# Yahoo! UI Library

### oop 3.0.0b1

Yahoo! UI Library > oop > oop.js (source view)
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    /**
     * Supplies object inheritance and manipulation utilities.  This adds
     * additional functionaity to what is provided in yui-base, and the
     * methods are applied directly to the YUI instance.  This module
     * is required for most YUI components.
     * @module oop
     */

        var L  = Y.Lang,
            A  = Y.Array,
            OP = Object.prototype;

        /**
         * The following methods are added to the YUI instance
         * @class YUI~oop
         */

        /**
         * Applies prototype properties from the supplier to the receiver.
         * The receiver can be a constructor or an instance.
         * @method augment
         * @param {Function} r  the object to receive the augmentation
         * @param {Function} s  the object that supplies the properties to augment
         * @param ov {boolean} if true, properties already on the receiver
         * will be overwritten if found on the supplier.
         * @param wl {string[]} a whitelist.  If supplied, only properties in
         * this list will be applied to the receiver.
         * @param args {Array | Any} arg or arguments to apply to the supplier
         * constructor when initializing.
         * @return {object} the augmented object
         *
         * @todo constructor optional?
         * @todo understanding what an instance is augmented with
         * @TODO best practices for overriding sequestered methods.
         */
        Y.augment = function(r, s, ov, wl, args) {
            var sProto           = s.prototype,
                newProto         = null,
                construct        = s,
                a                = (args) ? Y.Array(args) : [],
                rProto           = r.prototype,
                target           = rProto || r,
                applyConstructor = false,
                sequestered, replacements, i;

            // working on a class, so apply constructor infrastructure
            if (rProto && construct) {
                sequestered  = {};
                replacements = {};
                newProto     = {};

                // sequester all of the functions in the supplier and replace with
                // one that will restore all of them.
                Y.each(sProto, function(v, k) {
                    replacements[k] = function() {

    // Y.log('sequestered function "' + k + '" executed.  Initializing EventTarget');
    // overwrite the prototype with all of the sequestered functions,
    // but only if it hasn't been overridden
                        for (i in sequestered) {
                            if (sequestered.hasOwnProperty(i) && (this[i] === replacements[i])) {
                                // Y.log('... restoring ' + k);
                                this[i] = sequestered[i];
                            }
                        }

                        // apply the constructor
                        construct.apply(this, a);

                        // apply the original sequestered function
                        return sequestered[k].apply(this, arguments);
                    };

                    if ((!wl || (k in wl)) && (ov || !(k in this))) {
                        // Y.log('augment: ' + k);
                        if (L.isFunction(v)) {
                            // sequester the function
                            sequestered[k] = v;

    // replace the sequestered function with a function that will
    // restore all sequestered functions and exectue the constructor.
                            this[k] = replacements[k];
                        } else {
                            // Y.log('augment() applying non-function: ' + k);
                            this[k] = v;
                        }

                    }

                }, newProto, true);

            // augmenting an instance, so apply the constructor immediately
            } else {
                applyConstructor = true;
            }

            Y.mix(target, newProto || sProto, ov, wl);

            if (applyConstructor) {
                s.apply(target, a);
            }

            return r;
        };

        /**
         * Applies object properties from the supplier to the receiver.  If
         * the target has the property, and the property is an object, the target
         * object will be augmented with the supplier's value.  If the property
         * is an array, the suppliers value will be appended to the target.
         * @method aggregate
         * @param {Function} r  the object to receive the augmentation
         * @param {Function} s  the object that supplies the properties to augment
         * @param ov {boolean} if true, properties already on the receiver
         * will be overwritten if found on the supplier.
         * @param wl {string[]} a whitelist.  If supplied, only properties in
         * this list will be applied to the receiver.
         * @return {object} the extended object
         */
        Y.aggregate = function(r, s, ov, wl) {
            return Y.mix(r, s, ov, wl, 0, true);
        };

        /**
         * Utility to set up the prototype, constructor and superclass properties to
         * support an inheritance strategy that can chain constructors and methods.
         * Static members will not be inherited.
         *
         * @method extend
         * @param {Function} r   the object to modify
         * @param {Function} s the object to inherit
         * @param {Object} px prototype properties to add/override
         * @param {Object} sx static properties to add/override
         * @return {YUI} the YUI instance
         */
        Y.extend = function(r, s, px, sx) {
            if (!s||!r) {
                // @TODO error symbols
                Y.error("extend failed, verify dependencies");
            }

            var sp = s.prototype, rp=Y.Object(sp);
            r.prototype=rp;

            rp.constructor=r;
            r.superclass=sp;

            // assign constructor property
            if (s != Object && sp.constructor == OP.constructor) {
                sp.constructor=s;
            }

            // add prototype overrides
            if (px) {
                Y.mix(rp, px, true);
            }

            // add object overrides
            if (sx) {
                Y.mix(r, sx, true);
            }

            return r;
        };

        /**
         * Executes the supplied function for each item in
         * a collection.  Supports arrays, objects, and
         * Y.NodeLists
         * @method each
         * @param o the object to iterate
         * @param f the function to execute.  This function
         * receives the value, key, and object as parameters
         * @param proto if true, prototype properties are
         * iterated on objects
         * @return {YUI} the YUI instance
         */
        Y.each = function(o, f, c, proto) {

            if (o.each && o.item) {
                return o.each.call(o, f, c);
            } else {
                switch (A.test(o)) {
                    case 1:
                        return A.each(o, f, c);
                    case 2:
                        return A.each(Y.Array(o, 0, true), f, c);
                    default:
                        return Y.Object.each(o, f, c, proto);
                }
            }

            // return Y.Object.each(o, f, c);
        };

        /**
         * Deep obj/array copy.  Functions will are cloned with Y.bind.
         * Array-like objects are treated as arrays.
         * primitives are returned untouched.  Optionally a
         * function can be provided to handle other data types,
         * filter keys, validate values, etc.
         *
         * @method clone
         * @param o what to clone
         * @param safe {boolean} if true, objects will not have prototype
         * items from the source.  If false, it does.  In this case, the
         * original is initally protected, but the clone is not completely immune
         * from changes to the source object prototype.  Also, cloned prototype
         * items that are deleted from the clone will result in the value
         * of the source prototype to be exposed.  If operating on a non-safe
         * clone, items should be nulled out rather than deleted.
         * @TODO review
         * @param f optional function to apply to each item in a collection
         *          it will be executed prior to applying the value to
         *          the new object.  Return false to prevent the copy.
         * @param c optional execution context for f
         * @param owner Owner object passed when clone is iterating an
         * object.  Used to set up context for cloned functions.
         * @return {Array|Object} the cloned object
         */
        Y.clone = function(o, safe, f, c, owner) {

            if (!L.isObject(o)) {
                return o;
            }

            var o2;

            switch (L.type(o)) {
                case 'date':
                    return new Date(o);
                case 'regexp':
                    return new RegExp(o.source);
                case 'function':
                    o2 = Y.bind(o, owner);
                    break;
                case 'array':
                    o2 = [];
                    break;
                default:
                    o2 = (safe) ? {} : Y.Object(o);
            }

            Y.each(o, function(v, k) {
                if (!f || (f.call(c || this, v, k, this, o) !== false)) {
                    this[k] =  Y.clone(v, safe, f, c, this);
                }
            }, o2);

            return o2;
        };

        /**
         * Returns a function that will execute the supplied function in the
         * supplied object's context, optionally adding any additional
         * supplied parameters to the beginning of the arguments collection the
         * supplied to the function.
         *
         * @method bind
         * @param f {Function|String} the function to bind, or a function name
         * to execute on the context object
         * @param c the execution context
         * @param args* 0..n arguments to include before the arguments the
         * function is executed with.
         * @return {function} the wrapped function
         */
        Y.bind = function(f, c) {
            var xargs = arguments.length > 2 ? Y.Array(arguments, 2, true) : null;
            return function () {
                var fn = L.isString(f) ? c[f] : f,
                    args = (xargs) ? xargs.concat(Y.Array(arguments, 0, true)) : arguments;
                return fn.apply(c || fn, args);
            };
        };

        /**
         * Returns a function that will execute the supplied function in the
         * supplied object's context, optionally adding any additional
         * supplied parameters to the end of the arguments the function
         * is executed with.
         *
         * @method rbind
         * @param f {Function|String} the function to bind, or a function name
         * to execute on the context object
         * @param c the execution context
         * @param args* 0..n arguments to append to the end of arguments collection
         * supplied to the function
         * @return {function} the wrapped function
         */
        Y.rbind = function(f, c) {
            var xargs = arguments.length > 2 ? Y.Array(arguments, 2, true) : null;
            return function () {
                var fn = L.isString(f) ? c[f] : f,
                    args = (xargs) ? Y.Array(arguments, 0, true).concat(xargs) : arguments;
                return fn.apply(c || fn, args);
            };
        };

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