[clang-tools-extra] [llvm] [libcxx] [clang] [libcxx] adds ranges::fold_left_with_iter and ranges::fold_left (PR #75259)
Christopher Di Bella via cfe-commits
cfe-commits at lists.llvm.org
Thu Dec 28 14:28:15 PST 2023
================
@@ -0,0 +1,118 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_FOLD_H
+#define _LIBCPP___ALGORITHM_FOLD_H
+
+#include <__concepts/assignable.h>
+#include <__concepts/convertible_to.h>
+#include <__concepts/invocable.h>
+#include <__concepts/movable.h>
+#include <__config>
+#include <__functional/invoke.h>
+#include <__functional/reference_wrapper.h>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/invoke.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+namespace ranges {
+template <class _Ip, class _Tp>
+struct in_value_result {
+ _Ip in;
+ _Tp result;
+};
+
+template <class _Ip, class _Tp>
+using fold_left_with_iter_result = in_value_result<_Ip, _Tp>;
+
+template <class _Fp, class _Tp, class _Ip, class _Rp, class _Up = decay_t<_Rp>>
+concept __indirectly_binary_left_foldable_impl =
+ convertible_to<_Rp, _Up> && //
+ movable<_Tp> && //
+ movable<_Up> && //
+ convertible_to<_Tp, _Up> && //
+ invocable<_Fp&, _Up, iter_reference_t<_Ip>> && //
+ assignable_from<_Up&, invoke_result_t<_Fp&, _Up, iter_reference_t<_Ip>>>;
+
+template <class _Fp, class _Tp, class _Ip>
+concept __indirectly_binary_left_foldable =
+ copy_constructible<_Fp> && //
+ invocable<_Fp&, _Tp, iter_reference_t<_Ip>> && //
+ __indirectly_binary_left_foldable_impl<_Fp, _Tp, _Ip, invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
+
+struct __fold_left_with_iter {
+ template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto
+ operator()(_Ip __first, _Sp __last, _Tp __init, _Fp __f) {
+ using _Up = decay_t<invoke_result_t<_Fp&, _Tp, iter_reference_t<_Ip>>>;
+
+ if (__first == __last) {
+ return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), _Up(std::move(__init))};
+ }
+
+ _Up __result = std::invoke(__f, std::move(__init), *__first);
+ for (++__first; __first != __last; ++__first) {
+ __result = std::invoke(__f, std::move(__result), *__first);
+ }
+
+ return fold_left_with_iter_result<_Ip, _Up>{std::move(__first), std::move(__result)};
+ }
+
+ template <input_range _Rp, class _Tp, __indirectly_binary_left_foldable<_Tp, iterator_t<_Rp>> _Fp>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Rp&& __r, _Tp __init, _Fp __f) {
+ auto __result = operator()(ranges::begin(__r), ranges::end(__r), std::move(__init), std::ref(__f));
+
+ using _Up = decay_t<invoke_result_t<_Fp&, _Tp, range_reference_t<_Rp>>>;
+ return fold_left_with_iter_result<borrowed_iterator_t<_Rp>, _Up>{
+ std::move(__result.in), std::move(__result.result)};
+ }
+};
+
+inline namespace __cpo {
+inline constexpr auto fold_left_with_iter = __fold_left_with_iter();
+} // namespace __cpo
+
+struct __fold_left {
+ template <input_iterator _Ip, sentinel_for<_Ip> _Sp, class _Tp, __indirectly_binary_left_foldable<_Tp, _Ip> _Fp>
----------------
cjdb wrote:
See #76540 for the renaming patch.
https://github.com/llvm/llvm-project/pull/75259
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