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/*******************************************************************************

 jquery.mb.components

 Copyright (c) 2001-2010. Matteo Bicocchi (Pupunzi); Open lab srl, Firenze - Italy

 email: mbicocchi@open-lab.com

 site: http://pupunzi.com

 Licences: MIT, GPL

 http://www.opensource.org/licenses/mit-license.php

 http://www.gnu.org/licenses/gpl.html

 ******************************************************************************/

/**

 * Sets the type of metadata to use. Metadata is encoded in JSON, and each property

 * in the JSON will become a property of the element itself.

 *

 * There are three supported types of metadata storage:

 *

 *   attr:  Inside an attribute. The name parameter indicates *which* attribute.

 *          

 *   class: Inside the class attribute, wrapped in curly braces: { }

 *   

 *   elem:  Inside a child element (e.g. a script tag). The

 *          name parameter indicates *which* element.

 *          

 * The metadata for an element is loaded the first time the element is accessed via jQuery.

 *

 * As a result, you can define the metadata type, use $(expr) to load the metadata into the elements

 * matched by expr, then redefine the metadata type and run another $(expr) for other elements.

 * 

 * @name $.metadata.setType

 *

 * @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>

 * @before $.metadata.setType("class")

 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"

 * @desc Reads metadata from the class attribute

 * 

 * @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>

 * @before $.metadata.setType("attr", "data")

 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"

 * @desc Reads metadata from a "data" attribute

 * 

 * @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>

 * @before $.metadata.setType("elem", "script")

 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"

 * @desc Reads metadata from a nested script element

 * 

 * @param String type The encoding type

 * @param String name The name of the attribute to be used to get metadata (optional)

 * @cat Plugins/Metadata

 * @descr Sets the type of encoding to be used when loading metadata for the first time

 * @type undefined

 * @see metadata()

 */

(function($) {

$.extend({

        metadata : {

                defaults : {

                        type: 'class',

                        name: 'metadata',

                        cre: /({.*})/,

                        single: 'metadata'

                },

                setType: function( type, name ){

                        this.defaults.type = type;

                        this.defaults.name = name;

                },

                get: function( elem, opts ){

                        var settings = $.extend({},this.defaults,opts);

                        // check for empty string in single property

                        if ( !settings.single.length ) settings.single = 'metadata';

                        var data = $.data(elem, settings.single);

                        // returned cached data if it already exists

                        if ( data ) return data;

                        data = "{}";

                        if ( settings.type == "class" ) {

                                var m = settings.cre.exec( elem.className );

                                if ( m )

                                        data = m[1];

                        } else if ( settings.type == "elem" ) {

                                if( !elem.getElementsByTagName )

                                        return undefined;

                                var e = elem.getElementsByTagName(settings.name);

                                if ( e.length )

                                        data = $.trim(e[0].innerHTML);

                        } else if ( elem.getAttribute != undefined ) {

                                var attr = elem.getAttribute( settings.name );

                                if ( attr )

                                        data = attr;

                        }

                        if ( data.indexOf( '{' ) <0 )

                        data = "{" + data + "}";

                        data = eval("(" + data + ")");

                        $.data( elem, settings.single, data );

                        return data;

                }

        }

});

/**

 * Returns the metadata object for the first member of the jQuery object.

 *

 * @name metadata

 * @descr Returns element's metadata object

 * @param Object opts An object contianing settings to override the defaults

 * @type jQuery

 * @cat Plugins/Metadata

 */

$.fn.metadata = function( opts ){

        return $.metadata.get( this[0], opts );

};

})(jQuery);