New analyzer snapshot. Sorted unit members.

pkg/analyzer/lib/src/generated/html.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.html;
 
 import 'dart:collection';
 import 'java_core.dart';
 import 'java_engine.dart';
 import 'source.dart';
 import 'error.dart' show AnalysisErrorListener;
 import 'scanner.dart' as sc show Scanner, SubSequenceReader, Token;
 import 'parser.dart' show Parser;
 import 'ast.dart';
 import 'element.dart';
 import 'engine.dart' show AnalysisEngine, AngularHtmlUnitResolver, ExpressionVisitor;
 
 /**
- * Instances of the class `XmlExpression` represent an abstract expression embedded into
- * [XmlNode].
- */
-abstract class XmlExpression {
-  /**
-   * An empty array of expressions.
-   */
-  static List<XmlExpression> EMPTY_ARRAY = new List<XmlExpression>(0);
-
-  /**
-   * Check if the given offset belongs to the expression's source range.
-   */
-  bool contains(int offset) => this.offset <= offset && offset < end;
-
-  /**
-   * 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;
-
-  /**
-   * 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(Element element, int offset, int length) {
-    this.element = element;
-    this.offset = offset;
-    this.length = length;
-  }
-}
-
-/**
- * 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;
-}
-
-/**
  * 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;
@@ skipping 298 matching lines @@
         _emitWithOffsetAndLength(TokenType.TAG, start, -1);
       } else {
         // a non-char token
         _emitWithOffsetAndLength(TokenType.TEXT, start, 0);
         c = advance();
       }
     }
   }
 }
 
+class ExpressionVisitor_HtmlUnitUtils_getExpression extends ExpressionVisitor {
+  int offset = 0;
+
+  List<Expression> result;
+
+  ExpressionVisitor_HtmlUnitUtils_getExpression(this.offset, this.result) : super();
+
+  @override
+  void visitExpression(Expression expression) {
+    Expression at = HtmlUnitUtils._getExpressionAt(expression, offset);
+    if (at != null) {
+      result[0] = at;
+      throw new HtmlUnitUtils_FoundExpressionError();
+    }
+  }
+}
+
 /**
- * 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.
+ * Instances of the class `HtmlParser` are used to parse tokens into a AST structure comprised
+ * of [XmlNode]s.
  */
-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 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;
-
-  /**
-   * 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;
-
-  /**
-   * 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;
+class HtmlParser extends XmlParser {
+  /**
+   * The line information associated with the source being parsed.
+   */
+  LineInfo _lineInfo;
+
+  /**
+   * The error listener to which errors will be reported.
+   */
+  final AnalysisErrorListener _errorListener;
+
+  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 Set<String>.from(JavaArrays.asList(<String> [
+      "area",
+      "base",
+      "basefont",
+      "br",
+      "col",
+      "frame",
+      "hr",
+      "img",
+      "input",
+      "link",
+      "meta",
+      "param",
+      "!"]));
+
+  /**
+   * 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();
+  }
+
+  /**
+   * Construct a parser for the specified source.
+   *
+   * @param source the source being parsed
+   * @param errorListener the error listener to which errors will be reported
+   */
+  HtmlParser(Source source, this._errorListener) : super(source);
+
+  /**
+   * 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);
+  }
+
+  @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);
+
+  /**
+   * 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;
+  }
 }
 
 /**
- * Instances of `XmlTagNode` represent XML or HTML elements such as `` and
- * `<body foo="bar"> ... </body>`.
+ * Instances of the class `HtmlScriptTagNode` represent a script tag within an HTML file that
+ * references a Dart script.
  */
-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;
+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);
+
+  @override
+  accept(XmlVisitor visitor) => visitor.visitHtmlScriptTagNode(this);
+
+  /**
+   * 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;
+  }
+}
+
+/**
+ * Instances of the class `HtmlUnit` represent the contents of an HTML file.
+ */
+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;
 
   /**
-   * 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);
-  }
-
-  @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;
-  }
-
-  /**
-   * 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;
-
-  /**
-   * 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
-  Token get beginToken => nodeStart;
-
-  /**
-   * Answer 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.
-   *
-   * @return the content (not `null`)
-   */
-  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;
-    }
-    JavaStringBuilder buffer = new JavaStringBuilder();
-    while (!identical(token, contentEnd)) {
-      buffer.append(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;
+   * 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);
+  }
+
+  @override
+  accept(XmlVisitor visitor) => visitor.visitHtmlUnit(this);
+
+  /**
+   * 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;
 
   /**
    * 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
+  void set element(Element element) {
+    if (element != null && element is! HtmlElement) {
+      throw new IllegalArgumentException("HtmlElement expected, but ${element.runtimeType} given");
+    }
+    super.element = element;
+  }
 
   @override
   void visitChildren(XmlVisitor visitor) {
-    for (XmlAttributeNode node in _attributes) {
-      node.accept(visitor);
-    }
     for (XmlTagNode node in _tagNodes) {
       node.accept(visitor);
     }
   }
 }
 
 /**
- * Instances of the class `XmlParser` are used to parse tokens into a AST structure comprised
- * of [XmlNode]s.
+ * Utilities locating [Expression]s and [Element]s in [HtmlUnit].
  */
-class XmlParser {
+class HtmlUnitUtils {
   /**
-   * The source being parsed.
+   * Returns the [XmlAttributeNode] that is part of the given [HtmlUnit] and encloses
+   * the given offset.
    */
-  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);
-
-  /**
-   * 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;
+  static XmlAttributeNode getAttributeNode(HtmlUnit htmlUnit, int offset) {
+    if (htmlUnit == null) {
+      return null;
     }
-    return tagNodes;
+    List<XmlAttributeNode> result = [null];
+    try {
+      htmlUnit.accept(new RecursiveXmlVisitor_HtmlUnitUtils_getAttributeNode(offset, result));
+    } on HtmlUnitUtils_FoundAttributeNodeError catch (e) {
+      return result[0];
+    }
+    return null;
   }
 
   /**
-   * Answer the current token.
-   *
-   * @return the current token
+   * Returns the best [Element] of the given [Expression].
    */
-  Token get currentToken => _currentToken;
-
-  /**
-   * 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;
+  static Element getElement(Expression expression) {
+    if (expression == null) {
+      return null;
+    }
+    return ElementLocator.locate(expression);
   }
 
   /**
-   * 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`)
+   * Returns the [Element] of the [Expression] in the given [HtmlUnit], enclosing
+   * the given offset.
    */
-  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);
+  static Element getElementAtOffset(HtmlUnit htmlUnit, int offset) {
+    Expression expression = getExpression(htmlUnit, offset);
+    return getElement(expression);
   }
 
   /**
-   * 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)
+   * Returns the [Element] to open when requested at the given [Expression].
    */
-  List<XmlAttributeNode> _parseAttributes() {
-    TokenType type = _currentToken.type;
-    if (type == TokenType.GT || type == TokenType.SLASH_GT || type == TokenType.EOF) {
-      return XmlTagNode.NO_ATTRIBUTES;
+  static Element getElementToOpen(HtmlUnit htmlUnit, Expression expression) {
+    Element element = getElement(expression);
+    {
+      AngularElement angularElement = AngularHtmlUnitResolver.getAngularElement(element);
+      if (angularElement != null) {
+        return angularElement;
+      }
     }
-    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;
+    return element;
   }
 
   /**
-   * 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)
+   * Returns the [XmlTagNode] that is part of the given [HtmlUnit] and encloses the
+   * given offset.
    */
-  List<XmlTagNode> _parseChildTagNodes() {
-    TokenType type = _currentToken.type;
-    if (type == TokenType.LT_SLASH || type == TokenType.EOF) {
-      return XmlTagNode.NO_TAG_NODES;
+  static XmlTagNode getEnclosingTagNode(HtmlUnit htmlUnit, int offset) {
+    if (htmlUnit == null) {
+      return null;
     }
-    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;
+    List<XmlTagNode> result = [null];
+    try {
+      htmlUnit.accept(new RecursiveXmlVisitor_HtmlUnitUtils_getEnclosingTagNode(offset, result));
+    } on HtmlUnitUtils_FoundTagNodeError catch (e) {
+      return result[0];
     }
-    return nodes;
+    return null;
   }
 
   /**
-   * 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
+   * Returns the [Expression] that is part of the given [HtmlUnit] and encloses the
+   * given offset.
    */
-  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);
+  static Expression getExpression(HtmlUnit htmlUnit, int offset) {
+    if (htmlUnit == null) {
+      return null;
     }
-    // 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);
+    List<Expression> result = [null];
+    try {
+      // TODO(scheglov) this code is very Angular specific
+      htmlUnit.accept(new ExpressionVisitor_HtmlUnitUtils_getExpression(offset, result));
+    } on HtmlUnitUtils_FoundExpressionError catch (e) {
+      return result[0];
     }
-    // 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);
+    return null;
   }
 
   /**
-   * Report the current token as unexpected
+   * Returns the [XmlTagNode] that is part of the given [HtmlUnit] and its open or
+   * closing tag name encloses the given offset.
    */
-  void _reportUnexpectedToken() {
+  static XmlTagNode getTagNode(HtmlUnit htmlUnit, int offset) {
+    XmlTagNode node = getEnclosingTagNode(htmlUnit, offset);
+    // do we have an enclosing tag at all?
+    if (node == null) {
+      return null;
+    }
+    // is "offset" in the open tag?
+    Token openTag = node.tagToken;
+    if (openTag.offset <= offset && offset <= openTag.end) {
+      return node;
+    }
+    // is "offset" in the open tag?
+    Token closeTag = node.closingTag;
+    if (closeTag != null && closeTag.offset <= offset && offset <= closeTag.end) {
+      return node;
+    }
+    // not on a tag name
+    return null;
+  }
+
+  /**
+   * Returns the [Expression] that is part of the given root [AstNode] and encloses the
+   * given offset.
+   */
+  static Expression _getExpressionAt(AstNode root, int offset) {
+    if (root.offset <= offset && offset <= root.end) {
+      AstNode dartNode = new NodeLocator.con1(offset).searchWithin(root);
+      if (dartNode is Expression) {
+        return dartNode;
+      }
+    }
+    return null;
   }
 }
 
-/**
- * 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;
+class HtmlUnitUtils_FoundAttributeNodeError extends Error {
+}
 
-  /**
-   * The element associated with this node or `null` if the receiver is not resolved.
-   */
-  Element _element;
+class HtmlUnitUtils_FoundExpressionError extends Error {
+}
 
-  /**
-   * 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);
-
-  /**
-   * 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;
-
-  /**
-   * 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 element associated with this node.
-   *
-   * @param element the element
-   */
-  void set element(Element element) {
-    this._element = element;
-  }
-
-  @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);
-
-  /**
-   * 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) {
-      for (JavaIterator iter = new JavaIterator(children); iter.hasNext;) {
-        XmlNode node = iter.next();
-        node.parent = this;
-      }
-      // This will create ArrayList for exactly given number of elements.
-      return new List.from(children);
-    }
-    return children;
-  }
-
-  /**
-   * This method exists for debugging purposes only.
-   */
-  void _appendIdentifier(JavaStringBuilder builder, XmlNode node) {
-    if (node is XmlTagNode) {
-      builder.append(node.tag);
-    } else if (node is XmlAttributeNode) {
-      builder.append(node.name);
-    } else {
-      builder.append("htmlUnit");
-    }
-  }
-
-  /**
-   * This method exists for debugging purposes only.
-   */
-  String _buildRecursiveStructureMessage(XmlNode newParent) {
-    JavaStringBuilder builder = new JavaStringBuilder();
-    builder.append("Attempt to create recursive structure: ");
-    XmlNode current = newParent;
-    while (current != null) {
-      if (!identical(current, newParent)) {
-        builder.append(" -> ");
-      }
-      if (identical(current, this)) {
-        builder.appendChar(0x2A);
-        _appendIdentifier(builder, current);
-        builder.appendChar(0x2A);
-      } else {
-        _appendIdentifier(builder, current);
-      }
-      current = current.parent;
-    }
-    return builder.toString();
-  }
-
-  /**
-   * 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.logError2("Circular structure while setting an XML node's parent", new IllegalArgumentException(_buildRecursiveStructureMessage(newParent)));
-        return;
-      }
-      current = current.parent;
-    }
-    _parent = newParent;
-  }
+class HtmlUnitUtils_FoundTagNodeError extends Error {
 }
 
 /**
  * Implementation of [XmlExpression] for an [Expression] embedded without any wrapping
  * characters.
  */
 class RawXmlExpression extends XmlExpression {
   final Expression expression;
 
   RawXmlExpression(this.expression);
@@ skipping 12 matching lines @@
     AstNode node = new NodeLocator.con1(offset).searchWithin(expression);
     if (node != null) {
       Element element = ElementLocator.locate(node);
       return new XmlExpression_Reference(element, node.offset, node.length);
     }
     return null;
   }
 }
 
 /**
- * Utilities locating [Expression]s and [Element]s in [HtmlUnit].
+ * 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 HtmlUnitUtils {
-  /**
-   * Returns the [XmlAttributeNode] that is part of the given [HtmlUnit] and encloses
-   * the given offset.
-   */
-  static XmlAttributeNode getAttributeNode(HtmlUnit htmlUnit, int offset) {
-    if (htmlUnit == null) {
-      return null;
-    }
-    List<XmlAttributeNode> result = [null];
-    try {
-      htmlUnit.accept(new RecursiveXmlVisitor_HtmlUnitUtils_getAttributeNode(offset, result));
-    } on HtmlUnitUtils_FoundAttributeNodeError catch (e) {
-      return result[0];
-    }
+class RecursiveXmlVisitor<R> implements XmlVisitor<R> {
+  @override
+  R visitHtmlScriptTagNode(HtmlScriptTagNode node) {
+    node.visitChildren(this);
     return null;
   }
 
-  /**
-   * Returns the best [Element] of the given [Expression].
-   */
-  static Element getElement(Expression expression) {
-    if (expression == null) {
-      return null;
-    }
-    return ElementLocator.locate(expression);
-  }
-
-  /**
-   * Returns the [Element] of the [Expression] in the given [HtmlUnit], enclosing
-   * the given offset.
-   */
-  static Element getElementAtOffset(HtmlUnit htmlUnit, int offset) {
-    Expression expression = getExpression(htmlUnit, offset);
-    return getElement(expression);
-  }
-
-  /**
-   * Returns the [Element] to open when requested at the given [Expression].
-   */
-  static Element getElementToOpen(HtmlUnit htmlUnit, Expression expression) {
-    Element element = getElement(expression);
-    {
-      AngularElement angularElement = AngularHtmlUnitResolver.getAngularElement(element);
-      if (angularElement != null) {
-        return angularElement;
-      }
-    }
-    return element;
-  }
-
-  /**
-   * Returns the [XmlTagNode] that is part of the given [HtmlUnit] and encloses the
-   * given offset.
-   */
-  static XmlTagNode getEnclosingTagNode(HtmlUnit htmlUnit, int offset) {
-    if (htmlUnit == null) {
-      return null;
-    }
-    List<XmlTagNode> result = [null];
-    try {
-      htmlUnit.accept(new RecursiveXmlVisitor_HtmlUnitUtils_getEnclosingTagNode(offset, result));
-    } on HtmlUnitUtils_FoundTagNodeError catch (e) {
-      return result[0];
-    }
+  @override
+  R visitHtmlUnit(HtmlUnit node) {
+    node.visitChildren(this);
     return null;
   }
 
-  /**
-   * Returns the [Expression] that is part of the given [HtmlUnit] and encloses the
-   * given offset.
-   */
-  static Expression getExpression(HtmlUnit htmlUnit, int offset) {
-    if (htmlUnit == null) {
-      return null;
-    }
-    List<Expression> result = [null];
-    try {
-      // TODO(scheglov) this code is very Angular specific
-      htmlUnit.accept(new ExpressionVisitor_HtmlUnitUtils_getExpression(offset, result));
-    } on HtmlUnitUtils_FoundExpressionError catch (e) {
-      return result[0];
-    }
+  @override
+  R visitXmlAttributeNode(XmlAttributeNode node) {
+    node.visitChildren(this);
     return null;
   }
 
-  /**
-   * Returns the [XmlTagNode] that is part of the given [HtmlUnit] and its open or
-   * closing tag name encloses the given offset.
-   */
-  static XmlTagNode getTagNode(HtmlUnit htmlUnit, int offset) {
-    XmlTagNode node = getEnclosingTagNode(htmlUnit, offset);
-    // do we have an enclosing tag at all?
-    if (node == null) {
-      return null;
-    }
-    // is "offset" in the open tag?
-    Token openTag = node.tagToken;
-    if (openTag.offset <= offset && offset <= openTag.end) {
-      return node;
-    }
-    // is "offset" in the open tag?
-    Token closeTag = node.closingTag;
-    if (closeTag != null && closeTag.offset <= offset && offset <= closeTag.end) {
-      return node;
-    }
-    // not on a tag name
+  @override
+  R visitXmlTagNode(XmlTagNode node) {
+    node.visitChildren(this);
     return null;
   }
-
-  /**
-   * Returns the [Expression] that is part of the given root [AstNode] and encloses the
-   * given offset.
-   */
-  static Expression _getExpressionAt(AstNode root, int offset) {
-    if (root.offset <= offset && offset <= root.end) {
-      AstNode dartNode = new NodeLocator.con1(offset).searchWithin(root);
-      if (dartNode is Expression) {
-        return dartNode;
-      }
-    }
-    return null;
-  }
-}
-
-class HtmlUnitUtils_FoundAttributeNodeError extends Error {
-}
-
-class HtmlUnitUtils_FoundExpressionError extends Error {
-}
-
-class HtmlUnitUtils_FoundTagNodeError extends Error {
 }
 
 class RecursiveXmlVisitor_HtmlUnitUtils_getAttributeNode extends RecursiveXmlVisitor<Object> {
   int offset = 0;
 
   List<XmlAttributeNode> result;
 
   RecursiveXmlVisitor_HtmlUnitUtils_getAttributeNode(this.offset, this.result) : super();
 
   @override
@@ skipping 18 matching lines @@
   Object visitXmlTagNode(XmlTagNode node) {
     if (node.offset <= offset && offset < node.end) {
       result[0] = node;
       super.visitXmlTagNode(node);
       throw new HtmlUnitUtils_FoundTagNodeError();
     }
     return null;
   }
 }
 
-class ExpressionVisitor_HtmlUnitUtils_getExpression extends ExpressionVisitor {
-  int offset = 0;
-
-  List<Expression> result;
-
-  ExpressionVisitor_HtmlUnitUtils_getExpression(this.offset, this.result) : super();
-
-  @override
-  void visitExpression(Expression expression) {
-    Expression at = HtmlUnitUtils._getExpressionAt(expression, offset);
-    if (at != null) {
-      result[0] = at;
-      throw new HtmlUnitUtils_FoundExpressionError();
-    }
-  }
-}
-
 /**
- * The interface `XmlVisitor` defines the behavior of objects that can be used to visit an
- * [XmlNode] structure.
+ * 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.
  */
-abstract class XmlVisitor<R> {
-  R visitHtmlScriptTagNode(HtmlScriptTagNode node);
+class SimpleXmlVisitor<R> implements XmlVisitor<R> {
+  @override
+  R visitHtmlScriptTagNode(HtmlScriptTagNode node) => null;
 
-  R visitHtmlUnit(HtmlUnit htmlUnit);
+  @override
+  R visitHtmlUnit(HtmlUnit htmlUnit) => null;
 
-  R visitXmlAttributeNode(XmlAttributeNode xmlAttributeNode);
+  @override
+  R visitXmlAttributeNode(XmlAttributeNode xmlAttributeNode) => null;
 
-  R visitXmlTagNode(XmlTagNode xmlTagNode);
+  @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 `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;
 
   /**
@@ skipping 60 matching lines @@
    * @param node the node to be visited
    */
   void _visit(XmlNode node) {
     if (node != null) {
       node.accept(this);
     }
   }
 }
 
 /**
- * Instances of the class `HtmlUnit` represent the contents of an HTML file.
+ * 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 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);
+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 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;
+
+  /**
+   * 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;
+
+  /**
+   * 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
-  accept(XmlVisitor visitor) => visitor.visitHtmlUnit(this);
-
-  /**
-   * 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;
-
-  /**
-   * 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
-  void set element(Element element) {
-    if (element != null && element is! HtmlElement) {
-      throw new IllegalArgumentException("HtmlElement expected, but ${element.runtimeType} given");
-    }
-    super.element = element;
-  }
-
-  @override
-  void visitChildren(XmlVisitor visitor) {
-    for (XmlTagNode node in _tagNodes) {
-      node.accept(visitor);
-    }
-  }
-}
-
-/**
- * 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 `HtmlParser` are used to parse tokens into a AST structure comprised
- * of [XmlNode]s.
- */
-class HtmlParser extends XmlParser {
-  /**
-   * The line information associated with the source being parsed.
-   */
-  LineInfo _lineInfo;
-
-  /**
-   * The error listener to which errors will be reported.
-   */
-  final AnalysisErrorListener _errorListener;
-
-  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 Set<String>.from(JavaArrays.asList(<String> [
-      "area",
-      "base",
-      "basefont",
-      "br",
-      "col",
-      "frame",
-      "hr",
-      "img",
-      "input",
-      "link",
-      "meta",
-      "param",
-      "!"]));
-
-  /**
-   * 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();
-  }
-
-  /**
-   * Construct a parser for the specified source.
-   *
-   * @param source the source being parsed
-   * @param errorListener the error listener to which errors will be reported
-   */
-  HtmlParser(Source source, this._errorListener) : super(source);
-
-  /**
-   * 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);
-  }
-
-  @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);
-
-  /**
-   * 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;
-  }
-}
-
-/**
- * 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 `HtmlScriptTagNode` represent a script tag within an HTML file that
- * references a Dart script.
- */
-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);
-
-  @override
-  accept(XmlVisitor visitor) => visitor.visitHtmlScriptTagNode(this);
-
-  /**
-   * 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;
-  }
+  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.
    */
@@ skipping 147 matching lines @@
    * 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
   void visitChildren(XmlVisitor visitor) {
   }
+}
+
+/**
+ * Instances of the class `XmlExpression` represent an abstract expression embedded into
+ * [XmlNode].
+ */
+abstract class XmlExpression {
+  /**
+   * An empty array of expressions.
+   */
+  static List<XmlExpression> EMPTY_ARRAY = new List<XmlExpression>(0);
+
+  /**
+   * Check if the given offset belongs to the expression's source range.
+   */
+  bool contains(int offset) => this.offset <= offset && offset < end;
+
+  /**
+   * 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;
+
+  /**
+   * 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(Element element, int offset, int length) {
+    this.element = element;
+    this.offset = offset;
+    this.length = 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;
+
+  /**
+   * 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);
+
+  /**
+   * 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;
+
+  /**
+   * 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 element associated with this node.
+   *
+   * @param element the element
+   */
+  void set element(Element element) {
+    this._element = element;
+  }
+
+  @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);
+
+  /**
+   * 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) {
+      for (JavaIterator iter = new JavaIterator(children); iter.hasNext;) {
+        XmlNode node = iter.next();
+        node.parent = this;
+      }
+      // This will create ArrayList for exactly given number of elements.
+      return new List.from(children);
+    }
+    return children;
+  }
+
+  /**
+   * This method exists for debugging purposes only.
+   */
+  void _appendIdentifier(JavaStringBuilder builder, XmlNode node) {
+    if (node is XmlTagNode) {
+      builder.append(node.tag);
+    } else if (node is XmlAttributeNode) {
+      builder.append(node.name);
+    } else {
+      builder.append("htmlUnit");
+    }
+  }
+
+  /**
+   * This method exists for debugging purposes only.
+   */
+  String _buildRecursiveStructureMessage(XmlNode newParent) {
+    JavaStringBuilder builder = new JavaStringBuilder();
+    builder.append("Attempt to create recursive structure: ");
+    XmlNode current = newParent;
+    while (current != null) {
+      if (!identical(current, newParent)) {
+        builder.append(" -> ");
+      }
+      if (identical(current, this)) {
+        builder.appendChar(0x2A);
+        _appendIdentifier(builder, current);
+        builder.appendChar(0x2A);
+      } else {
+        _appendIdentifier(builder, current);
+      }
+      current = current.parent;
+    }
+    return builder.toString();
+  }
+
+  /**
+   * 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.logError2("Circular structure while setting an XML node's parent", new IllegalArgumentException(_buildRecursiveStructureMessage(newParent)));
+        return;
+      }
+      current = current.parent;
+    }
+    _parent = newParent;
+  }
+}
+
+/**
+ * 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);
+
+  /**
+   * 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;
+  }
+
+  /**
+   * Answer the current token.
+   *
+   * @return the current token
+   */
+  Token get currentToken => _currentToken;
+
+  /**
+   * 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() {
+  }
+}
+
+/**
+ * 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);
+  }
+
+  @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;
+  }
+
+  /**
+   * 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;
+
+  /**
+   * 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
+  Token get beginToken => nodeStart;
+
+  /**
+   * Answer 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.
+   *
+   * @return the content (not `null`)
+   */
+  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;
+    }
+    JavaStringBuilder buffer = new JavaStringBuilder();
+    while (!identical(token, contentEnd)) {
+      buffer.append(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
+  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);
 }