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https://bitbucket.org/chromiumembedded/cef
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200 lines
6.2 KiB
C
200 lines
6.2 KiB
C
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// Copyright (c) 2008 Marshall A. Greenblatt. Portions Copyright (c)
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// 2006-2008 Google Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the name Chromium Embedded
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// Framework nor the names of its contributors may be used to endorse
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// or promote products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef CEF_INCLUDE_INTERNAL_CEF_PTR_H_
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#define CEF_INCLUDE_INTERNAL_CEF_PTR_H_
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#pragma once
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#include <stddef.h>
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///
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// Smart pointer implementation borrowed from base/ref_counted.h
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// <p>
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// A smart pointer class for reference counted objects. Use this class instead
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// of calling AddRef and Release manually on a reference counted object to
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// avoid common memory leaks caused by forgetting to Release an object
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// reference. Sample usage:
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// <pre>
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// class MyFoo : public CefBase {
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// ...
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// };
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//
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// void some_function() {
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// // The MyFoo object that |foo| represents starts with a single
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// // reference.
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// CefRefPtr<MyFoo> foo = new MyFoo();
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// foo->Method(param);
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// // |foo| is released when this function returns
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// }
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//
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// void some_other_function() {
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// CefRefPtr<MyFoo> foo = new MyFoo();
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// ...
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// foo = NULL; // explicitly releases |foo|
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// ...
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// if (foo)
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// foo->Method(param);
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// }
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// </pre>
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// The above examples show how CefRefPtr<T> acts like a pointer to T.
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// Given two CefRefPtr<T> classes, it is also possible to exchange
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// references between the two objects, like so:
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// <pre>
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// {
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// CefRefPtr<MyFoo> a = new MyFoo();
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// CefRefPtr<MyFoo> b;
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//
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// b.swap(a);
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// // now, |b| references the MyFoo object, and |a| references NULL.
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// }
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// </pre>
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// To make both |a| and |b| in the above example reference the same MyFoo
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// object, simply use the assignment operator:
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// <pre>
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// {
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// CefRefPtr<MyFoo> a = new MyFoo();
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// CefRefPtr<MyFoo> b;
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//
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// b = a;
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// // now, |a| and |b| each own a reference to the same MyFoo object.
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// // the reference count of the underlying MyFoo object will be 2.
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// }
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// </pre>
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// Reference counted objects can also be passed as function parameters and
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// used as function return values:
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// <pre>
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// void some_func_with_param(CefRefPtr<MyFoo> param) {
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// // A reference is added to the MyFoo object that |param| represents
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// // during the scope of some_func_with_param() and released when
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// // some_func_with_param() goes out of scope.
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// }
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//
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// CefRefPtr<MyFoo> some_func_with_retval() {
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// // The MyFoo object that |foox| represents starts with a single
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// // reference.
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// CefRefPtr<MyFoo> foox = new MyFoo();
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//
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// // Creating the return value adds an additional reference.
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// return foox;
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//
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// // When some_func_with_retval() goes out of scope the original |foox|
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// // reference is released.
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// }
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//
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// void and_another_function() {
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// CefRefPtr<MyFoo> foo = new MyFoo();
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//
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// // pass |foo| as a parameter.
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// some_function(foo);
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//
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// CefRefPtr<MyFoo> foo2 = some_func_with_retval();
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// // Now, since we kept a reference to the some_func_with_retval() return
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// // value, |foo2| is the only class pointing to the MyFoo object created
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// in some_func_with_retval(), and it has a reference count of 1.
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//
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// some_func_with_retval();
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// // Now, since we didn't keep a reference to the some_func_with_retval()
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// // return value, the MyFoo object created in some_func_with_retval()
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// // will automatically be released.
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// }
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// </pre>
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// And in standard containers:
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// <pre>
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// {
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// // Create a vector that holds MyFoo objects.
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// std::vector<CefRefPtr<MyFoo> > MyFooVec;
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//
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// // The MyFoo object that |foo| represents starts with a single
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// // reference.
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// CefRefPtr<MyFoo> foo = new MyFoo();
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//
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// // When the MyFoo object is added to |MyFooVec| the reference count
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// // is increased to 2.
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// MyFooVec.push_back(foo);
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// }
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// </pre>
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// </p>
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///
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template <class T>
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class CefRefPtr {
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public:
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CefRefPtr() : ptr_(NULL) {
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}
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CefRefPtr(T* p) : ptr_(p) { // NOLINT(runtime/explicit)
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if (ptr_)
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ptr_->AddRef();
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}
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CefRefPtr(const CefRefPtr<T>& r) : ptr_(r.ptr_) {
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if (ptr_)
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ptr_->AddRef();
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}
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~CefRefPtr() {
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if (ptr_)
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ptr_->Release();
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}
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T* get() const { return ptr_; }
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operator T*() const { return ptr_; }
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T* operator->() const { return ptr_; }
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CefRefPtr<T>& operator=(T* p) {
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// AddRef first so that self assignment should work
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if (p)
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p->AddRef();
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if (ptr_ )
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ptr_ ->Release();
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ptr_ = p;
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return *this;
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}
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CefRefPtr<T>& operator=(const CefRefPtr<T>& r) {
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return *this = r.ptr_;
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}
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void swap(T** pp) {
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T* p = ptr_;
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ptr_ = *pp;
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*pp = p;
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}
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void swap(CefRefPtr<T>& r) {
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swap(&r.ptr_); // NOLINT(build/include_what_you_use)
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}
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private:
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T* ptr_;
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};
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#endif // CEF_INCLUDE_INTERNAL_CEF_PTR_H_
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