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Diffstat (limited to 'webrtc/base/scoped_ptr.h')
| -rw-r--r-- | webrtc/base/scoped_ptr.h | 636 |
1 files changed, 0 insertions, 636 deletions
diff --git a/webrtc/base/scoped_ptr.h b/webrtc/base/scoped_ptr.h deleted file mode 100644 index 203a001..0000000 --- a/webrtc/base/scoped_ptr.h +++ /dev/null @@ -1,636 +0,0 @@ -/* - * Copyright 2012 The WebRTC Project Authors. All rights reserved. - * - * Use of this source code is governed by a BSD-style license - * that can be found in the LICENSE file in the root of the source - * tree. An additional intellectual property rights grant can be found - * in the file PATENTS. All contributing project authors may - * be found in the AUTHORS file in the root of the source tree. - */ - -// Borrowed from Chromium's src/base/memory/scoped_ptr.h. - -// Scopers help you manage ownership of a pointer, helping you easily manage a -// pointer within a scope, and automatically destroying the pointer at the end -// of a scope. There are two main classes you will use, which correspond to the -// operators new/delete and new[]/delete[]. -// -// Example usage (scoped_ptr<T>): -// { -// scoped_ptr<Foo> foo(new Foo("wee")); -// } // foo goes out of scope, releasing the pointer with it. -// -// { -// scoped_ptr<Foo> foo; // No pointer managed. -// foo.reset(new Foo("wee")); // Now a pointer is managed. -// foo.reset(new Foo("wee2")); // Foo("wee") was destroyed. -// foo.reset(new Foo("wee3")); // Foo("wee2") was destroyed. -// foo->Method(); // Foo::Method() called. -// foo.get()->Method(); // Foo::Method() called. -// SomeFunc(foo.release()); // SomeFunc takes ownership, foo no longer -// // manages a pointer. -// foo.reset(new Foo("wee4")); // foo manages a pointer again. -// foo.reset(); // Foo("wee4") destroyed, foo no longer -// // manages a pointer. -// } // foo wasn't managing a pointer, so nothing was destroyed. -// -// Example usage (scoped_ptr<T[]>): -// { -// scoped_ptr<Foo[]> foo(new Foo[100]); -// foo.get()->Method(); // Foo::Method on the 0th element. -// foo[10].Method(); // Foo::Method on the 10th element. -// } -// -// These scopers also implement part of the functionality of C++11 unique_ptr -// in that they are "movable but not copyable." You can use the scopers in -// the parameter and return types of functions to signify ownership transfer -// in to and out of a function. When calling a function that has a scoper -// as the argument type, it must be called with the result of an analogous -// scoper's Pass() function or another function that generates a temporary; -// passing by copy will NOT work. Here is an example using scoped_ptr: -// -// void TakesOwnership(scoped_ptr<Foo> arg) { -// // Do something with arg -// } -// scoped_ptr<Foo> CreateFoo() { -// // No need for calling Pass() because we are constructing a temporary -// // for the return value. -// return scoped_ptr<Foo>(new Foo("new")); -// } -// scoped_ptr<Foo> PassThru(scoped_ptr<Foo> arg) { -// return arg.Pass(); -// } -// -// { -// scoped_ptr<Foo> ptr(new Foo("yay")); // ptr manages Foo("yay"). -// TakesOwnership(ptr.Pass()); // ptr no longer owns Foo("yay"). -// scoped_ptr<Foo> ptr2 = CreateFoo(); // ptr2 owns the return Foo. -// scoped_ptr<Foo> ptr3 = // ptr3 now owns what was in ptr2. -// PassThru(ptr2.Pass()); // ptr2 is correspondingly nullptr. -// } -// -// Notice that if you do not call Pass() when returning from PassThru(), or -// when invoking TakesOwnership(), the code will not compile because scopers -// are not copyable; they only implement move semantics which require calling -// the Pass() function to signify a destructive transfer of state. CreateFoo() -// is different though because we are constructing a temporary on the return -// line and thus can avoid needing to call Pass(). -// -// Pass() properly handles upcast in initialization, i.e. you can use a -// scoped_ptr<Child> to initialize a scoped_ptr<Parent>: -// -// scoped_ptr<Foo> foo(new Foo()); -// scoped_ptr<FooParent> parent(foo.Pass()); -// -// PassAs<>() should be used to upcast return value in return statement: -// -// scoped_ptr<Foo> CreateFoo() { -// scoped_ptr<FooChild> result(new FooChild()); -// return result.PassAs<Foo>(); -// } -// -// Note that PassAs<>() is implemented only for scoped_ptr<T>, but not for -// scoped_ptr<T[]>. This is because casting array pointers may not be safe. - -#ifndef WEBRTC_BASE_SCOPED_PTR_H__ -#define WEBRTC_BASE_SCOPED_PTR_H__ - -// This is an implementation designed to match the anticipated future TR2 -// implementation of the scoped_ptr class. - -#include <assert.h> -#include <stddef.h> -#include <stdlib.h> - -#include <algorithm> // For std::swap(). - -#include "webrtc/base/constructormagic.h" -#include "webrtc/base/template_util.h" -#include "webrtc/typedefs.h" - -namespace rtc { - -// Function object which deletes its parameter, which must be a pointer. -// If C is an array type, invokes 'delete[]' on the parameter; otherwise, -// invokes 'delete'. The default deleter for scoped_ptr<T>. -template <class T> -struct DefaultDeleter { - DefaultDeleter() {} - template <typename U> DefaultDeleter(const DefaultDeleter<U>& other) { - // IMPLEMENTATION NOTE: C++11 20.7.1.1.2p2 only provides this constructor - // if U* is implicitly convertible to T* and U is not an array type. - // - // Correct implementation should use SFINAE to disable this - // constructor. However, since there are no other 1-argument constructors, - // using a static_assert based on is_convertible<> and requiring - // complete types is simpler and will cause compile failures for equivalent - // misuses. - // - // Note, the is_convertible<U*, T*> check also ensures that U is not an - // array. T is guaranteed to be a non-array, so any U* where U is an array - // cannot convert to T*. - enum { T_must_be_complete = sizeof(T) }; - enum { U_must_be_complete = sizeof(U) }; - static_assert(rtc::is_convertible<U*, T*>::value, - "U* must implicitly convert to T*"); - } - inline void operator()(T* ptr) const { - enum { type_must_be_complete = sizeof(T) }; - delete ptr; - } -}; - -// Specialization of DefaultDeleter for array types. -template <class T> -struct DefaultDeleter<T[]> { - inline void operator()(T* ptr) const { - enum { type_must_be_complete = sizeof(T) }; - delete[] ptr; - } - - private: - // Disable this operator for any U != T because it is undefined to execute - // an array delete when the static type of the array mismatches the dynamic - // type. - // - // References: - // C++98 [expr.delete]p3 - // http://cplusplus.github.com/LWG/lwg-defects.html#938 - template <typename U> void operator()(U* array) const; -}; - -template <class T, int n> -struct DefaultDeleter<T[n]> { - // Never allow someone to declare something like scoped_ptr<int[10]>. - static_assert(sizeof(T) == -1, "do not use array with size as type"); -}; - -// Function object which invokes 'free' on its parameter, which must be -// a pointer. Can be used to store malloc-allocated pointers in scoped_ptr: -// -// scoped_ptr<int, rtc::FreeDeleter> foo_ptr( -// static_cast<int*>(malloc(sizeof(int)))); -struct FreeDeleter { - inline void operator()(void* ptr) const { - free(ptr); - } -}; - -namespace internal { - -template <typename T> -struct ShouldAbortOnSelfReset { - template <typename U> - static rtc::internal::NoType Test(const typename U::AllowSelfReset*); - - template <typename U> - static rtc::internal::YesType Test(...); - - static const bool value = - sizeof(Test<T>(0)) == sizeof(rtc::internal::YesType); -}; - -// Minimal implementation of the core logic of scoped_ptr, suitable for -// reuse in both scoped_ptr and its specializations. -template <class T, class D> -class scoped_ptr_impl { - public: - explicit scoped_ptr_impl(T* p) : data_(p) {} - - // Initializer for deleters that have data parameters. - scoped_ptr_impl(T* p, const D& d) : data_(p, d) {} - - // Templated constructor that destructively takes the value from another - // scoped_ptr_impl. - template <typename U, typename V> - scoped_ptr_impl(scoped_ptr_impl<U, V>* other) - : data_(other->release(), other->get_deleter()) { - // We do not support move-only deleters. We could modify our move - // emulation to have rtc::subtle::move() and rtc::subtle::forward() - // functions that are imperfect emulations of their C++11 equivalents, - // but until there's a requirement, just assume deleters are copyable. - } - - template <typename U, typename V> - void TakeState(scoped_ptr_impl<U, V>* other) { - // See comment in templated constructor above regarding lack of support - // for move-only deleters. - reset(other->release()); - get_deleter() = other->get_deleter(); - } - - ~scoped_ptr_impl() { - if (data_.ptr != nullptr) { - // Not using get_deleter() saves one function call in non-optimized - // builds. - static_cast<D&>(data_)(data_.ptr); - } - } - - void reset(T* p) { - // This is a self-reset, which is no longer allowed for default deleters: - // https://crbug.com/162971 - assert(!ShouldAbortOnSelfReset<D>::value || p == nullptr || p != data_.ptr); - - // Note that running data_.ptr = p can lead to undefined behavior if - // get_deleter()(get()) deletes this. In order to prevent this, reset() - // should update the stored pointer before deleting its old value. - // - // However, changing reset() to use that behavior may cause current code to - // break in unexpected ways. If the destruction of the owned object - // dereferences the scoped_ptr when it is destroyed by a call to reset(), - // then it will incorrectly dispatch calls to |p| rather than the original - // value of |data_.ptr|. - // - // During the transition period, set the stored pointer to nullptr while - // deleting the object. Eventually, this safety check will be removed to - // prevent the scenario initially described from occurring and - // http://crbug.com/176091 can be closed. - T* old = data_.ptr; - data_.ptr = nullptr; - if (old != nullptr) - static_cast<D&>(data_)(old); - data_.ptr = p; - } - - T* get() const { return data_.ptr; } - - D& get_deleter() { return data_; } - const D& get_deleter() const { return data_; } - - void swap(scoped_ptr_impl& p2) { - // Standard swap idiom: 'using std::swap' ensures that std::swap is - // present in the overload set, but we call swap unqualified so that - // any more-specific overloads can be used, if available. - using std::swap; - swap(static_cast<D&>(data_), static_cast<D&>(p2.data_)); - swap(data_.ptr, p2.data_.ptr); - } - - T* release() { - T* old_ptr = data_.ptr; - data_.ptr = nullptr; - return old_ptr; - } - - T** accept() { - reset(nullptr); - return &(data_.ptr); - } - - T** use() { - return &(data_.ptr); - } - - private: - // Needed to allow type-converting constructor. - template <typename U, typename V> friend class scoped_ptr_impl; - - // Use the empty base class optimization to allow us to have a D - // member, while avoiding any space overhead for it when D is an - // empty class. See e.g. http://www.cantrip.org/emptyopt.html for a good - // discussion of this technique. - struct Data : public D { - explicit Data(T* ptr_in) : ptr(ptr_in) {} - Data(T* ptr_in, const D& other) : D(other), ptr(ptr_in) {} - T* ptr; - }; - - Data data_; - - RTC_DISALLOW_COPY_AND_ASSIGN(scoped_ptr_impl); -}; - -} // namespace internal - -// A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T> -// automatically deletes the pointer it holds (if any). -// That is, scoped_ptr<T> owns the T object that it points to. -// Like a T*, a scoped_ptr<T> may hold either nullptr or a pointer to a T -// object. Also like T*, scoped_ptr<T> is thread-compatible, and once you -// dereference it, you get the thread safety guarantees of T. -// -// The size of scoped_ptr is small. On most compilers, when using the -// DefaultDeleter, sizeof(scoped_ptr<T>) == sizeof(T*). Custom deleters will -// increase the size proportional to whatever state they need to have. See -// comments inside scoped_ptr_impl<> for details. -// -// Current implementation targets having a strict subset of C++11's -// unique_ptr<> features. Known deficiencies include not supporting move-only -// deleters, function pointers as deleters, and deleters with reference -// types. -template <class T, class D = rtc::DefaultDeleter<T> > -class scoped_ptr { - - // TODO(ajm): If we ever import RefCountedBase, this check needs to be - // enabled. - //static_assert(rtc::internal::IsNotRefCounted<T>::value, - // "T is refcounted type and needs scoped refptr"); - - public: - // The element and deleter types. - typedef T element_type; - typedef D deleter_type; - - // Constructor. Defaults to initializing with nullptr. - scoped_ptr() : impl_(nullptr) {} - - // Constructor. Takes ownership of p. - explicit scoped_ptr(element_type* p) : impl_(p) {} - - // Constructor. Allows initialization of a stateful deleter. - scoped_ptr(element_type* p, const D& d) : impl_(p, d) {} - - // Constructor. Allows construction from a nullptr. - scoped_ptr(decltype(nullptr)) : impl_(nullptr) {} - - // Constructor. Allows construction from a scoped_ptr rvalue for a - // convertible type and deleter. - // - // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this constructor distinct - // from the normal move constructor. By C++11 20.7.1.2.1.21, this constructor - // has different post-conditions if D is a reference type. Since this - // implementation does not support deleters with reference type, - // we do not need a separate move constructor allowing us to avoid one - // use of SFINAE. You only need to care about this if you modify the - // implementation of scoped_ptr. - template <typename U, typename V> - scoped_ptr(scoped_ptr<U, V>&& other) - : impl_(&other.impl_) { - static_assert(!rtc::is_array<U>::value, "U cannot be an array"); - } - - // operator=. Allows assignment from a scoped_ptr rvalue for a convertible - // type and deleter. - // - // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from - // the normal move assignment operator. By C++11 20.7.1.2.3.4, this templated - // form has different requirements on for move-only Deleters. Since this - // implementation does not support move-only Deleters, we do not need a - // separate move assignment operator allowing us to avoid one use of SFINAE. - // You only need to care about this if you modify the implementation of - // scoped_ptr. - template <typename U, typename V> - scoped_ptr& operator=(scoped_ptr<U, V>&& rhs) { - static_assert(!rtc::is_array<U>::value, "U cannot be an array"); - impl_.TakeState(&rhs.impl_); - return *this; - } - - // operator=. Allows assignment from a nullptr. Deletes the currently owned - // object, if any. - scoped_ptr& operator=(decltype(nullptr)) { - reset(); - return *this; - } - - // Deleted copy constructor and copy assignment, to make the type move-only. - scoped_ptr(const scoped_ptr& other) = delete; - scoped_ptr& operator=(const scoped_ptr& other) = delete; - - // Get an rvalue reference. (sp.Pass() does the same thing as std::move(sp).) - scoped_ptr&& Pass() { return static_cast<scoped_ptr&&>(*this); } - - // Reset. Deletes the currently owned object, if any. - // Then takes ownership of a new object, if given. - void reset(element_type* p = nullptr) { impl_.reset(p); } - - // Accessors to get the owned object. - // operator* and operator-> will assert() if there is no current object. - element_type& operator*() const { - assert(impl_.get() != nullptr); - return *impl_.get(); - } - element_type* operator->() const { - assert(impl_.get() != nullptr); - return impl_.get(); - } - element_type* get() const { return impl_.get(); } - - // Access to the deleter. - deleter_type& get_deleter() { return impl_.get_deleter(); } - const deleter_type& get_deleter() const { return impl_.get_deleter(); } - - // Allow scoped_ptr<element_type> to be used in boolean expressions, but not - // implicitly convertible to a real bool (which is dangerous). - // - // Note that this trick is only safe when the == and != operators - // are declared explicitly, as otherwise "scoped_ptr1 == - // scoped_ptr2" will compile but do the wrong thing (i.e., convert - // to Testable and then do the comparison). - private: - typedef rtc::internal::scoped_ptr_impl<element_type, deleter_type> - scoped_ptr::*Testable; - - public: - operator Testable() const { - return impl_.get() ? &scoped_ptr::impl_ : nullptr; - } - - // Comparison operators. - // These return whether two scoped_ptr refer to the same object, not just to - // two different but equal objects. - bool operator==(const element_type* p) const { return impl_.get() == p; } - bool operator!=(const element_type* p) const { return impl_.get() != p; } - - // Swap two scoped pointers. - void swap(scoped_ptr& p2) { - impl_.swap(p2.impl_); - } - - // Release a pointer. - // The return value is the current pointer held by this object. If this object - // holds a nullptr, the return value is nullptr. After this operation, this - // object will hold a nullptr, and will not own the object any more. - element_type* release() WARN_UNUSED_RESULT { - return impl_.release(); - } - - // Delete the currently held pointer and return a pointer - // to allow overwriting of the current pointer address. - element_type** accept() WARN_UNUSED_RESULT { - return impl_.accept(); - } - - // Return a pointer to the current pointer address. - element_type** use() WARN_UNUSED_RESULT { - return impl_.use(); - } - - private: - // Needed to reach into |impl_| in the constructor. - template <typename U, typename V> friend class scoped_ptr; - rtc::internal::scoped_ptr_impl<element_type, deleter_type> impl_; - - // Forbidden for API compatibility with std::unique_ptr. - explicit scoped_ptr(int disallow_construction_from_null); - - // Forbid comparison of scoped_ptr types. If U != T, it totally - // doesn't make sense, and if U == T, it still doesn't make sense - // because you should never have the same object owned by two different - // scoped_ptrs. - template <class U> bool operator==(scoped_ptr<U> const& p2) const; - template <class U> bool operator!=(scoped_ptr<U> const& p2) const; -}; - -template <class T, class D> -class scoped_ptr<T[], D> { - public: - // The element and deleter types. - typedef T element_type; - typedef D deleter_type; - - // Constructor. Defaults to initializing with nullptr. - scoped_ptr() : impl_(nullptr) {} - - // Constructor. Stores the given array. Note that the argument's type - // must exactly match T*. In particular: - // - it cannot be a pointer to a type derived from T, because it is - // inherently unsafe in the general case to access an array through a - // pointer whose dynamic type does not match its static type (eg., if - // T and the derived types had different sizes access would be - // incorrectly calculated). Deletion is also always undefined - // (C++98 [expr.delete]p3). If you're doing this, fix your code. - // - it cannot be const-qualified differently from T per unique_ptr spec - // (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting - // to work around this may use implicit_cast<const T*>(). - // However, because of the first bullet in this comment, users MUST - // NOT use implicit_cast<Base*>() to upcast the static type of the array. - explicit scoped_ptr(element_type* array) : impl_(array) {} - - // Constructor. Allows construction from a nullptr. - scoped_ptr(decltype(nullptr)) : impl_(nullptr) {} - - // Constructor. Allows construction from a scoped_ptr rvalue. - scoped_ptr(scoped_ptr&& other) : impl_(&other.impl_) {} - - // operator=. Allows assignment from a scoped_ptr rvalue. - scoped_ptr& operator=(scoped_ptr&& rhs) { - impl_.TakeState(&rhs.impl_); - return *this; - } - - // operator=. Allows assignment from a nullptr. Deletes the currently owned - // array, if any. - scoped_ptr& operator=(decltype(nullptr)) { - reset(); - return *this; - } - - // Deleted copy constructor and copy assignment, to make the type move-only. - scoped_ptr(const scoped_ptr& other) = delete; - scoped_ptr& operator=(const scoped_ptr& other) = delete; - - // Get an rvalue reference. (sp.Pass() does the same thing as std::move(sp).) - scoped_ptr&& Pass() { return static_cast<scoped_ptr&&>(*this); } - - // Reset. Deletes the currently owned array, if any. - // Then takes ownership of a new object, if given. - void reset(element_type* array = nullptr) { impl_.reset(array); } - - // Accessors to get the owned array. - element_type& operator[](size_t i) const { - assert(impl_.get() != nullptr); - return impl_.get()[i]; - } - element_type* get() const { return impl_.get(); } - - // Access to the deleter. - deleter_type& get_deleter() { return impl_.get_deleter(); } - const deleter_type& get_deleter() const { return impl_.get_deleter(); } - - // Allow scoped_ptr<element_type> to be used in boolean expressions, but not - // implicitly convertible to a real bool (which is dangerous). - private: - typedef rtc::internal::scoped_ptr_impl<element_type, deleter_type> - scoped_ptr::*Testable; - - public: - operator Testable() const { - return impl_.get() ? &scoped_ptr::impl_ : nullptr; - } - - // Comparison operators. - // These return whether two scoped_ptr refer to the same object, not just to - // two different but equal objects. - bool operator==(element_type* array) const { return impl_.get() == array; } - bool operator!=(element_type* array) const { return impl_.get() != array; } - - // Swap two scoped pointers. - void swap(scoped_ptr& p2) { - impl_.swap(p2.impl_); - } - - // Release a pointer. - // The return value is the current pointer held by this object. If this object - // holds a nullptr, the return value is nullptr. After this operation, this - // object will hold a nullptr, and will not own the object any more. - element_type* release() WARN_UNUSED_RESULT { - return impl_.release(); - } - - // Delete the currently held pointer and return a pointer - // to allow overwriting of the current pointer address. - element_type** accept() WARN_UNUSED_RESULT { - return impl_.accept(); - } - - // Return a pointer to the current pointer address. - element_type** use() WARN_UNUSED_RESULT { - return impl_.use(); - } - - private: - // Force element_type to be a complete type. - enum { type_must_be_complete = sizeof(element_type) }; - - // Actually hold the data. - rtc::internal::scoped_ptr_impl<element_type, deleter_type> impl_; - - // Disable initialization from any type other than element_type*, by - // providing a constructor that matches such an initialization, but is - // private and has no definition. This is disabled because it is not safe to - // call delete[] on an array whose static type does not match its dynamic - // type. - template <typename U> explicit scoped_ptr(U* array); - explicit scoped_ptr(int disallow_construction_from_null); - - // Disable reset() from any type other than element_type*, for the same - // reasons as the constructor above. - template <typename U> void reset(U* array); - void reset(int disallow_reset_from_null); - - // Forbid comparison of scoped_ptr types. If U != T, it totally - // doesn't make sense, and if U == T, it still doesn't make sense - // because you should never have the same object owned by two different - // scoped_ptrs. - template <class U> bool operator==(scoped_ptr<U> const& p2) const; - template <class U> bool operator!=(scoped_ptr<U> const& p2) const; -}; - -template <class T, class D> -void swap(rtc::scoped_ptr<T, D>& p1, rtc::scoped_ptr<T, D>& p2) { - p1.swap(p2); -} - -} // namespace rtc - -template <class T, class D> -bool operator==(T* p1, const rtc::scoped_ptr<T, D>& p2) { - return p1 == p2.get(); -} - -template <class T, class D> -bool operator!=(T* p1, const rtc::scoped_ptr<T, D>& p2) { - return p1 != p2.get(); -} - -// A function to convert T* into scoped_ptr<T> -// Doing e.g. make_scoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation -// for scoped_ptr<FooBarBaz<type> >(new FooBarBaz<type>(arg)) -template <typename T> -rtc::scoped_ptr<T> rtc_make_scoped_ptr(T* ptr) { - return rtc::scoped_ptr<T>(ptr); -} - -#endif // #ifndef WEBRTC_BASE_SCOPED_PTR_H__ |