// Copyright (C) 2019 T. Zachary Laine
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// 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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#ifndef BOOST_STL_INTERFACES_FWD_HPP
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#define BOOST_STL_INTERFACES_FWD_HPP
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#include <iterator>
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#ifndef BOOST_STL_INTERFACES_DOXYGEN
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#if defined(_MSC_VER) || defined(__GNUC__) && __GNUC__ < 8
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#define BOOST_STL_INTERFACES_NO_HIDDEN_FRIEND_CONSTEXPR
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#define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR
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#else
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#define BOOST_STL_INTERFACES_HIDDEN_FRIEND_CONSTEXPR constexpr
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#endif
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#if defined(__GNUC__) && __GNUC__ < 9
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#define BOOST_STL_INTERFACES_CONCEPT concept bool
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#else
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#define BOOST_STL_INTERFACES_CONCEPT concept
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#endif
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#endif
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namespace boost { namespace stl_interfaces {
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inline namespace v1 {
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/** An enumeration used to indicate whether the underlying data have a
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contiguous or discontiguous layout when instantiating
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`view_interface` and `sequence_container_interface`. */
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enum class element_layout : bool {
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discontiguous = false,
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contiguous = true
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};
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namespace v1_dtl {
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template<typename... T>
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using void_t = void;
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template<typename Iter>
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using iter_difference_t =
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typename std::iterator_traits<Iter>::difference_type;
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template<typename Range, typename = void>
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struct iterator;
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template<typename Range>
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struct iterator<
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Range,
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void_t<decltype(std::declval<Range &>().begin())>>
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{
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using type = decltype(std::declval<Range &>().begin());
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};
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template<typename Range>
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using iterator_t = typename iterator<Range>::type;
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template<typename Range, typename = void>
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struct sentinel;
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template<typename Range>
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struct sentinel<
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Range,
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void_t<decltype(std::declval<Range &>().end())>>
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{
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using type = decltype(std::declval<Range &>().end());
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};
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template<typename Range>
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using sentinel_t = typename sentinel<Range>::type;
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template<typename Range>
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using range_difference_t = iter_difference_t<iterator_t<Range>>;
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template<typename Range>
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using common_range =
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std::is_same<iterator_t<Range>, sentinel_t<Range>>;
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template<typename Range, typename = void>
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struct decrementable_sentinel : std::false_type
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{
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};
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template<typename Range>
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struct decrementable_sentinel<
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Range,
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void_t<decltype(--std::declval<sentinel_t<Range> &>())>>
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: std::true_type
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{
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};
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}
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}
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}}
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#endif
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