      return _tokenizeSingleLineRawString(next, quoteChar, start);
+    } else {
+      return _tokenizeSingleLineString(next, quoteChar, start);
+    }
+  }
+
+  int _tokenizeStringInterpolation(int start) {
+    _beginToken();
+    int next = _reader.advance();
+    if (next == 0x7B) {
+      return _tokenizeInterpolatedExpression(next, start);
+    } else {
+      return _tokenizeInterpolatedIdentifier(next, start);
+    }
+  }
+
+  int _tokenizeTag(int next) {
+    // # or #!.*[\n\r]
+    if (_reader.offset == 0) {
+      if (_reader.peek() == 0x21) {
+        do {
+          next = _reader.advance();
+        } while (next != 0xA && next != 0xD && next > 0);
+        _appendStringToken(
+            TokenType.SCRIPT_TAG, _reader.getString(_tokenStart, 0));
+        return next;
+      }
+    }
+    _appendTokenOfType(TokenType.HASH);
+    return _reader.advance();
+  }
+
+  int _tokenizeTilde(int next) {
+    // ~ ~/ ~/=
+    next = _reader.advance();
+    if (next == 0x2F) {
+      return _select(0x3D, TokenType.TILDE_SLASH_EQ, TokenType.TILDE_SLASH);
+    } else {
+      _appendTokenOfType(TokenType.TILDE);
+      return next;
+    }
+  }
+
+  /**
+   * Checks if [value] is a single-line or multi-line comment.
+   */
+  static bool _isDocumentationComment(String value) {
+    return StringUtilities.startsWith3(value, 0, 0x2F, 0x2F, 0x2F) ||
+        StringUtilities.startsWith3(value, 0, 0x2F, 0x2A, 0x2A);
+  }
+}
+
+/**
+ * The error codes used for errors detected by the scanner.
+ */
+class ScannerErrorCode extends ErrorCode {
+  static const ScannerErrorCode ILLEGAL_CHARACTER =
+      const ScannerErrorCode('ILLEGAL_CHARACTER', "Illegal character {0}");
+
+  static const ScannerErrorCode MISSING_DIGIT =
+      const ScannerErrorCode('MISSING_DIGIT', "Decimal digit expected");
+
+  static const ScannerErrorCode MISSING_HEX_DIGIT =
+      const ScannerErrorCode('MISSING_HEX_DIGIT', "Hexidecimal digit expected");
+
+  static const ScannerErrorCode MISSING_QUOTE =
+      const ScannerErrorCode('MISSING_QUOTE', "Expected quote (' or \")");
+
+  static const ScannerErrorCode UNABLE_GET_CONTENT = const ScannerErrorCode(
+      'UNABLE_GET_CONTENT', "Unable to get content: {0}");
+
+  static const ScannerErrorCode UNTERMINATED_MULTI_LINE_COMMENT =
+      const ScannerErrorCode(
+          'UNTERMINATED_MULTI_LINE_COMMENT', "Unterminated multi-line comment");
+
+  static const ScannerErrorCode UNTERMINATED_STRING_LITERAL =
+      const ScannerErrorCode(
+          'UNTERMINATED_STRING_LITERAL', "Unterminated string literal");
+
+  /**
+   * Initialize a newly created error code to have the given [name]. The message
+   * associated with the error will be created from the given [message]
+   * template. The correction associated with the error will be created from the
+   * given [correction] template.
+   */
+  const ScannerErrorCode(String name, String message, [String correction])
+      : super(name, message, correction);
+
+  @override
+  ErrorSeverity get errorSeverity => ErrorSeverity.ERROR;
+
+  @override
+  ErrorType get type => ErrorType.SYNTACTIC_ERROR;
+}
+
+/**
+ * A token whose value is independent of it's type.
+ */
+class StringToken extends Token {
+  /**
+   * The lexeme represented by this token.
+   */
+  String _value;
+
+  /**
+   * Initialize a newly created token to represent a token of the given [type]
+   * with the given [value] at the given [offset].
+   */
+  StringToken(TokenType type, String value, int offset) : super(type, offset) {
+    this._value = StringUtilities.intern(value);
+  }
+
+  @override
+  String get lexeme => _value;
+
+  @override
+  Token copy() => new StringToken(type, _value, offset);
+
+  @override
+  String value() => _value;
+}
+
+/**
+ * A string token that is preceded by comments.
+ */
+class StringTokenWithComment extends StringToken {
+  /**
+   * The first comment in the list of comments that precede this token.
+   */
+  CommentToken _precedingComment;
+
+  /**
+   * Initialize a newly created token to have the given [type] at the given
+   * [offset] and to be preceded by the comments reachable from the given
+   * [comment].
+   */
+  StringTokenWithComment(
+      TokenType type, String value, int offset, this._precedingComment)
+      : super(type, value, offset) {
+    _setCommentParent(_precedingComment);
+  }
+
+  CommentToken get precedingComments => _precedingComment;
+
+  void set precedingComments(CommentToken comment) {
+    _precedingComment = comment;
+    _setCommentParent(_precedingComment);
+  }
+
+  @override
+  void applyDelta(int delta) {
+    super.applyDelta(delta);
+    Token token = precedingComments;
+    while (token != null) {
+      token.applyDelta(delta);
+      token = token.next;
+    }
+  }
+
+  @override
+  Token copy() => new StringTokenWithComment(
+      type, lexeme, offset, copyComments(precedingComments));
+}
+
+/**
+ * A [CharacterReader] that reads characters from a character sequence, but adds
+ * a delta when reporting the current character offset so that the character
+ * sequence can be a subsequence from a larger sequence.
+ */
+class SubSequenceReader extends CharSequenceReader {
+  /**
+   * The offset from the beginning of the file to the beginning of the source
+   * being scanned.
+   */
+  final int _offsetDelta;
+
+  /**
+   * Initialize a newly created reader to read the characters in the given
+   * [sequence]. The [_offsetDelta] is the offset from the beginning of the file
+   * to the beginning of the source being scanned
+   */
+  SubSequenceReader(String sequence, this._offsetDelta) : super(sequence);
+
+  @override
+  int get offset => _offsetDelta + super.offset;
+
+  @override
+  void set offset(int offset) {
+    super.offset = offset - _offsetDelta;
+  }
+
+  @override
+  String getString(int start, int endDelta) =>
+      super.getString(start - _offsetDelta, endDelta);
+}
+
+/**
+ * A token whose value is independent of it's type.
+ */
+class SyntheticStringToken extends StringToken {
+  /**
+   * Initialize a newly created token to represent a token of the given [type]
+   * with the given [value] at the given [offset].
+   */
+  SyntheticStringToken(TokenType type, String value, int offset)
+      : super(type, value, offset);
+
+  @override
+  bool get isSynthetic => true;
+}
+
+/**
+ * A token that was scanned from the input. Each token knows which tokens
+ * precede and follow it, acting as a link in a doubly linked list of tokens.
+ */
+class Token {
+  /**
+   * The type of the token.
+   */
+  final TokenType type;
+
+  /**
+   * The offset from the beginning of the file to the first character in the
+   * token.
+   */
+  int offset = 0;
+
+  /**
+   * The previous token in the token stream.
+   */
+  Token previous;
+
+  /**
+   * The next token in the token stream.
+   */
+  Token _next;
+
+  /**
+   * Initialize a newly created token to have the given [type] and [offset].
+   */
+  Token(this.type, this.offset);
+
+  /**
+   * Return the offset from the beginning of the file to the character after the
+   * last character of the token.
+   */
+  int get end => offset + length;
+
+  /**
+   * Return `true` if this token represents an operator.
+   */
+  bool get isOperator => type.isOperator;
+
+  /**
+   * Return `true` if this token is a synthetic token. A synthetic token is a
+   * token that was introduced by the parser in order to recover from an error
+   * in the code.
+   */
+  bool get isSynthetic => length == 0;
+
+  /**
+   * Return `true` if this token represents an operator that can be defined by
+   * users.
+   */
+  bool get isUserDefinableOperator => type.isUserDefinableOperator;
+
+  /**
+   * Return the number of characters in the node's source range.
+   */
+  int get length => lexeme.length;
+
+  /**
+   * Return the lexeme that represents this token.
+   */
+  String get lexeme => type.lexeme;
+
+  /**
+   * Return the next token in the token stream.
+   */
+  Token get next => _next;
+
+  /**
+   * Return the first comment in the list of comments that precede this token,
+   * or `null` if there are no comments preceding this token. Additional
+   * comments can be reached by following the token stream using [next] until
+   * `null` is returned.
+   *
+   * For example, if the original contents were "/* one */ /* two */ id", then
+   * the first preceding comment token will have a lexeme of "/* one */" and
+   * the next comment token will have a lexeme of "/* two */".
+   */
+  CommentToken get precedingComments => null;
+
+  /**
+   * Apply (add) the given [delta] to this token's offset.
+   */
+  void applyDelta(int delta) {
+    offset += delta;
+  }
+
+  /**
+   * Return a newly created token that is a copy of this token but that is not a
+   * part of any token stream.
+   */
+  Token copy() => new Token(type, offset);
+
+  /**
+   * Copy a linked list of comment tokens identical to the given comment tokens.
+   */
+  Token copyComments(Token token) {
+    if (token == null) {
+      return null;
+    }
+    Token head = token.copy();
+    Token tail = head;
+    token = token.next;
+    while (token != null) {
+      tail = tail.setNext(token.copy());
+      token = token.next;
+    }
+    return head;
+  }
+
+  /**
+   * Return `true` if this token has any one of the given [types].
+   */
+  bool matchesAny(List<TokenType> types) {
+    for (TokenType type in types) {
+      if (this.type == type) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Set the next token in the token stream to the given [token]. This has the
+   * side-effect of setting this token to be the previous token for the given
+   * token. Return the token that was passed in.
+   */
+  Token setNext(Token token) {
+    _next = token;
+    token.previous = this;
+    return token;
+  }
+
+  /**
+   * Set the next token in the token stream to the given token without changing
+   * which token is the previous token for the given token. Return the token
+   * that was passed in.
+   */
+  Token setNextWithoutSettingPrevious(Token token) {
+    _next = token;
+    return token;
+  }
+
+  @override
+  String toString() => lexeme;
+
+  /**
+   * Return the value of this token. For keyword tokens, this is the keyword
+   * associated with the token, for other tokens it is the lexeme associated
+   * with the token.
+   */
+  Object value() => type.lexeme;
+
+  /**
+   * Sets the `parent` property to `this` for the given [comment] and all the
+   * next tokens.
+   */
+  void _setCommentParent(CommentToken comment) {
+    while (comment != null) {
+      comment.parent = this;
+      comment = comment.next;
+    }
+  }
+
+  /**
+   * Compare the given [tokens] to find the token that appears first in the
+   * source being parsed. That is, return the left-most of all of the tokens.
+   * The list must be non-`null`, but the elements of the list are allowed to be
+   * `null`. Return the token with the smallest offset, or `null` if the list is
+   * empty or if all of the elements of the list are `null`.
+   */
+  static Token lexicallyFirst(List<Token> tokens) {
+    Token first = null;
+    int offset = -1;
+    for (Token token in tokens) {
+      if (token != null && (offset < 0 || token.offset < offset)) {
+        first = token;
+        offset = token.offset;
+      }
+    }
+    return first;
+  }
+}
+
+/**
+ * The classes (or groups) of tokens with a similar use.
+ */
+class TokenClass {
+  /**
+   * A value used to indicate that the token type is not part of any specific
+   * class of token.
+   */
+  static const TokenClass NO_CLASS = const TokenClass('NO_CLASS');
+
+  /**
+   * A value used to indicate that the token type is an additive operator.
+   */
+  static const TokenClass ADDITIVE_OPERATOR =
+      const TokenClass('ADDITIVE_OPERATOR', 13);
+
+  /**
+   * A value used to indicate that the token type is an assignment operator.
+   */
+  static const TokenClass ASSIGNMENT_OPERATOR =
+      const TokenClass('ASSIGNMENT_OPERATOR', 1);
+
+  /**
+   * A value used to indicate that the token type is a bitwise-and operator.
+   */
+  static const TokenClass BITWISE_AND_OPERATOR =
+      const TokenClass('BITWISE_AND_OPERATOR', 11);
+
+  /**
+   * A value used to indicate that the token type is a bitwise-or operator.
+   */
+  static const TokenClass BITWISE_OR_OPERATOR =
+      const TokenClass('BITWISE_OR_OPERATOR', 9);
+
+  /**
+   * A value used to indicate that the token type is a bitwise-xor operator.
+   */
+  static const TokenClass BITWISE_XOR_OPERATOR =
+      const TokenClass('BITWISE_XOR_OPERATOR', 10);
+
+  /**
+   * A value used to indicate that the token type is a cascade operator.
+   */
+  static const TokenClass CASCADE_OPERATOR =
+      const TokenClass('CASCADE_OPERATOR', 2);
+
+  /**
+   * A value used to indicate that the token type is a conditional operator.
+   */
+  static const TokenClass CONDITIONAL_OPERATOR =
+      const TokenClass('CONDITIONAL_OPERATOR', 3);
+
+  /**
+   * A value used to indicate that the token type is an equality operator.
+   */
+  static const TokenClass EQUALITY_OPERATOR =
+      const TokenClass('EQUALITY_OPERATOR', 7);
+
+  /**
+   * A value used to indicate that the token type is an if-null operator.
+   */
+  static const TokenClass IF_NULL_OPERATOR =
+      const TokenClass('IF_NULL_OPERATOR', 4);
+
+  /**
+   * A value used to indicate that the token type is a logical-and operator.
+   */
+  static const TokenClass LOGICAL_AND_OPERATOR =
+      const TokenClass('LOGICAL_AND_OPERATOR', 6);
+
+  /**
+   * A value used to indicate that the token type is a logical-or operator.
+   */
+  static const TokenClass LOGICAL_OR_OPERATOR =
+      const TokenClass('LOGICAL_OR_OPERATOR', 5);
+
+  /**
+   * A value used to indicate that the token type is a multiplicative operator.
+   */
+  static const TokenClass MULTIPLICATIVE_OPERATOR =
+      const TokenClass('MULTIPLICATIVE_OPERATOR', 14);
+
+  /**
+   * A value used to indicate that the token type is a relational operator.
+   */
+  static const TokenClass RELATIONAL_OPERATOR =
+      const TokenClass('RELATIONAL_OPERATOR', 8);
+
+  /**
+   * A value used to indicate that the token type is a shift operator.
+   */
+  static const TokenClass SHIFT_OPERATOR =
+      const TokenClass('SHIFT_OPERATOR', 12);
+
+  /**
+   * A value used to indicate that the token type is a unary operator.
+   */
+  static const TokenClass UNARY_POSTFIX_OPERATOR =
+      const TokenClass('UNARY_POSTFIX_OPERATOR', 16);
+
+  /**
+   * A value used to indicate that the token type is a unary operator.
+   */
+  static const TokenClass UNARY_PREFIX_OPERATOR =
+      const TokenClass('UNARY_PREFIX_OPERATOR', 15);
+
+  /**
+   * The name of the token class.
+   */
+  final String name;
+
+  /**
+   * The precedence of tokens of this class, or `0` if the such tokens do not
+   * represent an operator.
+   */
+  final int precedence;
+
+  const TokenClass(this.name, [this.precedence = 0]);
+
+  @override
+  String toString() => name;
+}
+
+/**
+ * The types of tokens that can be returned by the scanner.
+ */
+class TokenType {
+  /**
+   * The type of the token that marks the end of the input.
+   */
+  static const TokenType EOF = const TokenType_EOF('EOF');
+
+  static const TokenType DOUBLE = const TokenType('DOUBLE');
+
+  static const TokenType HEXADECIMAL = const TokenType('HEXADECIMAL');
+
+  static const TokenType IDENTIFIER = const TokenType('IDENTIFIER');
+
+  static const TokenType INT = const TokenType('INT');
+
+  static const TokenType KEYWORD = const TokenType('KEYWORD');
+
+  static const TokenType MULTI_LINE_COMMENT =
+      const TokenType('MULTI_LINE_COMMENT');
+
+  static const TokenType SCRIPT_TAG = const TokenType('SCRIPT_TAG');
+
+  static const TokenType SINGLE_LINE_COMMENT =
+      const TokenType('SINGLE_LINE_COMMENT');
+
+  static const TokenType STRING = const TokenType('STRING');
+
+  static const TokenType AMPERSAND =
+      const TokenType('AMPERSAND', TokenClass.BITWISE_AND_OPERATOR, "&");
+
+  static const TokenType AMPERSAND_AMPERSAND = const TokenType(
+      'AMPERSAND_AMPERSAND', TokenClass.LOGICAL_AND_OPERATOR, "&&");
+
+  static const TokenType AMPERSAND_EQ =
+      const TokenType('AMPERSAND_EQ', TokenClass.ASSIGNMENT_OPERATOR, "&=");
+
+  static const TokenType AT = const TokenType('AT', TokenClass.NO_CLASS, "@");
+
+  static const TokenType BANG =
+      const TokenType('BANG', TokenClass.UNARY_PREFIX_OPERATOR, "!");
+
+  static const TokenType BANG_EQ =
+      const TokenType('BANG_EQ', TokenClass.EQUALITY_OPERATOR, "!=");
+
+  static const TokenType BAR =
+      const TokenType('BAR', TokenClass.BITWISE_OR_OPERATOR, "|");
+
+  static const TokenType BAR_BAR =
+      const TokenType('BAR_BAR', TokenClass.LOGICAL_OR_OPERATOR, "||");
+
+  static const TokenType BAR_EQ =
+      const TokenType('BAR_EQ', TokenClass.ASSIGNMENT_OPERATOR, "|=");
+
+  static const TokenType COLON =
+      const TokenType('COLON', TokenClass.NO_CLASS, ":");
+
+  static const TokenType COMMA =
+      const TokenType('COMMA', TokenClass.NO_CLASS, ",");
+
+  static const TokenType CARET =
+      const TokenType('CARET', TokenClass.BITWISE_XOR_OPERATOR, "^");
+
+  static const TokenType CARET_EQ =
+      const TokenType('CARET_EQ', TokenClass.ASSIGNMENT_OPERATOR, "^=");
+
+  static const TokenType CLOSE_CURLY_BRACKET =
+      const TokenType('CLOSE_CURLY_BRACKET', TokenClass.NO_CLASS, "}");
+
+  static const TokenType CLOSE_PAREN =
+      const TokenType('CLOSE_PAREN', TokenClass.NO_CLASS, ")");
+
+  static const TokenType CLOSE_SQUARE_BRACKET =
+      const TokenType('CLOSE_SQUARE_BRACKET', TokenClass.NO_CLASS, "]");
+
+  static const TokenType EQ =
+      const TokenType('EQ', TokenClass.ASSIGNMENT_OPERATOR, "=");
+
+  static const TokenType EQ_EQ =
+      const TokenType('EQ_EQ', TokenClass.EQUALITY_OPERATOR, "==");
+
+  static const TokenType FUNCTION =
+      const TokenType('FUNCTION', TokenClass.NO_CLASS, "=>");
+
+  static const TokenType GT =
+      const TokenType('GT', TokenClass.RELATIONAL_OPERATOR, ">");
+
+  static const TokenType GT_EQ =
+      const TokenType('GT_EQ', TokenClass.RELATIONAL_OPERATOR, ">=");
+
+  static const TokenType GT_GT =
+      const TokenType('GT_GT', TokenClass.SHIFT_OPERATOR, ">>");
+
+  static const TokenType GT_GT_EQ =
+      const TokenType('GT_GT_EQ', TokenClass.ASSIGNMENT_OPERATOR, ">>=");
+
+  static const TokenType HASH =
+      const TokenType('HASH', TokenClass.NO_CLASS, "#");
+
+  static const TokenType INDEX =
+      const TokenType('INDEX', TokenClass.UNARY_POSTFIX_OPERATOR, "[]");
+
+  static const TokenType INDEX_EQ =
+      const TokenType('INDEX_EQ', TokenClass.UNARY_POSTFIX_OPERATOR, "[]=");
+
+  static const TokenType IS =
+      const TokenType('IS', TokenClass.RELATIONAL_OPERATOR, "is");
+
+  static const TokenType LT =
+      const TokenType('LT', TokenClass.RELATIONAL_OPERATOR, "<");
+
+  static const TokenType LT_EQ =
+      const TokenType('LT_EQ', TokenClass.RELATIONAL_OPERATOR, "<=");
+
+  static const TokenType LT_LT =
+      const TokenType('LT_LT', TokenClass.SHIFT_OPERATOR, "<<");
+
+  static const TokenType LT_LT_EQ =
+      const TokenType('LT_LT_EQ', TokenClass.ASSIGNMENT_OPERATOR, "<<=");
+
+  static const TokenType MINUS =
+      const TokenType('MINUS', TokenClass.ADDITIVE_OPERATOR, "-");
+
+  static const TokenType MINUS_EQ =
+      const TokenType('MINUS_EQ', TokenClass.ASSIGNMENT_OPERATOR, "-=");
+
+  static const TokenType MINUS_MINUS =
+      const TokenType('MINUS_MINUS', TokenClass.UNARY_PREFIX_OPERATOR, "--");
+
+  static const TokenType OPEN_CURLY_BRACKET =
+      const TokenType('OPEN_CURLY_BRACKET', TokenClass.NO_CLASS, "{");
+
+  static const TokenType OPEN_PAREN =
+      const TokenType('OPEN_PAREN', TokenClass.UNARY_POSTFIX_OPERATOR, "(");
+
+  static const TokenType OPEN_SQUARE_BRACKET = const TokenType(
+      'OPEN_SQUARE_BRACKET', TokenClass.UNARY_POSTFIX_OPERATOR, "[");
+
+  static const TokenType PERCENT =
+      const TokenType('PERCENT', TokenClass.MULTIPLICATIVE_OPERATOR, "%");
+
+  static const TokenType PERCENT_EQ =
+      const TokenType('PERCENT_EQ', TokenClass.ASSIGNMENT_OPERATOR, "%=");
+
+  static const TokenType PERIOD =
+      const TokenType('PERIOD', TokenClass.UNARY_POSTFIX_OPERATOR, ".");
+
+  static const TokenType PERIOD_PERIOD =
+      const TokenType('PERIOD_PERIOD', TokenClass.CASCADE_OPERATOR, "..");
+
+  static const TokenType PLUS =
+      const TokenType('PLUS', TokenClass.ADDITIVE_OPERATOR, "+");
+
+  static const TokenType PLUS_EQ =
+      const TokenType('PLUS_EQ', TokenClass.ASSIGNMENT_OPERATOR, "+=");
+
+  static const TokenType PLUS_PLUS =
+      const TokenType('PLUS_PLUS', TokenClass.UNARY_PREFIX_OPERATOR, "++");
+
+  static const TokenType QUESTION =
+      const TokenType('QUESTION', TokenClass.CONDITIONAL_OPERATOR, "?");
+
+  static const TokenType QUESTION_PERIOD = const TokenType(
+      'QUESTION_PERIOD', TokenClass.UNARY_POSTFIX_OPERATOR, '?.');
+
+  static const TokenType QUESTION_QUESTION =
+      const TokenType('QUESTION_QUESTION', TokenClass.IF_NULL_OPERATOR, '??');
+
+  static const TokenType QUESTION_QUESTION_EQ = const TokenType(
+      'QUESTION_QUESTION_EQ', TokenClass.ASSIGNMENT_OPERATOR, '??=');
+
+  static const TokenType SEMICOLON =
+      const TokenType('SEMICOLON', TokenClass.NO_CLASS, ";");
+
+  static const TokenType SLASH =
+      const TokenType('SLASH', TokenClass.MULTIPLICATIVE_OPERATOR, "/");
+
+  static const TokenType SLASH_EQ =
+      const TokenType('SLASH_EQ', TokenClass.ASSIGNMENT_OPERATOR, "/=");
+
+  static const TokenType STAR =
+      const TokenType('STAR', TokenClass.MULTIPLICATIVE_OPERATOR, "*");
+
+  static const TokenType STAR_EQ =
+      const TokenType('STAR_EQ', TokenClass.ASSIGNMENT_OPERATOR, "*=");
+
+  static const TokenType STRING_INTERPOLATION_EXPRESSION = const TokenType(
+      'STRING_INTERPOLATION_EXPRESSION', TokenClass.NO_CLASS, "\${");
+
+  static const TokenType STRING_INTERPOLATION_IDENTIFIER = const TokenType(
+      'STRING_INTERPOLATION_IDENTIFIER', TokenClass.NO_CLASS, "\$");
+
+  static const TokenType TILDE =
+      const TokenType('TILDE', TokenClass.UNARY_PREFIX_OPERATOR, "~");
+
+  static const TokenType TILDE_SLASH =
+      const TokenType('TILDE_SLASH', TokenClass.MULTIPLICATIVE_OPERATOR, "~/");
+
+  static const TokenType TILDE_SLASH_EQ =
+      const TokenType('TILDE_SLASH_EQ', TokenClass.ASSIGNMENT_OPERATOR, "~/=");
+
+  static const TokenType BACKPING =
+      const TokenType('BACKPING', TokenClass.NO_CLASS, "`");
+
+  static const TokenType BACKSLASH =
+      const TokenType('BACKSLASH', TokenClass.NO_CLASS, "\\");
+
+  static const TokenType PERIOD_PERIOD_PERIOD =
+      const TokenType('PERIOD_PERIOD_PERIOD', TokenClass.NO_CLASS, "...");
+
+  /**
+   * The class of the token.
+   */
+  final TokenClass _tokenClass;
+
+  /**
+   * The name of the token type.
+   */
+  final String name;
+
+  /**
+   * The lexeme that defines this type of token, or `null` if there is more than
+   * one possible lexeme for this type of token.
+   */
+  final String lexeme;
+
+  const TokenType(this.name,
+      [this._tokenClass = TokenClass.NO_CLASS, this.lexeme = null]);
+
+  /**
+   * Return `true` if this type of token represents an additive operator.
+   */
+  bool get isAdditiveOperator => _tokenClass == TokenClass.ADDITIVE_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents an assignment operator.
+   */
+  bool get isAssignmentOperator =>
+      _tokenClass == TokenClass.ASSIGNMENT_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents an associative operator. An
+   * associative operator is an operator for which the following equality is
+   * true: `(a * b) * c == a * (b * c)`. In other words, if the result of
+   * applying the operator to multiple operands does not depend on the order in
+   * which those applications occur.
+   *
+   * Note: This method considers the logical-and and logical-or operators to be
+   * associative, even though the order in which the application of those
+   * operators can have an effect because evaluation of the right-hand operand
+   * is conditional.
+   */
+  bool get isAssociativeOperator => this == AMPERSAND ||
+      this == AMPERSAND_AMPERSAND ||
+      this == BAR ||
+      this == BAR_BAR ||
+      this == CARET ||
+      this == PLUS ||
+      this == STAR;
+
+  /**
+   * Return `true` if this type of token represents an equality operator.
+   */
+  bool get isEqualityOperator => _tokenClass == TokenClass.EQUALITY_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents an increment operator.
+   */
+  bool get isIncrementOperator =>
+      identical(lexeme, "++") || identical(lexeme, "--");
+
+  /**
+   * Return `true` if this type of token represents a multiplicative operator.
+   */
+  bool get isMultiplicativeOperator =>
+      _tokenClass == TokenClass.MULTIPLICATIVE_OPERATOR;
+
+  /**
+   * Return `true` if this token type represents an operator.
+   */
+  bool get isOperator => _tokenClass != TokenClass.NO_CLASS &&
+      this != OPEN_PAREN &&
+      this != OPEN_SQUARE_BRACKET &&
+      this != PERIOD;
+
+  /**
+   * Return `true` if this type of token represents a relational operator.
+   */
+  bool get isRelationalOperator =>
+      _tokenClass == TokenClass.RELATIONAL_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents a shift operator.
+   */
+  bool get isShiftOperator => _tokenClass == TokenClass.SHIFT_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents a unary postfix operator.
+   */
+  bool get isUnaryPostfixOperator =>
+      _tokenClass == TokenClass.UNARY_POSTFIX_OPERATOR;
+
+  /**
+   * Return `true` if this type of token represents a unary prefix operator.
+   */
+  bool get isUnaryPrefixOperator =>
+      _tokenClass == TokenClass.UNARY_PREFIX_OPERATOR;
+
+  /**
+   * Return `true` if this token type represents an operator that can be defined
+   * by users.
+   */
+  bool get isUserDefinableOperator => identical(lexeme, "==") ||
+      identical(lexeme, "~") ||
+      identical(lexeme, "[]") ||
+      identical(lexeme, "[]=") ||
+      identical(lexeme, "*") ||
+      identical(lexeme, "/") ||
+      identical(lexeme, "%") ||
+      identical(lexeme, "~/") ||
+      identical(lexeme, "+") ||
+      identical(lexeme, "-") ||
+      identical(lexeme, "<<") ||
+      identical(lexeme, ">>") ||
+      identical(lexeme, ">=") ||
+      identical(lexeme, ">") ||
+      identical(lexeme, "<=") ||
+      identical(lexeme, "<") ||
+      identical(lexeme, "&") ||
+      identical(lexeme, "^") ||
+      identical(lexeme, "|");
+
+  /**
+   * Return the precedence of the token, or `0` if the token does not represent
+   * an operator.
+   */
+  int get precedence => _tokenClass.precedence;
+
+  @override
+  String toString() => name;
+}
+
+class TokenType_EOF extends TokenType {
+  const TokenType_EOF(String name) : super(name, TokenClass.NO_CLASS, "");
+
+  @override
+  String toString() => "-eof-";
+}
+
+/**
+ * A normal token that is preceded by comments.
+ */
+class TokenWithComment extends Token {
+  /**
+   * The first comment in the list of comments that precede this token.
+   */
+  CommentToken _precedingComment;
+
+  /**
+   * Initialize a newly created token to have the given [type] at the given
+   * [offset] and to be preceded by the comments reachable from the given
+   * [comment].
+   */
+  TokenWithComment(TokenType type, int offset, this._precedingComment)
+      : super(type, offset) {
+    _setCommentParent(_precedingComment);
+  }
+
+  CommentToken get precedingComments => _precedingComment;
+
+  void set precedingComments(CommentToken comment) {
+    _precedingComment = comment;
+    _setCommentParent(_precedingComment);
+  }
+
+  @override
+  Token copy() => new TokenWithComment(type, offset, precedingComments);
+}