1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/xpconnect/public/nsAutoJSValHolder.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,133 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef __NSAUTOJSVALHOLDER_H__
1.11 +#define __NSAUTOJSVALHOLDER_H__
1.12 +
1.13 +#include "nsDebug.h"
1.14 +#include "jsapi.h"
1.15 +
1.16 +/**
1.17 + * Simple class that looks and acts like a JS::Value except that it unroots
1.18 + * itself automatically if Root() is ever called. Designed to be rooted on the
1.19 + * context or runtime (but not both!).
1.20 + */
1.21 +class nsAutoJSValHolder
1.22 +{
1.23 +public:
1.24 + nsAutoJSValHolder()
1.25 + : mVal(JSVAL_NULL), mRt(nullptr)
1.26 + {
1.27 + // nothing to do
1.28 + }
1.29 +
1.30 + /**
1.31 + * Always release on destruction.
1.32 + */
1.33 + virtual ~nsAutoJSValHolder() {
1.34 + Release();
1.35 + }
1.36 +
1.37 + nsAutoJSValHolder(const nsAutoJSValHolder& aOther)
1.38 + : mVal(JSVAL_NULL), mRt(nullptr)
1.39 + {
1.40 + *this = aOther;
1.41 + }
1.42 +
1.43 + nsAutoJSValHolder& operator=(const nsAutoJSValHolder& aOther) {
1.44 + if (this != &aOther) {
1.45 + if (aOther.IsHeld()) {
1.46 + // XXX No error handling here...
1.47 + this->Hold(aOther.mRt);
1.48 + }
1.49 + else {
1.50 + this->Release();
1.51 + }
1.52 + *this = static_cast<JS::Value>(aOther);
1.53 + }
1.54 + return *this;
1.55 + }
1.56 +
1.57 + /**
1.58 + * Hold by rooting on the context's runtime.
1.59 + */
1.60 + bool Hold(JSContext* aCx) {
1.61 + return Hold(JS_GetRuntime(aCx));
1.62 + }
1.63 +
1.64 + /**
1.65 + * Hold by rooting on the runtime.
1.66 + * Note that mVal may be JSVAL_NULL, which is not a problem.
1.67 + */
1.68 + bool Hold(JSRuntime* aRt) {
1.69 + MOZ_ASSERT_IF(mRt, mRt == aRt);
1.70 +
1.71 + if (!mRt && JS::AddNamedValueRootRT(aRt, &mVal, "nsAutoJSValHolder")) {
1.72 + mRt = aRt;
1.73 + }
1.74 +
1.75 + return !!mRt;
1.76 + }
1.77 +
1.78 + /**
1.79 + * Manually release, nullifying mVal, and mRt, but returning
1.80 + * the original JS::Value.
1.81 + */
1.82 + JS::Value Release() {
1.83 + JS::Value oldval = mVal;
1.84 +
1.85 + if (mRt) {
1.86 + JS::RemoveValueRootRT(mRt, &mVal); // infallible
1.87 + mRt = nullptr;
1.88 + }
1.89 +
1.90 + mVal = JSVAL_NULL;
1.91 +
1.92 + return oldval;
1.93 + }
1.94 +
1.95 + /**
1.96 + * Determine if Hold has been called.
1.97 + */
1.98 + bool IsHeld() const {
1.99 + return !!mRt;
1.100 + }
1.101 +
1.102 + /**
1.103 + * Explicit JSObject* conversion.
1.104 + */
1.105 + JSObject* ToJSObject() const {
1.106 + return mVal.isObject()
1.107 + ? &mVal.toObject()
1.108 + : nullptr;
1.109 + }
1.110 +
1.111 + /**
1.112 + * Pretend to be a JS::Value.
1.113 + */
1.114 + operator JS::Value() const { return mVal; }
1.115 + JS::Value get() const { return mVal; }
1.116 +
1.117 + nsAutoJSValHolder &operator=(JSObject* aOther) {
1.118 + return *this = OBJECT_TO_JSVAL(aOther);
1.119 + }
1.120 +
1.121 + nsAutoJSValHolder &operator=(JS::Value aOther) {
1.122 +#ifdef DEBUG
1.123 + if (JSVAL_IS_GCTHING(aOther) && !JSVAL_IS_NULL(aOther)) {
1.124 + MOZ_ASSERT(IsHeld(), "Not rooted!");
1.125 + }
1.126 +#endif
1.127 + mVal = aOther;
1.128 + return *this;
1.129 + }
1.130 +
1.131 +private:
1.132 + JS::Heap<JS::Value> mVal;
1.133 + JSRuntime* mRt;
1.134 +};
1.135 +
1.136 +#endif /* __NSAUTOJSVALHOLDER_H__ */
