зеркало из https://github.com/mozilla/gecko-dev.git
138 строки
4.1 KiB
C++
138 строки
4.1 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 mozilla_DynamicallyLinkedFunctionPtr_h
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#define mozilla_DynamicallyLinkedFunctionPtr_h
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#include <windows.h>
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#include <utility>
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#include "mozilla/Attributes.h"
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namespace mozilla {
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namespace detail {
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template <typename T>
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struct FunctionPtrCracker;
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template <typename R, typename... Args>
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struct FunctionPtrCracker<R (*)(Args...)> {
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using ReturnT = R;
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using FunctionPtrT = R (*)(Args...);
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};
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#if defined(_M_IX86)
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template <typename R, typename... Args>
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struct FunctionPtrCracker<R(__stdcall*)(Args...)> {
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using ReturnT = R;
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using FunctionPtrT = R(__stdcall*)(Args...);
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};
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template <typename R, typename... Args>
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struct FunctionPtrCracker<R(__fastcall*)(Args...)> {
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using ReturnT = R;
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using FunctionPtrT = R(__fastcall*)(Args...);
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};
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#endif // defined(_M_IX86)
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template <typename T>
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class DynamicallyLinkedFunctionPtrBase {
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public:
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using ReturnT = typename FunctionPtrCracker<T>::ReturnT;
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using FunctionPtrT = typename FunctionPtrCracker<T>::FunctionPtrT;
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DynamicallyLinkedFunctionPtrBase(const wchar_t* aLibName,
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const char* aFuncName)
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: mModule(::LoadLibraryW(aLibName)), mFunction(nullptr) {
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if (!mModule) {
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return;
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}
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mFunction =
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reinterpret_cast<FunctionPtrT>(::GetProcAddress(mModule, aFuncName));
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if (!mFunction) {
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// Since the function doesn't exist, there is no point in holding a
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// reference to mModule anymore.
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::FreeLibrary(mModule);
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mModule = nullptr;
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}
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}
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DynamicallyLinkedFunctionPtrBase(const DynamicallyLinkedFunctionPtrBase&) =
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delete;
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DynamicallyLinkedFunctionPtrBase& operator=(
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const DynamicallyLinkedFunctionPtrBase&) = delete;
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DynamicallyLinkedFunctionPtrBase(DynamicallyLinkedFunctionPtrBase&&) = delete;
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DynamicallyLinkedFunctionPtrBase& operator=(
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DynamicallyLinkedFunctionPtrBase&&) = delete;
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template <typename... Args>
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ReturnT operator()(Args&&... args) const {
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return mFunction(std::forward<Args>(args)...);
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}
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explicit operator bool() const { return !!mFunction; }
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protected:
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HMODULE mModule;
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FunctionPtrT mFunction;
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};
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} // namespace detail
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/**
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* In most cases, this class is the one that you want to use for resolving a
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* dynamically-linked function pointer. It should be instantiated as a static
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* local variable.
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*
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* NB: It has a trivial destructor, so the DLL that is loaded is never freed.
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* Assuming that this function is called fairly often, this is the most
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* sensible option. OTOH, if the function you are calling is a one-off, or the
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* static local requirement is too restrictive, use DynamicallyLinkedFunctionPtr
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* instead.
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*/
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template <typename T>
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class MOZ_STATIC_LOCAL_CLASS StaticDynamicallyLinkedFunctionPtr final
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: public detail::DynamicallyLinkedFunctionPtrBase<T> {
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public:
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StaticDynamicallyLinkedFunctionPtr(const wchar_t* aLibName,
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const char* aFuncName)
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: detail::DynamicallyLinkedFunctionPtrBase<T>(aLibName, aFuncName) {}
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/**
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* We only offer this operator for the static local case, as it is not
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* possible for this object to be destroyed while the returned pointer is
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* being held.
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*/
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operator typename detail::DynamicallyLinkedFunctionPtrBase<T>::FunctionPtrT()
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const {
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return this->mFunction;
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}
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};
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template <typename T>
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class MOZ_NON_PARAM MOZ_NON_TEMPORARY_CLASS DynamicallyLinkedFunctionPtr final
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: public detail::DynamicallyLinkedFunctionPtrBase<T> {
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public:
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DynamicallyLinkedFunctionPtr(const wchar_t* aLibName, const char* aFuncName)
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: detail::DynamicallyLinkedFunctionPtrBase<T>(aLibName, aFuncName) {}
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~DynamicallyLinkedFunctionPtr() {
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if (!this->mModule) {
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return;
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}
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::FreeLibrary(this->mModule);
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}
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};
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} // namespace mozilla
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#endif // mozilla_DynamicallyLinkedFunctionPtr_h
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