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hof/fit/mutable.h
2014-08-01 17:09:23 -04:00

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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)
///
#include <fit/returns.h>
namespace fit {
template<class F>
struct mutable_adaptor
{
mutable F f;
template<class X>
mutable_adaptor(X x) : f(x)
{}
template<class... Ts>
auto operator()(Ts&&... xs) const FIT_RETURNS(f(std::forward<Ts>(xs)...));
};
template<class F>
mutable_adaptor<F> mutable_(F f)
{
return mutable_adaptor<F>(f);
}
}
#endif