libstdc++: Move some ranges algos to a new header <bits/ranges_algobase.h>
authorPatrick Palka <ppalka@redhat.com>
Wed, 12 Feb 2020 17:30:57 +0000 (12:30 -0500)
committerPatrick Palka <ppalka@redhat.com>
Thu, 13 Feb 2020 20:20:49 +0000 (15:20 -0500)
This roughly mirrors the existing split between <bits/stl_algo.h> and
<bits/stl_algobase.h>.  The ranges [specialized.algorithms] will use this new
header to avoid including all of of <bits/ranges_algo.h>.

libstdc++-v3/ChangeLog:

* include/Makefile.am: Add bits/ranges_algobase.h
* include/Makefile.in: Regenerate.
* bits/ranges_algo.h: Include <bits/ranges_algobase.h> and refactor
existing #includes.
(__detail::__is_normal_iterator, __detail::is_reverse_iterator,
__detail::__is_move_iterator, copy_result, move_result,
__equal, equal, copy_result, move_result, move_backward_result,
copy_backward_result, __copy_or_move_backward, __copy_or_move, copy,
move, copy_backward, move_backward, copy_n_result, copy_n, fill_n,
fill): Split out into ...
* bits/range_algobase.h: ... this new header.

libstdc++-v3/ChangeLog
libstdc++-v3/include/Makefile.am
libstdc++-v3/include/Makefile.in
libstdc++-v3/include/bits/ranges_algo.h
libstdc++-v3/include/bits/ranges_algobase.h [new file with mode: 0644]

index cc4cfb7da0fbdf21cd338923ea3d5a429d575055..8715e50daba4b7f97dc2bf3dcbcf6b17f7b3780d 100644 (file)
@@ -1,3 +1,17 @@
+2020-02-13  Patrick Palka  <ppalka@redhat.com>
+
+       * include/Makefile.am: Add bits/ranges_algobase.h
+       * include/Makefile.in: Regenerate.
+       * bits/ranges_algo.h: Include <bits/ranges_algobase.h> and refactor
+       existing #includes.
+       (__detail::__is_normal_iterator, __detail::is_reverse_iterator,
+       __detail::__is_move_iterator, copy_result, move_result,
+       __equal, equal, copy_result, move_result, move_backward_result,
+       copy_backward_result, __copy_or_move_backward, __copy_or_move, copy,
+       move, copy_backward, move_backward, copy_n_result, copy_n, fill_n,
+       fill): Split out into ...
+       * bits/range_algobase.h: ... this new header.
+
 2020-02-12  Patrick Palka  <ppalka@redhat.com>
 
        LWG 3389 and LWG 3390
index 1d342cecbccfbf0e4b60632f5efa3306eb93d9b6..614222db400b7a557702ccae76b9d71b8f28aed3 100644 (file)
@@ -157,6 +157,7 @@ bits_headers = \
        ${bits_srcdir}/random.tcc \
        ${bits_srcdir}/range_access.h \
        ${bits_srcdir}/range_cmp.h \
+       ${bits_srcdir}/ranges_algobase.h \
        ${bits_srcdir}/ranges_algo.h \
        ${bits_srcdir}/refwrap.h \
        ${bits_srcdir}/regex.h \
index c735d67a5d30f5e0f054ba496ae42cf1816ced50..7ee6a1e3f61abd526a6a72064454aa4cbf26d05a 100644 (file)
@@ -502,6 +502,7 @@ bits_headers = \
        ${bits_srcdir}/random.tcc \
        ${bits_srcdir}/range_access.h \
        ${bits_srcdir}/range_cmp.h \
+       ${bits_srcdir}/ranges_algobase.h \
        ${bits_srcdir}/ranges_algo.h \
        ${bits_srcdir}/refwrap.h \
        ${bits_srcdir}/regex.h \
index e065ff2a9740ff65fafc00eac9d17b14bc58d694..84a02cabb80d031c7cc5058709428d1fca7b5f27 100644 (file)
 
 #if __cplusplus > 201703L
 
-#include <compare>
-#include <cmath>
-#include <iterator>
-// #include <bits/range_concepts.h>
-#include <ranges>
-#include <bits/invoke.h>
-#include <bits/cpp_type_traits.h> // __is_byte
+#include <bits/ranges_algobase.h>
 #include <bits/random.h> // concept uniform_random_bit_generator
 
 #if __cpp_lib_concepts
@@ -49,28 +43,6 @@ namespace ranges
 {
   namespace __detail
   {
-    template<typename _Tp>
-      constexpr inline bool __is_normal_iterator = false;
-
-    template<typename _Iterator, typename _Container>
-      constexpr inline bool
-       __is_normal_iterator<__gnu_cxx::__normal_iterator<_Iterator,
-                                                         _Container>> = true;
-
-    template<typename _Tp>
-      constexpr inline bool __is_reverse_iterator = false;
-
-    template<typename _Iterator>
-      constexpr inline bool
-       __is_reverse_iterator<reverse_iterator<_Iterator>> = true;
-
-    template<typename _Tp>
-      constexpr inline bool __is_move_iterator = false;
-
-    template<typename _Iterator>
-      constexpr inline bool
-       __is_move_iterator<move_iterator<_Iterator>> = true;
-
     template<typename _Comp, typename _Proj>
       constexpr auto
       __make_comp_proj(_Comp& __comp, _Proj& __proj)
@@ -741,420 +713,6 @@ namespace ranges
                                    std::move(__proj1), std::move(__proj2));
     }
 
-  template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
-          input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
-          typename _Pred, typename _Proj1, typename _Proj2>
-    requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-    constexpr bool
-    __equal(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
-           _Pred __pred, _Proj1 __proj1, _Proj2 __proj2)
-    {
-      // TODO: implement more specializations to at least have parity with
-      // std::equal.
-      constexpr bool __sized_iters
-       = (sized_sentinel_for<_Sent1, _Iter1>
-          && sized_sentinel_for<_Sent2, _Iter2>);
-      if constexpr (__sized_iters)
-       {
-         auto __d1 = ranges::distance(__first1, __last1);
-         auto __d2 = ranges::distance(__first2, __last2);
-         if (__d1 != __d2)
-           return false;
-
-         using _ValueType1 = iter_value_t<_Iter1>;
-         using _ValueType2 = iter_value_t<_Iter2>;
-         constexpr bool __use_memcmp
-           = ((is_integral_v<_ValueType1> || is_pointer_v<_ValueType1>)
-              && is_same_v<_ValueType1, _ValueType2>
-              && is_pointer_v<_Iter1>
-              && is_pointer_v<_Iter2>
-              && is_same_v<_Pred, ranges::equal_to>
-              && is_same_v<_Proj1, identity>
-              && is_same_v<_Proj2, identity>);
-         if constexpr (__use_memcmp)
-           {
-             if (const size_t __len = (__last1 - __first1))
-               return !std::__memcmp(__first1, __first2, __len);
-             return true;
-           }
-         else
-           {
-             for (; __first1 != __last1; ++__first1, (void)++__first2)
-               if (!(bool)std::__invoke(__pred,
-                                        std::__invoke(__proj1, *__first1),
-                                        std::__invoke(__proj2, *__first2)))
-                 return false;
-             return true;
-           }
-       }
-      else
-       {
-         for (; __first1 != __last1 && __first2 != __last2;
-              ++__first1, (void)++__first2)
-           if (!(bool)std::__invoke(__pred,
-                                    std::__invoke(__proj1, *__first1),
-                                    std::__invoke(__proj2, *__first2)))
-             return false;
-         return __first1 == __last1 && __first2 == __last2;
-       }
-    }
-
-  template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
-          input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
-          typename _Pred = ranges::equal_to,
-          typename _Proj1 = identity, typename _Proj2 = identity>
-    requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
-    constexpr bool
-    equal(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
-         _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
-    {
-      return ranges::__equal(std::__niter_base(std::move(__first1)),
-                            std::__niter_base(std::move(__last1)),
-                            std::__niter_base(std::move(__first2)),
-                            std::__niter_base(std::move(__last2)),
-                            std::move(__pred),
-                            std::move(__proj1), std::move(__proj2));
-    }
-
-  template<input_range _Range1, input_range _Range2,
-          typename _Pred = ranges::equal_to,
-          typename _Proj1 = identity, typename _Proj2 = identity>
-    requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
-                                  _Pred, _Proj1, _Proj2>
-    constexpr bool
-    equal(_Range1&& __r1, _Range2&& __r2,
-         _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
-    {
-      return ranges::equal(ranges::begin(__r1), ranges::end(__r1),
-                          ranges::begin(__r2), ranges::end(__r2),
-                          std::move(__pred),
-                          std::move(__proj1), std::move(__proj2));
-    }
-
-  template<typename _Iter, typename _Out>
-    struct copy_result
-    {
-      [[no_unique_address]] _Iter in;
-      [[no_unique_address]] _Out out;
-
-      template<typename _Iter2, typename _Out2>
-       requires convertible_to<const _Iter&, _Iter2>
-         && convertible_to<const _Out&, _Out2>
-       operator copy_result<_Iter2, _Out2>() const &
-       { return {in, out}; }
-
-      template<typename _Iter2, typename _Out2>
-       requires convertible_to<_Iter, _Iter2>
-         && convertible_to<_Out, _Out2>
-       operator copy_result<_Iter2, _Out2>() &&
-       { return {std::move(in), std::move(out)}; }
-    };
-
-  template<typename _Iter, typename _Out>
-    using move_result = copy_result<_Iter, _Out>;
-
-  template<typename _Iter1, typename _Iter2>
-    using move_backward_result = copy_result<_Iter1, _Iter2>;
-
-  template<typename _Iter1, typename _Iter2>
-    using copy_backward_result = copy_result<_Iter1, _Iter2>;
-
-  template<bool _IsMove,
-          bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
-          bidirectional_iterator _Out>
-    requires (_IsMove
-             ? indirectly_movable<_Iter, _Out>
-             : indirectly_copyable<_Iter, _Out>)
-    constexpr conditional_t<_IsMove,
-                           move_backward_result<_Iter, _Out>,
-                           copy_backward_result<_Iter, _Out>>
-    __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result);
-
-  template<bool _IsMove,
-          input_iterator _Iter, sentinel_for<_Iter> _Sent,
-          weakly_incrementable _Out>
-    requires (_IsMove
-             ? indirectly_movable<_Iter, _Out>
-             : indirectly_copyable<_Iter, _Out>)
-    constexpr conditional_t<_IsMove,
-                           move_result<_Iter, _Out>,
-                           copy_result<_Iter, _Out>>
-    __copy_or_move(_Iter __first, _Sent __last, _Out __result)
-    {
-      // TODO: implement more specializations to be at least on par with
-      // std::copy/std::move.
-      constexpr bool __normal_iterator_p
-       = (__detail::__is_normal_iterator<_Iter>
-          || __detail::__is_normal_iterator<_Out>);
-      constexpr bool __reverse_p
-       = (__detail::__is_reverse_iterator<_Iter>
-          && __detail::__is_reverse_iterator<_Out>);
-      constexpr bool __move_iterator_p = __detail::__is_move_iterator<_Iter>;
-      if constexpr (__move_iterator_p)
-       {
-         auto [__in, __out]
-           = ranges::__copy_or_move<true>(std::move(__first).base(),
-                                          std::move(__last).base(),
-                                          std::move(__result));
-         return {move_iterator{std::move(__in)}, std::move(__out)};
-       }
-      else if constexpr (__reverse_p)
-       {
-         auto [__in,__out]
-           = ranges::__copy_or_move_backward<_IsMove>(__last.base(),
-                                                      __first.base(),
-                                                      __result.base());
-         return {reverse_iterator{std::move(__in)},
-                 reverse_iterator{std::move(__out)}};
-       }
-      else if constexpr (__normal_iterator_p)
-       {
-         auto [__in,__out]
-           = ranges::__copy_or_move<_IsMove>(std::__niter_base(__first),
-                                             std::__niter_base(__last),
-                                             std::__niter_base(__result));
-         return {std::__niter_wrap(__first, std::move(__in)),
-                 std::__niter_wrap(__result, std::move(__out))};
-       }
-      else if constexpr (sized_sentinel_for<_Sent, _Iter>)
-       {
-         using _ValueTypeI = iter_value_t<_Iter>;
-         using _ValueTypeO = iter_value_t<_Out>;
-         constexpr bool __use_memmove
-           = (is_trivially_copyable_v<_ValueTypeI>
-              && is_same_v<_ValueTypeI, _ValueTypeO>
-              && is_pointer_v<_Iter>
-              && is_pointer_v<_Out>);
-
-         if constexpr (__use_memmove)
-           {
-             static_assert(_IsMove
-                           ? is_move_assignable_v<_ValueTypeI>
-                           : is_copy_assignable_v<_ValueTypeI>);
-             auto __num = __last - __first;
-             if (__num)
-               std::__memmove<_IsMove>(__result, __first, __num);
-             return {__first + __num, __result + __num};
-           }
-         else
-           {
-             for (auto __n = __last - __first; __n > 0; --__n)
-               {
-                 if constexpr (_IsMove)
-                   *__result = std::move(*__first);
-                 else
-                   *__result = *__first;
-                 ++__first;
-                 ++__result;
-               }
-             return {std::move(__first), std::move(__result)};
-           }
-       }
-      else
-       {
-         while (__first != __last)
-           {
-             if constexpr (_IsMove)
-               *__result = std::move(*__first);
-             else
-               *__result = *__first;
-             ++__first;
-             ++__result;
-           }
-         return {std::move(__first), std::move(__result)};
-       }
-    }
-
-  template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
-          weakly_incrementable _Out>
-    requires indirectly_copyable<_Iter, _Out>
-    constexpr copy_result<_Iter, _Out>
-    copy(_Iter __first, _Sent __last, _Out __result)
-    {
-      return ranges::__copy_or_move<false>(std::move(__first),
-                                          std::move(__last),
-                                          std::move(__result));
-    }
-
-  template<input_range _Range, weakly_incrementable _Out>
-    requires indirectly_copyable<iterator_t<_Range>, _Out>
-    constexpr copy_result<safe_iterator_t<_Range>, _Out>
-    copy(_Range&& __r, _Out __result)
-    {
-      return ranges::copy(ranges::begin(__r), ranges::end(__r),
-                         std::move(__result));
-    }
-
-  template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
-          weakly_incrementable _Out>
-    requires indirectly_movable<_Iter, _Out>
-    constexpr move_result<_Iter, _Out>
-    move(_Iter __first, _Sent __last, _Out __result)
-    {
-      return ranges::__copy_or_move<true>(std::move(__first),
-                                         std::move(__last),
-                                         std::move(__result));
-    }
-
-  template<input_range _Range, weakly_incrementable _Out>
-    requires indirectly_movable<iterator_t<_Range>, _Out>
-    constexpr move_result<safe_iterator_t<_Range>, _Out>
-    move(_Range&& __r, _Out __result)
-    {
-      return ranges::move(ranges::begin(__r), ranges::end(__r),
-                         std::move(__result));
-    }
-
-  template<bool _IsMove,
-          bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
-          bidirectional_iterator _Out>
-    requires (_IsMove
-             ? indirectly_movable<_Iter, _Out>
-             : indirectly_copyable<_Iter, _Out>)
-    constexpr conditional_t<_IsMove,
-                           move_backward_result<_Iter, _Out>,
-                           copy_backward_result<_Iter, _Out>>
-    __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result)
-    {
-      // TODO: implement more specializations to be at least on par with
-      // std::copy_backward/std::move_backward.
-      constexpr bool __normal_iterator_p
-       = (__detail::__is_normal_iterator<_Iter>
-          || __detail::__is_normal_iterator<_Out>);
-      constexpr bool __reverse_p
-       = (__detail::__is_reverse_iterator<_Iter>
-          && __detail::__is_reverse_iterator<_Out>);
-      if constexpr (__reverse_p)
-       {
-         auto [__in,__out]
-           = ranges::__copy_or_move<_IsMove>(__last.base(),
-                                             __first.base(),
-                                             __result.base());
-         return {reverse_iterator{std::move(__in)},
-                 reverse_iterator{std::move(__out)}};
-       }
-      else if constexpr (__normal_iterator_p)
-       {
-         auto [__in,__out]
-           = ranges::__copy_or_move_backward<_IsMove>
-             (std::__niter_base(__first),
-              std::__niter_base(__last),
-              std::__niter_base(__result));
-         return {std::__niter_wrap(__first, std::move(__in)),
-                 std::__niter_wrap(__result, std::move(__out))};
-       }
-      else if constexpr (sized_sentinel_for<_Sent, _Iter>)
-       {
-         using _ValueTypeI = iter_value_t<_Iter>;
-         using _ValueTypeO = iter_value_t<_Out>;
-         constexpr bool __use_memmove
-           = (is_trivially_copyable_v<_ValueTypeI>
-              && is_same_v<_ValueTypeI, _ValueTypeO>
-              && is_pointer_v<_Iter>
-              && is_pointer_v<_Out>);
-         if constexpr (__use_memmove)
-           {
-             static_assert(_IsMove
-                           ? is_move_assignable_v<_ValueTypeI>
-                           : is_copy_assignable_v<_ValueTypeI>);
-             auto __num = __last - __first;
-             if (__num)
-               std::__memmove<_IsMove>(__result - __num, __first, __num);
-             return {__first + __num, __result - __num};
-           }
-         else
-           {
-             auto __lasti = ranges::next(__first, __last);
-             auto __tail = __lasti;
-
-             for (auto __n = __last - __first; __n > 0; --__n)
-               {
-                 --__tail;
-                 --__result;
-                 if constexpr (_IsMove)
-                   *__result = std::move(*__tail);
-                 else
-                   *__result = *__tail;
-               }
-             return {std::move(__lasti), std::move(__result)};
-           }
-       }
-      else
-       {
-         auto __lasti = ranges::next(__first, __last);
-         auto __tail = __lasti;
-
-         while (__first != __tail)
-           {
-             --__tail;
-             --__result;
-             if constexpr (_IsMove)
-               *__result = std::move(*__tail);
-             else
-               *__result = *__tail;
-           }
-         return {std::move(__lasti), std::move(__result)};
-       }
-    }
-
-  template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
-          bidirectional_iterator _Iter2>
-    requires indirectly_copyable<_Iter1, _Iter2>
-    constexpr copy_backward_result<_Iter1, _Iter2>
-    copy_backward(_Iter1 __first, _Sent1 __last, _Iter2 __result)
-    {
-      return ranges::__copy_or_move_backward<false>(std::move(__first),
-                                                   std::move(__last),
-                                                   std::move(__result));
-    }
-
-  template<bidirectional_range _Range, bidirectional_iterator _Iter>
-    requires indirectly_copyable<iterator_t<_Range>, _Iter>
-    constexpr copy_backward_result<safe_iterator_t<_Range>, _Iter>
-    copy_backward(_Range&& __r, _Iter __result)
-    {
-      return ranges::copy_backward(ranges::begin(__r), ranges::end(__r),
-                                  std::move(__result));
-    }
-
-  template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
-          bidirectional_iterator _Iter2>
-    requires indirectly_movable<_Iter1, _Iter2>
-    constexpr move_backward_result<_Iter1, _Iter2>
-    move_backward(_Iter1 __first, _Sent1 __last, _Iter2 __result)
-    {
-      return ranges::__copy_or_move_backward<true>(std::move(__first),
-                                                  std::move(__last),
-                                                  std::move(__result));
-    }
-
-  template<bidirectional_range _Range, bidirectional_iterator _Iter>
-    requires indirectly_movable<iterator_t<_Range>, _Iter>
-    constexpr move_backward_result<safe_iterator_t<_Range>, _Iter>
-    move_backward(_Range&& __r, _Iter __result)
-    {
-      return ranges::move_backward(ranges::begin(__r), ranges::end(__r),
-                                  std::move(__result));
-    }
-
-  template<typename _Iter, typename _Out>
-    using copy_n_result = copy_result<_Iter, _Out>;
-
-  template<input_iterator _Iter, weakly_incrementable _Out>
-    requires indirectly_copyable<_Iter, _Out>
-    constexpr copy_n_result<_Iter, _Out>
-    copy_n(_Iter __first, iter_difference_t<_Iter> __n, _Out __result)
-    {
-      if constexpr (random_access_iterator<_Iter>)
-       return ranges::copy(__first, __first + __n, std::move(__result));
-      else
-       {
-         for (; __n > 0; --__n, (void)++__result, (void)++__first)
-           *__result = *__first;
-         return {std::move(__first), std::move(__result)};
-       }
-    }
-
   template<typename _Iter, typename _Out>
     using copy_if_result = copy_result<_Iter, _Out>;
 
@@ -1434,70 +992,6 @@ namespace ranges
                                     __new_value, std::move(__proj));
     }
 
-  template<typename _Tp, output_iterator<const _Tp&> _Out>
-    constexpr _Out
-    fill_n(_Out __first, iter_difference_t<_Out> __n, const _Tp& __value)
-    {
-      // TODO: implement more specializations to be at least on par with
-      // std::fill_n
-      if (__n <= 0)
-       return __first;
-
-      // TODO: is __is_byte the best condition?
-      if constexpr (is_pointer_v<_Out> && __is_byte<_Tp>::__value)
-       {
-         __builtin_memset(__first, static_cast<unsigned char>(__value), __n);
-         return __first + __n;
-       }
-      else if constexpr (is_scalar_v<_Tp>)
-       {
-         const auto __tmp = __value;
-         for (; __n > 0; --__n, (void)++__first)
-           *__first = __tmp;
-         return __first;
-       }
-      else
-       {
-         for (; __n > 0; --__n, (void)++__first)
-           *__first = __value;
-         return __first;
-       }
-    }
-
-  template<typename _Tp,
-          output_iterator<const _Tp&> _Out, sentinel_for<_Out> _Sent>
-    constexpr _Out
-    fill(_Out __first, _Sent __last, const _Tp& __value)
-    {
-      // TODO: implement more specializations to be at least on par with
-      // std::fill
-      if constexpr (sized_sentinel_for<_Sent, _Out>)
-       {
-         const auto __len = __last - __first;
-         return ranges::fill_n(__first, __len, __value);
-       }
-      else if constexpr (is_scalar_v<_Tp>)
-       {
-         const auto __tmp = __value;
-         for (; __first != __last; ++__first)
-           *__first = __tmp;
-         return __first;
-       }
-      else
-       {
-         for (; __first != __last; ++__first)
-           *__first = __value;
-         return __first;
-       }
-    }
-
-  template<typename _Tp, output_range<const _Tp&> _Range>
-    constexpr safe_iterator_t<_Range>
-    fill(_Range&& __r, const _Tp& __value)
-    {
-      return ranges::fill(ranges::begin(__r), ranges::end(__r), __value);
-    }
-
   template<input_or_output_iterator _Out, copy_constructible _Fp>
     requires invocable<_Fp&>
       && indirectly_writable<_Out, invoke_result_t<_Fp&>>
diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h
new file mode 100644 (file)
index 0000000..f63c032
--- /dev/null
@@ -0,0 +1,556 @@
+// Core algorithmic facilities -*- C++ -*-
+
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file bits/ranges_algobase.h
+ *  This is an internal header file, included by other library headers.
+ *  Do not attempt to use it directly. @headername{algorithm}
+ */
+
+#ifndef _RANGES_ALGOBASE_H
+#define _RANGES_ALGOBASE_H 1
+
+#if __cplusplus > 201703L
+
+#include <cmath>
+#include <compare>
+#include <iterator>
+// #include <bits/range_concepts.h>
+#include <ranges>
+#include <bits/invoke.h>
+#include <bits/cpp_type_traits.h> // __is_byte
+
+#if __cpp_lib_concepts
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+namespace ranges
+{
+  namespace __detail
+  {
+    template<typename _Tp>
+      constexpr inline bool __is_normal_iterator = false;
+
+    template<typename _Iterator, typename _Container>
+      constexpr inline bool
+       __is_normal_iterator<__gnu_cxx::__normal_iterator<_Iterator,
+                                                         _Container>> = true;
+
+    template<typename _Tp>
+      constexpr inline bool __is_reverse_iterator = false;
+
+    template<typename _Iterator>
+      constexpr inline bool
+       __is_reverse_iterator<reverse_iterator<_Iterator>> = true;
+
+    template<typename _Tp>
+      constexpr inline bool __is_move_iterator = false;
+
+    template<typename _Iterator>
+      constexpr inline bool
+       __is_move_iterator<move_iterator<_Iterator>> = true;
+  } // namespace __detail
+
+  template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
+          input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
+          typename _Pred, typename _Proj1, typename _Proj2>
+    requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
+    constexpr bool
+    __equal(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
+           _Pred __pred, _Proj1 __proj1, _Proj2 __proj2)
+    {
+      // TODO: implement more specializations to at least have parity with
+      // std::equal.
+      constexpr bool __sized_iters
+       = (sized_sentinel_for<_Sent1, _Iter1>
+          && sized_sentinel_for<_Sent2, _Iter2>);
+      if constexpr (__sized_iters)
+       {
+         auto __d1 = ranges::distance(__first1, __last1);
+         auto __d2 = ranges::distance(__first2, __last2);
+         if (__d1 != __d2)
+           return false;
+
+         using _ValueType1 = iter_value_t<_Iter1>;
+         using _ValueType2 = iter_value_t<_Iter2>;
+         constexpr bool __use_memcmp
+           = ((is_integral_v<_ValueType1> || is_pointer_v<_ValueType1>)
+              && is_same_v<_ValueType1, _ValueType2>
+              && is_pointer_v<_Iter1>
+              && is_pointer_v<_Iter2>
+              && is_same_v<_Pred, ranges::equal_to>
+              && is_same_v<_Proj1, identity>
+              && is_same_v<_Proj2, identity>);
+         if constexpr (__use_memcmp)
+           {
+             if (const size_t __len = (__last1 - __first1))
+               return !std::__memcmp(__first1, __first2, __len);
+             return true;
+           }
+         else
+           {
+             for (; __first1 != __last1; ++__first1, (void)++__first2)
+               if (!(bool)std::__invoke(__pred,
+                                        std::__invoke(__proj1, *__first1),
+                                        std::__invoke(__proj2, *__first2)))
+                 return false;
+             return true;
+           }
+       }
+      else
+       {
+         for (; __first1 != __last1 && __first2 != __last2;
+              ++__first1, (void)++__first2)
+           if (!(bool)std::__invoke(__pred,
+                                    std::__invoke(__proj1, *__first1),
+                                    std::__invoke(__proj2, *__first2)))
+             return false;
+         return __first1 == __last1 && __first2 == __last2;
+       }
+    }
+
+  template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
+          input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
+          typename _Pred = ranges::equal_to,
+          typename _Proj1 = identity, typename _Proj2 = identity>
+    requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
+    constexpr bool
+    equal(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
+         _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
+    {
+      return ranges::__equal(std::__niter_base(std::move(__first1)),
+                            std::__niter_base(std::move(__last1)),
+                            std::__niter_base(std::move(__first2)),
+                            std::__niter_base(std::move(__last2)),
+                            std::move(__pred),
+                            std::move(__proj1), std::move(__proj2));
+    }
+
+  template<input_range _Range1, input_range _Range2,
+          typename _Pred = ranges::equal_to,
+          typename _Proj1 = identity, typename _Proj2 = identity>
+    requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
+                                  _Pred, _Proj1, _Proj2>
+    constexpr bool
+    equal(_Range1&& __r1, _Range2&& __r2,
+         _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
+    {
+      return ranges::equal(ranges::begin(__r1), ranges::end(__r1),
+                          ranges::begin(__r2), ranges::end(__r2),
+                          std::move(__pred),
+                          std::move(__proj1), std::move(__proj2));
+    }
+
+  template<typename _Iter, typename _Out>
+    struct copy_result
+    {
+      [[no_unique_address]] _Iter in;
+      [[no_unique_address]] _Out out;
+
+      template<typename _Iter2, typename _Out2>
+       requires convertible_to<const _Iter&, _Iter2>
+         && convertible_to<const _Out&, _Out2>
+       operator copy_result<_Iter2, _Out2>() const &
+       { return {in, out}; }
+
+      template<typename _Iter2, typename _Out2>
+       requires convertible_to<_Iter, _Iter2>
+         && convertible_to<_Out, _Out2>
+       operator copy_result<_Iter2, _Out2>() &&
+       { return {std::move(in), std::move(out)}; }
+    };
+
+  template<typename _Iter, typename _Out>
+    using move_result = copy_result<_Iter, _Out>;
+
+  template<typename _Iter1, typename _Iter2>
+    using move_backward_result = copy_result<_Iter1, _Iter2>;
+
+  template<typename _Iter1, typename _Iter2>
+    using copy_backward_result = copy_result<_Iter1, _Iter2>;
+
+  template<bool _IsMove,
+          bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
+          bidirectional_iterator _Out>
+    requires (_IsMove
+             ? indirectly_movable<_Iter, _Out>
+             : indirectly_copyable<_Iter, _Out>)
+    constexpr conditional_t<_IsMove,
+                           move_backward_result<_Iter, _Out>,
+                           copy_backward_result<_Iter, _Out>>
+    __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result);
+
+  template<bool _IsMove,
+          input_iterator _Iter, sentinel_for<_Iter> _Sent,
+          weakly_incrementable _Out>
+    requires (_IsMove
+             ? indirectly_movable<_Iter, _Out>
+             : indirectly_copyable<_Iter, _Out>)
+    constexpr conditional_t<_IsMove,
+                           move_result<_Iter, _Out>,
+                           copy_result<_Iter, _Out>>
+    __copy_or_move(_Iter __first, _Sent __last, _Out __result)
+    {
+      // TODO: implement more specializations to be at least on par with
+      // std::copy/std::move.
+      constexpr bool __normal_iterator_p
+       = (__detail::__is_normal_iterator<_Iter>
+          || __detail::__is_normal_iterator<_Out>);
+      constexpr bool __reverse_p
+       = (__detail::__is_reverse_iterator<_Iter>
+          && __detail::__is_reverse_iterator<_Out>);
+      constexpr bool __move_iterator_p = __detail::__is_move_iterator<_Iter>;
+      if constexpr (__move_iterator_p)
+       {
+         auto [__in, __out]
+           = ranges::__copy_or_move<true>(std::move(__first).base(),
+                                          std::move(__last).base(),
+                                          std::move(__result));
+         return {move_iterator{std::move(__in)}, std::move(__out)};
+       }
+      else if constexpr (__reverse_p)
+       {
+         auto [__in,__out]
+           = ranges::__copy_or_move_backward<_IsMove>(__last.base(),
+                                                      __first.base(),
+                                                      __result.base());
+         return {reverse_iterator{std::move(__in)},
+                 reverse_iterator{std::move(__out)}};
+       }
+      else if constexpr (__normal_iterator_p)
+       {
+         auto [__in,__out]
+           = ranges::__copy_or_move<_IsMove>(std::__niter_base(__first),
+                                             std::__niter_base(__last),
+                                             std::__niter_base(__result));
+         return {std::__niter_wrap(__first, std::move(__in)),
+                 std::__niter_wrap(__result, std::move(__out))};
+       }
+      else if constexpr (sized_sentinel_for<_Sent, _Iter>)
+       {
+         using _ValueTypeI = iter_value_t<_Iter>;
+         using _ValueTypeO = iter_value_t<_Out>;
+         constexpr bool __use_memmove
+           = (is_trivially_copyable_v<_ValueTypeI>
+              && is_same_v<_ValueTypeI, _ValueTypeO>
+              && is_pointer_v<_Iter>
+              && is_pointer_v<_Out>);
+
+         if constexpr (__use_memmove)
+           {
+             static_assert(_IsMove
+                           ? is_move_assignable_v<_ValueTypeI>
+                           : is_copy_assignable_v<_ValueTypeI>);
+             auto __num = __last - __first;
+             if (__num)
+               std::__memmove<_IsMove>(__result, __first, __num);
+             return {__first + __num, __result + __num};
+           }
+         else
+           {
+             for (auto __n = __last - __first; __n > 0; --__n)
+               {
+                 if constexpr (_IsMove)
+                   *__result = std::move(*__first);
+                 else
+                   *__result = *__first;
+                 ++__first;
+                 ++__result;
+               }
+             return {std::move(__first), std::move(__result)};
+           }
+       }
+      else
+       {
+         while (__first != __last)
+           {
+             if constexpr (_IsMove)
+               *__result = std::move(*__first);
+             else
+               *__result = *__first;
+             ++__first;
+             ++__result;
+           }
+         return {std::move(__first), std::move(__result)};
+       }
+    }
+
+  template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
+          weakly_incrementable _Out>
+    requires indirectly_copyable<_Iter, _Out>
+    constexpr copy_result<_Iter, _Out>
+    copy(_Iter __first, _Sent __last, _Out __result)
+    {
+      return ranges::__copy_or_move<false>(std::move(__first),
+                                          std::move(__last),
+                                          std::move(__result));
+    }
+
+  template<input_range _Range, weakly_incrementable _Out>
+    requires indirectly_copyable<iterator_t<_Range>, _Out>
+    constexpr copy_result<safe_iterator_t<_Range>, _Out>
+    copy(_Range&& __r, _Out __result)
+    {
+      return ranges::copy(ranges::begin(__r), ranges::end(__r),
+                         std::move(__result));
+    }
+
+  template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
+          weakly_incrementable _Out>
+    requires indirectly_movable<_Iter, _Out>
+    constexpr move_result<_Iter, _Out>
+    move(_Iter __first, _Sent __last, _Out __result)
+    {
+      return ranges::__copy_or_move<true>(std::move(__first),
+                                         std::move(__last),
+                                         std::move(__result));
+    }
+
+  template<input_range _Range, weakly_incrementable _Out>
+    requires indirectly_movable<iterator_t<_Range>, _Out>
+    constexpr move_result<safe_iterator_t<_Range>, _Out>
+    move(_Range&& __r, _Out __result)
+    {
+      return ranges::move(ranges::begin(__r), ranges::end(__r),
+                         std::move(__result));
+    }
+
+  template<bool _IsMove,
+          bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
+          bidirectional_iterator _Out>
+    requires (_IsMove
+             ? indirectly_movable<_Iter, _Out>
+             : indirectly_copyable<_Iter, _Out>)
+    constexpr conditional_t<_IsMove,
+                           move_backward_result<_Iter, _Out>,
+                           copy_backward_result<_Iter, _Out>>
+    __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result)
+    {
+      // TODO: implement more specializations to be at least on par with
+      // std::copy_backward/std::move_backward.
+      constexpr bool __normal_iterator_p
+       = (__detail::__is_normal_iterator<_Iter>
+          || __detail::__is_normal_iterator<_Out>);
+      constexpr bool __reverse_p
+       = (__detail::__is_reverse_iterator<_Iter>
+          && __detail::__is_reverse_iterator<_Out>);
+      if constexpr (__reverse_p)
+       {
+         auto [__in,__out]
+           = ranges::__copy_or_move<_IsMove>(__last.base(),
+                                             __first.base(),
+                                             __result.base());
+         return {reverse_iterator{std::move(__in)},
+                 reverse_iterator{std::move(__out)}};
+       }
+      else if constexpr (__normal_iterator_p)
+       {
+         auto [__in,__out]
+           = ranges::__copy_or_move_backward<_IsMove>
+             (std::__niter_base(__first),
+              std::__niter_base(__last),
+              std::__niter_base(__result));
+         return {std::__niter_wrap(__first, std::move(__in)),
+                 std::__niter_wrap(__result, std::move(__out))};
+       }
+      else if constexpr (sized_sentinel_for<_Sent, _Iter>)
+       {
+         using _ValueTypeI = iter_value_t<_Iter>;
+         using _ValueTypeO = iter_value_t<_Out>;
+         constexpr bool __use_memmove
+           = (is_trivially_copyable_v<_ValueTypeI>
+              && is_same_v<_ValueTypeI, _ValueTypeO>
+              && is_pointer_v<_Iter>
+              && is_pointer_v<_Out>);
+         if constexpr (__use_memmove)
+           {
+             static_assert(_IsMove
+                           ? is_move_assignable_v<_ValueTypeI>
+                           : is_copy_assignable_v<_ValueTypeI>);
+             auto __num = __last - __first;
+             if (__num)
+               std::__memmove<_IsMove>(__result - __num, __first, __num);
+             return {__first + __num, __result - __num};
+           }
+         else
+           {
+             auto __lasti = ranges::next(__first, __last);
+             auto __tail = __lasti;
+
+             for (auto __n = __last - __first; __n > 0; --__n)
+               {
+                 --__tail;
+                 --__result;
+                 if constexpr (_IsMove)
+                   *__result = std::move(*__tail);
+                 else
+                   *__result = *__tail;
+               }
+             return {std::move(__lasti), std::move(__result)};
+           }
+       }
+      else
+       {
+         auto __lasti = ranges::next(__first, __last);
+         auto __tail = __lasti;
+
+         while (__first != __tail)
+           {
+             --__tail;
+             --__result;
+             if constexpr (_IsMove)
+               *__result = std::move(*__tail);
+             else
+               *__result = *__tail;
+           }
+         return {std::move(__lasti), std::move(__result)};
+       }
+    }
+
+  template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
+          bidirectional_iterator _Iter2>
+    requires indirectly_copyable<_Iter1, _Iter2>
+    constexpr copy_backward_result<_Iter1, _Iter2>
+    copy_backward(_Iter1 __first, _Sent1 __last, _Iter2 __result)
+    {
+      return ranges::__copy_or_move_backward<false>(std::move(__first),
+                                                   std::move(__last),
+                                                   std::move(__result));
+    }
+
+  template<bidirectional_range _Range, bidirectional_iterator _Iter>
+    requires indirectly_copyable<iterator_t<_Range>, _Iter>
+    constexpr copy_backward_result<safe_iterator_t<_Range>, _Iter>
+    copy_backward(_Range&& __r, _Iter __result)
+    {
+      return ranges::copy_backward(ranges::begin(__r), ranges::end(__r),
+                                  std::move(__result));
+    }
+
+  template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
+          bidirectional_iterator _Iter2>
+    requires indirectly_movable<_Iter1, _Iter2>
+    constexpr move_backward_result<_Iter1, _Iter2>
+    move_backward(_Iter1 __first, _Sent1 __last, _Iter2 __result)
+    {
+      return ranges::__copy_or_move_backward<true>(std::move(__first),
+                                                  std::move(__last),
+                                                  std::move(__result));
+    }
+
+  template<bidirectional_range _Range, bidirectional_iterator _Iter>
+    requires indirectly_movable<iterator_t<_Range>, _Iter>
+    constexpr move_backward_result<safe_iterator_t<_Range>, _Iter>
+    move_backward(_Range&& __r, _Iter __result)
+    {
+      return ranges::move_backward(ranges::begin(__r), ranges::end(__r),
+                                  std::move(__result));
+    }
+
+  template<typename _Iter, typename _Out>
+    using copy_n_result = copy_result<_Iter, _Out>;
+
+  template<input_iterator _Iter, weakly_incrementable _Out>
+    requires indirectly_copyable<_Iter, _Out>
+    constexpr copy_n_result<_Iter, _Out>
+    copy_n(_Iter __first, iter_difference_t<_Iter> __n, _Out __result)
+    {
+      if constexpr (random_access_iterator<_Iter>)
+       return ranges::copy(__first, __first + __n, std::move(__result));
+      else
+       {
+         for (; __n > 0; --__n, (void)++__result, (void)++__first)
+           *__result = *__first;
+         return {std::move(__first), std::move(__result)};
+       }
+    }
+
+  template<typename _Tp, output_iterator<const _Tp&> _Out>
+    constexpr _Out
+    fill_n(_Out __first, iter_difference_t<_Out> __n, const _Tp& __value)
+    {
+      // TODO: implement more specializations to be at least on par with
+      // std::fill_n
+      if (__n <= 0)
+       return __first;
+
+      // TODO: is __is_byte the best condition?
+      if constexpr (is_pointer_v<_Out> && __is_byte<_Tp>::__value)
+       {
+         __builtin_memset(__first, static_cast<unsigned char>(__value), __n);
+         return __first + __n;
+       }
+      else if constexpr (is_scalar_v<_Tp>)
+       {
+         const auto __tmp = __value;
+         for (; __n > 0; --__n, (void)++__first)
+           *__first = __tmp;
+         return __first;
+       }
+      else
+       {
+         for (; __n > 0; --__n, (void)++__first)
+           *__first = __value;
+         return __first;
+       }
+    }
+
+  template<typename _Tp,
+          output_iterator<const _Tp&> _Out, sentinel_for<_Out> _Sent>
+    constexpr _Out
+    fill(_Out __first, _Sent __last, const _Tp& __value)
+    {
+      // TODO: implement more specializations to be at least on par with
+      // std::fill
+      if constexpr (sized_sentinel_for<_Sent, _Out>)
+       {
+         const auto __len = __last - __first;
+         return ranges::fill_n(__first, __len, __value);
+       }
+      else if constexpr (is_scalar_v<_Tp>)
+       {
+         const auto __tmp = __value;
+         for (; __first != __last; ++__first)
+           *__first = __tmp;
+         return __first;
+       }
+      else
+       {
+         for (; __first != __last; ++__first)
+           *__first = __value;
+         return __first;
+       }
+    }
+
+  template<typename _Tp, output_range<const _Tp&> _Range>
+    constexpr safe_iterator_t<_Range>
+    fill(_Range&& __r, const _Tp& __value)
+    {
+      return ranges::fill(ranges::begin(__r), ranges::end(__r), __value);
+    }
+}
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+#endif // concepts
+#endif // C++20
+#endif // _RANGES_ALGOBASE_H