JSClass.enumerate

Syntax

typedef JSBool (*JSNewEnumerateOp)(JSContext *cx, JSObject *obj,
    JSIterateOp enum_op, jsval *statep, jsid *idp);

Description

This callback enumerates the properties of an object. To use a JSNewEnumerateOp in a JSClass, set the JSCLASS_NEW_ENUMERATE bit in the JSClass.flags field and set the JSClass.enumerate field to your JSNewEnumerateOp, casting it to JSEnumerateOp. (SpiderMonkey, noting the JSCLASS_NEW_ENUMERATE flag, will cast that function pointer back to type JSNewEnumerateOp before calling it.)

The behavior depends on the value of enum_op:

JSENUMERATE_INIT

A new, opaque iterator state should be allocated and stored in *statep. (You can use PRIVATE_TO_JSVAL() to tag the pointer to be stored.)

The number of properties that will be enumerated should be returned as an integer jsval in *idp, if idp is non-null, and provided the number of enumerable properties is known. If idp is non-null and the number of enumerable properties can't be computed in advance, *idp should be set to JSVAL_ZERO.

JSENUMERATE_NEXT

A previously allocated opaque iterator state is passed in via statep. Return the next jsid in the iteration using *idp. The opaque iterator state pointed at by statep is destroyed and *statep is set to JSVAL_NULL if there are no properties left to enumerate.

JSENUMERATE_DESTROY

Destroy the opaque iterator state previously allocated in *statep by a call to this function when enum_op was JSENUMERATE_INIT.

The callback returns JS_TRUE to indicate success or JS_FALSE to indicate failure.