lrn@google.com
9b23dff467
This reverts commit r17907. TBR. Review URL: https://codereview.chromium.org//12090093 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@17918 260f80e4-7a28-3924-810f-c04153c831b5
111 lines
3.3 KiB
Dart
111 lines
3.3 KiB
Dart
// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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part of yaml;
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/// This class wraps behaves almost identically to the normal Dart Map
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/// implementation, with the following differences:
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///
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/// * It allows null, NaN, boolean, list, and map keys.
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/// * It defines `==` structurally. That is, `yamlMap1 == yamlMap2` if they
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/// have the same contents.
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/// * It has a compatible [hashCode] method.
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class YamlMap implements Map {
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Map _map;
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YamlMap() : _map = new Map();
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YamlMap.from(Map map) : _map = new Map.from(map);
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YamlMap._wrap(this._map);
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bool containsValue(value) => _map.containsValue(value);
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bool containsKey(key) => _map.containsKey(_wrapKey(key));
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operator [](key) => _map[_wrapKey(key)];
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operator []=(key, value) { _map[_wrapKey(key)] = value; }
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putIfAbsent(key, ifAbsent()) => _map.putIfAbsent(_wrapKey(key), ifAbsent);
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remove(key) => _map.remove(_wrapKey(key));
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void clear() => _map.clear();
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void forEach(void f(key, value)) =>
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_map.forEach((k, v) => f(_unwrapKey(k), v));
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Iterable get keys => _map.keys.map(_unwrapKey);
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Iterable get values => _map.values;
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int get length => _map.length;
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bool get isEmpty => _map.isEmpty;
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String toString() => _map.toString();
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int get hashCode => _hashCode(_map);
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bool operator ==(other) {
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if (other is! YamlMap) return false;
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return deepEquals(this, other);
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}
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/// Wraps an object for use as a key in the map.
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_wrapKey(obj) {
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if (obj != null && obj is! bool && obj is! List &&
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(obj is! double || !obj.isNan()) &&
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(obj is! Map || obj is YamlMap)) {
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return obj;
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} else if (obj is Map) {
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return new YamlMap._wrap(obj);
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}
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return new _WrappedHashKey(obj);
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}
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/// Unwraps an object that was used as a key in the map.
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_unwrapKey(obj) => obj is _WrappedHashKey ? obj.value : obj;
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}
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/// A class for wrapping normally-unhashable objects that are being used as keys
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/// in a YamlMap.
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class _WrappedHashKey {
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var value;
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_WrappedHashKey(this.value);
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int get hashCode => _hashCode(value);
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String toString() => value.toString();
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/// This is defined as both values being structurally equal.
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bool operator ==(other) {
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if (other is! _WrappedHashKey) return false;
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return deepEquals(this.value, other.value);
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}
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}
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/// Returns the hash code for [obj]. This includes null, true, false, maps, and
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/// lists. Also handles self-referential structures.
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int _hashCode(obj, [List parents]) {
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if (parents == null) {
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parents = [];
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} else if (parents.any((p) => identical(p, obj))) {
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return -1;
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}
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parents.add(obj);
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try {
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if (obj == null) return 0;
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if (obj == true) return 1;
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if (obj == false) return 2;
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if (obj is Map) {
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return _hashCode(obj.keys, parents) ^
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_hashCode(obj.values, parents);
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}
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if (obj is Iterable) {
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// This is probably a really bad hash function, but presumably we'll get
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// this in the standard library before it actually matters.
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int hash = 0;
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for (var e in obj) {
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hash ^= _hashCode(e, parents);
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}
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return hash;
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}
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return obj.hashCode;
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} finally {
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parents.removeLast();
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}
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}
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