commit 16661d8fef3057fa5ca47c7b3ca29701033c281b
author Nikolas Klauser <nikolasklauser@berlin.de> Thu Jun 23 12:23:41 2022 +0200
committer Copybara-Service <copybara-worker@google.com> Thu Jun 23 04:56:02 2022 -0700
tree 6ec7c305cd1a87beebd933b41637096e66f982a8
parent dce28bdcbeceeeceb44de9b60a0d1e6b028c8fbb

[libc++] Implement ranges::move{, _backward}

This patch also adds a new optimization to `std::move`. It unwraps three `reverse_iterator`s if the wrapped iterator is a `contiguous_iterator` and the iterated type is trivially_movable. This allows us to simplify `ranges::move_backward` to a forward to `std::move` without any pessimization.

Reviewed By: var-const, #libc

Spies: libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D126616

NOKEYCHECK=True
GitOrigin-RevId: 2c3bbac0c7154cd6a286e0e05aa62308836a3655

include/algorithm

diff --git a/include/algorithm b/include/algorithm
index 3db67af..cb1cb1d 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -450,6 +450,27 @@
       ranges::lexicographical_compare(R1&& r1, R2&& r2, Comp comp = {},
                                       Proj1 proj1 = {}, Proj2 proj2 = {});                    // since C++20
 
+  template<bidirectional_iterator I1, sentinel_for<I1> S1, bidirectional_iterator I2>
+    requires indirectly_movable<I1, I2>
+    constexpr ranges::move_backward_result<I1, I2>
+      ranges::move_backward(I1 first, S1 last, I2 result);                                          // since C++20
+
+  template<bidirectional_range R, bidirectional_iterator I>
+    requires indirectly_movable<iterator_t<R>, I>
+    constexpr ranges::move_backward_result<borrowed_iterator_t<R>, I>
+      ranges::move_backward(R&& r, I result);                                                       // since C++20
+
+  template<input_iterator I, sentinel_for<I> S, weakly_incrementable O>
+    requires indirectly_movable<I, O>
+    constexpr ranges::move_result<I, O>
+      ranges::move(I first, S last, O result);                                                      // since C++20
+
+  template<input_range R, weakly_incrementable O>
+    requires indirectly_movable<iterator_t<R>, O>
+    constexpr ranges::move_result<borrowed_iterator_t<R>, O>
+      ranges::move(R&& r, O result);                                                                // since C++20
+
+
 }
 
     constexpr bool     // constexpr in C++20
@@ -1195,6 +1216,8 @@
 #include <__algorithm/ranges_minmax.h>
 #include <__algorithm/ranges_minmax_element.h>
 #include <__algorithm/ranges_mismatch.h>
+#include <__algorithm/ranges_move.h>
+#include <__algorithm/ranges_move_backward.h>
 #include <__algorithm/ranges_none_of.h>
 #include <__algorithm/ranges_replace.h>
 #include <__algorithm/ranges_replace_if.h>