Remove deprecated code

pkg/analyzer/lib/src/generated/html.dart

Index: pkg/analyzer/lib/src/generated/html.dart
diff --git a/pkg/analyzer/lib/src/generated/html.dart b/pkg/analyzer/lib/src/generated/html.dart
deleted file mode 100644
index c0012c5d30e5417320628f20cc775b21ffb99c41..0000000000000000000000000000000000000000
--- a/pkg/analyzer/lib/src/generated/html.dart
+++ /dev/null
@@ -1,1905 +0,0 @@
-// 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.html;
-
-import 'dart:collection';
-
-import 'ast.dart';
-import 'element.dart';
-import 'engine.dart' show AnalysisOptions, AnalysisEngine;
-import 'error.dart' show AnalysisErrorListener;
-import 'java_core.dart';
-import 'java_engine.dart';
-import 'parser.dart' show Parser;
-import 'scanner.dart' as sc show Scanner, SubSequenceReader, Token;
-import 'source.dart';
-
-/**
- * The abstract class `AbstractScanner` implements a scanner for HTML code. Subclasses are
- * required to implement the interface used to access the characters being scanned.
- */
-abstract class AbstractScanner {
-  static List<String> _NO_PASS_THROUGH_ELEMENTS = <String>[];
-
-  /**
-   * The source being scanned.
-   */
-  final Source source;
-
-  /**
-   * The token pointing to the head of the linked list of tokens.
-   */
-  Token _tokens;
-
-  /**
-   * The last token that was scanned.
-   */
-  Token _tail;
-
-  /**
-   * A list containing the offsets of the first character of each line in the source code.
-   */
-  List<int> _lineStarts = new List<int>();
-
-  /**
-   * An array of element tags for which the content between tags should be consider a single token.
-   */
-  List<String> _passThroughElements = _NO_PASS_THROUGH_ELEMENTS;
-
-  /**
-   * Initialize a newly created scanner.
-   *
-   * @param source the source being scanned
-   */
-  AbstractScanner(this.source) {
-    _tokens = new Token.con1(TokenType.EOF, -1);
-    _tokens.setNext(_tokens);
-    _tail = _tokens;
-    recordStartOfLine();
-  }
-
-  /**
-   * Return an array containing the offsets of the first character of each line in the source code.
-   *
-   * @return an array containing the offsets of the first character of each line in the source code
-   */
-  List<int> get lineStarts => _lineStarts;
-
-  /**
-   * Return the current offset relative to the beginning of the file. 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 source code has been scanned.
-   *
-   * @return the current offset of the scanner in the source
-   */
-  int get offset;
-
-  /**
-   * Set array of element tags for which the content between tags should be consider a single token.
-   */
-  void set passThroughElements(List<String> passThroughElements) {
-    this._passThroughElements = passThroughElements != null
-        ? passThroughElements
-        : _NO_PASS_THROUGH_ELEMENTS;
-  }
-
-  /**
-   * Advance the current position and return the character at the new current position.
-   *
-   * @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 end delta.
-   *
-   * @param start the offset to the beginning of the string, relative to the start of the file
-   * @param endDelta the number of character 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
-   * @return the specified substring of the source code
-   */
-  String getString(int start, int endDelta);
-
-  /**
-   * Return the character at the current position without changing the current position.
-   *
-   * @return the character at the current position
-   */
-  int peek();
-
-  /**
-   * Record the fact that we are at the beginning of a new line in the source.
-   */
-  void recordStartOfLine() {
-    _lineStarts.add(offset);
-  }
-
-  /**
-   * Scan the source code to produce a list of tokens representing the source.
-   *
-   * @return the first token in the list of tokens that were produced
-   */
-  Token tokenize() {
-    _scan();
-    _appendEofToken();
-    return _firstToken();
-  }
-
-  void _appendEofToken() {
-    Token eofToken = new Token.con1(TokenType.EOF, offset);
-    // The EOF token points to itself so that there is always infinite
-    // look-ahead.
-    eofToken.setNext(eofToken);
-    _tail = _tail.setNext(eofToken);
-  }
-
-  Token _emit(Token token) {
-    _tail.setNext(token);
-    _tail = token;
-    return token;
-  }
-
-  Token _emitWithOffset(TokenType type, int start) =>
-      _emit(new Token.con1(type, start));
-
-  Token _emitWithOffsetAndLength(TokenType type, int start, int count) =>
-      _emit(new Token.con2(type, start, getString(start, count)));
-
-  Token _firstToken() => _tokens.next;
-
-  int _recordStartOfLineAndAdvance(int c) {
-    if (c == 0xD) {
-      c = advance();
-      if (c == 0xA) {
-        c = advance();
-      }
-      recordStartOfLine();
-    } else if (c == 0xA) {
-      c = advance();
-      recordStartOfLine();
-    } else {
-      c = advance();
-    }
-    return c;
-  }
-
-  void _scan() {
-    bool inBrackets = false;
-    String endPassThrough = null;
-    int c = advance();
-    while (c >= 0) {
-      int start = offset;
-      if (c == 0x3C) {
-        c = advance();
-        if (c == 0x21) {
-          c = advance();
-          if (c == 0x2D && peek() == 0x2D) {
-            // handle a comment
-            c = advance();
-            int dashCount = 1;
-            while (c >= 0) {
-              if (c == 0x2D) {
-                dashCount++;
-              } else if (c == 0x3E && dashCount >= 2) {
-                c = advance();
-                break;
-              } else {
-                dashCount = 0;
-              }
-              c = _recordStartOfLineAndAdvance(c);
-            }
-            _emitWithOffsetAndLength(TokenType.COMMENT, start, -1);
-            // Capture <!--> and <!---> as tokens but report an error
-            if (_tail.length < 7) {
-              // TODO (danrubel): Report invalid HTML comment
-            }
-          } else {
-            // handle a declaration
-            while (c >= 0) {
-              if (c == 0x3E) {
-                c = advance();
-                break;
-              }
-              c = _recordStartOfLineAndAdvance(c);
-            }
-            _emitWithOffsetAndLength(TokenType.DECLARATION, start, -1);
-            if (!StringUtilities.endsWithChar(_tail.lexeme, 0x3E)) {
-              // TODO (danrubel): Report missing '>' in directive
-            }
-          }
-        } else if (c == 0x3F) {
-          // handle a directive
-          while (c >= 0) {
-            if (c == 0x3F) {
-              c = advance();
-              if (c == 0x3E) {
-                c = advance();
-                break;
-              }
-            } else {
-              c = _recordStartOfLineAndAdvance(c);
-            }
-          }
-          _emitWithOffsetAndLength(TokenType.DIRECTIVE, start, -1);
-          if (_tail.length < 4) {
-            // TODO (danrubel): Report invalid directive
-          }
-        } else if (c == 0x2F) {
-          _emitWithOffset(TokenType.LT_SLASH, start);
-          inBrackets = true;
-          c = advance();
-        } else {
-          inBrackets = true;
-          _emitWithOffset(TokenType.LT, start);
-          // ignore whitespace in braces
-          while (Character.isWhitespace(c)) {
-            c = _recordStartOfLineAndAdvance(c);
-          }
-          // get tag
-          if (Character.isLetterOrDigit(c)) {
-            int tagStart = offset;
-            c = advance();
-            while (Character.isLetterOrDigit(c) || c == 0x2D || c == 0x5F) {
-              c = advance();
-            }
-            _emitWithOffsetAndLength(TokenType.TAG, tagStart, -1);
-            // check tag against passThrough elements
-            String tag = _tail.lexeme;
-            for (String str in _passThroughElements) {
-              if (str == tag) {
-                endPassThrough = "</$str>";
-                break;
-              }
-            }
-          }
-        }
-      } else if (c == 0x3E) {
-        _emitWithOffset(TokenType.GT, start);
-        inBrackets = false;
-        c = advance();
-        // if passThrough != null, read until we match it
-        if (endPassThrough != null) {
-          bool endFound = false;
-          int len = endPassThrough.length;
-          int firstC = endPassThrough.codeUnitAt(0);
-          int index = 0;
-          int nextC = firstC;
-          while (c >= 0) {
-            if (c == nextC) {
-              index++;
-              if (index == len) {
-                endFound = true;
-                break;
-              }
-              nextC = endPassThrough.codeUnitAt(index);
-            } else if (c == firstC) {
-              index = 1;
-              nextC = endPassThrough.codeUnitAt(1);
-            } else {
-              index = 0;
-              nextC = firstC;
-            }
-            c = _recordStartOfLineAndAdvance(c);
-          }
-          if (start + 1 < offset) {
-            if (endFound) {
-              _emitWithOffsetAndLength(TokenType.TEXT, start + 1, -len);
-              _emitWithOffset(TokenType.LT_SLASH, offset - len + 1);
-              _emitWithOffsetAndLength(TokenType.TAG, offset - len + 3, -1);
-            } else {
-              _emitWithOffsetAndLength(TokenType.TEXT, start + 1, -1);
-            }
-          }
-          endPassThrough = null;
-        }
-      } else if (c == 0x2F && peek() == 0x3E) {
-        advance();
-        _emitWithOffset(TokenType.SLASH_GT, start);
-        inBrackets = false;
-        c = advance();
-      } else if (!inBrackets) {
-        c = _recordStartOfLineAndAdvance(c);
-        while (c != 0x3C && c >= 0) {
-          c = _recordStartOfLineAndAdvance(c);
-        }
-        _emitWithOffsetAndLength(TokenType.TEXT, start, -1);
-      } else if (c == 0x22 || c == 0x27) {
-        // read a string
-        int endQuote = c;
-        c = advance();
-        while (c >= 0) {
-          if (c == endQuote) {
-            c = advance();
-            break;
-          }
-          c = _recordStartOfLineAndAdvance(c);
-        }
-        _emitWithOffsetAndLength(TokenType.STRING, start, -1);
-      } else if (c == 0x3D) {
-        // a non-char token
-        _emitWithOffset(TokenType.EQ, start);
-        c = advance();
-      } else if (Character.isWhitespace(c)) {
-        // ignore whitespace in braces
-        do {
-          c = _recordStartOfLineAndAdvance(c);
-        } while (Character.isWhitespace(c));
-      } else if (Character.isLetterOrDigit(c)) {
-        c = advance();
-        while (Character.isLetterOrDigit(c) || c == 0x2D || c == 0x5F) {
-          c = advance();
-        }
-        _emitWithOffsetAndLength(TokenType.TAG, start, -1);
-      } else {
-        // a non-char token
-        _emitWithOffsetAndLength(TokenType.TEXT, start, 0);
-        c = advance();
-      }
-    }
-  }
-}
-
-/**
- * Instances of the class `HtmlParser` are used to parse tokens into a AST structure comprised
- * of [XmlNode]s.
- */
-class HtmlParser extends XmlParser {
-  static String _APPLICATION_DART_IN_DOUBLE_QUOTES = "\"application/dart\"";
-
-  static String _APPLICATION_DART_IN_SINGLE_QUOTES = "'application/dart'";
-
-  static String _SCRIPT = "script";
-
-  static String _TYPE = "type";
-
-  /**
-   * A set containing the names of tags that do not have a closing tag.
-   */
-  static Set<String> SELF_CLOSING = new HashSet<String>.from(<String>[
-    "area",
-    "base",
-    "basefont",
-    "br",
-    "col",
-    "frame",
-    "hr",
-    "img",
-    "input",
-    "link",
-    "meta",
-    "param",
-    "!"
-  ]);
-
-  /**
-   * The line information associated with the source being parsed.
-   */
-  LineInfo _lineInfo;
-
-  /**
-   * The error listener to which errors will be reported.
-   */
-  final AnalysisErrorListener _errorListener;
-
-  final AnalysisOptions _options;
-
-  /**
-   * Construct a parser for the specified source.
-   *
-   * [source] is the source being parsed.  [_errorListener] is the error
-   * listener to which errors will be reported.  [_options] is the analysis
-   * options which should be used for parsing.
-   */
-  HtmlParser(Source source, this._errorListener, this._options) : super(source);
-
-  @override
-  XmlAttributeNode createAttributeNode(Token name, Token equals, Token value) =>
-      new XmlAttributeNode(name, equals, value);
-
-  @override
-  XmlTagNode createTagNode(
-      Token nodeStart,
-      Token tag,
-      List<XmlAttributeNode> attributes,
-      Token attributeEnd,
-      List<XmlTagNode> tagNodes,
-      Token contentEnd,
-      Token closingTag,
-      Token nodeEnd) {
-    if (_isScriptNode(tag, attributes, tagNodes)) {
-      HtmlScriptTagNode tagNode = new HtmlScriptTagNode(nodeStart, tag,
-          attributes, attributeEnd, tagNodes, contentEnd, closingTag, nodeEnd);
-      String contents = tagNode.content;
-      int contentOffset = attributeEnd.end;
-      LineInfo_Location location = _lineInfo.getLocation(contentOffset);
-      sc.Scanner scanner = new sc.Scanner(source,
-          new sc.SubSequenceReader(contents, contentOffset), _errorListener);
-      scanner.setSourceStart(location.lineNumber, location.columnNumber);
-      sc.Token firstToken = scanner.tokenize();
-      Parser parser = new Parser(source, _errorListener);
-      CompilationUnit unit = parser.parseCompilationUnit(firstToken);
-      unit.lineInfo = _lineInfo;
-      tagNode.script = unit;
-      return tagNode;
-    }
-    return new XmlTagNode(nodeStart, tag, attributes, attributeEnd, tagNodes,
-        contentEnd, closingTag, nodeEnd);
-  }
-
-  @override
-  bool isSelfClosing(Token tag) => SELF_CLOSING.contains(tag.lexeme);
-
-  /**
-   * Parse the given tokens.
-   *
-   * @param token the first token in the stream of tokens to be parsed
-   * @param lineInfo the line information created by the scanner
-   * @return the parse result (not `null`)
-   */
-  HtmlUnit parse(Token token, LineInfo lineInfo) {
-    this._lineInfo = lineInfo;
-    List<XmlTagNode> tagNodes = parseTopTagNodes(token);
-    return new HtmlUnit(token, tagNodes, currentToken);
-  }
-
-  /**
-   * Determine if the specified node is a Dart script.
-   *
-   * @param node the node to be tested (not `null`)
-   * @return `true` if the node is a Dart script
-   */
-  bool _isScriptNode(
-      Token tag, List<XmlAttributeNode> attributes, List<XmlTagNode> tagNodes) {
-    if (tagNodes.length != 0 || tag.lexeme != _SCRIPT) {
-      return false;
-    }
-    for (XmlAttributeNode attribute in attributes) {
-      if (attribute.name == _TYPE) {
-        Token valueToken = attribute.valueToken;
-        if (valueToken != null) {
-          String value = valueToken.lexeme;
-          if (value == _APPLICATION_DART_IN_DOUBLE_QUOTES ||
-              value == _APPLICATION_DART_IN_SINGLE_QUOTES) {
-            return true;
-          }
-        }
-      }
-    }
-    return false;
-  }
-
-  /**
-   * Given the contents of an embedded expression that occurs at the given offset, parse it as a
-   * Dart expression. The contents should not include the expression's delimiters.
-   *
-   * @param source the source that contains that given token
-   * @param token the token to start parsing from
-   * @return the Dart expression that was parsed
-   */
-  static Expression parseEmbeddedExpression(
-      Source source, sc.Token token, AnalysisErrorListener errorListener) {
-    Parser parser = new Parser(source, errorListener);
-    return parser.parseExpression(token);
-  }
-
-  /**
-   * Given the contents of an embedded expression that occurs at the given offset, scans it as a
-   * Dart code.
-   *
-   * @param source the source of that contains the given contents
-   * @param contents the contents to scan
-   * @param contentOffset the offset of the contents in the larger file
-   * @return the first Dart token
-   */
-  static sc.Token scanDartSource(Source source, LineInfo lineInfo,
-      String contents, int contentOffset, AnalysisErrorListener errorListener) {
-    LineInfo_Location location = lineInfo.getLocation(contentOffset);
-    sc.Scanner scanner = new sc.Scanner(source,
-        new sc.SubSequenceReader(contents, contentOffset), errorListener);
-    scanner.setSourceStart(location.lineNumber, location.columnNumber);
-    return scanner.tokenize();
-  }
-}
-
-/**
- * Instances of the class `HtmlScriptTagNode` represent a script tag within an HTML file that
- * references a Dart script.
- */
-@deprecated
-class HtmlScriptTagNode extends XmlTagNode {
-  /**
-   * The AST structure representing the Dart code within this tag.
-   */
-  CompilationUnit _script;
-
-  /**
-   * The element representing this script.
-   */
-  HtmlScriptElement scriptElement;
-
-  /**
-   * Initialize a newly created node to represent a script tag within an HTML file that references a
-   * Dart script.
-   *
-   * @param nodeStart the token marking the beginning of the tag
-   * @param tag the name of the tag
-   * @param attributes the attributes in the tag
-   * @param attributeEnd the token terminating the region where attributes can be
-   * @param tagNodes the children of the tag
-   * @param contentEnd the token that starts the closing tag
-   * @param closingTag the name of the tag that occurs in the closing tag
-   * @param nodeEnd the last token in the tag
-   */
-  HtmlScriptTagNode(
-      Token nodeStart,
-      Token tag,
-      List<XmlAttributeNode> attributes,
-      Token attributeEnd,
-      List<XmlTagNode> tagNodes,
-      Token contentEnd,
-      Token closingTag,
-      Token nodeEnd)
-      : super(nodeStart, tag, attributes, attributeEnd, tagNodes, contentEnd,
-            closingTag, nodeEnd);
-
-  /**
-   * Return the AST structure representing the Dart code within this tag, or `null` if this
-   * tag references an external script.
-   *
-   * @return the AST structure representing the Dart code within this tag
-   */
-  CompilationUnit get script => _script;
-
-  /**
-   * Set the AST structure representing the Dart code within this tag to the given compilation unit.
-   *
-   * @param unit the AST structure representing the Dart code within this tag
-   */
-  void set script(CompilationUnit unit) {
-    _script = unit;
-  }
-
-  @override
-  accept(XmlVisitor visitor) => visitor.visitHtmlScriptTagNode(this);
-}
-
-/**
- * Instances of the class `HtmlUnit` represent the contents of an HTML file.
- */
-@deprecated
-class HtmlUnit extends XmlNode {
-  /**
-   * The first token in the token stream that was parsed to form this HTML unit.
-   */
-  final Token beginToken;
-
-  /**
-   * The last token in the token stream that was parsed to form this compilation unit. This token
-   * should always have a type of [TokenType.EOF].
-   */
-  final Token endToken;
-
-  /**
-   * The tag nodes contained in the receiver (not `null`, contains no `null`s).
-   */
-  List<XmlTagNode> _tagNodes;
-
-  /**
-   * Construct a new instance representing the content of an HTML file.
-   *
-   * @param beginToken the first token in the file (not `null`)
-   * @param tagNodes child tag nodes of the receiver (not `null`, contains no `null`s)
-   * @param endToken the last token in the token stream which should be of type
-   *          [TokenType.EOF]
-   */
-  HtmlUnit(this.beginToken, List<XmlTagNode> tagNodes, this.endToken) {
-    this._tagNodes = becomeParentOfAll(tagNodes);
-  }
-
-  /**
-   * Return the element associated with this HTML unit.
-   *
-   * @return the element or `null` if the receiver is not resolved
-   */
-  @override
-  HtmlElement get element => super.element as HtmlElement;
-
-  @override
-  void set element(Element element) {
-    if (element != null && element is! HtmlElement) {
-      throw new IllegalArgumentException(
-          "HtmlElement expected, but ${element.runtimeType} given");
-    }
-    super.element = element;
-  }
-
-  /**
-   * Answer the tag nodes contained in the receiver. Callers should not manipulate the returned list
-   * to edit the AST structure.
-   *
-   * @return the children (not `null`, contains no `null`s)
-   */
-  List<XmlTagNode> get tagNodes => _tagNodes;
-
-  @override
-  accept(XmlVisitor visitor) => visitor.visitHtmlUnit(this);
-
-  @override
-  void visitChildren(XmlVisitor visitor) {
-    for (XmlTagNode node in _tagNodes) {
-      node.accept(visitor);
-    }
-  }
-}
-
-/**
- * Instances of the class `RecursiveXmlVisitor` implement an XML visitor that will recursively
- * visit all of the nodes in an XML structure. For example, using an instance of this class to visit
- * a [XmlTagNode] will also cause all of the contained [XmlAttributeNode]s and
- * [XmlTagNode]s to be visited.
- *
- * Subclasses that override a visit method must either invoke the overridden visit method or must
- * explicitly ask the visited node to visit its children. Failure to do so will cause the children
- * of the visited node to not be visited.
- */
-class RecursiveXmlVisitor<R> implements XmlVisitor<R> {
-  @override
-  R visitHtmlScriptTagNode(HtmlScriptTagNode node) {
-    node.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitHtmlUnit(HtmlUnit node) {
-    node.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitXmlAttributeNode(XmlAttributeNode node) {
-    node.visitChildren(this);
-    return null;
-  }
-
-  @override
-  R visitXmlTagNode(XmlTagNode node) {
-    node.visitChildren(this);
-    return null;
-  }
-}
-
-/**
- * Instances of the class `SimpleXmlVisitor` implement an AST visitor that will do nothing
- * when visiting an AST node. It is intended to be a superclass for classes that use the visitor
- * pattern primarily as a dispatch mechanism (and hence don't need to recursively visit a whole
- * structure) and that only need to visit a small number of node types.
- */
-class SimpleXmlVisitor<R> implements XmlVisitor<R> {
-  @override
-  R visitHtmlScriptTagNode(HtmlScriptTagNode node) => null;
-
-  @override
-  R visitHtmlUnit(HtmlUnit htmlUnit) => null;
-
-  @override
-  R visitXmlAttributeNode(XmlAttributeNode xmlAttributeNode) => null;
-
-  @override
-  R visitXmlTagNode(XmlTagNode xmlTagNode) => null;
-}
-
-/**
- * Instances of the class `StringScanner` implement a scanner that reads from a string. The
- * scanning logic is in the superclass.
- */
-class StringScanner extends AbstractScanner {
-  /**
-   * The string from which characters will be read.
-   */
-  final String _string;
-
-  /**
-   * 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 scanner to scan the characters in the given string.
-   *
-   * @param source the source being scanned
-   * @param string the string from which characters will be read
-   */
-  StringScanner(Source source, this._string) : super(source) {
-    this._stringLength = _string.length;
-    this._charOffset = -1;
-  }
-
-  @override
-  int get offset => _charOffset;
-
-  void set offset(int offset) {
-    _charOffset = offset;
-  }
-
-  @override
-  int advance() {
-    if (++_charOffset < _stringLength) {
-      return _string.codeUnitAt(_charOffset);
-    }
-    _charOffset = _stringLength;
-    return -1;
-  }
-
-  @override
-  String getString(int start, int endDelta) =>
-      _string.substring(start, _charOffset + 1 + endDelta).toString();
-
-  @override
-  int peek() {
-    if (_charOffset + 1 < _stringLength) {
-      return _string.codeUnitAt(_charOffset + 1);
-    }
-    return -1;
-  }
-}
-
-/**
- * Instances of the class `Token` represent a token that was scanned from the input. Each
- * token knows which token follows it, acting as the head of a linked list of tokens.
- */
-class Token {
-  /**
-   * The offset from the beginning of the file to the first character in the token.
-   */
-  final int offset;
-
-  /**
-   * The previous token in the token stream.
-   */
-  Token previous;
-
-  /**
-   * The next token in the token stream.
-   */
-  Token _next;
-
-  /**
-   * The type of the token.
-   */
-  final TokenType type;
-
-  /**
-   * The lexeme represented by this token.
-   */
-  String _value;
-
-  /**
-   * Initialize a newly created token.
-   *
-   * @param type the token type (not `null`)
-   * @param offset the offset from the beginning of the file to the first character in the token
-   */
-  Token.con1(TokenType type, int offset) : this.con2(type, offset, type.lexeme);
-
-  /**
-   * Initialize a newly created token.
-   *
-   * @param type the token type (not `null`)
-   * @param offset the offset from the beginning of the file to the first character in the token
-   * @param value the lexeme represented by this token (not `null`)
-   */
-  Token.con2(this.type, this.offset, String value) {
-    this._value = StringUtilities.intern(value);
-  }
-
-  /**
-   * Return the offset from the beginning of the file to the character after last character of the
-   * token.
-   *
-   * @return the offset from the beginning of the file to the first character after last character
-   *         of the token
-   */
-  int get end => offset + length;
-
-  /**
-   * 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. Synthetic tokens always
-   * have a length of zero (`0`).
-   *
-   * @return `true` if this token is a synthetic token
-   */
-  bool get isSynthetic => length == 0;
-
-  /**
-   * Return the number of characters in the node's source range.
-   *
-   * @return the number of characters in the node's source range
-   */
-  int get length => lexeme.length;
-
-  /**
-   * Return the lexeme that represents this token.
-   *
-   * @return the lexeme (not `null`)
-   */
-  String get lexeme => _value;
-
-  /**
-   * Return the next token in the token stream.
-   *
-   * @return the next token in the token stream
-   */
-  Token get next => _next;
-
-  /**
-   * 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.
-   *
-   * @param token the next token in the token stream
-   * @return the token that was passed in
-   */
-  Token setNext(Token token) {
-    _next = token;
-    token.previous = this;
-    return token;
-  }
-
-  @override
-  String toString() => lexeme;
-}
-
-/**
- * The enumeration `TokenType` defines the types of tokens that can be returned by the
- * scanner.
- */
-class TokenType extends Enum<TokenType> {
-  /**
-   * The type of the token that marks the end of the input.
-   */
-  static const TokenType EOF = const TokenType_EOF('EOF', 0, "");
-
-  static const TokenType EQ = const TokenType('EQ', 1, "=");
-
-  static const TokenType GT = const TokenType('GT', 2, ">");
-
-  static const TokenType LT_SLASH = const TokenType('LT_SLASH', 3, "</");
-
-  static const TokenType LT = const TokenType('LT', 4, "<");
-
-  static const TokenType SLASH_GT = const TokenType('SLASH_GT', 5, "/>");
-
-  static const TokenType COMMENT = const TokenType('COMMENT', 6, null);
-
-  static const TokenType DECLARATION = const TokenType('DECLARATION', 7, null);
-
-  static const TokenType DIRECTIVE = const TokenType('DIRECTIVE', 8, null);
-
-  static const TokenType STRING = const TokenType('STRING', 9, null);
-
-  static const TokenType TAG = const TokenType('TAG', 10, null);
-
-  static const TokenType TEXT = const TokenType('TEXT', 11, null);
-
-  static const List<TokenType> values = const [
-    EOF,
-    EQ,
-    GT,
-    LT_SLASH,
-    LT,
-    SLASH_GT,
-    COMMENT,
-    DECLARATION,
-    DIRECTIVE,
-    STRING,
-    TAG,
-    TEXT
-  ];
-
-  /**
-   * 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(String name, int ordinal, this.lexeme) : super(name, ordinal);
-}
-
-class TokenType_EOF extends TokenType {
-  const TokenType_EOF(String name, int ordinal, String arg0)
-      : super(name, ordinal, arg0);
-
-  @override
-  String toString() => "-eof-";
-}
-
-/**
- * Instances of the class `ToSourceVisitor` write a source representation of a visited XML
- * node (and all of it's children) to a writer.
- */
-class ToSourceVisitor implements XmlVisitor<Object> {
-  /**
-   * The writer to which the source is to be written.
-   */
-  final PrintWriter _writer;
-
-  /**
-   * Initialize a newly created visitor to write source code representing the visited nodes to the
-   * given writer.
-   *
-   * @param writer the writer to which the source is to be written
-   */
-  ToSourceVisitor(this._writer);
-
-  @override
-  Object visitHtmlScriptTagNode(HtmlScriptTagNode node) =>
-      visitXmlTagNode(node);
-
-  @override
-  Object visitHtmlUnit(HtmlUnit node) {
-    for (XmlTagNode child in node.tagNodes) {
-      _visit(child);
-    }
-    return null;
-  }
-
-  @override
-  Object visitXmlAttributeNode(XmlAttributeNode node) {
-    String name = node.name;
-    Token value = node.valueToken;
-    if (name.length == 0) {
-      _writer.print("__");
-    } else {
-      _writer.print(name);
-    }
-    _writer.print("=");
-    if (value == null) {
-      _writer.print("__");
-    } else {
-      _writer.print(value.lexeme);
-    }
-    return null;
-  }
-
-  @override
-  Object visitXmlTagNode(XmlTagNode node) {
-    _writer.print("<");
-    String tagName = node.tag;
-    _writer.print(tagName);
-    for (XmlAttributeNode attribute in node.attributes) {
-      _writer.print(" ");
-      _visit(attribute);
-    }
-    _writer.print(node.attributeEnd.lexeme);
-    if (node.closingTag != null) {
-      for (XmlTagNode child in node.tagNodes) {
-        _visit(child);
-      }
-      _writer.print("</");
-      _writer.print(tagName);
-      _writer.print(">");
-    }
-    return null;
-  }
-
-  /**
-   * Safely visit the given node.
-   *
-   * @param node the node to be visited
-   */
-  void _visit(XmlNode node) {
-    if (node != null) {
-      node.accept(this);
-    }
-  }
-}
-
-/**
- * Instances of `XmlAttributeNode` represent name/value pairs owned by an [XmlTagNode].
- */
-class XmlAttributeNode extends XmlNode {
-  /**
-   * An empty list of XML attribute nodes.
-   */
-  static const List<XmlAttributeNode> EMPTY_LIST = const <XmlAttributeNode>[];
-
-  final Token _name;
-
-  final Token equals;
-
-  final Token _value;
-
-  List<XmlExpression> expressions = XmlExpression.EMPTY_ARRAY;
-
-  /**
-   * Construct a new instance representing an XML attribute.
-   *
-   * @param name the name token (not `null`). This may be a zero length token if the attribute
-   *          is badly formed.
-   * @param equals the equals sign or `null` if none
-   * @param value the value token (not `null`)
-   */
-  XmlAttributeNode(this._name, this.equals, this._value);
-
-  @override
-  Token get beginToken => _name;
-
-  @override
-  Token get endToken => _value;
-
-  /**
-   * Answer the attribute name. This may be a zero length string if the attribute is badly formed.
-   *
-   * @return the name (not `null`)
-   */
-  String get name => _name.lexeme;
-
-  /**
-   * Answer the attribute name token. This may be a zero length token if the attribute is badly
-   * formed.
-   *
-   * @return the name token (not `null`)
-   */
-  Token get nameToken => _name;
-
-  /**
-   * Answer the lexeme for the value token without the leading and trailing quotes.
-   *
-   * @return the text or `null` if the value is not specified
-   */
-  String get text {
-    if (_value == null) {
-      return null;
-    }
-    //TODO (danrubel): replace HTML character encodings with the actual
-    // characters
-    String text = _value.lexeme;
-    int len = text.length;
-    if (len > 0) {
-      if (text.codeUnitAt(0) == 0x22) {
-        if (len > 1 && text.codeUnitAt(len - 1) == 0x22) {
-          return text.substring(1, len - 1);
-        } else {
-          return text.substring(1);
-        }
-      } else if (text.codeUnitAt(0) == 0x27) {
-        if (len > 1 && text.codeUnitAt(len - 1) == 0x27) {
-          return text.substring(1, len - 1);
-        } else {
-          return text.substring(1);
-        }
-      }
-    }
-    return text;
-  }
-
-  /**
-   * Answer the offset of the value after the leading quote.
-   *
-   * @return the offset of the value, or `-1` if the value is not specified
-   */
-  int get textOffset {
-    if (_value == null) {
-      return -1;
-    }
-    String text = _value.lexeme;
-    if (StringUtilities.startsWithChar(text, 0x22) ||
-        StringUtilities.startsWithChar(text, 0x27)) {
-      return _value.offset + 1;
-    }
-    return _value.offset;
-  }
-
-  /**
-   * Answer the attribute value token. A properly formed value will start and end with matching
-   * quote characters, but the value returned may not be properly formed.
-   *
-   * @return the value token or `null` if this represents a badly formed attribute
-   */
-  Token get valueToken => _value;
-
-  @override
-  accept(XmlVisitor visitor) => visitor.visitXmlAttributeNode(this);
-
-  @override
-  void visitChildren(XmlVisitor visitor) {
-    // no children to visit
-  }
-}
-
-/**
- * Instances of the class `XmlExpression` represent an abstract expression embedded into
- * [XmlNode].
- */
-abstract class XmlExpression {
-  /**
-   * An empty list of expressions.
-   */
-  static const List<XmlExpression> EMPTY_ARRAY = const <XmlExpression>[];
-
-  /**
-   * Return the offset of the character immediately following the last character of this
-   * expression's source range. This is equivalent to `getOffset() + getLength()`.
-   *
-   * @return the offset of the character just past the expression's source range
-   */
-  int get end;
-
-  /**
-   * Return the number of characters in the expression's source range.
-   */
-  int get length;
-
-  /**
-   * Return the offset of the first character in the expression's source range.
-   */
-  int get offset;
-
-  /**
-   * Check if the given offset belongs to the expression's source range.
-   */
-  bool contains(int offset) => this.offset <= offset && offset < end;
-
-  /**
-   * Return the [Reference] at the given offset.
-   *
-   * @param offset the offset from the beginning of the file
-   * @return the [Reference] at the given offset, maybe `null`
-   */
-  XmlExpression_Reference getReference(int offset);
-}
-
-/**
- * The reference to the [Element].
- */
-class XmlExpression_Reference {
-  Element element;
-
-  int offset = 0;
-
-  int length = 0;
-
-  XmlExpression_Reference(this.element, this.offset, this.length);
-}
-
-/**
- * The abstract class `XmlNode` defines behavior common to all XML/HTML nodes.
- */
-abstract class XmlNode {
-  /**
-   * The parent of the node, or `null` if the node is the root of an AST structure.
-   */
-  XmlNode _parent;
-
-  /**
-   * The element associated with this node or `null` if the receiver is not resolved.
-   */
-  Element _element;
-
-  /**
-   * Return the first token included in this node's source range.
-   *
-   * @return the first token or `null` if none
-   */
-  Token get beginToken;
-
-  /**
-   * Return the element associated with this node.
-   *
-   * @return the element or `null` if the receiver is not resolved
-   */
-  Element get element => _element;
-
-  /**
-   * Set the element associated with this node.
-   *
-   * @param element the element
-   */
-  void set element(Element element) {
-    this._element = element;
-  }
-
-  /**
-   * Return the offset of the character immediately following the last character of this node's
-   * source range. This is equivalent to `node.getOffset() + node.getLength()`. For an html
-   * unit this will be equal to the length of the unit's source.
-   *
-   * @return the offset of the character just past the node's source range
-   */
-  int get end => offset + length;
-
-  /**
-   * Return the last token included in this node's source range.
-   *
-   * @return the last token or `null` if none
-   */
-  Token get endToken;
-
-  /**
-   * Return the number of characters in the node's source range.
-   *
-   * @return the number of characters in the node's source range
-   */
-  int get length {
-    Token beginToken = this.beginToken;
-    Token endToken = this.endToken;
-    if (beginToken == null || endToken == null) {
-      return -1;
-    }
-    return endToken.offset + endToken.length - beginToken.offset;
-  }
-
-  /**
-   * Return the offset from the beginning of the file to the first character in the node's source
-   * range.
-   *
-   * @return the offset from the beginning of the file to the first character in the node's source
-   *         range
-   */
-  int get offset {
-    Token beginToken = this.beginToken;
-    if (beginToken == null) {
-      return -1;
-    }
-    return this.beginToken.offset;
-  }
-
-  /**
-   * Return this node's parent node, or `null` if this node is the root of an AST structure.
-   *
-   * Note that the relationship between an AST node and its parent node may change over the lifetime
-   * of a node.
-   *
-   * @return the parent of this node, or `null` if none
-   */
-  XmlNode get parent => _parent;
-
-  /**
-   * Set the parent of this node to the given node.
-   *
-   * @param newParent the node that is to be made the parent of this node
-   */
-  void set parent(XmlNode newParent) {
-    XmlNode current = newParent;
-    while (current != null) {
-      if (identical(current, this)) {
-        AnalysisEngine.instance.logger.logError(
-            "Circular structure while setting an XML node's parent",
-            new CaughtException(
-                new ArgumentError(_buildRecursiveStructureMessage(newParent)),
-                null));
-        return;
-      }
-      current = current.parent;
-    }
-    _parent = newParent;
-  }
-
-  /**
-   * Use the given visitor to visit this node.
-   *
-   * @param visitor the visitor that will visit this node
-   * @return the value returned by the visitor as a result of visiting this node
-   */
-  accept(XmlVisitor visitor);
-
-  /**
-   * Make this node the parent of the given child node.
-   *
-   * @param child the node that will become a child of this node
-   * @return the node that was made a child of this node
-   */
-  XmlNode becomeParentOf(XmlNode child) {
-    if (child != null) {
-      XmlNode node = child;
-      node.parent = this;
-    }
-    return child;
-  }
-
-  /**
-   * Make this node the parent of the given child nodes.
-   *
-   * @param children the nodes that will become the children of this node
-   * @param ifEmpty the (empty) nodes to return if "children" is empty
-   * @return the nodes that were made children of this node
-   */
-  List becomeParentOfAll(List children, {List ifEmpty}) {
-    if (children == null || children.isEmpty) {
-      if (ifEmpty != null) {
-        return ifEmpty;
-      }
-    }
-    if (children != null) {
-      children.forEach((XmlNode node) {
-        node.parent = this;
-      });
-    }
-    return children;
-  }
-
-  @override
-  String toString() {
-    PrintStringWriter writer = new PrintStringWriter();
-    accept(new ToSourceVisitor(writer));
-    return writer.toString();
-  }
-
-  /**
-   * Use the given visitor to visit all of the children of this node. The children will be visited
-   * in source order.
-   *
-   * @param visitor the visitor that will be used to visit the children of this node
-   */
-  void visitChildren(XmlVisitor visitor);
-
-  /**
-   * This method exists for debugging purposes only.
-   */
-  void _appendIdentifier(StringBuffer buffer, XmlNode node) {
-    if (node is XmlTagNode) {
-      buffer.write(node.tag);
-    } else if (node is XmlAttributeNode) {
-      buffer.write(node.name);
-    } else {
-      buffer.write("htmlUnit");
-    }
-  }
-
-  /**
-   * This method exists for debugging purposes only.
-   */
-  String _buildRecursiveStructureMessage(XmlNode newParent) {
-    StringBuffer buffer = new StringBuffer();
-    buffer.write("Attempt to create recursive structure: ");
-    XmlNode current = newParent;
-    while (current != null) {
-      if (!identical(current, newParent)) {
-        buffer.write(" -> ");
-      }
-      if (identical(current, this)) {
-        buffer.writeCharCode(0x2A);
-        _appendIdentifier(buffer, current);
-        buffer.writeCharCode(0x2A);
-      } else {
-        _appendIdentifier(buffer, current);
-      }
-      current = current.parent;
-    }
-    return buffer.toString();
-  }
-}
-
-/**
- * Instances of the class `XmlParser` are used to parse tokens into a AST structure comprised
- * of [XmlNode]s.
- */
-class XmlParser {
-  /**
-   * The source being parsed.
-   */
-  final Source source;
-
-  /**
-   * The next token to be parsed.
-   */
-  Token _currentToken;
-
-  /**
-   * Construct a parser for the specified source.
-   *
-   * @param source the source being parsed
-   */
-  XmlParser(this.source);
-
-  /**
-   * Answer the current token.
-   *
-   * @return the current token
-   */
-  Token get currentToken => _currentToken;
-
-  /**
-   * Create a node representing an attribute.
-   *
-   * @param name the name of the attribute
-   * @param equals the equals sign, or `null` if there is no value
-   * @param value the value of the attribute
-   * @return the node that was created
-   */
-  XmlAttributeNode createAttributeNode(Token name, Token equals, Token value) =>
-      new XmlAttributeNode(name, equals, value);
-
-  /**
-   * Create a node representing a tag.
-   *
-   * @param nodeStart the token marking the beginning of the tag
-   * @param tag the name of the tag
-   * @param attributes the attributes in the tag
-   * @param attributeEnd the token terminating the region where attributes can be
-   * @param tagNodes the children of the tag
-   * @param contentEnd the token that starts the closing tag
-   * @param closingTag the name of the tag that occurs in the closing tag
-   * @param nodeEnd the last token in the tag
-   * @return the node that was created
-   */
-  XmlTagNode createTagNode(
-          Token nodeStart,
-          Token tag,
-          List<XmlAttributeNode> attributes,
-          Token attributeEnd,
-          List<XmlTagNode> tagNodes,
-          Token contentEnd,
-          Token closingTag,
-          Token nodeEnd) =>
-      new XmlTagNode(nodeStart, tag, attributes, attributeEnd, tagNodes,
-          contentEnd, closingTag, nodeEnd);
-
-  /**
-   * Answer `true` if the specified tag is self closing and thus should never have content or
-   * child tag nodes.
-   *
-   * @param tag the tag (not `null`)
-   * @return `true` if self closing
-   */
-  bool isSelfClosing(Token tag) => false;
-
-  /**
-   * Parse the entire token stream and in the process, advance the current token to the end of the
-   * token stream.
-   *
-   * @return the list of tag nodes found (not `null`, contains no `null`)
-   */
-  List<XmlTagNode> parseTopTagNodes(Token firstToken) {
-    _currentToken = firstToken;
-    List<XmlTagNode> tagNodes = new List<XmlTagNode>();
-    TokenType type = _currentToken.type;
-    while (type != TokenType.EOF) {
-      if (type == TokenType.LT) {
-        tagNodes.add(_parseTagNode());
-      } else if (type == TokenType.DECLARATION ||
-          type == TokenType.DIRECTIVE ||
-          type == TokenType.COMMENT) {
-        // ignored tokens
-        _currentToken = _currentToken.next;
-      } else {
-        _reportUnexpectedToken();
-        _currentToken = _currentToken.next;
-      }
-      type = _currentToken.type;
-    }
-    return tagNodes;
-  }
-
-  /**
-   * Insert a synthetic token of the specified type before the current token
-   *
-   * @param type the type of token to be inserted (not `null`)
-   * @return the synthetic token that was inserted (not `null`)
-   */
-  Token _insertSyntheticToken(TokenType type) {
-    Token token = new Token.con2(type, _currentToken.offset, "");
-    _currentToken.previous.setNext(token);
-    token.setNext(_currentToken);
-    return token;
-  }
-
-  /**
-   * Parse the token stream for an attribute. This method advances the current token over the
-   * attribute, but should not be called if the [currentToken] is not [TokenType.TAG].
-   *
-   * @return the attribute (not `null`)
-   */
-  XmlAttributeNode _parseAttribute() {
-    // Assume the current token is a tag
-    Token name = _currentToken;
-    _currentToken = _currentToken.next;
-    // Equals sign
-    Token equals;
-    if (_currentToken.type == TokenType.EQ) {
-      equals = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      equals = _insertSyntheticToken(TokenType.EQ);
-    }
-    // String value
-    Token value;
-    if (_currentToken.type == TokenType.STRING) {
-      value = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      value = _insertSyntheticToken(TokenType.STRING);
-    }
-    return createAttributeNode(name, equals, value);
-  }
-
-  /**
-   * Parse the stream for a sequence of attributes. This method advances the current token to the
-   * next [TokenType.GT], [TokenType.SLASH_GT], or [TokenType.EOF].
-   *
-   * @return a collection of zero or more attributes (not `null`, contains no `null`s)
-   */
-  List<XmlAttributeNode> _parseAttributes() {
-    TokenType type = _currentToken.type;
-    if (type == TokenType.GT ||
-        type == TokenType.SLASH_GT ||
-        type == TokenType.EOF) {
-      return XmlTagNode.NO_ATTRIBUTES;
-    }
-    List<XmlAttributeNode> attributes = new List<XmlAttributeNode>();
-    while (type != TokenType.GT &&
-        type != TokenType.SLASH_GT &&
-        type != TokenType.EOF) {
-      if (type == TokenType.TAG) {
-        attributes.add(_parseAttribute());
-      } else {
-        _reportUnexpectedToken();
-        _currentToken = _currentToken.next;
-      }
-      type = _currentToken.type;
-    }
-    return attributes;
-  }
-
-  /**
-   * Parse the stream for a sequence of tag nodes existing within a parent tag node. This method
-   * advances the current token to the next [TokenType.LT_SLASH] or [TokenType.EOF].
-   *
-   * @return a list of nodes (not `null`, contains no `null`s)
-   */
-  List<XmlTagNode> _parseChildTagNodes() {
-    TokenType type = _currentToken.type;
-    if (type == TokenType.LT_SLASH || type == TokenType.EOF) {
-      return XmlTagNode.NO_TAG_NODES;
-    }
-    List<XmlTagNode> nodes = new List<XmlTagNode>();
-    while (type != TokenType.LT_SLASH && type != TokenType.EOF) {
-      if (type == TokenType.LT) {
-        nodes.add(_parseTagNode());
-      } else if (type == TokenType.COMMENT) {
-        // ignored token
-        _currentToken = _currentToken.next;
-      } else {
-        _reportUnexpectedToken();
-        _currentToken = _currentToken.next;
-      }
-      type = _currentToken.type;
-    }
-    return nodes;
-  }
-
-  /**
-   * Parse the token stream for the next tag node. This method advances current token over the
-   * parsed tag node, but should only be called if the current token is [TokenType.LT]
-   *
-   * @return the tag node or `null` if none found
-   */
-  XmlTagNode _parseTagNode() {
-    // Assume that the current node is a tag node start TokenType.LT
-    Token nodeStart = _currentToken;
-    _currentToken = _currentToken.next;
-    // Get the tag or create a synthetic tag and report an error
-    Token tag;
-    if (_currentToken.type == TokenType.TAG) {
-      tag = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      tag = _insertSyntheticToken(TokenType.TAG);
-    }
-    // Parse the attributes
-    List<XmlAttributeNode> attributes = _parseAttributes();
-    // Token ending attribute list
-    Token attributeEnd;
-    if (_currentToken.type == TokenType.GT ||
-        _currentToken.type == TokenType.SLASH_GT) {
-      attributeEnd = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      attributeEnd = _insertSyntheticToken(TokenType.SLASH_GT);
-    }
-    // If the node has no children, then return the node
-    if (attributeEnd.type == TokenType.SLASH_GT || isSelfClosing(tag)) {
-      return createTagNode(nodeStart, tag, attributes, attributeEnd,
-          XmlTagNode.NO_TAG_NODES, _currentToken, null, attributeEnd);
-    }
-    // Parse the child tag nodes
-    List<XmlTagNode> tagNodes = _parseChildTagNodes();
-    // Token ending child tag nodes
-    Token contentEnd;
-    if (_currentToken.type == TokenType.LT_SLASH) {
-      contentEnd = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      // TODO (danrubel): handle self closing HTML elements by inserting
-      // synthetic tokens but not reporting an error
-      _reportUnexpectedToken();
-      contentEnd = _insertSyntheticToken(TokenType.LT_SLASH);
-    }
-    // Closing tag
-    Token closingTag;
-    if (_currentToken.type == TokenType.TAG) {
-      closingTag = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      closingTag = _insertSyntheticToken(TokenType.TAG);
-    }
-    // Token ending node
-    Token nodeEnd;
-    if (_currentToken.type == TokenType.GT) {
-      nodeEnd = _currentToken;
-      _currentToken = _currentToken.next;
-    } else {
-      _reportUnexpectedToken();
-      nodeEnd = _insertSyntheticToken(TokenType.GT);
-    }
-    return createTagNode(nodeStart, tag, attributes, attributeEnd, tagNodes,
-        contentEnd, closingTag, nodeEnd);
-  }
-
-  /**
-   * Report the current token as unexpected
-   */
-  void _reportUnexpectedToken() {
-    // TODO (danrubel): report unexpected token
-  }
-}
-
-/**
- * Instances of `XmlTagNode` represent XML or HTML elements such as `` and
- * `<body foo="bar"> ... </body>`.
- */
-class XmlTagNode extends XmlNode {
-  /**
-   * Constant representing empty list of attributes.
-   */
-  static List<XmlAttributeNode> NO_ATTRIBUTES =
-      new UnmodifiableListView(new List<XmlAttributeNode>());
-
-  /**
-   * Constant representing empty list of tag nodes.
-   */
-  static List<XmlTagNode> NO_TAG_NODES =
-      new UnmodifiableListView(new List<XmlTagNode>());
-
-  /**
-   * The starting [TokenType.LT] token (not `null`).
-   */
-  final Token nodeStart;
-
-  /**
-   * The [TokenType.TAG] token after the starting '&lt;' (not `null`).
-   */
-  final Token _tag;
-
-  /**
-   * The attributes contained by the receiver (not `null`, contains no `null`s).
-   */
-  List<XmlAttributeNode> _attributes;
-
-  /**
-   * The [TokenType.GT] or [TokenType.SLASH_GT] token after the attributes (not
-   * `null`). The token may be the same token as [nodeEnd] if there are no child
-   * [tagNodes].
-   */
-  final Token attributeEnd;
-
-  /**
-   * The tag nodes contained in the receiver (not `null`, contains no `null`s).
-   */
-  List<XmlTagNode> _tagNodes;
-
-  /**
-   * The token (not `null`) after the content, which may be
-   * * (1) [TokenType.LT_SLASH] for nodes with open and close tags, or
-   * * (2) the [TokenType.LT] nodeStart of the next sibling node if this node is self
-   * closing or the attributeEnd is [TokenType.SLASH_GT], or
-   * * (3) [TokenType.EOF] if the node does not have a closing tag and is the last node in
-   * the stream [TokenType.LT_SLASH] token after the content, or `null` if there is no
-   * content and the attributes ended with [TokenType.SLASH_GT].
-   */
-  final Token contentEnd;
-
-  /**
-   * The closing [TokenType.TAG] after the child elements or `null` if there is no
-   * content and the attributes ended with [TokenType.SLASH_GT]
-   */
-  final Token closingTag;
-
-  /**
-   * The ending [TokenType.GT] or [TokenType.SLASH_GT] token (not `null`).
-   */
-  final Token nodeEnd;
-
-  /**
-   * The expressions that are embedded in the tag's content.
-   */
-  List<XmlExpression> expressions = XmlExpression.EMPTY_ARRAY;
-
-  /**
-   * Construct a new instance representing an XML or HTML element
-   *
-   * @param nodeStart the starting [TokenType.LT] token (not `null`)
-   * @param tag the [TokenType.TAG] token after the starting '&lt;' (not `null`).
-   * @param attributes the attributes associated with this element or [NO_ATTRIBUTES] (not
-   *          `null`, contains no `null`s)
-   * @param attributeEnd The [TokenType.GT] or [TokenType.SLASH_GT] token after the
-   *          attributes (not `null`). The token may be the same token as [nodeEnd] if
-   *          there are no child [tagNodes].
-   * @param tagNodes child tag nodes of the receiver or [NO_TAG_NODES] (not `null`,
-   *          contains no `null`s)
-   * @param contentEnd the token (not `null`) after the content, which may be
-   *          * (1) [TokenType.LT_SLASH] for nodes with open and close tags, or
-   *          * (2) the [TokenType.LT] nodeStart of the next sibling node if this node is
-   *          self closing or the attributeEnd is [TokenType.SLASH_GT], or
-   *          * (3) [TokenType.EOF] if the node does not have a closing tag and is the last
-   *          node in the stream [TokenType.LT_SLASH] token after the content, or `null`
-   *          if there is no content and the attributes ended with [TokenType.SLASH_GT].
-   * @param closingTag the closing [TokenType.TAG] after the child elements or `null` if
-   *          there is no content and the attributes ended with [TokenType.SLASH_GT]
-   * @param nodeEnd the ending [TokenType.GT] or [TokenType.SLASH_GT] token (not
-   *          `null`)
-   */
-  XmlTagNode(
-      this.nodeStart,
-      this._tag,
-      List<XmlAttributeNode> attributes,
-      this.attributeEnd,
-      List<XmlTagNode> tagNodes,
-      this.contentEnd,
-      this.closingTag,
-      this.nodeEnd) {
-    this._attributes = becomeParentOfAll(attributes, ifEmpty: NO_ATTRIBUTES);
-    this._tagNodes = becomeParentOfAll(tagNodes, ifEmpty: NO_TAG_NODES);
-  }
-
-  /**
-   * Answer the receiver's attributes. Callers should not manipulate the returned list to edit the
-   * AST structure.
-   *
-   * @return the attributes (not `null`, contains no `null`s)
-   */
-  List<XmlAttributeNode> get attributes => _attributes;
-
-  @override
-  Token get beginToken => nodeStart;
-
-  /**
-   * Return a string representing the content contained in the receiver. This
-   * includes the textual representation of any child tag nodes ([getTagNodes]).
-   * Whitespace between '&lt;', '&lt;/', and '>', '/>' is discarded, but all
-   * other whitespace is preserved.
-   */
-  String get content {
-    Token token = attributeEnd.next;
-    if (identical(token, contentEnd)) {
-      return "";
-    }
-    // TODO(danrubel) Handle CDATA and replace HTML character encodings with
-    // the actual characters.
-    String content = token.lexeme;
-    token = token.next;
-    if (identical(token, contentEnd)) {
-      return content;
-    }
-    StringBuffer buffer = new StringBuffer();
-    buffer.write(content);
-    while (!identical(token, contentEnd)) {
-      buffer.write(token.lexeme);
-      token = token.next;
-    }
-    return buffer.toString();
-  }
-
-  @override
-  Token get endToken {
-    if (nodeEnd != null) {
-      return nodeEnd;
-    }
-    if (closingTag != null) {
-      return closingTag;
-    }
-    if (contentEnd != null) {
-      return contentEnd;
-    }
-    if (!_tagNodes.isEmpty) {
-      return _tagNodes[_tagNodes.length - 1].endToken;
-    }
-    if (attributeEnd != null) {
-      return attributeEnd;
-    }
-    if (!_attributes.isEmpty) {
-      return _attributes[_attributes.length - 1].endToken;
-    }
-    return _tag;
-  }
-
-  /**
-   * Answer the tag name after the starting '&lt;'.
-   *
-   * @return the tag name (not `null`)
-   */
-  String get tag => _tag.lexeme;
-
-  /**
-   * Answer the tag nodes contained in the receiver. Callers should not manipulate the returned list
-   * to edit the AST structure.
-   *
-   * @return the children (not `null`, contains no `null`s)
-   */
-  List<XmlTagNode> get tagNodes => _tagNodes;
-
-  /**
-   * Answer the [TokenType.TAG] token after the starting '&lt;'.
-   *
-   * @return the token (not `null`)
-   */
-  Token get tagToken => _tag;
-
-  @override
-  accept(XmlVisitor visitor) => visitor.visitXmlTagNode(this);
-
-  /**
-   * Answer the attribute with the specified name.
-   *
-   * @param name the attribute name
-   * @return the attribute or `null` if no matching attribute is found
-   */
-  XmlAttributeNode getAttribute(String name) {
-    for (XmlAttributeNode attribute in _attributes) {
-      if (attribute.name == name) {
-        return attribute;
-      }
-    }
-    return null;
-  }
-
-  /**
-   * Find the attribute with the given name (see [getAttribute] and answer the lexeme
-   * for the attribute's value token without the leading and trailing quotes (see
-   * [XmlAttributeNode.getText]).
-   *
-   * @param name the attribute name
-   * @return the attribute text or `null` if no matching attribute is found
-   */
-  String getAttributeText(String name) {
-    XmlAttributeNode attribute = getAttribute(name);
-    return attribute != null ? attribute.text : null;
-  }
-
-  @override
-  void visitChildren(XmlVisitor visitor) {
-    for (XmlAttributeNode node in _attributes) {
-      node.accept(visitor);
-    }
-    for (XmlTagNode node in _tagNodes) {
-      node.accept(visitor);
-    }
-  }
-}
-
-/**
- * The interface `XmlVisitor` defines the behavior of objects that can be used to visit an
- * [XmlNode] structure.
- */
-abstract class XmlVisitor<R> {
-  R visitHtmlScriptTagNode(HtmlScriptTagNode node);
-
-  R visitHtmlUnit(HtmlUnit htmlUnit);
-
-  R visitXmlAttributeNode(XmlAttributeNode xmlAttributeNode);
-
-  R visitXmlTagNode(XmlTagNode xmlTagNode);
-}