Function iterator_next

src/PyBytesProxyHandler.cc:86–151

static JSClass bytesIteratorClass = {"BytesIterator", JSCLASS_HAS_RESERVED_SLOTS(BytesIteratorSlotCount)};

static bool iterator_next(JSContext *cx, unsigned argc, JS::Value *vp) {
  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
  JS::RootedObject thisObj(cx);
  if (!args.computeThis(cx, &thisObj)) return false;

  JS::PersistentRootedObject *arrayBuffer = JS::GetMaybePtrFromReservedSlot<JS::PersistentRootedObject>(thisObj, BytesIteratorSlotIteratedObject);
  JS::RootedObject rootedArrayBuffer(cx, arrayBuffer->get());

  JS::RootedValue rootedNextIndex(cx, JS::GetReservedSlot(thisObj, BytesIteratorSlotNextIndex));
  JS::RootedValue rootedItemKind(cx, JS::GetReservedSlot(thisObj, BytesIteratorSlotItemKind));

  int32_t nextIndex;
  int32_t itemKind;
  if (!JS::ToInt32(cx, rootedNextIndex, &nextIndex) || !JS::ToInt32(cx, rootedItemKind, &itemKind)) return false;

  JS::RootedObject result(cx, JS_NewPlainObject(cx));

  Py_ssize_t len = JS::GetArrayBufferByteLength(rootedArrayBuffer);

  if (nextIndex >= len) {
    // UnsafeSetReservedSlot(obj, ITERATOR_SLOT_TARGET, null); // TODO lose ref
    JS::RootedValue done(cx, JS::BooleanValue(true));
    if (!JS_SetProperty(cx, result, "done", done)) return false;
    args.rval().setObject(*result);
    return result;
  }

  JS::SetReservedSlot(thisObj, BytesIteratorSlotNextIndex, JS::Int32Value(nextIndex + 1));

  JS::RootedValue done(cx, JS::BooleanValue(false));
  if (!JS_SetProperty(cx, result, "done", done)) return false;

  if (itemKind == ITEM_KIND_VALUE) {
    bool isSharedMemory;
    JS::AutoCheckCannotGC autoNoGC(cx);
    uint8_t *data = JS::GetArrayBufferData(rootedArrayBuffer, &isSharedMemory, autoNoGC);

    JS::RootedValue value(cx, JS::Int32Value(data[nextIndex]));
    if (!JS_SetProperty(cx, result, "value", value)) return false;
  }
  else if (itemKind == ITEM_KIND_KEY_AND_VALUE) {
    JS::Rooted<JS::ValueArray<2>> items(cx);

    JS::RootedValue rootedNextIndex(cx, JS::Int32Value(nextIndex));
    items[0].set(rootedNextIndex);

    bool isSharedMemory;
    JS::AutoCheckCannotGC autoNoGC(cx);
    uint8_t *data = JS::GetArrayBufferData(rootedArrayBuffer, &isSharedMemory, autoNoGC);

    JS::RootedValue value(cx, JS::Int32Value(data[nextIndex]));
    items[1].set(value);

    JS::RootedValue pair(cx);
    JSObject *array = JS::NewArrayObject(cx, items);
    pair.setObject(*array);
    if (!JS_SetProperty(cx, result, "value", pair)) return false;
  }