File: collection/js/arraylist.js

            /**
             * Collection utilities beyond what is provided in the YUI core
             * @module collection
             * @submodule arraylist
             */
            
            var YArray      = Y.Array,
                YArray_each = YArray.each,
                ArrayListProto;
            
            /**
             * Generic ArrayList class for managing lists of items and iterating operations
             * over them.  The targeted use for this class is for augmentation onto a
             * class that is responsible for managing multiple instances of another class
             * (e.g. NodeList for Nodes).  The recommended use is to augment your class with
             * ArrayList, then use ArrayList.addMethod to mirror the API of the constituent
             * items on the list's API.
             *
             * The default implementation creates immutable lists, but mutability can be
             * provided via the arraylist-add submodule or by implementing mutation methods
             * directly on the augmented class's prototype.
             *
             * @class ArrayList
             * @constructor
             * @param items { Array } array of items this list will be responsible for
             */
            function ArrayList( items ) {
                if ( items !== undefined ) {
                    this._items = Y.Lang.isArray( items ) ? items : YArray( items );
                } else {
                    // ||= to support lazy initialization from augment
                    this._items = this._items || [];
                }
            }
            
            ArrayListProto = {
                /**
                 * Get an item by index from the list.  Override this method if managing a
                 * list of objects that have a different public representation (e.g. Node
                 * instances vs DOM nodes).  The iteration methods that accept a user
                 * function will use this method for access list items for operation.
                 *
                 * @method item
                 * @param i { Integer } index to fetch
                 * @return { mixed } the item at the requested index
                 */
                item: function ( i ) {
                    return this._items[i];
                },
            
                /**
                 * <p>Execute a function on each item of the list, optionally providing a
                 * custom execution context.  Default context is the item.</p>
                 *
                 * <p>The callback signature is <code>callback( item, index )</code>.</p>
                 *
                 * @method each
                 * @param fn { Function } the function to execute
                 * @param context { mixed } optional override 'this' in the function
                 * @return { ArrayList } this instance
                 * @chainable
                 */
                each: function ( fn, context ) {
                    YArray_each( this._items, function ( item, i ) {
                        item = this.item( i );
            
                        fn.call( context || item, item, i, this );
                    }, this);
            
                    return this;
                },
            
                /**
                 * <p>Execute a function on each item of the list, optionally providing a
                 * custom execution context.  Default context is the item.</p>
                 *
                 * <p>The callback signature is <code>callback( item, index )</code>.</p>
                 *
                 * <p>Unlike <code>each</code>, if the callback returns true, the
                 * iteration will stop.</p>
                 *
                 * @method some
                 * @param fn { Function } the function to execute
                 * @param context { mixed } optional override 'this' in the function
                 * @return { Boolean } True if the function returned true on an item
                 */
                some: function ( fn, context ) {
                    return YArray.some( this._items, function ( item, i ) {
                        item = this.item( i );
            
                        return fn.call( context || item, item, i, this );
                    }, this);
                },
            
                /**
                 * Finds the first index of the needle in the managed array of items.
                 *
                 * @method indexOf
                 * @param needle { mixed } The item to search for
                 * @return { Integer } Array index if found.  Otherwise -1
                 */
                indexOf: function ( needle ) {
                    return YArray.indexOf( this._items, needle );
                },
            
                /**
                 * How many items are in this list?
                 *
                 * @method size
                 * @return { Integer } Number of items in the list
                 */
                size: function () {
                    return this._items.length;
                },
            
                /**
                 * Is this instance managing any items?
                 *
                 * @method isEmpty
                 * @return { Boolean } true if 1 or more items are being managed
                 */
                isEmpty: function () {
                    return !this.size();
                },
            
                /**
                 * Provides an array-like representation for JSON.stringify.
                 *
                 * @method toJSON
                 * @return { Array } an array representation of the ArrayList
                 */
                toJSON: function () {
                    return this._items;
                }
            };
            // Default implementation does not distinguish between public and private
            // item getter
            /**
             * Protected method for optimizations that may be appropriate for API
             * mirroring. Similar in functionality to <code>item</code>, but is used by
             * methods added with <code>ArrayList.addMethod()</code>.
             *
             * @method _item
             * @protected
             * @param i { Integer } Index of item to fetch
             * @return { mixed } The item appropriate for pass through API methods
             */
            ArrayListProto._item = ArrayListProto.item;
            
            // Mixed onto existing proto to preserve constructor NOT being an own property.
            // This has bitten me when composing classes by enumerating, copying prototypes.
            Y.mix(ArrayList.prototype, ArrayListProto);
            
            Y.mix( ArrayList, {
            
                /**
                 * <p>Adds a pass through method to dest (typically the prototype of a list
                 * class) that calls the named method on each item in the list with
                 * whatever parameters are passed in.  Allows for API indirection via list
                 * instances.</p>
                 *
                 * <p>Accepts a single string name or an array of string names.</p>
                 *
                 * <pre><code>list.each( function ( item ) {
                 *     item.methodName( 1, 2, 3 );
                 * } );
                 * // becomes
                 * list.methodName( 1, 2, 3 );</code></pre>
                 *
                 * <p>Additionally, the pass through methods use the item retrieved by the
                 * <code>_item</code> method in case there is any special behavior that is
                 * appropriate for API mirroring.</p>
                 *
                 * <p>If the iterated method returns a value, the return value from the
                 * added method will be an array of values with each value being at the
                 * corresponding index for that item.  If the iterated method does not
                 * return a value, the added method will be chainable.
                 *
                 * @method addMethod
                 * @static
                 * @param dest {Object} Object or prototype to receive the iterator method
                 * @param name {String|String[]} Name of method of methods to create
                 */
                addMethod: function ( dest, names ) {
            
                    names = YArray( names );
            
                    YArray_each( names, function ( name ) {
                        dest[ name ] = function () {
                            var args = YArray( arguments, 0, true ),
                                ret  = [];
            
                            YArray_each( this._items, function ( item, i ) {
                                item = this._item( i );
            
                                var result = item[ name ].apply( item, args );
            
                                if ( result !== undefined && result !== item ) {
                                    ret[i] = result;
                                }
                            }, this);
            
                            return ret.length ? ret : this;
                        };
                    } );
                }
            } );
            
            Y.ArrayList = ArrayList;