add Chapter18

Chapter18/cib/libs/boost/mp11/detail/mp_min_element.hpp

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+#ifndef BOOST_MP11_DETAIL_MP_MIN_ELEMENT_HPP_INCLUDED
+#define BOOST_MP11_DETAIL_MP_MIN_ELEMENT_HPP_INCLUDED
+
+//  Copyright 2015-2017 Peter Dimov.
+//
+//  Distributed under the Boost Software License, Version 1.0.
+//
+//  See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/detail/mp_fold.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+
+namespace boost
+{
+namespace mp11
+{
+
+// mp_min_element<L, P>
+namespace detail
+{
+
+template<template<class...> class P> struct select_min
+{
+    template<class T1, class T2> using fn = mp_if<P<T1, T2>, T1, T2>;
+};
+
+} // namespace detail
+
+template<class L, template<class...> class P> using mp_min_element = mp_fold_q<mp_rest<L>, mp_first<L>, detail::select_min<P>>;
+template<class L, class Q> using mp_min_element_q = mp_min_element<L, Q::template fn>;
+
+// mp_max_element<L, P>
+namespace detail
+{
+
+template<template<class...> class P> struct select_max
+{
+    template<class T1, class T2> using fn = mp_if<P<T2, T1>, T1, T2>;
+};
+
+} // namespace detail
+
+template<class L, template<class...> class P> using mp_max_element = mp_fold_q<mp_rest<L>, mp_first<L>, detail::select_max<P>>;
+template<class L, class Q> using mp_max_element_q = mp_max_element<L, Q::template fn>;
+
+} // namespace mp11
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_DETAIL_MP_MIN_ELEMENT_HPP_INCLUDED