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