jquery/src/data.js

var rbrace = /(?:\{[\s\S]*\}|\[[\s\S]*\])$/,
	rmultiDash = /([A-Z])/g;

jQuery.extend({
	cache: {},

	deletedIds: [],

	// Remove at next major release (1.9/2.0)
	uuid: 0,

	// Unique for each copy of jQuery on the page
	// Non-digits removed to match rinlinejQuery
	expando: "jQuery" + ( jQuery.fn.jquery + Math.random() ).replace( /\D/g, "" ),

	// The following elements throw uncatchable exceptions if you
	// attempt to add expando properties to them.
	noData: {
		"embed": true,
		// Ban all objects except for Flash (which handle expandos)
		"object": "clsid:D27CDB6E-AE6D-11cf-96B8-444553540000",
		"applet": true
	},

	hasData: function( elem ) {
		elem = elem.nodeType ? jQuery.cache[ elem[jQuery.expando] ] : elem[ jQuery.expando ];
		return !!elem && !isEmptyDataObject( elem );
	},

	data: function( elem, name, data, pvt /* Internal Use Only */ ) {
		if ( !jQuery.acceptData( elem ) ) {
			return;
		}

		var thisCache, ret,
			internalKey = jQuery.expando,
			getByName = typeof name === "string",

			// We have to handle DOM nodes and JS objects differently because IE6-7
			// can't GC object references properly across the DOM-JS boundary
			isNode = elem.nodeType,

			// Only DOM nodes need the global jQuery cache; JS object data is
			// attached directly to the object so GC can occur automatically
			cache = isNode ? jQuery.cache : elem,

			// Only defining an ID for JS objects if its cache already exists allows
			// the code to shortcut on the same path as a DOM node with no cache
			id = isNode ? elem[ internalKey ] : elem[ internalKey ] && internalKey;

		// Avoid doing any more work than we need to when trying to get data on an
		// object that has no data at all
		if ( (!id || !cache[id] || (!pvt && !cache[id].data)) && getByName && data === undefined ) {
			return;
		}

		if ( !id ) {
			// Only DOM nodes need a new unique ID for each element since their data
			// ends up in the global cache
			if ( isNode ) {
				elem[ internalKey ] = id = jQuery.deletedIds.pop() || jQuery.guid++;
			} else {
				id = internalKey;
			}
		}

		if ( !cache[ id ] ) {
			cache[ id ] = {};

			// Avoids exposing jQuery metadata on plain JS objects when the object
			// is serialized using JSON.stringify
			if ( !isNode ) {
				cache[ id ].toJSON = jQuery.noop;
			}
		}

		// An object can be passed to jQuery.data instead of a key/value pair; this gets
		// shallow copied over onto the existing cache
		if ( typeof name === "object" || typeof name === "function" ) {
			if ( pvt ) {
				cache[ id ] = jQuery.extend( cache[ id ], name );
			} else {
				cache[ id ].data = jQuery.extend( cache[ id ].data, name );
			}
		}

		thisCache = cache[ id ];

		// jQuery data() is stored in a separate object inside the object's internal data
		// cache in order to avoid key collisions between internal data and user-defined
		// data.
		if ( !pvt ) {
			if ( !thisCache.data ) {
				thisCache.data = {};
			}

			thisCache = thisCache.data;
		}

		if ( data !== undefined ) {
			thisCache[ jQuery.camelCase( name ) ] = data;
		}

		// Check for both converted-to-camel and non-converted data property names
		// If a data property was specified
		if ( getByName ) {

			// First Try to find as-is property data
			ret = thisCache[ name ];

			// Test for null|undefined property data
			if ( ret == null ) {

				// Try to find the camelCased property
				ret = thisCache[ jQuery.camelCase( name ) ];
			}
		} else {
			ret = thisCache;
		}

		return ret;
	},

	removeData: function( elem, name, pvt /* Internal Use Only */ ) {
		if ( !jQuery.acceptData( elem ) ) {
			return;
		}

		var thisCache, i, l,

			isNode = elem.nodeType,

			// See jQuery.data for more information
			cache = isNode ? jQuery.cache : elem,
			id = isNode ? elem[ jQuery.expando ] : jQuery.expando;

		// If there is already no cache entry for this object, there is no
		// purpose in continuing
		if ( !cache[ id ] ) {
			return;
		}

		if ( name ) {

			thisCache = pvt ? cache[ id ] : cache[ id ].data;

			if ( thisCache ) {

				// Support array or space separated string names for data keys
				if ( !jQuery.isArray( name ) ) {

					// try the string as a key before any manipulation
					if ( name in thisCache ) {
						name = [ name ];
					} else {

						// split the camel cased version by spaces unless a key with the spaces exists
						name = jQuery.camelCase( name );
						if ( name in thisCache ) {
							name = [ name ];
						} else {
							name = name.split(" ");
						}
					}
				}

				for ( i = 0, l = name.length; i < l; i++ ) {
					delete thisCache[ name[i] ];
				}

				// If there is no data left in the cache, we want to continue
				// and let the cache object itself get destroyed
				if ( !( pvt ? isEmptyDataObject : jQuery.isEmptyObject )( thisCache ) ) {
					return;
				}
			}
		}

		// See jQuery.data for more information
		if ( !pvt ) {
			delete cache[ id ].data;

			// Don't destroy the parent cache unless the internal data object
			// had been the only thing left in it
			if ( !isEmptyDataObject( cache[ id ] ) ) {
				return;
			}
		}

		// Destroy the cache
		if ( isNode ) {
			jQuery.cleanData( [ elem ], true );

		// Use delete when supported for expandos or `cache` is not a window per isWindow (#10080)
		} else if ( jQuery.support.deleteExpando || cache != cache.window ) {
			delete cache[ id ];

		// When all else fails, null
		} else {
			cache[ id ] = null;
		}
	},

	// For internal use only.
	_data: function( elem, name, data ) {
		return jQuery.data( elem, name, data, true );
	},

	// A method for determining if a DOM node can handle the data expando
	acceptData: function( elem ) {
		var noData = elem.nodeName && jQuery.noData[ elem.nodeName.toLowerCase() ];

		// nodes accept data unless otherwise specified; rejection can be conditional
		return !noData || noData !== true && elem.getAttribute("classid") === noData;
	}
});

jQuery.fn.extend({
	data: function( key, value ) {
		var parts, part, attr, name, l,
			elem = this[0],
			i = 0,
			data = null;

		// Gets all values
		if ( key === undefined ) {
			if ( this.length ) {
				data = jQuery.data( elem );

				if ( elem.nodeType === 1 && !jQuery._data( elem, "parsedAttrs" ) ) {
					attr = elem.attributes;
					for ( l = attr.length; i < l; i++ ) {
						name = attr[i].name;

						if ( !name.indexOf( "data-" ) ) {
							name = jQuery.camelCase( name.substring(5) );

							dataAttr( elem, name, data[ name ] );
						}
					}
					jQuery._data( elem, "parsedAttrs", true );
				}
			}

			return data;
		}

		// Sets multiple values
		if ( typeof key === "object" ) {
			return this.each(function() {
				jQuery.data( this, key );
			});
		}

		parts = key.split( ".", 2 );
		parts[1] = parts[1] ? "." + parts[1] : "";
		part = parts[1] + "!";

		return jQuery.access( this, function( value ) {

			if ( value === undefined ) {
				data = this.triggerHandler( "getData" + part, [ parts[0] ] );

				// Try to fetch any internally stored data first
				if ( data === undefined && elem ) {
					data = jQuery.data( elem, key );
					data = dataAttr( elem, key, data );
				}

				return data === undefined && parts[1] ?
					this.data( parts[0] ) :
					data;
			}

			parts[1] = value;
			this.each(function() {
				var self = jQuery( this );

				self.triggerHandler( "setData" + part, parts );
				jQuery.data( this, key, value );
				self.triggerHandler( "changeData" + part, parts );
			});
		}, null, value, arguments.length > 1, null, false );
	},

	removeData: function( key ) {
		return this.each(function() {
			jQuery.removeData( this, key );
		});
	}
});

function dataAttr( elem, key, data ) {
	// If nothing was found internally, try to fetch any
	// data from the HTML5 data-* attribute
	if ( data === undefined && elem.nodeType === 1 ) {

		var name = "data-" + key.replace( rmultiDash, "-$1" ).toLowerCase();

		data = elem.getAttribute( name );

		if ( typeof data === "string" ) {
			try {
				data = data === "true" ? true :
				data === "false" ? false :
				data === "null" ? null :
				// Only convert to a number if it doesn't change the string
				+data + "" === data ? +data :
				rbrace.test( data ) ? jQuery.parseJSON( data ) :
					data;
			} catch( e ) {}

			// Make sure we set the data so it isn't changed later
			jQuery.data( elem, key, data );

		} else {
			data = undefined;
		}
	}

	return data;
}

// checks a cache object for emptiness
function isEmptyDataObject( obj ) {
	var name;
	for ( name in obj ) {

		// if the public data object is empty, the private is still empty
		if ( name === "data" && jQuery.isEmptyObject( obj[name] ) ) {
			continue;
		}
		if ( name !== "toJSON" ) {
			return false;
		}
	}

	return true;
}