/*

 * Metadata - jQuery plugin for parsing metadata from elements

 *

 * Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan

 *

 * Dual licensed under the MIT and GPL licenses:

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

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

 *

 * Revision: $Id: jquery.metadata.js 4187 2007-12-16 17:15:27Z joern.zaefferer $

 *

 */



/**

 * 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);