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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "js/ForOfIterator.h"
#include "js/friend/ErrorMessages.h" // js::GetErrorMessage, JSMSG_*
#include "vm/Interpreter.h"
#include "vm/JSContext.h"
#include "vm/JSObject.h"
#include "vm/PIC.h"
#include "vm/Realm.h"
#include "vm/JSObject-inl.h"
using namespace js;
using JS::ForOfIterator;
bool ForOfIterator::init(HandleValue iterable,
NonIterableBehavior nonIterableBehavior) {
JSContext* cx = cx_;
RootedObject iterableObj(cx, ToObject(cx, iterable));
if (!iterableObj) {
return false;
}
MOZ_ASSERT(index == NOT_ARRAY);
// Check the PIC first for a match.
if (iterableObj->is<ArrayObject>()) {
ForOfPIC::Chain* stubChain = ForOfPIC::getOrCreate(cx);
if (!stubChain) {
return false;
}
bool optimized;
if (!stubChain->tryOptimizeArray(cx, iterableObj.as<ArrayObject>(),
&optimized)) {
return false;
}
if (optimized) {
// Got optimized stub. Array is optimizable.
index = 0;
iterator = iterableObj;
nextMethod.setUndefined();
return true;
}
}
MOZ_ASSERT(index == NOT_ARRAY);
RootedValue callee(cx);
RootedId iteratorId(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().iterator));
if (!GetProperty(cx, iterableObj, iterable, iteratorId, &callee)) {
return false;
}
// If obj[@@iterator] is undefined and we were asked to allow non-iterables,
// bail out now without setting iterator. This will make valueIsIterable(),
// which our caller should check, return false.
if (nonIterableBehavior == AllowNonIterable && callee.isUndefined()) {
return true;
}
// Throw if obj[@@iterator] isn't callable.
// js::Invoke is about to check for this kind of error anyway, but it would
// throw an inscrutable error message about |method| rather than this nice
// one about |obj|.
if (!callee.isObject() || !callee.toObject().isCallable()) {
UniqueChars bytes =
DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, iterable, nullptr);
if (!bytes) {
return false;
}
JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_NOT_ITERABLE,
bytes.get());
return false;
}
RootedValue res(cx);
if (!js::Call(cx, callee, iterable, &res)) {
return false;
}
if (!res.isObject()) {
return ThrowCheckIsObject(cx, CheckIsObjectKind::GetIterator);
}
RootedObject iteratorObj(cx, &res.toObject());
if (!GetProperty(cx, iteratorObj, iteratorObj, cx->names().next, &res)) {
return false;
}
iterator = iteratorObj;
nextMethod = res;
return true;
}
inline bool ForOfIterator::nextFromOptimizedArray(MutableHandleValue vp,
bool* done) {
MOZ_ASSERT(index != NOT_ARRAY);
if (!CheckForInterrupt(cx_)) {
return false;
}
ArrayObject* arr = &iterator->as<ArrayObject>();
if (index >= arr->length()) {
vp.setUndefined();
*done = true;
return true;
}
*done = false;
// Try to get array element via direct access.
if (index < arr->getDenseInitializedLength()) {
vp.set(arr->getDenseElement(index));
if (!vp.isMagic(JS_ELEMENTS_HOLE)) {
++index;
return true;
}
}
return GetElement(cx_, iterator, iterator, index++, vp);
}
bool ForOfIterator::next(MutableHandleValue vp, bool* done) {
MOZ_ASSERT(iterator);
if (index != NOT_ARRAY) {
return nextFromOptimizedArray(vp, done);
}
RootedValue v(cx_);
if (!js::Call(cx_, nextMethod, iterator, &v)) {
return false;
}
if (!v.isObject()) {
return ThrowCheckIsObject(cx_, CheckIsObjectKind::IteratorNext);
}
RootedObject resultObj(cx_, &v.toObject());
if (!GetProperty(cx_, resultObj, resultObj, cx_->names().done, &v)) {
return false;
}
*done = ToBoolean(v);
if (*done) {
vp.setUndefined();
return true;
}
return GetProperty(cx_, resultObj, resultObj, cx_->names().value, vp);
}
// ES 2017 draft 0f10dba4ad18de92d47d421f378233a2eae8f077 7.4.6.
// When completion.[[Type]] is throw.
void ForOfIterator::closeThrow() {
MOZ_ASSERT(iterator);
RootedValue completionException(cx_);
RootedSavedFrame completionExceptionStack(cx_);
if (cx_->isExceptionPending()) {
if (!GetAndClearExceptionAndStack(cx_, &completionException,
&completionExceptionStack)) {
completionException.setUndefined();
completionExceptionStack = nullptr;
}
}
// Steps 1-2 (implicit)
// Step 3 (partial).
RootedValue returnVal(cx_);
if (!GetProperty(cx_, iterator, iterator, cx_->names().return_, &returnVal)) {
return;
}
// Step 4.
if (returnVal.isUndefined()) {
cx_->setPendingException(completionException, completionExceptionStack);
return;
}
// Step 3 (remaining part)
if (!returnVal.isObject()) {
JS_ReportErrorNumberASCII(cx_, GetErrorMessage, nullptr,
JSMSG_RETURN_NOT_CALLABLE);
return;
}
RootedObject returnObj(cx_, &returnVal.toObject());
if (!returnObj->isCallable()) {
JS_ReportErrorNumberASCII(cx_, GetErrorMessage, nullptr,
JSMSG_RETURN_NOT_CALLABLE);
return;
}
// Step 5.
RootedValue innerResultValue(cx_);
if (!js::Call(cx_, returnVal, iterator, &innerResultValue)) {
if (cx_->isExceptionPending()) {
cx_->clearPendingException();
}
}
// Step 6.
cx_->setPendingException(completionException, completionExceptionStack);
}