libstdc++: Simplify copy-pasted algorithms in <ranges>

The <ranges> header currently copies some simple algorithms from
<bits/ranges_algo.h>, which was originally done in order to avoid a
circular dependency with the header.  This is no longer an issue since
the latter header now includes <bits/ranges_util.h> instead of all of
<ranges>.

This means we could now just include <bits/ranges_algo.h> and remove the
copied algorithms, but that'd increase the size of <ranges> by ~10%.
And we can't use the corresponding STL-style algorithms here because
they assume input iterators are copyable.  So this patch instead
simplifies these copied algorithms, removing their constraints and
unused parameters, and keeps them around.  In a subsequent patch we're
going to copy (a simplified version of) ranges::find into <ranges> as
well.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::find_if): Simplify.
	(__detail::find_if_not): Likewise.
	(__detail::min): Remove.
	(__detail::mismatch): Simplify.
	(take_view::size): Use std::min instead of __detail::min.

diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index cfcbcaba06552642c44560136aa5c3526ee3e0ba..9077271e4e6c70a3b2c3630d7155e22b1d01d1b3 100644 (file)
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -978,65 +978,40 @@ namespace views::__adaptor
       using all_t = decltype(all(std::declval<_Range>()));
   } // namespace views
 
-  // XXX: the following algos are copied from ranges_algo.h to avoid a circular
-  // dependency with that header.
+  // The following simple algos are transcribed from ranges_algo.h to avoid
+  // having to include that entire header.
   namespace __detail
   {
-    template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
-            typename _Proj = identity,
-            indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
+    template<typename _Iter, typename _Sent, typename _Pred>
       constexpr _Iter
-      find_if(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {})
+      find_if(_Iter __first, _Sent __last, _Pred __pred)
       {
        while (__first != __last
-           && !(bool)std::__invoke(__pred, std::__invoke(__proj, *__first)))
+              && !(bool)std::__invoke(__pred, *__first))
          ++__first;
        return __first;
       }
 
-    template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
-            typename _Proj = identity,
-            indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
+    template<typename _Iter, typename _Sent, typename _Pred>
       constexpr _Iter
-      find_if_not(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {})
+      find_if_not(_Iter __first, _Sent __last, _Pred __pred)
       {
        while (__first != __last
-           && (bool)std::__invoke(__pred, std::__invoke(__proj, *__first)))
+              && (bool)std::__invoke(__pred, *__first))
          ++__first;
        return __first;
       }
 
-    template<typename _Tp, typename _Proj = identity,
-            indirect_strict_weak_order<projected<const _Tp*, _Proj>>
-              _Comp = ranges::less>
-      constexpr const _Tp&
-      min(const _Tp& __a, const _Tp& __b, _Comp __comp = {}, _Proj __proj = {})
-      {
-       if (std::__invoke(std::move(__comp),
-                         std::__invoke(__proj, __b),
-                         std::__invoke(__proj, __a)))
-         return __b;
-       else
-         return __a;
-      }
-
-    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>
+    template<typename _Iter1, typename _Sent1, typename _Iter2, typename _Sent2>
       constexpr pair<_Iter1, _Iter2>
-      mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
-              _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {})
+      mismatch(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2)
       {
        while (__first1 != __last1 && __first2 != __last2
-              && (bool)std::__invoke(__pred,
-                                     std::__invoke(__proj1, *__first1),
-                                     std::__invoke(__proj2, *__first2)))
-       {
-         ++__first1;
-         ++__first2;
-       }
+              && (bool)ranges::equal_to{}(*__first1, *__first2))
+         {
+           ++__first1;
+           ++__first2;
+         }
        return { std::move(__first1), std::move(__first2) };
       }
   } // namespace __detail
@@ -1847,14 +1822,14 @@ namespace views::__adaptor
       size() requires sized_range<_Vp>
       {
        auto __n = ranges::size(_M_base);
-       return __detail::min(__n, static_cast<decltype(__n)>(_M_count));
+       return std::min(__n, static_cast<decltype(__n)>(_M_count));
       }
 
       constexpr auto
       size() const requires sized_range<const _Vp>
       {
        auto __n = ranges::size(_M_base);
-       return __detail::min(__n, static_cast<decltype(__n)>(_M_count));
+       return std::min(__n, static_cast<decltype(__n)>(_M_count));
       }
     };