The Tor Browser / file comparison
comparison: js/xpconnect/public/nsAutoJSValHolder.h
js/xpconnect/public/nsAutoJSValHolder.h
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| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ | |
| 3 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef __NSAUTOJSVALHOLDER_H__ | |
| 8 #define __NSAUTOJSVALHOLDER_H__ | |
| 9 | |
| 10 #include "nsDebug.h" | |
| 11 #include "jsapi.h" | |
| 12 | |
| 13 /** | |
| 14 * Simple class that looks and acts like a JS::Value except that it unroots | |
| 15 * itself automatically if Root() is ever called. Designed to be rooted on the | |
| 16 * context or runtime (but not both!). | |
| 17 */ | |
| 18 class nsAutoJSValHolder | |
| 19 { | |
| 20 public: | |
| 21 nsAutoJSValHolder() | |
| 22 : mVal(JSVAL_NULL), mRt(nullptr) | |
| 23 { | |
| 24 // nothing to do | |
| 25 } | |
| 26 | |
| 27 /** | |
| 28 * Always release on destruction. | |
| 29 */ | |
| 30 virtual ~nsAutoJSValHolder() { | |
| 31 Release(); | |
| 32 } | |
| 33 | |
| 34 nsAutoJSValHolder(const nsAutoJSValHolder& aOther) | |
| 35 : mVal(JSVAL_NULL), mRt(nullptr) | |
| 36 { | |
| 37 *this = aOther; | |
| 38 } | |
| 39 | |
| 40 nsAutoJSValHolder& operator=(const nsAutoJSValHolder& aOther) { | |
| 41 if (this != &aOther) { | |
| 42 if (aOther.IsHeld()) { | |
| 43 // XXX No error handling here... | |
| 44 this->Hold(aOther.mRt); | |
| 45 } | |
| 46 else { | |
| 47 this->Release(); | |
| 48 } | |
| 49 *this = static_cast<JS::Value>(aOther); | |
| 50 } | |
| 51 return *this; | |
| 52 } | |
| 53 | |
| 54 /** | |
| 55 * Hold by rooting on the context's runtime. | |
| 56 */ | |
| 57 bool Hold(JSContext* aCx) { | |
| 58 return Hold(JS_GetRuntime(aCx)); | |
| 59 } | |
| 60 | |
| 61 /** | |
| 62 * Hold by rooting on the runtime. | |
| 63 * Note that mVal may be JSVAL_NULL, which is not a problem. | |
| 64 */ | |
| 65 bool Hold(JSRuntime* aRt) { | |
| 66 MOZ_ASSERT_IF(mRt, mRt == aRt); | |
| 67 | |
| 68 if (!mRt && JS::AddNamedValueRootRT(aRt, &mVal, "nsAutoJSValHolder")) { | |
| 69 mRt = aRt; | |
| 70 } | |
| 71 | |
| 72 return !!mRt; | |
| 73 } | |
| 74 | |
| 75 /** | |
| 76 * Manually release, nullifying mVal, and mRt, but returning | |
| 77 * the original JS::Value. | |
| 78 */ | |
| 79 JS::Value Release() { | |
| 80 JS::Value oldval = mVal; | |
| 81 | |
| 82 if (mRt) { | |
| 83 JS::RemoveValueRootRT(mRt, &mVal); // infallible | |
| 84 mRt = nullptr; | |
| 85 } | |
| 86 | |
| 87 mVal = JSVAL_NULL; | |
| 88 | |
| 89 return oldval; | |
| 90 } | |
| 91 | |
| 92 /** | |
| 93 * Determine if Hold has been called. | |
| 94 */ | |
| 95 bool IsHeld() const { | |
| 96 return !!mRt; | |
| 97 } | |
| 98 | |
| 99 /** | |
| 100 * Explicit JSObject* conversion. | |
| 101 */ | |
| 102 JSObject* ToJSObject() const { | |
| 103 return mVal.isObject() | |
| 104 ? &mVal.toObject() | |
| 105 : nullptr; | |
| 106 } | |
| 107 | |
| 108 /** | |
| 109 * Pretend to be a JS::Value. | |
| 110 */ | |
| 111 operator JS::Value() const { return mVal; } | |
| 112 JS::Value get() const { return mVal; } | |
| 113 | |
| 114 nsAutoJSValHolder &operator=(JSObject* aOther) { | |
| 115 return *this = OBJECT_TO_JSVAL(aOther); | |
| 116 } | |
| 117 | |
| 118 nsAutoJSValHolder &operator=(JS::Value aOther) { | |
| 119 #ifdef DEBUG | |
| 120 if (JSVAL_IS_GCTHING(aOther) && !JSVAL_IS_NULL(aOther)) { | |
| 121 MOZ_ASSERT(IsHeld(), "Not rooted!"); | |
| 122 } | |
| 123 #endif | |
| 124 mVal = aOther; | |
| 125 return *this; | |
| 126 } | |
| 127 | |
| 128 private: | |
| 129 JS::Heap<JS::Value> mVal; | |
| 130 JSRuntime* mRt; | |
| 131 }; | |
| 132 | |
| 133 #endif /* __NSAUTOJSVALHOLDER_H__ */ |
