cef/include/base/cef_callback_helpers.h

// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2012
// Google Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the name Chromium Embedded
// Framework nor the names of its contributors may be used to endorse
// or promote products derived from this software without specific prior
// written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// This defines helpful methods for dealing with Callbacks.  Because Callbacks
// are implemented using templates, with a class per callback signature, adding
// methods to Callback<> itself is unattractive (lots of extra code gets
// generated).  Instead, consider adding methods here.
//
// ResetAndReturn(&cb) is like cb.Reset() but allows executing a callback (via a
// copy) after the original callback is Reset().  This can be handy if Run()
// reads/writes the variable holding the Callback.

#ifndef CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
#define CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_
#pragma once

#if defined(BASE_CALLBACK_HELPERS_H_)
// Do nothing if the Chromium header has already been included.
// This can happen in cases where Chromium code is used directly by the
// client application. When using Chromium code directly always include
// the Chromium header first to avoid type conflicts.
#elif defined(BUILDING_CEF_SHARED)
// When building CEF include the Chromium header directly.
#include "base/callback_helpers.h"
#else  // !BUILDING_CEF_SHARED
// The following is substantially similar to the Chromium implementation.
// If the Chromium implementation diverges the below implementation should be
// updated to match.

#include "include/base/cef_basictypes.h"
#include "include/base/cef_build.h"
#include "include/base/cef_callback.h"
#include "include/base/cef_macros.h"

namespace base {

template <typename Sig>
base::Callback<Sig> ResetAndReturn(base::Callback<Sig>* cb) {
  base::Callback<Sig> ret(*cb);
  cb->Reset();
  return ret;
}

// ScopedClosureRunner is akin to scoped_ptr for Closures. It ensures that the
// Closure is executed and deleted no matter how the current scope exits.
class ScopedClosureRunner {
 public:
  ScopedClosureRunner();
  explicit ScopedClosureRunner(const Closure& closure);
  ~ScopedClosureRunner();

  void Reset();
  void Reset(const Closure& closure);
  Closure Release() WARN_UNUSED_RESULT;

 private:
  Closure closure_;

  DISALLOW_COPY_AND_ASSIGN(ScopedClosureRunner);
};

}  // namespace base

#endif  // !BUILDING_CEF_SHARED

#endif  // CEF_INCLUDE_BASE_CEF_CALLBACK_HELPERS_H_