blob: 9de94daa080d6864d529bf5a6868cd42657ac23f [file] [log] [blame]
// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
const cr = (function() {
/**
* Whether we are using a Mac or not.
* @type {boolean}
*/
const isMac = /Mac/.test(navigator.platform);
/**
* Builds an object structure for the provided namespace path,
* ensuring that names that already exist are not overwritten. For
* example:
* "a.b.c" -> a = {};a.b={};a.b.c={};
* @param {string} name Name of the object that this file defines.
* @param {*=} opt_object The object to expose at the end of the path.
* @param {Object=} opt_objectToExportTo The object to add the path to;
* default is {@code window}.
* @private
*/
function exportPath(name, opt_object, opt_objectToExportTo) {
var parts = name.split('.');
var cur = opt_objectToExportTo || window /* global */;
for (var part; parts.length && (part = parts.shift());) {
if (!parts.length && opt_object !== undefined) {
// last part and we have an object; use it
cur[part] = opt_object;
} else if (part in cur) {
cur = cur[part];
} else {
cur = cur[part] = {};
}
}
return cur;
};
/**
* Fires a property change event on the target.
* @param {EventTarget} target The target to dispatch the event on.
* @param {string} propertyName The name of the property that changed.
* @param {*} newValue The new value for the property.
* @param {*} oldValue The old value for the property.
*/
function dispatchPropertyChange(target, propertyName, newValue, oldValue) {
// TODO(arv): Depending on cr.Event here is a bit ugly.
var e = new cr.Event(propertyName + 'Change');
e.propertyName = propertyName;
e.newValue = newValue;
e.oldValue = oldValue;
target.dispatchEvent(e);
}
/**
* The kind of property to define in {@code defineProperty}.
* @enum {number}
*/
const PropertyKind = {
/**
* Plain old JS property where the backing data is stored as a "private"
* field on the object.
*/
JS: 'js',
/**
* The property backing data is stored as an attribute on an element.
*/
ATTR: 'attr',
/**
* The property backing data is stored as an attribute on an element. If the
* element has the attribute then the value is true.
*/
BOOL_ATTR: 'boolAttr'
};
/**
* Helper function for defineProperty that returns the getter to use for the
* property.
* @param {string} name
* @param {cr.PropertyKind} kind
* @param {*} defaultValue The default value. This is only used for the ATTR
* kind.
* @return {function():*} The getter for the property.
*/
function getGetter(name, kind, defaultValue) {
switch (kind) {
case PropertyKind.JS:
var privateName = name + '_';
return function() {
return this[privateName];
};
case PropertyKind.ATTR:
// For attr with default value we return the default value if the
// element is missing the attribute.
if (defaultValue == undefined) {
return function() {
return this.getAttribute(name);
};
} else {
return function() {
// WebKit uses null for non existant attributes.
var value = this.getAttribute(name);
return value !== null ? value : defaultValue;
};
}
case PropertyKind.BOOL_ATTR:
// Boolean attributes don't support default values.
return function() {
return this.hasAttribute(name);
};
}
}
/**
* Helper function for defineProperty that returns the setter of the right
* kind.
* @param {string} name The name of the property we are defining the setter
* for.
* @param {cr.PropertyKind} kind The kind of property we are getting the
* setter for.
* @return {function(*):void} The function to use as a setter.
*/
function getSetter(name, kind) {
switch (kind) {
case PropertyKind.JS:
var privateName = name + '_';
return function(value) {
var oldValue = this[privateName];
if (value !== oldValue) {
this[privateName] = value;
dispatchPropertyChange(this, name, value, oldValue);
}
};
case PropertyKind.ATTR:
return function(value) {
var oldValue = this[name];
if (value !== oldValue) {
this.setAttribute(name, value);
dispatchPropertyChange(this, name, value, oldValue);
}
};
case PropertyKind.BOOL_ATTR:
return function(value) {
var oldValue = this[name];
if (value !== oldValue) {
if (value)
this.setAttribute(name, name);
else
this.removeAttribute(name);
dispatchPropertyChange(this, name, value, oldValue);
}
};
}
}
/**
* Defines a property on an object. When the setter changes the value a
* property change event with the type {@code name + 'Change'} is fired.
* @param {!Object} The object to define the property for.
* @param {string} The name of the property.
* @param {cr.PropertyKind=} opt_kind What kind of underlying storage to use.
* @param {*} opt_defaultValue The default value.
*/
function defineProperty(obj, name, opt_kind, opt_default) {
if (typeof obj == 'function')
obj = obj.prototype;
var kind = opt_kind || PropertyKind.JS;
if (!obj.__lookupGetter__(name)) {
// For js properties we set the default value on the prototype.
if (kind == PropertyKind.JS && arguments.length > 3) {
var privateName = name + '_';
obj[privateName] = opt_default;
}
obj.__defineGetter__(name, getGetter(name, kind, opt_default));
}
if (!obj.__lookupSetter__(name)) {
obj.__defineSetter__(name, getSetter(name, kind));
}
}
/**
* Counter for use with createUid
*/
var uidCounter = 1;
/**
* @return {number} A new unique ID.
*/
function createUid() {
return uidCounter++;
}
/**
* Returns a unique ID for the item. This mutates the item so it needs to be
* an object
* @param {!Object} item The item to get the unique ID for.
* @return {number} The unique ID for the item.
*/
function getUid(item) {
if (item.hasOwnProperty('uid'))
return item.uid;
return item.uid = createUid();
}
/**
* Partially applies this function to a particular 'this object' and zero or
* more arguments. The result is a new function with some arguments of the
* first function pre-filled and the value of |this| 'pre-specified'.
*
* Remaining arguments specified at call-time are appended to the pre-
* specified ones.
*
* Usage:
* <pre>var barMethBound = bind(myFunction, myObj, 'arg1', 'arg2');
* barMethBound('arg3', 'arg4');</pre>
*
* @param {Function} fn A function to partially apply.
* @param {Object|undefined} selfObj Specifies the object which |this| should
* point to when the function is run. If the value is null or undefined,
* it will default to the global object.
* @param {...*} var_args Additional arguments that are partially
* applied to the function.
*
* @return {!Function} A partially-applied form of the function bind() was
* invoked as a method of.
*/
function bind(fn, selfObj, var_args) {
var boundArgs = Array.prototype.slice.call(arguments, 2);
return function() {
var args = Array.prototype.slice.call(arguments);
args.unshift.apply(args, boundArgs);
return fn.apply(selfObj, args);
}
}
/**
* Dispatches a simple event on an event target.
* @param {!EventTarget} target The event target to dispatch the event on.
* @param {string} type The type of the event.
* @param {boolean=} opt_bubbles Whether the event bubbles or not.
* @param {boolean=} opt_cancelable Whether the default action of the event
* can be prevented.
* @return {boolean} If any of the listeners called {@code preventDefault}
* during the dispatch this will return false.
*/
function dispatchSimpleEvent(target, type, opt_bubbles, opt_cancelable) {
var e = new cr.Event(type, opt_bubbles, opt_cancelable);
return target.dispatchEvent(e);
}
/**
* @param {string} name
* @param {!Function} fun
*/
function define(name, fun) {
var obj = exportPath(name);
var exports = fun();
for (var key in exports) {
obj[key] = exports[key];
}
}
/**
* Document used for various document related operations.
* @type {!Document}
*/
var doc = document;
/**
* Allows you to run func in the context of a different document.
* @param {!Document} document The document to use.
* @param {function():*} func The function to call.
*/
function withDoc(document, func) {
var oldDoc = doc;
doc = document;
try {
func();
} finally {
doc = oldDoc;
}
}
return {
isMac: isMac,
define: define,
defineProperty: defineProperty,
PropertyKind: PropertyKind,
createUid: createUid,
getUid: getUid,
bind: bind,
dispatchSimpleEvent: dispatchSimpleEvent,
dispatchPropertyChange: dispatchPropertyChange,
/**
* The document that we are currently using.
* @type {!Document}
*/
get doc() {
return doc;
},
withDoc: withDoc
};
})();