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hof/include/fit/mutable.hpp
2016-06-14 00:24:08 -05:00

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/*=============================================================================
Copyright (c) 2014 Paul Fultz II
mutable.h
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#ifndef FIT_GUARD_FUNCTION_MUTABLE_H
#define FIT_GUARD_FUNCTION_MUTABLE_H
/// mutable
/// =======
///
/// Description
/// -----------
///
/// The `mutable` function adaptor allows using a non-const function object
/// inside of a const-function object. In Fit, all the function adaptors use
/// `const` call overloads, so if there is a function that has a non-const
/// call operator, it couldn't be used directly. So, `mutable_` allows the
/// function to be used inside of the call operator.
///
/// NOTE: This function should be used with caution since many functions are
/// copied, so relying on some internal shared state can be error-prone.
///
/// Synopsis
/// --------
///
/// template<class F>
/// mutable_adaptor<F> mutable_(F f)
///
/// Requirements
/// ------------
///
/// F must be:
///
/// * [MutableFunctionObject](MutableFunctionObject)
/// * MoveConstructible
///
#include <fit/detail/result_of.hpp>
#include <fit/detail/delegate.hpp>
#include <fit/detail/move.hpp>
#include <fit/detail/make.hpp>
#include <fit/detail/static_const_var.hpp>
namespace fit {
template<class F>
struct mutable_adaptor
{
mutable F f;
FIT_DELGATE_CONSTRUCTOR(mutable_adaptor, F, f);
FIT_RETURNS_CLASS(mutable_adaptor);
template<class... Ts>
FIT_SFINAE_RESULT(F, id_<Ts>...)
operator()(Ts&&... xs) const FIT_SFINAE_RETURNS(FIT_CONST_THIS->f(FIT_FORWARD(Ts)(xs)...));
};
FIT_DECLARE_STATIC_VAR(mutable_, detail::make<mutable_adaptor>);
} // namespace fit
#endif