[libc++][ranges] P2387R3: Pipe support for user-defined range adaptors #89148
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@llvm/pr-subscribers-libcxx Author: Xiaoyang Liu (xiaoyang-sde) ChangesAbstractThis pull request aims to finalize the // [range.adaptor.object], range adaptor objects
template<class D>
requires is_class_v<D> && same_as<D, remove_cv_t<D>>
class range_adaptor_closure { };ImplementationThe current implementation of
ReferenceFull diff: https://github.com/llvm/llvm-project/pull/89148.diff 6 Files Affected:
diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index 53cc7a77d1af48..bccbe2f10d13f0 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -49,6 +49,7 @@ Implemented Papers
- P2302R4 - ``std::ranges::contains``
- P1659R3 - ``std::ranges::starts_with`` and ``std::ranges::ends_with``
- P3029R1 - Better ``mdspan``'s CTAD
+- P2387R3 - Pipe support for user-defined range adaptors
Improvements and New Features
-----------------------------
diff --git a/libcxx/docs/Status/Cxx23.rst b/libcxx/docs/Status/Cxx23.rst
index b19ff4fdc0f79e..23d30c8128d71e 100644
--- a/libcxx/docs/Status/Cxx23.rst
+++ b/libcxx/docs/Status/Cxx23.rst
@@ -43,7 +43,6 @@ Paper Status
.. [#note-P0533R9] P0533R9: ``isfinite``, ``isinf``, ``isnan`` and ``isnormal`` are implemented.
.. [#note-P1413R3] P1413R3: ``std::aligned_storage_t`` and ``std::aligned_union_t`` are marked deprecated, but
clang doesn't issue a diagnostic for deprecated using template declarations.
- .. [#note-P2387R3] P2387R3: ``bind_back`` only
.. [#note-P2520R0] P2520R0: Libc++ implemented this paper as a DR in C++20 as well.
.. [#note-P2711R1] P2711R1: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.
.. [#note-P2770R0] P2770R0: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.
diff --git a/libcxx/docs/Status/Cxx23Papers.csv b/libcxx/docs/Status/Cxx23Papers.csv
index 065db97a0b0b15..f75dd288304b27 100644
--- a/libcxx/docs/Status/Cxx23Papers.csv
+++ b/libcxx/docs/Status/Cxx23Papers.csv
@@ -45,7 +45,7 @@
"`P1413R3 <https://wg21.link/P1413R3>`__","LWG","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","February 2022","|Complete| [#note-P1413R3]_",""
"`P2255R2 <https://wg21.link/P2255R2>`__","LWG","A type trait to detect reference binding to temporary","February 2022","",""
"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Complete|","16.0"
-"`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","|Partial| [#note-P2387R3]_","","|ranges|"
+"`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","|Complete|","19.0","|ranges|"
"`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","","","|ranges|"
"`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_with``","February 2022","|In Progress|","","|ranges|"
"`P2442R1 <https://wg21.link/P2442R1>`__","LWG","Windowing range adaptors: ``views::chunk`` and ``views::slide``","February 2022","","","|ranges|"
diff --git a/libcxx/include/__ranges/range_adaptor.h b/libcxx/include/__ranges/range_adaptor.h
index 726b7eda019ee3..a8b33ac620c4d2 100644
--- a/libcxx/include/__ranges/range_adaptor.h
+++ b/libcxx/include/__ranges/range_adaptor.h
@@ -19,6 +19,7 @@
#include <__functional/invoke.h>
#include <__ranges/concepts.h>
#include <__type_traits/decay.h>
+#include <__type_traits/is_class.h>
#include <__type_traits/is_nothrow_constructible.h>
#include <__type_traits/remove_cvref.h>
#include <__utility/forward.h>
@@ -41,6 +42,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
// - `x | f` is equivalent to `f(x)`
// - `f1 | f2` is an adaptor closure `g` such that `g(x)` is equivalent to `f2(f1(x))`
template <class _Tp>
+ requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>>
struct __range_adaptor_closure;
// Type that wraps an arbitrary function object and makes it into a range adaptor closure,
@@ -52,15 +54,21 @@ struct __range_adaptor_closure_t : _Fn, __range_adaptor_closure<__range_adaptor_
_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(__range_adaptor_closure_t);
template <class _Tp>
-concept _RangeAdaptorClosure = derived_from<remove_cvref_t<_Tp>, __range_adaptor_closure<remove_cvref_t<_Tp>>>;
+_Tp __derived_from_range_adaptor_closure(__range_adaptor_closure<_Tp>*);
template <class _Tp>
+concept _RangeAdaptorClosure = !ranges::range<remove_cvref_t<_Tp>> && requires {
+ { __derived_from_range_adaptor_closure((remove_cvref_t<_Tp>*)nullptr) } -> same_as<remove_cvref_t<_Tp>>;
+};
+
+template <class _Tp>
+ requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>>
struct __range_adaptor_closure {
- template <ranges::viewable_range _View, _RangeAdaptorClosure _Closure>
- requires same_as<_Tp, remove_cvref_t<_Closure>> && invocable<_Closure, _View>
+ template <ranges::range _Range, _RangeAdaptorClosure _Closure>
+ requires same_as<_Tp, remove_cvref_t<_Closure>> && invocable<_Closure, _Range>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr decltype(auto)
- operator|(_View&& __view, _Closure&& __closure) noexcept(is_nothrow_invocable_v<_Closure, _View>) {
- return std::invoke(std::forward<_Closure>(__closure), std::forward<_View>(__view));
+ operator|(_Range&& __range, _Closure&& __closure) noexcept(is_nothrow_invocable_v<_Closure, _Range>) {
+ return std::invoke(std::forward<_Closure>(__closure), std::forward<_Range>(__range));
}
template <_RangeAdaptorClosure _Closure, _RangeAdaptorClosure _OtherClosure>
@@ -73,6 +81,13 @@ struct __range_adaptor_closure {
}
};
+# if _LIBCPP_STD_VER >= 23
+namespace ranges {
+template <class _Tp>
+using range_adaptor_closure = __range_adaptor_closure<_Tp>;
+} // namespace ranges
+# endif // _LIBCPP_STD_VER >= 23
+
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
index 167d2137eaf454..07a525ed8641fd 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -93,6 +93,11 @@ namespace std::ranges {
template<class T>
concept viewable_range = see below;
+ // [range.adaptor.object], range adaptor objects
+ template<class D>
+ requires is_class_v<D> && same_as<D, remove_cv_t<D>>
+ class range_adaptor_closure { }; // Since c++23
+
// [view.interface], class template view_interface
template<class D>
requires is_class_v<D> && same_as<D, remove_cv_t<D>>
diff --git a/libcxx/test/std/ranges/range.adaptors/range.adaptor.object/range_adaptor_closure.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.adaptor.object/range_adaptor_closure.pass.cpp
new file mode 100644
index 00000000000000..546a8626c80e18
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.adaptor.object/range_adaptor_closure.pass.cpp
@@ -0,0 +1,128 @@
+//===----------------------------------------------------------------------===//
+//
+// 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::range_adaptor_closure;
+
+#include <ranges>
+
+#include <algorithm>
+#include <vector>
+
+#include "test_range.h"
+
+using range_t = std::vector<int>;
+
+template <class T>
+concept RangeAdaptorClosure =
+ CanBePiped<range_t, T&> && CanBePiped<range_t, const T&> && CanBePiped<range_t, T&&> &&
+ CanBePiped<range_t, const T&&>;
+
+struct callable : std::ranges::range_adaptor_closure<callable> {
+ static void operator()(const range_t&) {}
+};
+static_assert(RangeAdaptorClosure<callable>);
+
+// `not_callable_1` doesn't have an `operator()`
+struct not_callable_1 : std::ranges::range_adaptor_closure<not_callable_1> {};
+static_assert(!RangeAdaptorClosure<not_callable_1>);
+
+// `not_callable_2` doesn't have an `operator()` that accepts a `range` argument
+struct not_callable_2 : std::ranges::range_adaptor_closure<not_callable_2> {
+ static void operator()() {}
+};
+static_assert(!RangeAdaptorClosure<not_callable_2>);
+
+// `not_derived_from_1` doesn't derive from `std::ranges::range_adaptor_closure`
+struct not_derived_from_1 {
+ static void operator()(const range_t&) {}
+};
+static_assert(!RangeAdaptorClosure<not_derived_from_1>);
+
+// `not_derived_from_2` doesn't publicly derive from `std::ranges::range_adaptor_closure`
+struct not_derived_from_2 : private std::ranges::range_adaptor_closure<not_derived_from_2> {
+ static void operator()(const range_t&) {}
+};
+static_assert(!RangeAdaptorClosure<not_derived_from_2>);
+
+// `not_derived_from_3` doesn't derive from the correct specialization of `std::ranges::range_adaptor_closure`
+struct not_derived_from_3 : std::ranges::range_adaptor_closure<callable> {
+ static void operator()(const range_t&) {}
+};
+static_assert(!RangeAdaptorClosure<not_derived_from_3>);
+
+// `not_derived_from_4` doesn't derive from a unique `std::ranges::range_adaptor_closure`
+struct not_derived_from_4
+ : std::ranges::range_adaptor_closure<not_derived_from_4>,
+ std::ranges::range_adaptor_closure<callable> {
+ static void operator()(const range_t&) {}
+};
+static_assert(!RangeAdaptorClosure<not_derived_from_4>);
+
+// `is_range` models `range`
+struct is_range : std::ranges::range_adaptor_closure<is_range> {
+ static void operator()(const range_t&) {}
+ int* begin() const { return nullptr; }
+ int* end() const { return nullptr; }
+};
+static_assert(std::ranges::range<is_range> && std::ranges::range<const is_range>);
+static_assert(!RangeAdaptorClosure<is_range>);
+
+// user-defined range adaptor closure object
+struct negate_fn : std::ranges::range_adaptor_closure<negate_fn> {
+ template <std::ranges::range Range>
+ static constexpr decltype(auto) operator()(Range&& range) {
+ return std::forward<Range>(range) | std::views::transform([](auto element) { return -element; });
+ }
+};
+static_assert(RangeAdaptorClosure<negate_fn>);
+constexpr auto negate = negate_fn{};
+
+// user-defined range adaptor closure object
+struct plus_1_fn : std::ranges::range_adaptor_closure<plus_1_fn> {
+ template <std::ranges::range Range>
+ static constexpr decltype(auto) operator()(Range&& range) {
+ return std::forward<Range>(range) | std::views::transform([](auto element) { return element + 1; });
+ }
+};
+static_assert(RangeAdaptorClosure<plus_1_fn>);
+constexpr auto plus_1 = plus_1_fn{};
+
+constexpr bool test() {
+ const std::vector<int> n{1, 2, 3, 4, 5};
+ const std::vector<int> n_negate{-1, -2, -3, -4, -5};
+ const std::vector<int> n_negate_plus_1{0, -1, -2, -3, -4};
+ const std::vector<int> n_plus_1_negate{-2, -3, -4, -5, -6};
+
+ assert(std::ranges::equal(n | negate, n_negate));
+ assert(std::ranges::equal(negate(n), n_negate));
+
+ assert(std::ranges::equal(n | negate | negate, n));
+ assert(std::ranges::equal(n | (negate | negate), n));
+ assert(std::ranges::equal((n | negate) | negate, n));
+ assert(std::ranges::equal(negate(n) | negate, n));
+ assert(std::ranges::equal(negate(n | negate), n));
+ assert(std::ranges::equal((negate | negate)(n), n));
+ assert(std::ranges::equal(negate(negate(n)), n));
+
+ assert(std::ranges::equal(n | negate | plus_1, n_negate_plus_1));
+ assert(std::ranges::equal(
+ n | plus_1 | std::views::transform([](auto element) { return element; }) | negate, n_plus_1_negate));
+
+ assert(std::ranges::equal(n | plus_1 | negate, n_plus_1_negate));
+ assert(std::ranges::equal(n | std::views::reverse | negate | plus_1 | std::views::reverse, n_negate_plus_1));
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
|
xiaoyang-sde
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libcxx/test/std/ranges/range.adaptors/range.adaptor.object/range_adaptor_closure.pass.cpp
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This patch exports the `std::ranges::range_adaptor_closure` class template implemented in #89148 from the C++ Modules file.
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May 13, 2024
* Some docs should've been updated in llvm#74534, this PR does this. * llvm#89148 should've bumped `__cpp_lib_ranges` macro to 202211 (value mentioned by "P2602R2 Poison Pills are Too Toxic") * Drive-by: fix order of notes in `Cxx23.rst`
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Abstract
This pull request aims to finalize the
std::ranges::range_adaptor_closureclass template from P2387R3.Implementation
The current implementation of
__range_adaptor_closurewas introduced in ee44dd8 and has served as the foundation for the range adaptors in libc++ for a while. This pull request keeps its implementation, with the exception of the following changes:__range_adaptor_closurenow includes the missing constraintsis_class_v<D> && same_as<D, remove_cv_t<D>>to restrict the type of class that can inherit from it. ([ranges.syn])operator|of__range_adaptor_closureno longer requires its first argument to modelviewable_range. ([range.adaptor.object]/1)_RangeAdaptorClosureconcept is refined to exclude cases whereTmodelsrangeor whereThas base classes of typerange_adaptor_closure<U>for another typeU. ([range.adaptor.object]/2)Reference