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No need to lookup parent/proto for iteration objects used for enumeration, and cache the last free iteration object for re-use (558058, r=brendan).

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This commit is contained in:
Andreas Gal
2010-04-08 10:55:58 -07:00
parent dad9a6e34e
commit ccc2834654
3 changed files with 37 additions and 8 deletions
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37
js/src/jsiter.cpp
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@@ -392,15 +392,29 @@ js_ValueToIterator(JSContext *cx, uintN flags, jsval *vp)
default_iter:
/*
* Fail over to the default enumerating native iterator.
*
* Create iterobj with a NULL parent to ensure that we use the
* correct scope chain to lookup the iterator's constructor. Since
* we use the parent slot to keep track of the iterable, we must
* fix it up after.
*/
iterobj = js_NewObject(cx, &js_IteratorClass, NULL, NULL);
if (!iterobj)
return false;
if (flags & JSITER_ENUMERATE) {
/*
* The iterator object for JSITER_ENUMERATE never escapes, so we
* don't care for the proper parent/proto to be set. This also
* allows us to re-use a previous iterator object that was freed
* by JSOP_ENDITER.
*/
if ((iterobj = JS_THREAD_DATA(cx)->cachedIteratorObject) != NULL) {
JS_THREAD_DATA(cx)->cachedIteratorObject = NULL;
} else {
if (!(iterobj = js_NewObjectWithGivenProto(cx, &js_IteratorClass, NULL, NULL)))
return false;
}
} else {
/*
* These objects don't escape either, but we construct a
* StopIteration exception based on the parent of the iterator
* object, so we need the correct parent here.
*/
if (!(iterobj = js_NewObject(cx, &js_IteratorClass, NULL, NULL)))
return false;
}
/* Store in *vp to protect it from GC (callers must root vp). */
*vp = OBJECT_TO_JSVAL(iterobj);
@@ -434,6 +448,13 @@ js_CloseIterator(JSContext *cx, jsval v)
if (clasp == &js_IteratorClass) {
js_CloseNativeIterator(cx, obj);
/*
* Note that we don't care what kind of iterator we close here. Even if it
* is not JSITER_ENUMERATE, it is safe to re-use the object later on for a
* JSITER_ENUMERATE iteration.
*/
JS_THREAD_DATA(cx)->cachedIteratorObject = obj;
}
#if JS_HAS_GENERATORS
else if (clasp == &js_GeneratorClass) {