forerunnerdb
Version:
A NoSQL document store database for browsers and Node.js.
354 lines (300 loc) • 8.9 kB
JavaScript
"use strict";
var idCounter = 0,
Overload = require('./Overload'),
Serialiser = require('./Serialiser'),
Common,
serialiser = new Serialiser(),
crcTable;
crcTable = (function () {
var crcTable = [],
c, n, k;
for (n = 0; n < 256; n++) {
c = n;
for (k = 0; k < 8; k++) {
c = ((c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1)); // jshint ignore:line
}
crcTable[n] = c;
}
return crcTable;
}());
/**
* Provides commonly used methods to most classes in ForerunnerDB.
* @mixin
*/
Common = {
// Expose the serialiser object so it can be extended with new data handlers.
serialiser: serialiser,
/**
* Generates a JSON serialisation-compatible object instance. After the
* instance has been passed through this method, it will be able to survive
* a JSON.stringify() and JSON.parse() cycle and still end up as an
* instance at the end. Further information about this process can be found
* in the ForerunnerDB wiki at: https://github.com/Irrelon/ForerunnerDB/wiki/Serialiser-&-Performance-Benchmarks
* @param {*} val The object instance such as "new Date()" or "new RegExp()".
*/
make: function (val) {
// This is a conversion request, hand over to serialiser
return serialiser.convert(val);
},
/**
* Gets / sets data in the item store. The store can be used to set and
* retrieve data against a key. Useful for adding arbitrary key/value data
* to a collection / view etc and retrieving it later.
* @param {String|*} key The key under which to store the passed value or
* retrieve the existing stored value.
* @param {*=} val Optional value. If passed will overwrite the existing value
* stored against the specified key if one currently exists.
* @returns {*}
*/
store: function (key, val) {
if (key !== undefined) {
if (val !== undefined) {
// Store the data
this._store = this._store || {};
this._store[key] = val;
return this;
}
if (this._store) {
return this._store[key];
}
}
return undefined;
},
/**
* Removes a previously stored key/value pair from the item store, set previously
* by using the store() method.
* @param {String|*} key The key of the key/value pair to remove;
* @returns {Common} Returns this for chaining.
*/
unStore: function (key) {
if (key !== undefined) {
delete this._store[key];
}
return this;
},
/**
* Returns a non-referenced version of the passed object / array.
* @param {Object} data The object or array to return as a non-referenced version.
* @param {Number=} copies Optional number of copies to produce. If specified, the return
* value will be an array of decoupled objects, each distinct from the other.
* @returns {*}
*/
decouple: function (data, copies) {
if (data !== undefined && data !== "") {
if (!copies) {
return this.jParse(this.jStringify(data));
} else {
var i,
json = this.jStringify(data),
copyArr = [];
for (i = 0; i < copies; i++) {
copyArr.push(this.jParse(json));
}
return copyArr;
}
}
return undefined;
},
/**
* Parses and returns data from stringified version.
* @param {String} data The stringified version of data to parse.
* @returns {Object} The parsed JSON object from the data.
*/
jParse: function (data) {
return JSON.parse(data, serialiser.reviver());
},
/**
* Converts a JSON object into a stringified version.
* @param {Object} data The data to stringify.
* @returns {String} The stringified data.
*/
jStringify: JSON.stringify,
/**
* Generates a new 16-character hexadecimal unique ID or
* generates a new 16-character hexadecimal ID based on
* the passed string. Will always generate the same ID
* for the same string.
* @param {String=} str A string to generate the ID from.
* @return {String}
*/
objectId: function (str) {
var id,
pow = Math.pow(10, 17);
if (!str) {
idCounter++;
id = (idCounter + (
Math.random() * pow +
Math.random() * pow +
Math.random() * pow +
Math.random() * pow
)).toString(16);
} else {
var val = 0,
count = str.length,
i;
for (i = 0; i < count; i++) {
val += str.charCodeAt(i) * pow;
}
id = val.toString(16);
}
return id;
},
/**
* Generates a unique hash for the passed object.
* @param {Object} obj The object to generate a hash for.
* @returns {String}
*/
hash: function (obj) {
return JSON.stringify(obj);
},
/**
* Gets / sets debug flag that can enable debug message output to the
* console if required.
* @param {Boolean} val The value to set debug flag to.
* @return {Boolean} True if enabled, false otherwise.
*/
/**
* Sets debug flag for a particular type that can enable debug message
* output to the console if required.
* @param {String} type The name of the debug type to set flag for.
* @param {Boolean} val The value to set debug flag to.
* @return {Boolean} True if enabled, false otherwise.
*/
debug: new Overload([
function () {
return this._debug && this._debug.all;
},
function (val) {
if (val !== undefined) {
if (typeof val === 'boolean') {
this._debug = this._debug || {};
this._debug.all = val;
this.chainSend('debug', this._debug);
return this;
} else {
return (this._debug && this._debug[val]) || (this._db && this._db._debug && this._db._debug[val]) || (this._debug && this._debug.all);
}
}
return this._debug && this._debug.all;
},
function (type, val) {
if (type !== undefined) {
if (val !== undefined) {
this._debug = this._debug || {};
this._debug[type] = val;
this.chainSend('debug', this._debug);
return this;
}
return (this._debug && this._debug[val]) || (this._db && this._db._debug && this._db._debug[type]);
}
return this._debug && this._debug.all;
}
]),
/**
* Returns a string describing the class this instance is derived from.
* @returns {String}
*/
classIdentifier: function () {
return 'ForerunnerDB.' + this.className;
},
/**
* Returns a string describing the instance by it's class name and instance
* object name.
* @returns {String} The instance identifier.
*/
instanceIdentifier: function () {
return '[' + this.className + ']' + this.name();
},
/**
* Returns a string used to denote a console log against this instance,
* consisting of the class identifier and instance identifier.
* @returns {String} The log identifier.
*/
logIdentifier: function () {
return 'ForerunnerDB ' + this.instanceIdentifier();
},
/**
* Converts a query object with MongoDB dot notation syntax
* to Forerunner's object notation syntax.
* @param {Object} obj The object to convert.
*/
convertToFdb: function (obj) {
var varName,
splitArr,
objCopy,
i;
for (i in obj) {
if (obj.hasOwnProperty(i)) {
objCopy = obj;
if (i.indexOf('.') > -1) {
// Replace .$ with a placeholder before splitting by . char
i = i.replace('.$', '[|$|]');
splitArr = i.split('.');
while ((varName = splitArr.shift())) {
// Replace placeholder back to original .$
varName = varName.replace('[|$|]', '.$');
if (splitArr.length) {
objCopy[varName] = {};
} else {
objCopy[varName] = obj[i];
}
objCopy = objCopy[varName];
}
delete obj[i];
}
}
}
},
/**
* Checks if the state is dropped.
* @returns {boolean} True when dropped, false otherwise.
*/
isDropped: function () {
return this._state === 'dropped';
},
/**
* Registers a timed callback that will overwrite itself if
* the same id is used within the timeout period. Useful
* for de-bouncing fast-calls.
* @param {String} id An ID for the call (use the same one
* to debounce the same calls).
* @param {Function} callback The callback method to call on
* timeout.
* @param {Number} timeout The timeout in milliseconds before
* the callback is called.
*/
debounce: function (id, callback, timeout) {
var self = this,
newData;
self._debounce = self._debounce || {};
if (self._debounce[id]) {
// Clear timeout for this item
clearTimeout(self._debounce[id].timeout);
}
newData = {
callback: callback,
timeout: setTimeout(function () {
// Delete existing reference
delete self._debounce[id];
// Call the callback
callback();
}, timeout)
};
// Save current data
self._debounce[id] = newData;
},
/**
* Returns a checksum of a string.
* @param {String} str The string to checksum.
* @return {Number} The checksum generated.
*/
checksum: function (str) {
var crc = 0 ^ (-1), // jshint ignore:line
i;
for (i = 0; i < str.length; i++) {
crc = (crc >>> 8) ^ crcTable[(crc ^ str.charCodeAt(i)) & 0xFF]; // jshint ignore:line
}
return (crc ^ (-1)) >>> 0; // jshint ignore:line
}
};
module.exports = Common;