Restructure YAML package suitable for pub lish

utils/pub/yaml/model.dart

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// 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.
-
-/** A tag that indicates the type of a YAML node. */
-class _Tag {
-  // TODO(nweiz): it would better match the semantics of the spec if there were
-  // a singleton instance of this class for each tag.
-
-  static const SCALAR_KIND = 0;
-  static const SEQUENCE_KIND = 1;
-  static const MAPPING_KIND = 2;
-
-  static const String YAML_URI_PREFIX = 'tag:yaml.org,2002:';
-
-  /** The name of the tag, either a URI or a local tag beginning with "!". */
-  final String name;
-
-  /** The kind of the tag: SCALAR_KIND, SEQUENCE_KIND, or MAPPING_KIND. */
-  final int kind;
-
-  _Tag(this.name, this.kind);
-
-  _Tag.scalar(String name) : this(name, SCALAR_KIND);
-  _Tag.sequence(String name) : this(name, SEQUENCE_KIND);
-  _Tag.mapping(String name) : this(name, MAPPING_KIND);
-
-  /** Returns the standard YAML tag URI for [type]. */
-  static String yaml(String type) => "tag:yaml.org,2002:$type";
-
-  /** Two tags are equal if their URIs are equal. */
-  operator ==(other) {
-    if (other is! _Tag) return false;
-    return name == other.name;
-  }
-
-  String toString() {
-    if (name.startsWith(YAML_URI_PREFIX)) {
-      return '!!${name.substring(YAML_URI_PREFIX.length)}';
-    } else {
-      return '!<$name>';
-    }
-  }
-
-  int get hashCode => name.hashCode;
-}
-
-/** The abstract class for YAML nodes. */
-abstract class _Node {
-  /** Every YAML node has a tag that describes its type. */
-  _Tag tag;
-
-  /** Any YAML node can have an anchor associated with it. */
-  String anchor;
-
-  _Node(this.tag, [this.anchor]);
-
-  bool operator ==(other) {
-    if (other is! _Node) return false;
-    return tag == other.tag;
-  }
-
-  int get hashCode => _hashCode([tag, anchor]);
-
-  visit(_Visitor v);
-}
-
-/** A sequence node represents an ordered list of nodes. */
-class _SequenceNode extends _Node {
-  /** The nodes in the sequence. */
-  List<_Node> content;
-
-  _SequenceNode(String tagName, this.content)
-    : super(new _Tag.sequence(tagName));
-
-  /** Two sequences are equal if their tags and contents are equal. */
-  bool operator ==(other) {
-    // Should be super != other; bug 2554
-    if (!(super == other) || other is! _SequenceNode) return false;
-    if (content.length != other.content.length) return false;
-    for (var i = 0; i < content.length; i++) {
-      if (content[i] != other.content[i]) return false;
-    }
-    return true;
-  }
-
-  String toString() => '$tag [${Strings.join(content.map((e) => '$e'), ', ')}]';
-
-  int get hashCode => super.hashCode ^ _hashCode(content);
-
-  visit(_Visitor v) => v.visitSequence(this);
-}
-
-/** An alias node is a reference to an anchor. */
-class _AliasNode extends _Node {
-  _AliasNode(String anchor) : super(new _Tag.scalar(_Tag.yaml("str")), 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, {String content, this.value})
-   : _content = content,
-     super(new _Tag.scalar(tagName));
-
-  /** 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 '$value';
-
-    if (value is num) {
-      // 20 is the maximum value for this argument, which we use since YAML
-      // doesn't specify a maximum.
-      return value.toStringAsExponential(20).
-        replaceFirst(new RegExp("0+e"), "e");
-    }
-
-    if (value is String) {
-      // TODO(nweiz): This could be faster if we used a RegExp to check for
-      // special characters and short-circuited if they didn't exist.
-
-      var escapedValue = value.charCodes.map((c) {
-        switch (c) {
-        case _Parser.TAB: return "\\t";
-        case _Parser.LF: return "\\n";
-        case _Parser.CR: return "\\r";
-        case _Parser.DOUBLE_QUOTE: return '\\"';
-        case _Parser.NULL: return "\\0";
-        case _Parser.BELL: return "\\a";
-        case _Parser.BACKSPACE: return "\\b";
-        case _Parser.VERTICAL_TAB: return "\\v";
-        case _Parser.FORM_FEED: return "\\f";
-        case _Parser.ESCAPE: return "\\e";
-        case _Parser.BACKSLASH: return "\\\\";
-        case _Parser.NEL: return "\\N";
-        case _Parser.NBSP: return "\\_";
-        case _Parser.LINE_SEPARATOR: return "\\L";
-        case _Parser.PARAGRAPH_SEPARATOR: return "\\P";
-        default:
-          if (c < 0x20 || (c >= 0x7f && c < 0x100)) {
-            return "\\x${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 '"${Strings.join(escapedValue, '')}"';
-    }
-
-    throw new YamlException("unknown scalar value: $value");
-  }
-
-  String toString() => '$tag "$content"';
-
-  /**
-   * Left-pads [str] with zeros so that it's at least [length] characters
-   * long.
-   */
-  String zeroPad(String str, int length) {
-    assert(length >= str.length);
-    var prefix = [];
-    prefix.insertRange(0, length - str.length, '0');
-    return '${Strings.join(prefix, '')}$str';
-  }
-
-  int get hashCode => super.hashCode ^ content.hashCode;
-
-  visit(_Visitor v) => v.visitScalar(this);
-}
-
-/** A mapping node represents an unordered map of nodes to nodes. */
-class _MappingNode extends _Node {
-  /** The node map. */
-  Map<_Node, _Node> content;
-
-  _MappingNode(String tagName, this.content)
-    : super(new _Tag.mapping(tagName));
-
-  /** Two mappings are equal if their tags and contents are equal. */
-  bool operator ==(other) {
-    // Should be super != other; bug 2554
-    if (!(super == other) || other is! _MappingNode) return false;
-    if (content.length != other.content.length) return false;
-    for (var key in content.keys) {
-      if (!other.content.containsKey(key)) return false;
-      if (content[key] != other.content[key]) return false;
-    }
-    return true;
-  }
-
-  String toString() {
-    var strContent = Strings.join(content.keys.
-        map((k) => '${k}: ${content[k]}'), ', ');
-    return '$tag {$strContent}';
-  }
-
-  int get hashCode => super.hashCode ^ _hashCode(content);
-
-  visit(_Visitor v) => v.visitMapping(this);
-}