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[libc++][ranges] implement ranges::elements_of
#91414
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@llvm/pr-subscribers-libcxx Author: Xiaoyang Liu (xiaoyang-sde) ChangesIntroductionThis patch implements template <bool YieldElements>
std::generator<std::any> f(std::ranges::input_range auto &&r) {
if constexpr (YieldElements) {
co_yield std::ranges::elements_of(r);
} else {
co_yield r;
}
} ReferenceFull diff: https://github.com/llvm/llvm-project/pull/91414.diff 5 Files Affected:
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index fd7eb125e007b..b1f9be1dc3d7d 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -646,6 +646,7 @@ set(files
__ranges/data.h
__ranges/drop_view.h
__ranges/drop_while_view.h
+ __ranges/elements_of.h
__ranges/elements_view.h
__ranges/empty.h
__ranges/empty_view.h
diff --git a/libcxx/include/__ranges/elements_of.h b/libcxx/include/__ranges/elements_of.h
new file mode 100644
index 0000000000000..d7cb1937563c6
--- /dev/null
+++ b/libcxx/include/__ranges/elements_of.h
@@ -0,0 +1,48 @@
+// -*- 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___RANGES_ELEMENTS_OF_H
+#define _LIBCPP___RANGES_ELEMENTS_OF_H
+
+#include <__config>
+#include <__memory/allocator.h>
+#include <__ranges/concepts.h>
+#include <cstddef>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+namespace ranges {
+
+template <range _Range, class _Allocator = allocator<byte>>
+struct elements_of {
+ _LIBCPP_NO_UNIQUE_ADDRESS _Range range;
+ _LIBCPP_NO_UNIQUE_ADDRESS _Allocator allocator = _Allocator();
+};
+
+template <class _Range, class _Allocator = allocator<byte>>
+elements_of(_Range&&, _Allocator = _Allocator()) -> elements_of<_Range&&, _Allocator>;
+
+} // namespace ranges
+
+#endif // _LIBCPP_STD_VER >= 23
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_ELEMENTS_OF_H
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
index 07a525ed8641f..a8fbfc462bf0d 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -116,6 +116,10 @@ namespace std::ranges {
// [range.dangling], dangling iterator handling
struct dangling;
+ // [range.elementsof], class template elements_of
+ template<range R, class Allocator = allocator<byte>>
+ struct elements_of;
+
template<range R>
using borrowed_iterator_t = see below;
@@ -392,6 +396,7 @@ namespace std {
#include <__ranges/data.h>
#include <__ranges/drop_view.h>
#include <__ranges/drop_while_view.h>
+#include <__ranges/elements_of.h>
#include <__ranges/elements_view.h>
#include <__ranges/empty.h>
#include <__ranges/empty_view.h>
diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index 80f31c79a1a40..94f3defdcbc35 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -83,8 +83,10 @@ export namespace std {
// [range.dangling], dangling iterator handling
using std::ranges::dangling;
+#if _LIBCPP_STD_VER >= 23
// [range.elementsof], class template elements_of
- // using std::ranges::elements_of;
+ using std::ranges::elements_of;
+#endif
using std::ranges::borrowed_iterator_t;
diff --git a/libcxx/test/std/ranges/range.utility/range.elementsof/elements_of.pass.cpp b/libcxx/test/std/ranges/range.utility/range.elementsof/elements_of.pass.cpp
new file mode 100644
index 0000000000000..378bcb0a2f13f
--- /dev/null
+++ b/libcxx/test/std/ranges/range.utility/range.elementsof/elements_of.pass.cpp
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// std::ranges::elements_of;
+
+#include <ranges>
+
+#include <concepts>
+#include <memory>
+#include <vector>
+
+constexpr bool test() {
+ {
+ auto elements_of = std::ranges::elements_of(std::vector<int>());
+ static_assert(
+ std::same_as<decltype(elements_of), std::ranges::elements_of<std::vector<int>&&, std::allocator<std::byte>>>);
+ static_assert(std::same_as<decltype(elements_of.range), std::vector<int>&&>);
+ static_assert(std::same_as<decltype(elements_of.allocator), std::allocator<std::byte>>);
+ }
+ {
+ auto elements_of = std::ranges::elements_of(std::vector<int>(), std::allocator<int>());
+ static_assert(
+ std::same_as<decltype(elements_of), std::ranges::elements_of<std::vector<int>&&, std::allocator<int>>>);
+ static_assert(std::same_as<decltype(elements_of.range), std::vector<int>&&>);
+ static_assert(std::same_as<decltype(elements_of.allocator), std::allocator<int>>);
+ }
+ return true;
+}
+
+int main() {
+ test();
+ static_assert(test());
+}
|
libcxx/test/std/ranges/range.utility/range.elementsof/elements_of.pass.cpp
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I've made some progress with an incomplete implementation, but it's not quite ready for review. (Should be finalized in a day or two though.) If you've already have a finalized implementation, I'm willing to take a look! |
Introduction
This patch implements
ranges::elements_of
from P2502R2. Specializations ofelements_of
encapsulate a range and act as a tag in overload sets to disambiguate when a range should be treated as a sequence rather than a single value.Reference
std::generator
: Synchronous Coroutine Generator for Ranges