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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_CALLBACK_H_
#define BASE_CALLBACK_H_
#include "base/callback_forward.h"
#include "base/callback_internal.h"
// NOTE: Header files that do not require the full definition of Callback or
// Closure should #include "base/callback_forward.h" instead of this file.
// -----------------------------------------------------------------------------
// Usage documentation
// -----------------------------------------------------------------------------
//
// See //docs/callback.md for documentation.
namespace base {
template <typename R, typename... Args>
class OnceCallback<R(Args...)> : public internal::CallbackBase {
public:
using RunType = R(Args...);
using PolymorphicInvoke = R (*)(internal::BindStateBase*, Args&&...);
OnceCallback() : internal::CallbackBase(nullptr) {}
explicit OnceCallback(internal::BindStateBase* bind_state)
: internal::CallbackBase(bind_state) {}
OnceCallback(const OnceCallback&) = delete;
OnceCallback& operator=(const OnceCallback&) = delete;
OnceCallback(OnceCallback&&) = default;
OnceCallback& operator=(OnceCallback&&) = default;
OnceCallback(RepeatingCallback<RunType> other)
: internal::CallbackBase(std::move(other)) {}
OnceCallback& operator=(RepeatingCallback<RunType> other) {
static_cast<internal::CallbackBase&>(*this) = std::move(other);
return *this;
}
bool Equals(const OnceCallback& other) const { return EqualsInternal(other); }
R Run(Args... args) const & {
static_assert(!sizeof(*this),
"OnceCallback::Run() may only be invoked on a non-const "
"rvalue, i.e. std::move(callback).Run().");
NOTREACHED();
}
R Run(Args... args) && {
// Move the callback instance into a local variable before the invocation,
// that ensures the internal state is cleared after the invocation.
// It's not safe to touch |this| after the invocation, since running the
// bound function may destroy |this|.
OnceCallback cb = std::move(*this);
PolymorphicInvoke f =
reinterpret_cast<PolymorphicInvoke>(cb.polymorphic_invoke());
return f(cb.bind_state_.get(), std::forward<Args>(args)...);
}
};
template <typename R, typename... Args>
class RepeatingCallback<R(Args...)> : public internal::CallbackBaseCopyable {
public:
using RunType = R(Args...);
using PolymorphicInvoke = R (*)(internal::BindStateBase*, Args&&...);
RepeatingCallback() : internal::CallbackBaseCopyable(nullptr) {}
explicit RepeatingCallback(internal::BindStateBase* bind_state)
: internal::CallbackBaseCopyable(bind_state) {}
// Copyable and movabl.
RepeatingCallback(const RepeatingCallback&) = default;
RepeatingCallback& operator=(const RepeatingCallback&) = default;
RepeatingCallback(RepeatingCallback&&) = default;
RepeatingCallback& operator=(RepeatingCallback&&) = default;
bool Equals(const RepeatingCallback& other) const {
return EqualsInternal(other);
}
R Run(Args... args) const & {
PolymorphicInvoke f =
reinterpret_cast<PolymorphicInvoke>(this->polymorphic_invoke());
return f(this->bind_state_.get(), std::forward<Args>(args)...);
}
R Run(Args... args) && {
// Move the callback instance into a local variable before the invocation,
// that ensures the internal state is cleared after the invocation.
// It's not safe to touch |this| after the invocation, since running the
// bound function may destroy |this|.
RepeatingCallback cb = std::move(*this);
PolymorphicInvoke f =
reinterpret_cast<PolymorphicInvoke>(cb.polymorphic_invoke());
return f(cb.bind_state_.get(), std::forward<Args>(args)...);
}
};
} // namespace base
#endif // BASE_CALLBACK_H_
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