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// Utilities for representing and manipulating ranges -*- C++ -*- |
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|
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// Copyright (C) 2019-2021 Free Software Foundation, Inc. |
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// |
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// This file is part of the GNU ISO C++ Library. This library is free |
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// software; you can redistribute it and/or modify it under the |
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// terms of the GNU General Public License as published by the |
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// Free Software Foundation; either version 3, or (at your option) |
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// any later version. |
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|
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// This library is distributed in the hope that it will be useful, |
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// but WITHOUT ANY WARRANTY; without even the implied warranty of |
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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// GNU General Public License for more details. |
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|
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// Under Section 7 of GPL version 3, you are granted additional |
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// permissions described in the GCC Runtime Library Exception, version |
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// 3.1, as published by the Free Software Foundation. |
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|
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// You should have received a copy of the GNU General Public License and |
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// a copy of the GCC Runtime Library Exception along with this program; |
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
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// <http://www.gnu.org/licenses/>. |
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|
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/** @file bits/ranges_util.h |
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* This is an internal header file, included by other library headers. |
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* Do not attempt to use it directly. @headername{ranges} |
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*/ |
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|
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#ifndef _RANGES_UTIL_H |
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#define _RANGES_UTIL_H 1 |
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|
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#if __cplusplus > 201703L |
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# include <bits/ranges_base.h> |
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|
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#ifdef __cpp_lib_ranges |
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namespace std _GLIBCXX_VISIBILITY(default) |
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{ |
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_GLIBCXX_BEGIN_NAMESPACE_VERSION |
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namespace ranges |
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{ |
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// C++20 24.5 [range.utility] Range utilities |
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|
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namespace __detail |
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{ |
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template<typename _Range> |
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concept __simple_view = view<_Range> && range<const _Range> |
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&& same_as<iterator_t<_Range>, iterator_t<const _Range>> |
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&& same_as<sentinel_t<_Range>, sentinel_t<const _Range>>; |
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|
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template<typename _It> |
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concept __has_arrow = input_iterator<_It> |
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&& (is_pointer_v<_It> || requires(_It __it) { __it.operator->(); }); |
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|
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template<typename _Tp, typename _Up> |
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concept __not_same_as |
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= !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>; |
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} // namespace __detail |
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|
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/// The ranges::view_interface class template |
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template<typename _Derived> |
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requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>> |
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class view_interface : public view_base |
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{ |
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private: |
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constexpr _Derived& _M_derived() noexcept |
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{ |
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static_assert(derived_from<_Derived, view_interface<_Derived>>); |
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static_assert(view<_Derived>); |
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return static_cast<_Derived&>(*this); |
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} |
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|
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constexpr const _Derived& _M_derived() const noexcept |
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{ |
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static_assert(derived_from<_Derived, view_interface<_Derived>>); |
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static_assert(view<_Derived>); |
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return static_cast<const _Derived&>(*this); |
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} |
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|
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public: |
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constexpr bool |
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empty() requires forward_range<_Derived> |
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{ return ranges::begin(_M_derived()) == ranges::end(_M_derived()); } |
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|
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constexpr bool |
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empty() const requires forward_range<const _Derived> |
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{ return ranges::begin(_M_derived()) == ranges::end(_M_derived()); } |
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|
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constexpr explicit |
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operator bool() requires requires { ranges::empty(_M_derived()); } |
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{ return !ranges::empty(_M_derived()); } |
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|
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constexpr explicit |
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operator bool() const requires requires { ranges::empty(_M_derived()); } |
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{ return !ranges::empty(_M_derived()); } |
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|
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constexpr auto |
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data() requires contiguous_iterator<iterator_t<_Derived>> |
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{ return to_address(ranges::begin(_M_derived())); } |
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|
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constexpr auto |
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data() const |
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requires range<const _Derived> |
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&& contiguous_iterator<iterator_t<const _Derived>> |
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{ return to_address(ranges::begin(_M_derived())); } |
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|
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constexpr auto |
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size() |
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requires forward_range<_Derived> |
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&& sized_sentinel_for<sentinel_t<_Derived>, iterator_t<_Derived>> |
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{ return ranges::end(_M_derived()) - ranges::begin(_M_derived()); } |
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|
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constexpr auto |
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size() const |
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requires forward_range<const _Derived> |
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&& sized_sentinel_for<sentinel_t<const _Derived>, |
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iterator_t<const _Derived>> |
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{ return ranges::end(_M_derived()) - ranges::begin(_M_derived()); } |
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|
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constexpr decltype(auto) |
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front() requires forward_range<_Derived> |
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{ |
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__glibcxx_assert(!empty()); |
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return *ranges::begin(_M_derived()); |
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} |
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|
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constexpr decltype(auto) |
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front() const requires forward_range<const _Derived> |
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{ |
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__glibcxx_assert(!empty()); |
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return *ranges::begin(_M_derived()); |
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} |
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|
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constexpr decltype(auto) |
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back() |
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requires bidirectional_range<_Derived> && common_range<_Derived> |
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{ |
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__glibcxx_assert(!empty()); |
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return *ranges::prev(ranges::end(_M_derived())); |
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} |
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|
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constexpr decltype(auto) |
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back() const |
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requires bidirectional_range<const _Derived> |
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&& common_range<const _Derived> |
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{ |
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__glibcxx_assert(!empty()); |
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return *ranges::prev(ranges::end(_M_derived())); |
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} |
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|
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template<random_access_range _Range = _Derived> |
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constexpr decltype(auto) |
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operator[](range_difference_t<_Range> __n) |
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{ return ranges::begin(_M_derived())[__n]; } |
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|
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template<random_access_range _Range = const _Derived> |
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constexpr decltype(auto) |
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operator[](range_difference_t<_Range> __n) const |
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{ return ranges::begin(_M_derived())[__n]; } |
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}; |
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|
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namespace __detail |
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{ |
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template<class _From, class _To> |
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concept __convertible_to_non_slicing = convertible_to<_From, _To> |
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&& !(is_pointer_v<decay_t<_From>> && is_pointer_v<decay_t<_To>> |
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&& __not_same_as<remove_pointer_t<decay_t<_From>>, |
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remove_pointer_t<decay_t<_To>>>); |
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|
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template<typename _Tp> |
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concept __pair_like |
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= !is_reference_v<_Tp> && requires(_Tp __t) |
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{ |
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typename tuple_size<_Tp>::type; |
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requires derived_from<tuple_size<_Tp>, integral_constant<size_t, 2>>; |
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typename tuple_element_t<0, remove_const_t<_Tp>>; |
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typename tuple_element_t<1, remove_const_t<_Tp>>; |
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{ get<0>(__t) } -> convertible_to<const tuple_element_t<0, _Tp>&>; |
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{ get<1>(__t) } -> convertible_to<const tuple_element_t<1, _Tp>&>; |
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}; |
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|
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template<typename _Tp, typename _Up, typename _Vp> |
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concept __pair_like_convertible_from |
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= !range<_Tp> && __pair_like<_Tp> |
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&& constructible_from<_Tp, _Up, _Vp> |
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&& __convertible_to_non_slicing<_Up, tuple_element_t<0, _Tp>> |
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&& convertible_to<_Vp, tuple_element_t<1, _Tp>>; |
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|
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} // namespace __detail |
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|
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enum class subrange_kind : bool { unsized, sized }; |
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|
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/// The ranges::subrange class template |
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template<input_or_output_iterator _It, sentinel_for<_It> _Sent = _It, |
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subrange_kind _Kind = sized_sentinel_for<_Sent, _It> |
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? subrange_kind::sized : subrange_kind::unsized> |
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requires (_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _It>) |
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class subrange : public view_interface<subrange<_It, _Sent, _Kind>> |
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{ |
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private: |
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// XXX: gcc complains when using constexpr here |
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static const bool _S_store_size |
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= _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>; |
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|
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_It _M_begin = _It(); |
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[[no_unique_address]] _Sent _M_end = _Sent(); |
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|
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using __size_type |
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= __detail::__make_unsigned_like_t<iter_difference_t<_It>>; |
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|
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template<typename, bool = _S_store_size> |
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struct _Size |
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{ }; |
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template<typename _Tp> |
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struct _Size<_Tp, true> |
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{ _Tp _M_size; }; |
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[[no_unique_address]] _Size<__size_type> _M_size = {}; |
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|
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public: |
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subrange() = default; |
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|
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constexpr |
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subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s) |
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requires (!_S_store_size) |
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: _M_begin(std::move(__i)), _M_end(__s) |
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{ } |
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|
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constexpr |
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subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s, |
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__size_type __n) |
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requires (_Kind == subrange_kind::sized) |
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: _M_begin(std::move(__i)), _M_end(__s) |
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{ |
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if constexpr (_S_store_size) |
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_M_size._M_size = __n; |
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} |
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|
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template<__detail::__not_same_as<subrange> _Rng> |
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requires borrowed_range<_Rng> |
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&& __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> |
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&& convertible_to<sentinel_t<_Rng>, _Sent> |
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constexpr |
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subrange(_Rng&& __r) requires _S_store_size && sized_range<_Rng> |
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: subrange(__r, ranges::size(__r)) |
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{ } |
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|
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template<__detail::__not_same_as<subrange> _Rng> |
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requires borrowed_range<_Rng> |
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&& __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> |
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&& convertible_to<sentinel_t<_Rng>, _Sent> |
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constexpr |
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subrange(_Rng&& __r) requires (!_S_store_size) |
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: subrange(ranges::begin(__r), ranges::end(__r)) |
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{ } |
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|
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template<borrowed_range _Rng> |
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requires __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> |
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&& convertible_to<sentinel_t<_Rng>, _Sent> |
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constexpr |
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subrange(_Rng&& __r, __size_type __n) |
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requires (_Kind == subrange_kind::sized) |
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: subrange{ranges::begin(__r), ranges::end(__r), __n} |
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{ } |
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|
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template<__detail::__not_same_as<subrange> _PairLike> |
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requires __detail::__pair_like_convertible_from<_PairLike, const _It&, |
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const _Sent&> |
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constexpr |
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operator _PairLike() const |
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{ return _PairLike(_M_begin, _M_end); } |
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|
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constexpr _It |
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begin() const requires copyable<_It> |
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{ return _M_begin; } |
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|
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[[nodiscard]] constexpr _It |
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begin() requires (!copyable<_It>) |
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{ return std::move(_M_begin); } |
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|
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constexpr _Sent end() const { return _M_end; } |
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|
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constexpr bool empty() const { return _M_begin == _M_end; } |
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|
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constexpr __size_type |
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size() const requires (_Kind == subrange_kind::sized) |
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{ |
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if constexpr (_S_store_size) |
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return _M_size._M_size; |
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else |
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return __detail::__to_unsigned_like(_M_end - _M_begin); |
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} |
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|
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[[nodiscard]] constexpr subrange |
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next(iter_difference_t<_It> __n = 1) const & |
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requires forward_iterator<_It> |
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{ |
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auto __tmp = *this; |
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__tmp.advance(__n); |
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return __tmp; |
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} |
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|
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[[nodiscard]] constexpr subrange |
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next(iter_difference_t<_It> __n = 1) && |
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{ |
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advance(__n); |
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return std::move(*this); |
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} |
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|
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[[nodiscard]] constexpr subrange |
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prev(iter_difference_t<_It> __n = 1) const |
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requires bidirectional_iterator<_It> |
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{ |
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auto __tmp = *this; |
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__tmp.advance(-__n); |
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return __tmp; |
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} |
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|
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constexpr subrange& |
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advance(iter_difference_t<_It> __n) |
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{ |
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// _GLIBCXX_RESOLVE_LIB_DEFECTS |
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// 3433. subrange::advance(n) has UB when n < 0 |
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if constexpr (bidirectional_iterator<_It>) |
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if (__n < 0) |
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{ |
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ranges::advance(_M_begin, __n); |
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if constexpr (_S_store_size) |
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_M_size._M_size += __detail::__to_unsigned_like(-__n); |
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return *this; |
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} |
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|
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__glibcxx_assert(__n >= 0); |
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auto __d = __n - ranges::advance(_M_begin, __n, _M_end); |
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if constexpr (_S_store_size) |
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_M_size._M_size -= __detail::__to_unsigned_like(__d); |
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return *this; |
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} |
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}; |
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|
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template<input_or_output_iterator _It, sentinel_for<_It> _Sent> |
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subrange(_It, _Sent) -> subrange<_It, _Sent>; |
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|
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template<input_or_output_iterator _It, sentinel_for<_It> _Sent> |
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subrange(_It, _Sent, |
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__detail::__make_unsigned_like_t<iter_difference_t<_It>>) |
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-> subrange<_It, _Sent, subrange_kind::sized>; |
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|
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template<borrowed_range _Rng> |
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subrange(_Rng&&) |
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-> subrange<iterator_t<_Rng>, sentinel_t<_Rng>, |
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(sized_range<_Rng> |
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|| sized_sentinel_for<sentinel_t<_Rng>, iterator_t<_Rng>>) |
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? subrange_kind::sized : subrange_kind::unsized>; |
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|
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template<borrowed_range _Rng> |
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subrange(_Rng&&, |
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__detail::__make_unsigned_like_t<range_difference_t<_Rng>>) |
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-> subrange<iterator_t<_Rng>, sentinel_t<_Rng>, subrange_kind::sized>; |
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|
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template<size_t _Num, class _It, class _Sent, subrange_kind _Kind> |
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requires (_Num < 2) |
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constexpr auto |
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get(const subrange<_It, _Sent, _Kind>& __r) |
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{ |
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if constexpr (_Num == 0) |
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return __r.begin(); |
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else |
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return __r.end(); |
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} |
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|
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template<size_t _Num, class _It, class _Sent, subrange_kind _Kind> |
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requires (_Num < 2) |
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constexpr auto |
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get(subrange<_It, _Sent, _Kind>&& __r) |
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{ |
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if constexpr (_Num == 0) |
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return __r.begin(); |
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else |
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return __r.end(); |
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} |
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|
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template<input_or_output_iterator _It, sentinel_for<_It> _Sent, |
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subrange_kind _Kind> |
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inline constexpr bool |
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enable_borrowed_range<subrange<_It, _Sent, _Kind>> = true; |
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|
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template<range _Range> |
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using borrowed_subrange_t = conditional_t<borrowed_range<_Range>, |
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subrange<iterator_t<_Range>>, |
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dangling>; |
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|
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} // namespace ranges |
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|
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using ranges::get; |
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|
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template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
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struct tuple_size<ranges::subrange<_Iter, _Sent, _Kind>> |
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: integral_constant<size_t, 2> |
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{ }; |
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|
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template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
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struct tuple_element<0, ranges::subrange<_Iter, _Sent, _Kind>> |
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{ using type = _Iter; }; |
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|
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template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
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struct tuple_element<1, ranges::subrange<_Iter, _Sent, _Kind>> |
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{ using type = _Sent; }; |
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|
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template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
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struct tuple_element<0, const ranges::subrange<_Iter, _Sent, _Kind>> |
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{ using type = _Iter; }; |
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|
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template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
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struct tuple_element<1, const ranges::subrange<_Iter, _Sent, _Kind>> |
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{ using type = _Sent; }; |
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|
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_GLIBCXX_END_NAMESPACE_VERSION |
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} // namespace std |
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#endif // library concepts |
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#endif // C++20 |
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#endif // _RANGES_UTIL_H |
