mirror of
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134 lines
2.8 KiB
C++
134 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef __NSAUTOJSVALHOLDER_H__
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#define __NSAUTOJSVALHOLDER_H__
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#include "nsDebug.h"
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#include "jsapi.h"
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/**
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* Simple class that looks and acts like a JS::Value except that it unroots
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* itself automatically if Root() is ever called. Designed to be rooted on the
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* context or runtime (but not both!).
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*/
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class nsAutoJSValHolder
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{
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public:
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nsAutoJSValHolder()
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: mVal(JSVAL_NULL), mRt(nullptr)
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{
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// nothing to do
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}
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/**
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* Always release on destruction.
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*/
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virtual ~nsAutoJSValHolder() {
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Release();
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}
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nsAutoJSValHolder(const nsAutoJSValHolder& aOther)
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: mVal(JSVAL_NULL), mRt(nullptr)
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{
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*this = aOther;
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}
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nsAutoJSValHolder& operator=(const nsAutoJSValHolder& aOther) {
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if (this != &aOther) {
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if (aOther.IsHeld()) {
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// XXX No error handling here...
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this->Hold(aOther.mRt);
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}
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else {
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this->Release();
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}
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*this = static_cast<JS::Value>(aOther);
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}
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return *this;
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}
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/**
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* Hold by rooting on the context's runtime.
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*/
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bool Hold(JSContext* aCx) {
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return Hold(JS_GetRuntime(aCx));
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}
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/**
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* Hold by rooting on the runtime.
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* Note that mVal may be JSVAL_NULL, which is not a problem.
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*/
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bool Hold(JSRuntime* aRt) {
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MOZ_ASSERT_IF(mRt, mRt == aRt);
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if (!mRt && JS::AddNamedValueRootRT(aRt, &mVal, "nsAutoJSValHolder")) {
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mRt = aRt;
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}
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return !!mRt;
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}
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/**
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* Manually release, nullifying mVal, and mRt, but returning
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* the original JS::Value.
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*/
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JS::Value Release() {
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JS::Value oldval = mVal;
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if (mRt) {
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JS::RemoveValueRootRT(mRt, &mVal); // infallible
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mRt = nullptr;
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}
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mVal = JSVAL_NULL;
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return oldval;
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}
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/**
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* Determine if Hold has been called.
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*/
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bool IsHeld() const {
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return !!mRt;
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}
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/**
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* Explicit JSObject* conversion.
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*/
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JSObject* ToJSObject() const {
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return mVal.isObject()
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? &mVal.toObject()
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: nullptr;
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}
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/**
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* Pretend to be a JS::Value.
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*/
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operator JS::Value() const { return mVal; }
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JS::Value get() const { return mVal; }
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nsAutoJSValHolder &operator=(JSObject* aOther) {
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return *this = OBJECT_TO_JSVAL(aOther);
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}
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nsAutoJSValHolder &operator=(JS::Value aOther) {
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#ifdef DEBUG
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if (aOther.isGCThing() && !aOther.isNull()) {
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MOZ_ASSERT(IsHeld(), "Not rooted!");
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}
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#endif
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mVal = aOther;
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return *this;
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}
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private:
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JS::Heap<JS::Value> mVal;
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JSRuntime* mRt;
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};
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#endif /* __NSAUTOJSVALHOLDER_H__ */
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