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// Copyright (c) 2013 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.
'use strict';
base.require('base.events');
base.exportTo('base', function() {
/**
* 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,
opt_bubbles, opt_cancelable) {
var e = new base.Event(propertyName + 'Change',
opt_bubbles, opt_cancelable);
e.propertyName = propertyName;
e.newValue = newValue;
e.oldValue = oldValue;
var error;
e.throwError = function(err) { // workaround CR 239648
error = err;
};
target.dispatchEvent(e);
if (error)
throw error;
}
function setPropertyAndDispatchChange(obj, propertyName, newValue) {
var privateName = propertyName + '_';
var oldValue = obj[propertyName];
obj[privateName] = newValue;
if (oldValue !== newValue)
base.dispatchPropertyChange(obj, propertyName,
newValue, oldValue, true, false);
}
/**
* Converts a camelCase javascript property name to a hyphenated-lower-case
* attribute name.
* @param {string} jsName The javascript camelCase property name.
* @return {string} The equivalent hyphenated-lower-case attribute name.
*/
function getAttributeName(jsName) {
return jsName.replace(/([A-Z])/g, '-$1').toLowerCase();
}
/* Creates a private name unlikely to collide with object properties names
* @param {string} name The defineProperty name
* @return {string} an obfuscated name
*/
function getPrivateName(name) {
return name + '_base_';
}
/**
* The kind of property to define in {@code defineProperty}.
* @enum {number}
* @const
*/
var 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 The name of the property.
* @param {base.PropertyKind} kind The kind of the property.
* @return {function():*} The getter for the property.
*/
function getGetter(name, kind) {
switch (kind) {
case PropertyKind.JS:
var privateName = getPrivateName(name);
return function() {
return this[privateName];
};
case PropertyKind.ATTR:
var attributeName = getAttributeName(name);
return function() {
return this.getAttribute(attributeName);
};
case PropertyKind.BOOL_ATTR:
var attributeName = getAttributeName(name);
return function() {
return this.hasAttribute(attributeName);
};
}
}
/**
* 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 {base.PropertyKind} kind The kind of property we are getting the
* setter for.
* @param {function(*):void=} opt_setHook A function to run after the property
* is set, but before the propertyChange event is fired.
* @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 {function(*):void} The function to use as a setter.
*/
function getSetter(name, kind, opt_setHook, opt_bubbles, opt_cancelable) {
switch (kind) {
case PropertyKind.JS:
var privateName = getPrivateName(name);
return function(value) {
var oldValue = this[privateName];
if (value !== oldValue) {
this[privateName] = value;
if (opt_setHook)
opt_setHook.call(this, value, oldValue);
dispatchPropertyChange(this, name, value, oldValue,
opt_bubbles, opt_cancelable);
}
};
case PropertyKind.ATTR:
var attributeName = getAttributeName(name);
return function(value) {
var oldValue = this.getAttribute(attributeName);
if (value !== oldValue) {
if (value == undefined)
this.removeAttribute(attributeName);
else
this.setAttribute(attributeName, value);
if (opt_setHook)
opt_setHook.call(this, value, oldValue);
dispatchPropertyChange(this, name, value, oldValue,
opt_bubbles, opt_cancelable);
}
};
case PropertyKind.BOOL_ATTR:
var attributeName = getAttributeName(name);
return function(value) {
var oldValue = (this.getAttribute(attributeName) === name);
if (value !== oldValue) {
if (value)
this.setAttribute(attributeName, name);
else
this.removeAttribute(attributeName);
if (opt_setHook)
opt_setHook.call(this, value, oldValue);
dispatchPropertyChange(this, name, value, oldValue,
opt_bubbles, opt_cancelable);
}
};
}
}
/**
* 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} obj The object to define the property for.
* @param {string} name The name of the property.
* @param {base.PropertyKind=} opt_kind What kind of underlying storage to
* use.
* @param {function(*):void=} opt_setHook A function to run after the
* property is set, but before the propertyChange event is fired.
* @param {boolean=} opt_bubbles Whether the event bubbles or not.
* @param {boolean=} opt_cancelable Whether the default action of the event
* can be prevented.
*/
function defineProperty(obj, name, opt_kind, opt_setHook,
opt_bubbles, opt_cancelable) {
console.error("Don't use base.defineProperty");
if (typeof obj == 'function')
obj = obj.prototype;
var kind = opt_kind || PropertyKind.JS;
if (!obj.__lookupGetter__(name))
obj.__defineGetter__(name, getGetter(name, kind));
if (!obj.__lookupSetter__(name))
obj.__defineSetter__(name, getSetter(name, kind, opt_setHook,
opt_bubbles, opt_cancelable));
}
return {
PropertyKind: PropertyKind,
defineProperty: defineProperty,
dispatchPropertyChange: dispatchPropertyChange,
setPropertyAndDispatchChange: setPropertyAndDispatchChange
};
});
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