inheritance, mixins and other stuff, mainly to encapsulate objects
当前为
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// ==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 {{extend, TruthyFalsy, Truthy, Falsy, emptyFunction}}
*/
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
var descriptors = {};
Object.getOwnPropertyNames(obj.prototype).forEach(function(propName) {
descriptors[propName] = Object.getOwnPropertyDescriptor(obj.prototype, propName);
});
// create new 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') return false;
if (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 from their prototype objects.
* @param {Object} obj - The extending object
* @return {{from: extendFrom, mixWith: mixWith}}
*/
var extend = function(obj) {
/**
* Clones the properties of the super object if it does not yet exists in the target object.
* @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
* @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(TruthyFalsy.prototype.valueOf.call(this));
}
};
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);
/** placeholder for empty callbacks */
function emptyFunction() {}
/**
* 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;
}
};
return {
extend: extend,
TruthyFalsy: TruthyFalsy,
Truthy: Truthy,
Falsy: Falsy,
Keeper: Keeper,
get emptyFunction() { return emptyFunction }
};
})();