370 lines
10 KiB
JavaScript
370 lines
10 KiB
JavaScript
/**
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* Copyright 2010 Tim Down.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* jshashtable
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*
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* jshashtable is a JavaScript implementation of a hash table. It creates a single constructor function called Hashtable
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* in the global scope.
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*
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* Author: Tim Down <tim@timdown.co.uk>
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* Version: 2.1
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* Build date: 21 March 2010
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* Website: http://www.timdown.co.uk/jshashtable
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*/
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var Hashtable = (function() {
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var FUNCTION = "function";
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var arrayRemoveAt = (typeof Array.prototype.splice == FUNCTION) ?
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function(arr, idx) {
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arr.splice(idx, 1);
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} :
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function(arr, idx) {
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var itemsAfterDeleted, i, len;
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if (idx === arr.length - 1) {
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arr.length = idx;
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} else {
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itemsAfterDeleted = arr.slice(idx + 1);
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arr.length = idx;
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for (i = 0, len = itemsAfterDeleted.length; i < len; ++i) {
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arr[idx + i] = itemsAfterDeleted[i];
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}
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}
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};
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function hashObject(obj) {
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var hashCode;
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if (typeof obj == "string") {
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return obj;
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} else if (typeof obj.hashCode == FUNCTION) {
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// Check the hashCode method really has returned a string
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hashCode = obj.hashCode();
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return (typeof hashCode == "string") ? hashCode : hashObject(hashCode);
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} else if (typeof obj.toString == FUNCTION) {
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return obj.toString();
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} else {
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try {
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return String(obj);
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} catch (ex) {
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// For host objects (such as ActiveObjects in IE) that have no toString() method and throw an error when
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// passed to String()
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return Object.prototype.toString.call(obj);
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}
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}
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}
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function equals_fixedValueHasEquals(fixedValue, variableValue) {
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return fixedValue.equals(variableValue);
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}
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function equals_fixedValueNoEquals(fixedValue, variableValue) {
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return (typeof variableValue.equals == FUNCTION) ?
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variableValue.equals(fixedValue) : (fixedValue === variableValue);
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}
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function createKeyValCheck(kvStr) {
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return function(kv) {
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if (kv === null) {
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throw new Error("null is not a valid " + kvStr);
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} else if (typeof kv == "undefined") {
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throw new Error(kvStr + " must not be undefined");
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}
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};
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}
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var checkKey = createKeyValCheck("key"), checkValue = createKeyValCheck("value");
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/*----------------------------------------------------------------------------------------------------------------*/
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function Bucket(hash, firstKey, firstValue, equalityFunction) {
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this[0] = hash;
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this.entries = [];
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this.addEntry(firstKey, firstValue);
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if (equalityFunction !== null) {
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this.getEqualityFunction = function() {
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return equalityFunction;
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};
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}
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}
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var EXISTENCE = 0, ENTRY = 1, ENTRY_INDEX_AND_VALUE = 2;
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function createBucketSearcher(mode) {
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return function(key) {
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var i = this.entries.length, entry, equals = this.getEqualityFunction(key);
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while (i--) {
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entry = this.entries[i];
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if ( equals(key, entry[0]) ) {
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switch (mode) {
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case EXISTENCE:
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return true;
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case ENTRY:
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return entry;
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case ENTRY_INDEX_AND_VALUE:
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return [ i, entry[1] ];
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}
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}
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}
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return false;
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};
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}
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function createBucketLister(entryProperty) {
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return function(aggregatedArr) {
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var startIndex = aggregatedArr.length;
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for (var i = 0, len = this.entries.length; i < len; ++i) {
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aggregatedArr[startIndex + i] = this.entries[i][entryProperty];
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}
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};
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}
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Bucket.prototype = {
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getEqualityFunction: function(searchValue) {
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return (typeof searchValue.equals == FUNCTION) ? equals_fixedValueHasEquals : equals_fixedValueNoEquals;
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},
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getEntryForKey: createBucketSearcher(ENTRY),
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getEntryAndIndexForKey: createBucketSearcher(ENTRY_INDEX_AND_VALUE),
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removeEntryForKey: function(key) {
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var result = this.getEntryAndIndexForKey(key);
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if (result) {
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arrayRemoveAt(this.entries, result[0]);
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return result[1];
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}
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return null;
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},
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addEntry: function(key, value) {
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this.entries[this.entries.length] = [key, value];
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},
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keys: createBucketLister(0),
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values: createBucketLister(1),
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getEntries: function(entries) {
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var startIndex = entries.length;
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for (var i = 0, len = this.entries.length; i < len; ++i) {
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// Clone the entry stored in the bucket before adding to array
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entries[startIndex + i] = this.entries[i].slice(0);
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}
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},
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containsKey: createBucketSearcher(EXISTENCE),
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containsValue: function(value) {
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var i = this.entries.length;
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while (i--) {
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if ( value === this.entries[i][1] ) {
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return true;
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}
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}
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return false;
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}
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};
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/*----------------------------------------------------------------------------------------------------------------*/
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// Supporting functions for searching hashtable buckets
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function searchBuckets(buckets, hash) {
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var i = buckets.length, bucket;
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while (i--) {
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bucket = buckets[i];
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if (hash === bucket[0]) {
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return i;
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}
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}
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return null;
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}
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function getBucketForHash(bucketsByHash, hash) {
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var bucket = bucketsByHash[hash];
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// Check that this is a genuine bucket and not something inherited from the bucketsByHash's prototype
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return ( bucket && (bucket instanceof Bucket) ) ? bucket : null;
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}
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/*----------------------------------------------------------------------------------------------------------------*/
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function Hashtable(hashingFunctionParam, equalityFunctionParam) {
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var that = this;
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var buckets = [];
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var bucketsByHash = {};
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var hashingFunction = (typeof hashingFunctionParam == FUNCTION) ? hashingFunctionParam : hashObject;
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var equalityFunction = (typeof equalityFunctionParam == FUNCTION) ? equalityFunctionParam : null;
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this.put = function(key, value) {
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checkKey(key);
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checkValue(value);
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var hash = hashingFunction(key), bucket, bucketEntry, oldValue = null;
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// Check if a bucket exists for the bucket key
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bucket = getBucketForHash(bucketsByHash, hash);
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if (bucket) {
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// Check this bucket to see if it already contains this key
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bucketEntry = bucket.getEntryForKey(key);
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if (bucketEntry) {
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// This bucket entry is the current mapping of key to value, so replace old value and we're done.
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oldValue = bucketEntry[1];
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bucketEntry[1] = value;
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} else {
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// The bucket does not contain an entry for this key, so add one
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bucket.addEntry(key, value);
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}
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} else {
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// No bucket exists for the key, so create one and put our key/value mapping in
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bucket = new Bucket(hash, key, value, equalityFunction);
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buckets[buckets.length] = bucket;
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bucketsByHash[hash] = bucket;
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}
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return oldValue;
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};
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this.get = function(key) {
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checkKey(key);
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var hash = hashingFunction(key);
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// Check if a bucket exists for the bucket key
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var bucket = getBucketForHash(bucketsByHash, hash);
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if (bucket) {
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// Check this bucket to see if it contains this key
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var bucketEntry = bucket.getEntryForKey(key);
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if (bucketEntry) {
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// This bucket entry is the current mapping of key to value, so return the value.
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return bucketEntry[1];
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}
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}
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return null;
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};
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this.containsKey = function(key) {
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checkKey(key);
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var bucketKey = hashingFunction(key);
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// Check if a bucket exists for the bucket key
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var bucket = getBucketForHash(bucketsByHash, bucketKey);
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return bucket ? bucket.containsKey(key) : false;
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};
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this.containsValue = function(value) {
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checkValue(value);
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var i = buckets.length;
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while (i--) {
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if (buckets[i].containsValue(value)) {
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return true;
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}
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}
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return false;
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};
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this.clear = function() {
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buckets.length = 0;
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bucketsByHash = {};
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};
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this.isEmpty = function() {
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return !buckets.length;
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};
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var createBucketAggregator = function(bucketFuncName) {
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return function() {
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var aggregated = [], i = buckets.length;
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while (i--) {
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buckets[i][bucketFuncName](aggregated);
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}
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return aggregated;
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};
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};
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this.keys = createBucketAggregator("keys");
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this.values = createBucketAggregator("values");
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this.entries = createBucketAggregator("getEntries");
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this.remove = function(key) {
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checkKey(key);
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var hash = hashingFunction(key), bucketIndex, oldValue = null;
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// Check if a bucket exists for the bucket key
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var bucket = getBucketForHash(bucketsByHash, hash);
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if (bucket) {
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// Remove entry from this bucket for this key
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oldValue = bucket.removeEntryForKey(key);
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if (oldValue !== null) {
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// Entry was removed, so check if bucket is empty
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if (!bucket.entries.length) {
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// Bucket is empty, so remove it from the bucket collections
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bucketIndex = searchBuckets(buckets, hash);
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arrayRemoveAt(buckets, bucketIndex);
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delete bucketsByHash[hash];
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}
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}
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}
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return oldValue;
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};
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this.size = function() {
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var total = 0, i = buckets.length;
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while (i--) {
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total += buckets[i].entries.length;
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}
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return total;
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};
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this.each = function(callback) {
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var entries = that.entries(), i = entries.length, entry;
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while (i--) {
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entry = entries[i];
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callback(entry[0], entry[1]);
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}
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};
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this.putAll = function(hashtable, conflictCallback) {
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var entries = hashtable.entries();
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var entry, key, value, thisValue, i = entries.length;
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var hasConflictCallback = (typeof conflictCallback == FUNCTION);
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while (i--) {
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entry = entries[i];
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key = entry[0];
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value = entry[1];
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// Check for a conflict. The default behaviour is to overwrite the value for an existing key
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if ( hasConflictCallback && (thisValue = that.get(key)) ) {
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value = conflictCallback(key, thisValue, value);
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}
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that.put(key, value);
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}
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};
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this.clone = function() {
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var clone = new Hashtable(hashingFunctionParam, equalityFunctionParam);
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clone.putAll(that);
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return clone;
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};
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}
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return Hashtable;
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})(); |