forerunnerdb
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A NoSQL document store database for browsers and Node.js.
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<h1 class="page-title">Source: IndexHashMap.js</h1>
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<pre class="prettyprint source linenums"><code>"use strict";
var Shared = require('./Shared'),
Path = require('./Path');
/**
* The index class used to instantiate hash map indexes that the database can
* use to speed up queries on collections and views.
* @constructor
*/
var IndexHashMap = function () {
this.init.apply(this, arguments);
};
IndexHashMap.prototype.init = function (keys, options, collection) {
this._crossRef = {};
this._size = 0;
this._id = this._itemKeyHash(keys, keys);
this.data({});
this.unique(options && options.unique ? options.unique : false);
if (keys !== undefined) {
this.keys(keys);
}
if (collection !== undefined) {
this.collection(collection);
}
this.name(options && options.name ? options.name : this._id);
};
Shared.addModule('IndexHashMap', IndexHashMap);
Shared.mixin(IndexHashMap.prototype, 'Mixin.ChainReactor');
IndexHashMap.prototype.id = function () {
return this._id;
};
IndexHashMap.prototype.state = function () {
return this._state;
};
IndexHashMap.prototype.size = function () {
return this._size;
};
Shared.synthesize(IndexHashMap.prototype, 'data');
Shared.synthesize(IndexHashMap.prototype, 'name');
Shared.synthesize(IndexHashMap.prototype, 'collection');
Shared.synthesize(IndexHashMap.prototype, 'type');
Shared.synthesize(IndexHashMap.prototype, 'unique');
IndexHashMap.prototype.keys = function (val) {
if (val !== undefined) {
this._keys = val;
// Count the keys
this._keyCount = (new Path()).parse(this._keys).length;
return this;
}
return this._keys;
};
IndexHashMap.prototype.rebuild = function () {
// Do we have a collection?
if (this._collection) {
// Get sorted data
var collection = this._collection.subset({}, {
$decouple: false,
$orderBy: this._keys
}),
collectionData = collection.find(),
dataIndex,
dataCount = collectionData.length;
// Clear the index data for the index
this._data = {};
if (this._unique) {
this._uniqueLookup = {};
}
// Loop the collection data
for (dataIndex = 0; dataIndex < dataCount; dataIndex++) {
this.insert(collectionData[dataIndex]);
}
}
this._state = {
name: this._name,
keys: this._keys,
indexSize: this._size,
built: new Date(),
updated: new Date(),
ok: true
};
};
IndexHashMap.prototype.insert = function (dataItem, options) {
var uniqueFlag = this._unique,
uniqueHash,
itemHashArr,
hashIndex;
if (uniqueFlag) {
uniqueHash = this._itemHash(dataItem, this._keys);
this._uniqueLookup[uniqueHash] = dataItem;
}
// Generate item hash
itemHashArr = this._itemHashArr(dataItem, this._keys);
// Get the path search results and store them
for (hashIndex = 0; hashIndex < itemHashArr.length; hashIndex++) {
this.pushToPathValue(itemHashArr[hashIndex], dataItem);
}
};
IndexHashMap.prototype.update = function (dataItem, options) {
// TODO: Write updates to work
// 1: Get uniqueHash for the dataItem primary key value (may need to generate a store for this)
// 2: Remove the uniqueHash as it currently stands
// 3: Generate a new uniqueHash for dataItem
// 4: Insert the new uniqueHash
};
IndexHashMap.prototype.remove = function (dataItem, options) {
var uniqueFlag = this._unique,
uniqueHash,
itemHashArr,
hashIndex;
if (uniqueFlag) {
uniqueHash = this._itemHash(dataItem, this._keys);
delete this._uniqueLookup[uniqueHash];
}
// Generate item hash
itemHashArr = this._itemHashArr(dataItem, this._keys);
// Get the path search results and store them
for (hashIndex = 0; hashIndex < itemHashArr.length; hashIndex++) {
this.pullFromPathValue(itemHashArr[hashIndex], dataItem);
}
};
IndexHashMap.prototype.violation = function (dataItem) {
// Generate item hash
var uniqueHash = this._itemHash(dataItem, this._keys);
// Check if the item breaks the unique constraint
return Boolean(this._uniqueLookup[uniqueHash]);
};
IndexHashMap.prototype.hashViolation = function (uniqueHash) {
// Check if the item breaks the unique constraint
return Boolean(this._uniqueLookup[uniqueHash]);
};
IndexHashMap.prototype.pushToPathValue = function (hash, obj) {
var pathValArr = this._data[hash] = this._data[hash] || [];
// Make sure we have not already indexed this object at this path/value
if (pathValArr.indexOf(obj) === -1) {
// Index the object
pathValArr.push(obj);
// Record the reference to this object in our index size
this._size++;
// Cross-reference this association for later lookup
this.pushToCrossRef(obj, pathValArr);
}
};
IndexHashMap.prototype.pullFromPathValue = function (hash, obj) {
var pathValArr = this._data[hash],
indexOfObject;
// Make sure we have already indexed this object at this path/value
indexOfObject = pathValArr.indexOf(obj);
if (indexOfObject > -1) {
// Un-index the object
pathValArr.splice(indexOfObject, 1);
// Record the reference to this object in our index size
this._size--;
// Remove object cross-reference
this.pullFromCrossRef(obj, pathValArr);
}
// Check if we should remove the path value array
if (!pathValArr.length) {
// Remove the array
delete this._data[hash];
}
};
IndexHashMap.prototype.pull = function (obj) {
// Get all places the object has been used and remove them
var id = obj[this._collection.primaryKey()],
crossRefArr = this._crossRef[id],
arrIndex,
arrCount = crossRefArr.length,
arrItem;
for (arrIndex = 0; arrIndex < arrCount; arrIndex++) {
arrItem = crossRefArr[arrIndex];
// Remove item from this index lookup array
this._pullFromArray(arrItem, obj);
}
// Record the reference to this object in our index size
this._size--;
// Now remove the cross-reference entry for this object
delete this._crossRef[id];
};
IndexHashMap.prototype._pullFromArray = function (arr, obj) {
var arrCount = arr.length;
while (arrCount--) {
if (arr[arrCount] === obj) {
arr.splice(arrCount, 1);
}
}
};
IndexHashMap.prototype.pushToCrossRef = function (obj, pathValArr) {
var id = obj[this._collection.primaryKey()],
crObj;
this._crossRef[id] = this._crossRef[id] || [];
// Check if the cross-reference to the pathVal array already exists
crObj = this._crossRef[id];
if (crObj.indexOf(pathValArr) === -1) {
// Add the cross-reference
crObj.push(pathValArr);
}
};
IndexHashMap.prototype.pullFromCrossRef = function (obj, pathValArr) {
var id = obj[this._collection.primaryKey()];
delete this._crossRef[id];
};
IndexHashMap.prototype.lookup = function (query) {
return this._data[this._itemHash(query, this._keys)] || [];
};
IndexHashMap.prototype.match = function (query, options) {
// Check if the passed query has data in the keys our index
// operates on and if so, is the query sort matching our order
var pathSolver = new Path();
var indexKeyArr = pathSolver.parseArr(this._keys),
queryArr = pathSolver.parseArr(query),
matchedKeys = [],
matchedKeyCount = 0,
i;
// Loop the query array and check the order of keys against the
// index key array to see if this index can be used
for (i = 0; i < indexKeyArr.length; i++) {
if (queryArr[i] === indexKeyArr[i]) {
matchedKeyCount++;
matchedKeys.push(queryArr[i]);
} else {
// Query match failed - this is a hash map index so partial key match won't work
return {
matchedKeys: [],
totalKeyCount: queryArr.length,
score: 0
};
}
}
return {
matchedKeys: matchedKeys,
totalKeyCount: queryArr.length,
score: matchedKeyCount
};
//return pathSolver.countObjectPaths(this._keys, query);
};
IndexHashMap.prototype._itemHash = function (item, keys) {
var path = new Path(),
pathData,
hash = '',
k;
pathData = path.parse(keys);
for (k = 0; k < pathData.length; k++) {
if (hash) { hash += '_'; }
hash += path.value(item, pathData[k].path).join(':');
}
return hash;
};
IndexHashMap.prototype._itemKeyHash = function (item, keys) {
var path = new Path(),
pathData,
hash = '',
k;
pathData = path.parse(keys);
for (k = 0; k < pathData.length; k++) {
if (hash) { hash += '_'; }
hash += path.keyValue(item, pathData[k].path);
}
return hash;
};
IndexHashMap.prototype._itemHashArr = function (item, keys) {
var path = new Path(),
pathData,
//hash = '',
hashArr = [],
valArr,
i, k, j;
pathData = path.parse(keys);
for (k = 0; k < pathData.length; k++) {
valArr = path.value(item, pathData[k].path);
for (i = 0; i < valArr.length; i++) {
if (k === 0) {
// Setup the initial hash array
hashArr.push(valArr[i]);
} else {
// Loop the hash array and concat the value to it
for (j = 0; j < hashArr.length; j++) {
hashArr[j] = hashArr[j] + '_' + valArr[i];
}
}
}
}
return hashArr;
};
Shared.finishModule('IndexHashMap');
module.exports = IndexHashMap;</code></pre>
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