inheritance, mixins and other stuff, mainly to encapsulate objects
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/22752/146271/object-utils.js
// ==UserScript==
// @name object-utils
// @name:de object-utils
// @namespace dannysaurus.camamba
// @version 0.1
// @license MIT License
// @description inheritance, mixins and other stuff, mainly to encapsulate objects
// @description:de inheritance, mixins and other stuff, mainly to encapsulate objects
// ==/UserScript==
var LIB = LIB || {};
/**
*
* @type {{mixin, extend, TruthyFalsy, Truthy, Falsy, Keeper, BackingData, emptyFunction, emptyDate}}
*/
LIB.objectUtils = (function() {
'use strict';
/**
* Extends an object from another object through the prototype chain
* @param {Object} superObj - The object to be extended
* @param {Object} obj - The object extending the superObj
* @return {boolean} true, if executed successfully
*/
function _extend(superObj, obj){
if (typeof superObj === 'undefined') return false;
if (typeof obj === 'undefined') return false;
// save properties of prototype of the obj
var descriptors = {};
Object.getOwnPropertyNames(obj.prototype).forEach(function(propName) {
descriptors[propName] = Object.getOwnPropertyDescriptor(obj.prototype, propName);
});
// create a new extended prototype
obj.prototype = Object.create(superObj.prototype, descriptors);
obj.prototype.constructor = obj;
return true;
}
/**
* Clones properties from one object to another.
* A property only gets cloned if it does not yet exist in the target object.
* @param {Object} receiver - the target object receiver the properties
* @param {Object} supplier - the source object supplying the properties
* @param {Array} [props] - names of the relevant properties
* @return {boolean} true, if executed successfully
*/
function _mixin(receiver, supplier, props) {
if (typeof supplier !== 'object' || typeof receiver !== 'object') {
return false;
}
var propNames = Array.isArray(props) ? props : Object.getOwnPropertyNames(supplier);
propNames.forEach(function(propName) {
if (!Object.prototype.hasOwnProperty.call(receiver, propName)) {
var desc = Object.getOwnPropertyDescriptor(supplier, propName);
if (typeof desc !== 'undefined') {
Object.defineProperty(receiver, propName, desc);
}
}
});
return true;
}
/**
* Has an object extending a super object by their prototype objects.
* @param {Object} obj - The extending object
* @return {{from: extendFrom, mixWith: mixWith}}
*/
var extend = function(obj) {
/**
* Clones the prototype properties of the super object in the target object if the property does not yet exist there.
* @param {Object} superObj - the source object supplying the properties
* @param {Array} [props] - names of the relevant properties
* @return {{thenWith: mixWith}}
*/
var mixWith = function(superObj, props) {
if (_mixin(obj.prototype, superObj.prototype, props)){
return {
thenWith : mixWith
};
}
};
/**
* Extends the super object from the prototype chain
* @param superObj The super object to be extended
* @return {{mixWith: mixWith}}
*/
var extendFrom = function (superObj) {
if (_extend(superObj, obj)) {
return {
mixWith : mixWith
};
}
};
return {
from : extendFrom,
mixWith : mixWith
};
};
/**
* Defines an object that holds a value and specific values.
* In case the value is a Truthy, Falsy or undefined it is overwritten with specific values.
* @param value The common value.
* @param [ifTruthy] if not undefined it overwrites value when it is a Truthy
* @param [ifFalsy] if not undefined it overwrites value when it is a Falsy
* @param [ifUndefined] if not undefined it overwrites value when it is undefined
* @returns {TruthyFalsy}
* @constructor
*/
function TruthyFalsy(value, ifTruthy, ifFalsy, ifUndefined) {
if (!this instanceof TruthyFalsy) {
return new TruthyFalsy(value, ifTruthy, ifFalsy, ifUndefined);
}
this.value = value;
if (ifTruthy !== 'undefined') { this.ifTruthy = ifTruthy; }
if (ifFalsy !== 'undefined') { this.ifFalsy = ifFalsy; }
if (ifUndefined !== 'undefined') { this.ifUndefined = ifUndefined; }
}
TruthyFalsy.prototype = {
constructor : TruthyFalsy,
valueOf: function() {
var result = this.value;
if (typeof this.ifUndefined !== "undefined" && typeof result === "undefined") {
result = this.ifUndefined;
} else if (typeof this.ifTruthy !== "undefined" && result) {
result = this.ifTruthy;
} else if (typeof this.ifFalsy !== "undefined" && result) {
result = this.ifFalsy;
}
return result;
},
toString: function() {
return String(this.valueOf());
}
};
function Falsy(value, ifFalsy, ifUndefined) {
if (!(this instanceof Falsy)) {
return new Falsy(value, ifFalsy, ifUndefined);
}
TruthyFalsy.call(this, value, undefined, ifFalsy, ifUndefined);
}
extend(Falsy).from(TruthyFalsy);
function Truthy(value, ifTruthy, ifUndefined) {
if (!(this instanceof Truthy)) {
return new Truthy(value, ifTruthy, ifUndefined);
}
TruthyFalsy.call(this, value, ifTruthy, undefined, ifUndefined);
}
extend(Truthy).from(TruthyFalsy);
/**
* Keeps elements assigned by an index
* @param {number} [initialCapacity] - initial size of the array used to store the elements
* @constructor
*/
function Keeper(initialCapacity) {
if (!(this instanceof Keeper)) {
return new Keeper(initialCapacity);
}
var _store = new Array(initialCapacity || 16);
var _pointer = 0;
Object.defineProperties(this, {
store: {
get: function() { return _store },
configurable: false, enumerable: false
},
pointer: {
get: function() { return _pointer },
configurable: false, enumerable: false
}
})
}
Keeper.prototype = {
constructor: Keeper,
/**
* Adds a new element
* @param {*|Object} item - The element to keep. Must not be type of <code>undefined</code>.
* @return {number} The index (key) of the added element.<br>
* <code>-1</code> if the element could not be added.
*/
push: function(item) {
if (typeof item !== 'undefined') {
var index = this.pointer;
this.store[index] = item;
for (this.pointer = index + 1; this.pointer <= this.store.length; this.pointer++) {
if (typeof this.store[pointer] === 'undefined') { break; }
}
if (this.pointer === this.store.length) {
this.store.length *= 2;
}
return index;
}
return -1;
},
/**
* Removes an element.
* @param index The index (key) of the element to be removed.
* @return {boolean} <code>true</code> if the element could be removed successfully
*/
remove: function(index) {
if (index + 1 >= this.store.length) {
this.store[index] = undefined;
this.pointer = index;
return true;
}
return false;
},
/**
* Gets the element with the specified index
* @param {number} index - Index (key) of the element
* @return {*|Object} the element with the specified index or <code>undefined</code>
*/
get: function (index) {
if (index + 1 <= this.store.length) {
return this.store[index];
}
return undefined;
}
};
/**
* This callback is displayed as part of the Requester class.
* @callback OnSetCallback
* @param {*} oldValue - old value
* @param {*} newValue - new value to be set
*/
/**
* Defines an accessor properties
* @param {Object} sourceNode - the source object with the defining property
* @param {Object} targetNode - the target object to define the accessor property
* @param {string} propertyName - the name of the property which must exist on the <code>sourceNode</code>
* @param {OnSetCallback} [onSetCallback] - called when the property gets assigned a value on the <code>targetNode</code>
*/
var definePropRecursive = function(sourceNode, targetNode, propertyName, onSetCallback) {
if (typeof onSetCallback !== "function") {
onSetCallback = emptyFunction;
}
var srcProperty = sourceNode[propertyName];
var isNode = (srcProperty !== null && typeof srcProperty === 'object' && Object.getPrototypeOf(srcProperty) === Object.prototype);
if (isNode) {
var childrenPropertyNames = Object.keys(srcProperty);
var targetProperty = targetNode[propertyName] = {};
childrenPropertyNames.forEach(function(childPropName) {
definePropRecursive(srcProperty, targetProperty, childPropName, onSetCallback);
});
} else {
Object.defineProperty(targetNode, propertyName, {
enumerable: true,
configurable: true,
get: function() { return sourceNode[propertyName]; },
set: function(value) {
onSetCallback(sourceNode[propertyName], value);
sourceNode[propertyName] = value;
}
});
}
};
/**
* Backing data that can be stored in the userscript database.
* intially defines getter and setter on the front
* @param {Object} frontObject - the object to define the properties on according to <code>dataObject</code>
* @param {Object} dataObject - the Object defining the backing data structure and initial values
* @param {string} dbKey - key for storing the data in the userscript db
* @param {OnSetCallback} [onSet] - function called when a property of <code>dataObject</code> gets assigned a value through the <code>frontObject</code>
* @returns {BackingData}
* @constructor
*/
function BackingData(frontObject, dataObject, dbKey, onSet) {
if (!(this instanceof BackingData)) {
return new BackingData(frontObject, dataObject, dbKey, onSet);
}
_mixin(this, dataObject);
Object.defineProperties(this, {
dbKey: { enumerable: false, configurable: true, writable: true, value: dbKey },
frontObject: { enumerable: false, configurable: true, writable: true, value: frontObject },
onSet: { enumerable: false, configurable: true, writable: true, value: onSet }
});
Object.keys(this).forEach(function(propName) {
definePropRecursive(this, frontObject, propName, onSet);
}, this);
}
BackingData.prototype = {
constructor: BackingData,
load: function() {
var loadedObjSerialized = GM_getValue(this.dbKey);
if (typeof loadedObjSerialized === "undefined") {
return false;
}
var loadedObj = JSON.parse(loadedObjSerialized);
Object.keys(this).forEach(function(propName) {
var prop = loadedObj[propName];
if (typeof prop !== "undefined") {
this[propName] = prop;
}
}, this);
Object.keys(this).forEach(function(propName) {
definePropRecursive(this, this.frontObject, propName, this.onSet);
}, this);
return true;
},
save: function() {
var savingObj = {};
_mixin(savingObj, this);
var savingObjSerialized = JSON.stringify(savingObj);
GM_setValue(this.dbKey, savingObjSerialized);
},
remove: function() {
GM_deleteValue(this.dbKey);
}
};
/** placeholder for empty callbacks */
function emptyFunction() {}
/** placeholder for an undefined date */
var emptyDate = new Date('invalid');
return {
mixin: _mixin,
extend: extend,
TruthyFalsy: TruthyFalsy,
Truthy: Truthy,
Falsy: Falsy,
Keeper: Keeper,
BackingData: BackingData,
get emptyFunction() { return emptyFunction },
get emptyDate() { return emptyDate }
};
})();