Subj : Re: Iterating through all Array elements from C
To   : netscape.public.mozilla.jseng
From : Matthew Mondor
Date : Sat Feb 12 2005 01:08 pm

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On Thu, 10 Feb 2005 10:41:10 -0500
Matthew Mondor <mm_lists@pulsar-zone.net> wrote:
 
> Using SpiderMonkey, I have a static function of a class which requires
> an array as a parameter.  I can get the parameter, verify that it is
> indeed an Array...  However, I seem to have trouble to iterate though
> all its elements, if the indexes are either non-contiguous or
> non-numeric at initialization:

I could make it work, creating an iterator function as attached. 
Unfortunately, I had to use JS_Enumerate() with an JSIdArray, which
seems to be marked as being private API according to the reference docs.
At least it solved my problem for now.

Matt

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static JSBool	object_iterate(JSContext *, JSObject *, void *,
		    JSBool (*)(JSContext *, jsval *, jsval *, void *));

/*
 * Was written to be able to iterate over all elements of an array object,
 * despite being an associated array or not, or a mix of both.  Unfortunately
 * uses marked as private JSIdArray structure.
 */
static JSBool
object_iterate(JSContext *cx, JSObject *obj, void *udata,
    JSBool (*func)(JSContext *, jsval *, jsval *, void *))
{
	JSIdArray	*a;
	jsval		id, val;
	char		*name;
	jsint		i;
	JSBool		ret = JS_FALSE;

	if ((a = JS_Enumerate(cx, obj)) != NULL) {
		for (i = 0; i < a->length; i++) {
			JS_IdToValue(cx, a->vector[i], &id);
			if (JSVAL_IS_STRING(id)) {
				/*
				 * Property id is a string, attempt to
				 * lookup its value by name.
				 */
				name = JS_GetStringBytes(JSVAL_TO_STRING(id));
				if (!JS_LookupProperty(cx, obj, name, &val))
					continue;
			} else {
				/*
				 * Property id is a number, attempt to
				 * lookup its array element by index.
				 */
				if (!JS_LookupElement(cx, obj,
				    JSVAL_TO_INT(id), &val))
						continue;
			}
			if (!(ret = func(cx, &id, &val, udata)))
				break;
		}
		JS_DestroyIdArray(cx, a);
	}

	return ret;
}


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