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112 lines
2.6 KiB
C++
112 lines
2.6 KiB
C++
/*=============================================================================
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Copyright (c) 2015 Paul Fultz II
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construct.h
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef FIT_GUARD_CONSTRUCT_H
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#define FIT_GUARD_CONSTRUCT_H
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/// construct
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/// =========
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///
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/// Description
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/// -----------
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///
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/// The `construct` function returns a function object that will construct the
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/// object when the called. A template can also be givien, which it will
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/// deduce the parameters to the template.
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///
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/// Synopsis
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/// --------
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///
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/// template<class T>
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/// constexpr auto construct();
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///
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/// template<template<class...> class Template>
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/// constexpr auto construct();
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///
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/// Requirements
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/// ------------
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///
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/// T or Template must be:
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///
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/// MoveConstructible
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///
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/// Example
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/// -------
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///
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/// auto v = fit::construct<std::vector<int>>()(5, 5);
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/// assert(v.size() == 5);
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///
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#include <fit/detail/forward.h>
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#include <fit/detail/move.h>
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#include <fit/detail/delegate.h>
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#include <fit/detail/join.h>
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#include <initializer_list>
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namespace fit { namespace detail {
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template<class T>
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struct construct_f
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{
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constexpr construct_f()
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{}
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template<class... Ts, FIT_ENABLE_IF_CONSTRUCTIBLE(T, Ts...)>
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constexpr T operator()(Ts&&... xs) const
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{
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return T(fit::forward<Ts>(xs)...);
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}
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template<class X, FIT_ENABLE_IF_CONSTRUCTIBLE(T, std::initializer_list<X>&&)>
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constexpr T operator()(std::initializer_list<X>&& x) const
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{
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return T(fit::move(x));
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}
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template<class X, FIT_ENABLE_IF_CONSTRUCTIBLE(T, std::initializer_list<X>&)>
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constexpr T operator()(std::initializer_list<X>& x) const
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{
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return T(x);
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}
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template<class X, FIT_ENABLE_IF_CONSTRUCTIBLE(T, const std::initializer_list<X>&)>
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constexpr T operator()(const std::initializer_list<X>& x) const
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{
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return T(x);
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}
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};
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template<template<class...> class Template>
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struct construct_template_f
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{
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constexpr construct_template_f()
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{}
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template<class... Ts, class Result=FIT_JOIN(Template, Ts...),
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FIT_ENABLE_IF_CONSTRUCTIBLE(Result, Ts...)>
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constexpr Result operator()(Ts&&... xs) const
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{
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return Result(fit::forward<Ts>(xs)...);
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}
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};
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}
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template<class T>
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constexpr detail::construct_f<T> construct()
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{
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return {};
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}
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template<template<class...> class Template>
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constexpr detail::construct_template_f<Template> construct()
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{
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return {};
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}
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}
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#endif
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