45 lines
1.8 KiB
C++
45 lines
1.8 KiB
C++
// common_type.hpp ---------------------------------------------------------//
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// Copyright 2010 Vicente J. Botet Escriba
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// Distributed under the Boost Software License, Version 1.0.
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// See http://www.boost.org/LICENSE_1_0.txt
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#ifndef BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP
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#define BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP
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#include <boost/config.hpp>
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//----------------------------------------------------------------------------//
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#include <boost/type_traits/add_rvalue_reference.hpp>
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//----------------------------------------------------------------------------//
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// //
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// C++03 implementation of //
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// Written by Vicente J. Botet Escriba //
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//~ 20.3.4 Function template declval [declval]
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//~ 1 The library provides the function template declval to simplify the definition of expressions which occur as
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//~ unevaluated operands.
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//~ 2 Remarks: If this function is used, the program is ill-formed.
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//~ 3 Remarks: The template parameter T of declval may be an incomplete type.
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//~ [ Example:
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//~ template <class To, class From>
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//~ decltype(static_cast<To>(declval<From>())) convert(From&&);
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//~ declares a function template convert which only participats in overloading if the type From can be
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//~ explicitly converted to type To. For another example see class template common_type (20.7.6.6). —end
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//~ example ]
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// //
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//----------------------------------------------------------------------------//
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namespace boost {
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template <typename T>
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typename add_rvalue_reference<T>::type declval(); //noexcept; // as unevaluated operand
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} // namespace boost
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#endif // BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP
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