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Implement a way to use fast _filtered inheritance trick and still use #hasOwnProperty() checks in Base#_set()

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This commit is contained in:
Jürg Lehni 2013-10-19 12:05:53 +02:00
parent 0b7e128426
commit d59ed6d7c0
1 changed files with 19 additions and 9 deletions
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28
src/core/Base.js
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@ -75,13 +75,16 @@ Base.inject(/** @lends Base# */{
*/
_set: function(props, exclude) {
if (props && Base.isPlainObject(props)) {
for (var key in props) {
// Note: We don't use key.hasOwnProperty() so we can use the
// efficient _filtered inheritance trick in the argument reading
// code, where undefined is used to mask already consumed
// named arguments in the inherited object.
if (key in this && (!exclude || !exclude[key])) {
// If props is a filtering object, we need to execute hasOwnProperty
// on the original object (it's parent / prototype). See _filtered
// inheritance trick in the argument reading code.
var orig = props._filtering ? Object.getPrototypeOf(props) : props;
for (var key in orig) {
if (key in this && orig.hasOwnProperty(key)
&& (!exclude || !exclude[key])) {
var value = props[key];
// Due to the _filtered inheritance trick, undefined is used
// to mask already consumed named arguments.
if (value !== undefined)
this[key] = value;
}
@ -257,9 +260,16 @@ Base.inject(/** @lends Base# */{
if (hasObject) {
// Create a _filtered object that inherits from argument 0, and
// override all fields that were already read with undefined.
if (!list._filtered)
list._filtered = Base.create(list[0]);
list._filtered[name] = undefined; // Delete won't work
var filtered = list._filtered;
if (!filtered) {
filtered = list._filtered = Base.create(list[0]);
// Mark as _filtering so Base#_set() can execute
// hasOwnProperty on its parent.
filtered._filtering = true;
}
// delete wouldn't work since the masked parent's value would
// shine through.
filtered[name] = undefined;
}
return this.read(hasObject ? [value] : list, start, length, options);
},