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59 lines
1.2 KiB
C++
59 lines
1.2 KiB
C++
/*=============================================================================
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Copyright (c) 2012 Paul Fultz II
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identity.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_FUNCTION_IDENTITY_H
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#define FIT_GUARD_FUNCTION_IDENTITY_H
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/// identity
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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 `identity` function is an unary function object that returns whats given to it.
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///
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/// Semantics
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/// ---------
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///
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/// assert(identity(x) == x);
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///
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/// Synopsis
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/// --------
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///
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/// struct
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/// {
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/// template<class T>
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/// constexpr T operator()(T&& x) const
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/// {
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/// return fit::forward<T>(x);
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/// }
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/// } identity;
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///
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#include <utility>
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#include <fit/detail/forward.hpp>
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#include <fit/detail/static_const_var.hpp>
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namespace fit { namespace detail {
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struct identity_base
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{
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template<class T>
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constexpr T operator()(T&& x) const
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{
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return FIT_FORWARD(T)(x);
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}
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};
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}
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FIT_DECLARE_STATIC_VAR(identity, detail::identity_base);
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} // namespace fit
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#endif
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