mirror of https://github.com/axmolengine/axmol.git
142 lines
3.9 KiB
C++
142 lines
3.9 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Eric Niebler 2013-present
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Project home: https://github.com/ericniebler/range-v3
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//
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#ifndef RANGES_V3_VIEW_SINGLE_HPP
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#define RANGES_V3_VIEW_SINGLE_HPP
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#include <type_traits>
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#include <utility>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/iterator/concepts.hpp>
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#include <range/v3/iterator/traits.hpp>
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#include <range/v3/range/access.hpp>
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#include <range/v3/range/concepts.hpp>
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#include <range/v3/range/traits.hpp>
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#include <range/v3/utility/addressof.hpp>
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#include <range/v3/utility/optional.hpp>
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#include <range/v3/utility/semiregular_box.hpp>
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#include <range/v3/utility/static_const.hpp>
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#include <range/v3/view/facade.hpp>
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#include <range/v3/detail/prologue.hpp>
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namespace ranges
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{
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/// \addtogroup group-views
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/// @{
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template<typename T>
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struct single_view : view_interface<single_view<T>, (cardinality)1>
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{
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private:
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CPP_assert(copy_constructible<T>);
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static_assert(std::is_object<T>::value,
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"The template parameter of single_view must be an object type");
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semiregular_box_t<T> value_;
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template<typename... Args>
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constexpr single_view(in_place_t, std::true_type, Args &&... args)
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: value_{static_cast<Args &&>(args)...}
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{}
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template<typename... Args>
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constexpr single_view(in_place_t, std::false_type, Args &&... args)
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: value_{in_place, static_cast<Args &&>(args)...}
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{}
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public:
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single_view() = default;
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constexpr explicit single_view(T const & t)
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: value_(t)
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{}
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constexpr explicit single_view(T && t)
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: value_(std::move(t))
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{}
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template(class... Args)(
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requires constructible_from<T, Args...>)
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constexpr single_view(in_place_t, Args &&... args)
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: single_view{in_place,
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meta::bool_<(bool)semiregular<T>>{},
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static_cast<Args &&>(args)...}
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{}
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constexpr T * begin() noexcept
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{
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return data();
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}
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constexpr T const * begin() const noexcept
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{
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return data();
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}
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constexpr T * end() noexcept
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{
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return data() + 1;
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}
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constexpr T const * end() const noexcept
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{
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return data() + 1;
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}
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static constexpr std::size_t size() noexcept
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{
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return 1u;
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}
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constexpr T * data() noexcept
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{
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return detail::addressof(static_cast<T &>(value_));
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}
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constexpr T const * data() const noexcept
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{
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return detail::addressof(static_cast<T const &>(value_));
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}
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};
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#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
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template<class T>
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explicit single_view(T &&) //
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-> single_view<detail::decay_t<T>>;
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#endif
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namespace views
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{
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struct single_fn
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{
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template(typename Val)(
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requires copy_constructible<Val>)
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single_view<Val> operator()(Val value) const
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{
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return single_view<Val>{std::move(value)};
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}
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};
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/// \relates single_fn
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/// \ingroup group-views
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RANGES_INLINE_VARIABLE(single_fn, single)
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} // namespace views
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namespace cpp20
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{
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namespace views
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{
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using ranges::views::single;
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}
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template(typename T)(
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requires std::is_object<T>::value) //
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using single_view = ranges::single_view<T>;
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} // namespace cpp20
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/// @}
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#include <range/v3/detail/satisfy_boost_range.hpp>
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RANGES_SATISFY_BOOST_RANGE(::ranges::single_view)
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#endif
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