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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_
#define BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_
#include <memory>
namespace base {
class SequencedTaskRunner;
// Template helpers which use function indirection to erase T from the
// function signature while still remembering it so we can call the
// correct destructor/release function.
//
// We use this trick so we don't need to include bind.h in a header
// file like sequenced_task_runner.h. We also wrap the helpers in a
// templated class to make it easier for users of DeleteSoon to
// declare the helper as a friend.
template <class T>
class DeleteHelper {
private:
static void DoDelete(const void* object) {
delete static_cast<const T*>(object);
}
friend class SequencedTaskRunner;
};
template <class T>
class DeleteUniquePtrHelper {
private:
static void DoDelete(const void* object) {
// Carefully unwrap `object`. T could have originally been const-qualified
// or not, and it is important to ensure that the constness matches in order
// to use the right specialization of std::default_delete<T>...
std::unique_ptr<T> destroyer(const_cast<T*>(static_cast<const T*>(object)));
}
friend class SequencedTaskRunner;
};
template <class T>
class ReleaseHelper {
private:
static void DoRelease(const void* object) {
static_cast<const T*>(object)->Release();
}
friend class SequencedTaskRunner;
};
} // namespace base
#endif // BASE_TASK_SEQUENCED_TASK_RUNNER_HELPERS_H_
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