1/*============================================================================= 2 Copyright (c) 2014 Paul Fultz II 3 mutable.h 4 Distributed under the Boost Software License, Version 1.0. (See accompanying 5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6==============================================================================*/ 7 8#ifndef BOOST_HOF_GUARD_FUNCTION_MUTABLE_H 9#define BOOST_HOF_GUARD_FUNCTION_MUTABLE_H 10 11/// mutable 12/// ======= 13/// 14/// Description 15/// ----------- 16/// 17/// The `mutable` function adaptor allows using a non-const function object 18/// inside of a const-function object. In Fit, all the function adaptors use 19/// `const` call overloads, so if there is a function that has a non-const 20/// call operator, it couldn't be used directly. So, `mutable_` allows the 21/// function to be used inside of the call operator. 22/// 23/// NOTE: This function should be used with caution since many functions are 24/// copied, so relying on some internal shared state can be error-prone. 25/// 26/// Synopsis 27/// -------- 28/// 29/// template<class F> 30/// mutable_adaptor<F> mutable_(F f) 31/// 32/// Requirements 33/// ------------ 34/// 35/// F must be: 36/// 37/// * [MutableFunctionObject](MutableFunctionObject) 38/// * MoveConstructible 39/// 40 41#include <boost/hof/detail/result_of.hpp> 42#include <boost/hof/detail/delegate.hpp> 43#include <boost/hof/detail/move.hpp> 44#include <boost/hof/detail/make.hpp> 45#include <boost/hof/detail/static_const_var.hpp> 46 47namespace boost { namespace hof { 48 49template<class F> 50struct mutable_adaptor 51{ 52 mutable F f; 53 54 BOOST_HOF_DELEGATE_CONSTRUCTOR(mutable_adaptor, F, f); 55 56 BOOST_HOF_RETURNS_CLASS(mutable_adaptor); 57 58 template<class... Ts> 59 BOOST_HOF_SFINAE_RESULT(F, id_<Ts>...) 60 operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS(BOOST_HOF_CONST_THIS->f(BOOST_HOF_FORWARD(Ts)(xs)...)); 61}; 62 63BOOST_HOF_DECLARE_STATIC_VAR(mutable_, detail::make<mutable_adaptor>); 64 65}} // namespace boost::hof 66 67 68#endif 69