120 lines
3.0 KiB
C++
120 lines
3.0 KiB
C++
// Boost enable_if library
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// Copyright 2003 (c) The Trustees of Indiana University.
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// Use, modification, and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Authors: Jaakko Jarvi (jajarvi at osl.iu.edu)
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// Jeremiah Willcock (jewillco at osl.iu.edu)
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// Andrew Lumsdaine (lums at osl.iu.edu)
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#ifndef BOOST_UTILITY_ENABLE_IF_HPP
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#define BOOST_UTILITY_ENABLE_IF_HPP
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#include "boost/config.hpp"
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// Even the definition of enable_if causes problems on some compilers,
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// so it's macroed out for all compilers that do not support SFINAE
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#ifndef BOOST_NO_SFINAE
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namespace boost
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{
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template <bool B, class T = void>
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struct enable_if_c {
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typedef T type;
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};
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template <class T>
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struct enable_if_c<false, T> {};
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template <class Cond, class T = void>
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struct enable_if : public enable_if_c<Cond::value, T> {};
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template <bool B, class T>
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struct lazy_enable_if_c {
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typedef typename T::type type;
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};
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template <class T>
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struct lazy_enable_if_c<false, T> {};
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template <class Cond, class T>
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struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
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template <bool B, class T = void>
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struct disable_if_c {
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typedef T type;
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};
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template <class T>
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struct disable_if_c<true, T> {};
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template <class Cond, class T = void>
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struct disable_if : public disable_if_c<Cond::value, T> {};
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template <bool B, class T>
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struct lazy_disable_if_c {
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typedef typename T::type type;
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};
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template <class T>
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struct lazy_disable_if_c<true, T> {};
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template <class Cond, class T>
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struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
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} // namespace boost
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#else
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namespace boost {
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namespace detail { typedef void enable_if_default_T; }
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template <typename T>
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struct enable_if_does_not_work_on_this_compiler;
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template <bool B, class T = detail::enable_if_default_T>
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struct enable_if_c : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <bool B, class T = detail::enable_if_default_T>
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struct disable_if_c : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <bool B, class T = detail::enable_if_default_T>
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struct lazy_enable_if_c : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <bool B, class T = detail::enable_if_default_T>
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struct lazy_disable_if_c : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <class Cond, class T = detail::enable_if_default_T>
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struct enable_if : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <class Cond, class T = detail::enable_if_default_T>
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struct disable_if : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <class Cond, class T = detail::enable_if_default_T>
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struct lazy_enable_if : enable_if_does_not_work_on_this_compiler<T>
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{ };
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template <class Cond, class T = detail::enable_if_default_T>
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struct lazy_disable_if : enable_if_does_not_work_on_this_compiler<T>
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{ };
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} // namespace boost
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#endif // BOOST_NO_SFINAE
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#endif
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