callbacks.js

(function( jQuery ) {

// String to Object flags format cache
var flagsCache = {};

// Convert String-formatted flags into Object-formatted ones and store in cache
function createFlags( flags ) {
	var object = flagsCache[ flags ] = {},
		i, length;
	flags = flags.split( /\s+/ );
	for ( i = 0, length = flags.length; i < length; i++ ) {
		object[ flags[i] ] = true;
	}
	return object;
}

/*
 * Create a callback list using the following parameters:
 *
 *	flags:	an optional list of space-separated flags that will change how
 *			the callback list behaves
 *
 * By default a callback list will act like an event callback list and can be
 * "fired" multiple times.
 *
 * Possible flags:
 *
 *	once:			will ensure the callback list can only be fired once (like a Deferred)
 *
 *	memory:			will keep track of previous values and will call any callback added
 *					after the list has been fired right away with the latest "memorized"
 *					values (like a Deferred)
 *
 *	unique:			will ensure a callback can only be added once (no duplicate in the list)
 *
 *	stopOnFalse:	interrupt callings when a callback returns false
 *
 */
jQuery.Callbacks = function( flags ) {

	// Convert flags from String-formatted to Object-formatted
	// (we check in cache first)
	flags = flags ? ( flagsCache[ flags ] || createFlags( flags ) ) : {};

	var // Actual callback list
		list = [],
		// Stack of fire calls for repeatable lists
		stack = [],
		// Last fire value (for non-forgettable lists)
		memory,
		// Flag to know if list is currently firing
		firing,
		// First callback to fire (used internally by add and fireWith)
		firingStart,
		// End of the loop when firing
		firingLength,
		// Index of currently firing callback (modified by remove if needed)
		firingIndex,
		// Add one or several callbacks to the list
		add = function( args ) {
			var i,
				length,
				elem,
				type,
				actual;
			for ( i = 0, length = args.length; i < length; i++ ) {
				elem = args[ i ];
				type = jQuery.type( elem );
				if ( type === "array" ) {
					// Inspect recursively
					add( elem );
				} else if ( type === "function" ) {
					// Add if not in unique mode and callback is not in
					if ( !flags.unique || !self.has( elem ) ) {
						list.push( elem );
					}
				}
			}
		},
		// Fire callbacks
		fire = function( context, args ) {
			args = args || [];
			memory = !flags.memory || [ context, args ];
			firing = true;
			firingIndex = firingStart || 0;
			firingStart = 0;
			firingLength = list.length;
			for ( ; list && firingIndex < firingLength; firingIndex++ ) {
				if ( list[ firingIndex ].apply( context, args ) === false && flags.stopOnFalse ) {
					memory = true; // Mark as halted
					break;
				}
			}
			firing = false;
			if ( list ) {
				if ( !flags.once ) {
					if ( stack && stack.length ) {
						memory = stack.shift();
						self.fireWith( memory[ 0 ], memory[ 1 ] );
					}
				} else if ( memory === true ) {
					self.disable();
				} else {
					list = [];
				}
			}
		},
		// Actual Callbacks object
		self = {
			// Add a callback or a collection of callbacks to the list
			add: function() {
				if ( list ) {
					var length = list.length;
					add( arguments );
					// Do we need to add the callbacks to the
					// current firing batch?
					if ( firing ) {
						firingLength = list.length;
					// With memory, if we're not firing then
					// we should call right away, unless previous
					// firing was halted (stopOnFalse)
					} else if ( memory && memory !== true ) {
						firingStart = length;
						fire( memory[ 0 ], memory[ 1 ] );
					}
				}
				return this;
			},
			// Remove a callback from the list
			remove: function() {
				if ( list ) {
					var args = arguments,
						argIndex = 0,
						argLength = args.length;
					for ( ; argIndex < argLength ; argIndex++ ) {
						for ( var i = 0; i < list.length; i++ ) {
							if ( args[ argIndex ] === list[ i ] ) {
								// Handle firingIndex and firingLength
								if ( firing ) {
									if ( i <= firingLength ) {
										firingLength--;
										if ( i <= firingIndex ) {
											firingIndex--;
										}
									}
								}
								// Remove the element
								list.splice( i--, 1 );
								// If we have some unicity property then
								// we only need to do this once
								if ( flags.unique ) {
									break;
								}
							}
						}
					}
				}
				return this;
			},
			// Control if a given callback is in the list
			has: function( fn ) {
				if ( list ) {
					var i = 0,
						length = list.length;
					for ( ; i < length; i++ ) {
						if ( fn === list[ i ] ) {
							return true;
						}
					}
				}
				return false;
			},
			// Remove all callbacks from the list
			empty: function() {
				list = [];
				return this;
			},
			// Have the list do nothing anymore
			disable: function() {
				list = stack = memory = undefined;
				return this;
			},
			// Is it disabled?
			disabled: function() {
				return !list;
			},
			// Lock the list in its current state
			lock: function() {
				stack = undefined;
				if ( !memory || memory === true ) {
					self.disable();
				}
				return this;
			},
			// Is it locked?
			locked: function() {
				return !stack;
			},
			// Call all callbacks with the given context and arguments
			fireWith: function( context, args ) {
				if ( stack ) {
					if ( firing ) {
						if ( !flags.once ) {
							stack.push( [ context, args ] );
						}
					} else if ( !( flags.once && memory ) ) {
						fire( context, args );
					}
				}
				return this;
			},
			// Call all the callbacks with the given arguments
			fire: function() {
				self.fireWith( this, arguments );
				return this;
			},
			// To know if the callbacks have already been called at least once
			fired: function() {
				return !!memory;
			}
		};

	return self;
};

})( jQuery );