mirror of https://github.com/axmolengine/axmol.git
138 lines
4.7 KiB
C++
138 lines
4.7 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Eric Niebler 2014-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_FACADE_HPP
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#define RANGES_V3_VIEW_FACADE_HPP
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#include <type_traits>
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#include <utility>
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#include <meta/meta.hpp>
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#include <concepts/concepts.hpp>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/iterator/basic_iterator.hpp>
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#include <range/v3/iterator/default_sentinel.hpp>
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#include <range/v3/iterator/traits.hpp>
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#include <range/v3/view/interface.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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/// \cond
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namespace detail
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{
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template<typename Derived>
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using begin_cursor_t = detail::decay_t<decltype(
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range_access::begin_cursor(std::declval<Derived &>()))>;
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template<typename Derived>
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using end_cursor_t = detail::decay_t<decltype(
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range_access::end_cursor(std::declval<Derived &>()))>;
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template<typename Derived>
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using facade_iterator_t = basic_iterator<begin_cursor_t<Derived>>;
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template<typename Derived>
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using facade_sentinel_t =
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meta::if_c<same_as<begin_cursor_t<Derived>, end_cursor_t<Derived>>,
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facade_iterator_t<Derived>, end_cursor_t<Derived>>;
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} // namespace detail
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/// \endcond
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/// \addtogroup group-views
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/// @{
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/// \brief A utility for constructing a view from a (derived) type that
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/// implements begin and end cursors.
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/// \tparam Derived A type that derives from `view_facade` and implements
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/// begin and end cursors. This type is permitted to be incomplete.
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/// \tparam Cardinality The cardinality of this view: `finite`, `infinite`,
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/// or `unknown`. See `ranges::cardinality`.
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template<typename Derived, cardinality Cardinality>
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struct view_facade : view_interface<Derived, Cardinality>
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{
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protected:
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friend range_access;
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struct view_as_cursor : Derived
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{
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view_as_cursor() = default;
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explicit view_as_cursor(Derived const * derived)
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: Derived(*derived)
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{}
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explicit operator bool() = delete;
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explicit operator bool() const = delete;
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};
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// Default implementations
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constexpr view_as_cursor begin_cursor() const
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{
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return view_as_cursor{static_cast<Derived const *>(this)};
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}
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constexpr default_sentinel_t end_cursor() const
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{
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return {};
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}
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public:
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/// Let `d` be `static_cast<Derived &>(*this)`. Let `b` be
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/// `std::as_const(d).begin_cursor()` if that expression is well-formed;
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/// otherwise, let `b` be `d.begin_cursor()`. Let `B` be the type of
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/// `b`.
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/// \return `ranges::basic_iterator<B>(b)`
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template(typename D = Derived)(
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requires same_as<D, Derived>)
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constexpr auto begin() -> detail::facade_iterator_t<D>
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{
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return detail::facade_iterator_t<D>{
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range_access::begin_cursor(*static_cast<Derived *>(this))};
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}
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/// \overload
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template(typename D = Derived)(
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requires same_as<D, Derived>)
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constexpr auto begin() const -> detail::facade_iterator_t<D const>
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{
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return detail::facade_iterator_t<D const>{
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range_access::begin_cursor(*static_cast<Derived const *>(this))};
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}
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/// Let `d` be `static_cast<Derived &>(*this)`. Let `e` be
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/// `std::as_const(d).end_cursor()` if that expression is well-formed;
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/// otherwise, let `e` be `d.end_cursor()`. Let `E` be the type of
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/// `e`.
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/// \return `ranges::basic_iterator<E>(e)` if `E` is the same
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/// as `B` computed above for `begin()`; otherwise, return `e`.
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template(typename D = Derived)(
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requires same_as<D, Derived>)
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constexpr auto end() -> detail::facade_sentinel_t<D>
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{
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return static_cast<detail::facade_sentinel_t<D>>(
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range_access::end_cursor(*static_cast<Derived *>(this)));
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}
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/// \overload
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template(typename D = Derived)(
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requires same_as<D, Derived>)
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constexpr auto end() const -> detail::facade_sentinel_t<D const>
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{
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return static_cast<detail::facade_sentinel_t<D const>>(
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range_access::end_cursor(*static_cast<Derived const *>(this)));
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}
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};
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/// @}
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#endif
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