Rewrite the pkg/yaml parser.

pkg/yaml/lib/src/model.dart

Index: pkg/yaml/lib/src/model.dart
diff --git a/pkg/yaml/lib/src/model.dart b/pkg/yaml/lib/src/model.dart
deleted file mode 100644
index 93cb49c7a36901fbad5935ff3827fbac645960b9..0000000000000000000000000000000000000000
--- a/pkg/yaml/lib/src/model.dart
+++ /dev/null
@@ -1,259 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/// This file contains the node classes for the internal representations of YAML
-/// documents. These nodes are used for both the serialization tree and the
-/// representation graph.
-library yaml.model;
-
-import 'package:source_span/source_span.dart';
-
-import 'equality.dart';
-import 'parser.dart';
-import 'visitor.dart';
-import 'yaml_exception.dart';
-
-/// The prefix for tag types defined by the YAML spec.
-const _YAML_URI_PREFIX = "tag:yaml.org,2002:";
-
-/// A tag that indicates the type of a YAML node.
-class Tag {
-  /// The name of the tag, either a URI or a local tag beginning with "!".
-  final String name;
-
-  /// The kind of the tag.
-  final TagKind kind;
-
-  /// Returns the standard YAML tag URI for [type].
-  static String yaml(String type) => "tag:yaml.org,2002:$type";
-
-  const Tag(this.name, this.kind);
-
-  const Tag.scalar(String name)
-      : this(name, TagKind.SCALAR);
-
-  const Tag.sequence(String name)
-      : this(name, TagKind.SEQUENCE);
-
-  const Tag.mapping(String name)
-      : this(name, TagKind.MAPPING);
-
-  /// Two tags are equal if their URIs are equal.
-  operator ==(other) {
-    if (other is! Tag) return false;
-    return name == other.name;
-  }
-
-  String toString() {
-    if (name.startsWith(_YAML_URI_PREFIX)) {
-      return '!!${name.substring(_YAML_URI_PREFIX.length)}';
-    } else {
-      return '!<$name>';
-    }
-  }
-
-  int get hashCode => name.hashCode;
-}
-
-/// An enum for kinds of tags.
-class TagKind {
-  /// A tag indicating that the value is a scalar.
-  static const SCALAR = const TagKind._("scalar");
-
-  /// A tag indicating that the value is a sequence.
-  static const SEQUENCE = const TagKind._("sequence");
-
-  /// A tag indicating that the value is a mapping.
-  static const MAPPING = const TagKind._("mapping");
-
-  final String name;
-
-  const TagKind._(this.name);
-
-  String toString() => name;
-}
-
-/// The abstract class for YAML nodes.
-abstract class Node {
-  /// Every YAML node has a tag that describes its type.
-  Tag tag;
-
-  /// Any YAML node can have an anchor associated with it.
-  String anchor;
-
-  /// The source span for this node.
-  SourceSpan span;
-
-  Node(this.tag, this.span, [this.anchor]);
-
-  bool operator ==(other) {
-    if (other is! Node) return false;
-    return tag == other.tag;
-  }
-
-  int get hashCode => tag.hashCode ^ anchor.hashCode;
-
-  visit(Visitor v);
-}
-
-/// A sequence node represents an ordered list of nodes.
-class SequenceNode extends Node {
-  /// The nodes in the sequence.
-  List<Node> content;
-
-  SequenceNode(String tagName, this.content, SourceSpan span)
-    : super(new Tag.sequence(tagName), span);
-
-  /// Two sequences are equal if their tags and contents are equal.
-  bool operator ==(other) {
-    // Should be super != other; bug 2554
-    if (!(super == other) || other is! SequenceNode) return false;
-    if (content.length != other.content.length) return false;
-    for (var i = 0; i < content.length; i++) {
-      if (content[i] != other.content[i]) return false;
-    }
-    return true;
-  }
-
-  String toString() => '$tag [${content.map((e) => '$e').join(', ')}]';
-
-  int get hashCode => super.hashCode ^ deepHashCode(content);
-
-  visit(Visitor v) => v.visitSequence(this);
-}
-
-/// An alias node is a reference to an anchor.
-class AliasNode extends Node {
-  AliasNode(String anchor, SourceSpan span)
-      : super(new Tag.scalar(Tag.yaml("str")), span, anchor);
-
-  visit(Visitor v) => v.visitAlias(this);
-}
-
-/// A scalar node represents all YAML nodes that have a single value.
-class ScalarNode extends Node {
-  /// The string value of the scalar node, if it was created by the parser.
-  final String _content;
-
-  /// The Dart value of the scalar node, if it was created by the composer.
-  final value;
-
-  /// Creates a new Scalar node.
-  ///
-  /// Exactly one of [content] and [value] should be specified. Content should
-  /// be specified for a newly-parsed scalar that hasn't yet been composed.
-  /// Value should be specified for a composed scalar, although `null` is a
-  /// valid value.
-  ScalarNode(String tagName, SourceSpan span, {String content, this.value})
-   : _content = content,
-     super(new Tag.scalar(tagName), span);
-
-  /// Two scalars are equal if their string representations are equal.
-  bool operator ==(other) {
-    // Should be super != other; bug 2554
-    if (!(super == other) || other is! ScalarNode) return false;
-    return content == other.content;
-  }
-
-  /// Returns the string representation of the scalar. After composition, this
-  /// is equal to the canonical serialization of the value of the scalar.
-  String get content => _content != null ? _content : canonicalContent;
-
-  /// Returns the canonical serialization of the value of the scalar. If the
-  /// value isn't given, the result of this will be "null".
-  String get canonicalContent {
-    if (value == null || value is bool || value is int) return '$value';
-
-    if (value is num) {
-      // 20 is the maximum value for this argument, which we use since YAML
-      // doesn't specify a maximum.
-      return value.toStringAsExponential(20).
-        replaceFirst(new RegExp("0+e"), "e");
-    }
-
-    if (value is String) {
-      // TODO(nweiz): This could be faster if we used a RegExp to check for
-      // special characters and short-circuited if they didn't exist.
-
-      var escapedValue = value.codeUnits.map((c) {
-        switch (c) {
-        case Parser.TAB: return "\\t";
-        case Parser.LF: return "\\n";
-        case Parser.CR: return "\\r";
-        case Parser.DOUBLE_QUOTE: return '\\"';
-        case Parser.NULL: return "\\0";
-        case Parser.BELL: return "\\a";
-        case Parser.BACKSPACE: return "\\b";
-        case Parser.VERTICAL_TAB: return "\\v";
-        case Parser.FORM_FEED: return "\\f";
-        case Parser.ESCAPE: return "\\e";
-        case Parser.BACKSLASH: return "\\\\";
-        case Parser.NEL: return "\\N";
-        case Parser.NBSP: return "\\_";
-        case Parser.LINE_SEPARATOR: return "\\L";
-        case Parser.PARAGRAPH_SEPARATOR: return "\\P";
-        default:
-          if (c < 0x20 || (c >= 0x7f && c < 0x100)) {
-            return "\\x${zeroPad(c.toRadixString(16).toUpperCase(), 2)}";
-          } else if (c >= 0x100 && c < 0x10000) {
-            return "\\u${zeroPad(c.toRadixString(16).toUpperCase(), 4)}";
-          } else if (c >= 0x10000) {
-            return "\\u${zeroPad(c.toRadixString(16).toUpperCase(), 8)}";
-          } else {
-            return new String.fromCharCodes([c]);
-          }
-        }
-      });
-      return '"${escapedValue.join()}"';
-    }
-
-    throw new YamlException('Unknown scalar value.', span);
-  }
-
-  String toString() => '$tag "$content"';
-
-  /// Left-pads [str] with zeros so that it's at least [length] characters
-  /// long.
-  String zeroPad(String str, int length) {
-    assert(length >= str.length);
-    var prefix = new List.filled(length - str.length, '0');
-    return '${prefix.join()}$str';
-  }
-
-  int get hashCode => super.hashCode ^ content.hashCode;
-
-  visit(Visitor v) => v.visitScalar(this);
-}
-
-/// A mapping node represents an unordered map of nodes to nodes.
-class MappingNode extends Node {
-  /// The node map.
-  Map<Node, Node> content;
-
-  MappingNode(String tagName, this.content, SourceSpan span)
-    : super(new Tag.mapping(tagName), span);
-
-  /// Two mappings are equal if their tags and contents are equal.
-  bool operator ==(other) {
-    // Should be super != other; bug 2554
-    if (!(super == other) || other is! MappingNode) return false;
-    if (content.length != other.content.length) return false;
-    for (var key in content.keys) {
-      if (!other.content.containsKey(key)) return false;
-      if (content[key] != other.content[key]) return false;
-    }
-    return true;
-  }
-
-  String toString() {
-    var strContent = content.keys
-        .map((k) => '${k}: ${content[k]}')
-        .join(', ');
-    return '$tag {$strContent}';
-  }
-
-  int get hashCode => super.hashCode ^ deepHashCode(content);
-
-  visit(Visitor v) => v.visitMapping(this);
-}