// 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_