/js/lib/SortedLookupTable.js

  1/**
  2File:
  3	SortedLookupTable.js
  4Created By:
  5	(Class from http://blog.jcoglan.com/2010/10/18/i-am-a-fast-loop/)
  6	Copy->Pasted->Modified by Mario Gonzalez
  7	
  8Project	:
  9	Ogilvy Holiday Card 2010
 10Abstract:
 11
 12	A sorted LookupTable is a data structure that provides us a way to iterate thru objects at a speed
 13	comparable to reverse while, but also have named keys as we would if we used an object (which provides very slow iteration)
 14	It also gives us O(log n) removal of objects.
 15Basic Usage:
 16
 17	http://blog.jcoglan.com/2010/10/18/i-am-a-fast-loop/
 18*/
 19// @getify's solution
 20//var Set = (function()
 21//{
 22//	var indexOf = Array.prototype.indexOf;
 23//
 24//	if (typeof indexOf !== 'function')
 25//	{
 26//		indexOf = function(value)
 27//		{
 28//			for (var index = 0, length = this.length; index < length; index++)
 29//			{
 30//				if (this[index] === value)
 31//				{
 32//					return index;
 33//				}
 34//			}
 35//			return -1;
 36//		};
 37//	}
 38//
 39//	function Set()
 40//	{
 41//		this.set = [];
 42//	}
 43//
 44//	Set.prototype = {
 45//		'constructor': Set,
 46//		'put': function(value, key)
 47//		{
 48//			var index = indexOf.call(this.set, key);
 49//			if (index !== -1 && index % 2 === 0)
 50//			{
 51//				this.set.splice(index, 2);
 52//			}
 53//			this.set.push(key, value);
 54//		},
 55//		'get': function(key)
 56//		{
 57//			var index = indexOf.call(this.set, key);
 58//			return (index !== -1 && index % 2 === 0) ? this.set[++index] : null;
 59//		},
 60//		'containsKey': function(key)
 61//		{
 62//			var index = indexOf.call(this.set, key);
 63//			return (index !== -1 && index % 2 === 0);
 64//		},
 65//		'containsValue': function(value)
 66//		{
 67//			var index = indexOf.call(this.set, value);
 68//			return (index !== -1 && index % 2 !== 0);
 69//		},
 70//		'remove': function(key)
 71//		{
 72//			var index = indexOf.call(this.set, key),
 73//					value = null;
 74//			if (index !== -1 && index % 2 === 0)
 75//			{
 76//				value = this.set.splice(index, 2)[1];
 77//			}
 78//			return value;
 79//		},
 80//
 81//		'forEach': function(block, context)
 82//		{
 83//			var set = this.set,
 84//				i = this.set.length-1,
 85//				key;
 86//
 87//			while (i > 0)
 88//			{
 89//				block.call(context, set[i - 1], set[key]);
 90//				i-=2;
 91//			}
 92//		}
 93//	};
 94//
 95//	return Set;
 96//}());
 97
 98(function() {
 99	/**
100	 *	LookupTable
101	 */
102	LookupTable = function()
103	{
104		this._keys = [];
105		this._data = {};
106		this.nextUUID = 0;
107	};
108
109
110	LookupTable.prototype.setObjectForKey = function(value, key)
111	{
112		if (!this._data.hasOwnProperty(key)) this._keys.push(key);
113		this._data[key] = value;
114
115		return value;
116	};
117
118	LookupTable.prototype.objectForKey = function(key)
119	{
120		return this._data[key];
121	};
122
123	LookupTable.prototype.forEach = function(block, context)
124	{
125		var keys = this._keys,
126			data = this._data,
127			i = keys.length,
128			key;
129
130		while (i--)
131		{
132			key = keys[i];
133			block.call(context, key, data[key]);
134		}
135	};
136
137	LookupTable.prototype.count = function()
138	{
139		return this._keys.length;
140	};
141
142	LookupTable.prototype.dealloc = function()
143	{
144		delete this._keys;
145		delete this._data;
146	};
147
148
149
150	/**
151	*	Sorted LookupTable,
152	*/
153	SortedLookupTable = function()
154	{
155		LookupTable.call(this);
156	};
157
158	SortedLookupTable.prototype = new LookupTable();
159
160	SortedLookupTable.prototype.setObjectForKey = function(value, key)
161	{
162		if( !this._data.hasOwnProperty( key ) )
163		{
164			var index = this._indexOf(key);
165			this._keys.splice(index, 0, key);
166		}
167		this._data[key] = value;
168
169		return value;
170	};
171
172	SortedLookupTable.prototype.remove = function(key)
173	{
174		if (!this._data.hasOwnProperty(key)) return;
175		delete this._data[key];
176		var index = this._indexOf(key);
177		this._keys.splice(index, 1);
178	};
179
180	SortedLookupTable.prototype._indexOf = function(key)
181	{
182		var keys = this._keys,
183			n = keys.length,
184			i = 0,
185			d = n;
186
187		if (n === 0) return 0;
188		if (key < keys[0]) return 0;
189		if (key > keys[n - 1]) return n;
190
191		while (key !== keys[i] && d > 0.5) {
192			d = d / 2;
193			i += (key > keys[i] ? 1: -1) * Math.round(d);
194			if (key > keys[i - 1] && key < keys[i]) d = 0;
195		}
196		return i;
197	};
198
199	return SortedLookupTable;
200})();