1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___RANGES_RANGE_ADAPTOR_H 11 #define _LIBCPP___RANGES_RANGE_ADAPTOR_H 12 13 #include <__concepts/constructible.h> 14 #include <__concepts/derived_from.h> 15 #include <__concepts/invocable.h> 16 #include <__concepts/same_as.h> 17 #include <__config> 18 #include <__functional/compose.h> 19 #include <__functional/invoke.h> 20 #include <__ranges/concepts.h> 21 #include <__type_traits/decay.h> 22 #include <__type_traits/invoke.h> 23 #include <__type_traits/is_class.h> 24 #include <__type_traits/is_nothrow_constructible.h> 25 #include <__type_traits/remove_cv.h> 26 #include <__type_traits/remove_cvref.h> 27 #include <__utility/forward.h> 28 #include <__utility/move.h> 29 30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 31 # pragma GCC system_header 32 #endif 33 34 _LIBCPP_PUSH_MACROS 35 #include <__undef_macros> 36 37 _LIBCPP_BEGIN_NAMESPACE_STD 38 39 #if _LIBCPP_STD_VER >= 20 40 41 namespace ranges { 42 43 // CRTP base that one can derive from in order to be considered a range adaptor closure 44 // by the library. When deriving from this class, a pipe operator will be provided to 45 // make the following hold: 46 // - `x | f` is equivalent to `f(x)` 47 // - `f1 | f2` is an adaptor closure `g` such that `g(x)` is equivalent to `f2(f1(x))` 48 template <class _Tp> 49 requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> 50 struct __range_adaptor_closure {}; 51 52 // Type that wraps an arbitrary function object and makes it into a range adaptor closure, 53 // i.e. something that can be called via the `x | f` notation. 54 template <class _Fn> 55 struct __pipeable : _Fn, __range_adaptor_closure<__pipeable<_Fn>> { 56 _LIBCPP_HIDE_FROM_ABI constexpr explicit __pipeable(_Fn&& __f) : _Fn(std::move(__f)) {} 57 }; 58 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(__pipeable); 59 60 template <class _Tp> 61 _Tp __derived_from_range_adaptor_closure(__range_adaptor_closure<_Tp>*); 62 63 template <class _Tp> 64 concept _RangeAdaptorClosure = !ranges::range<remove_cvref_t<_Tp>> && requires { 65 // Ensure that `remove_cvref_t<_Tp>` is derived from `__range_adaptor_closure<remove_cvref_t<_Tp>>` and isn't derived 66 // from `__range_adaptor_closure<U>` for any other type `U`. 67 { ranges::__derived_from_range_adaptor_closure((remove_cvref_t<_Tp>*)nullptr) } -> same_as<remove_cvref_t<_Tp>>; 68 }; 69 70 template <ranges::range _Range, _RangeAdaptorClosure _Closure> 71 requires invocable<_Closure, _Range> 72 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) 73 operator|(_Range&& __range, _Closure&& __closure) noexcept(is_nothrow_invocable_v<_Closure, _Range>) { 74 return std::invoke(std::forward<_Closure>(__closure), std::forward<_Range>(__range)); 75 } 76 77 template <_RangeAdaptorClosure _Closure, _RangeAdaptorClosure _OtherClosure> 78 requires constructible_from<decay_t<_Closure>, _Closure> && constructible_from<decay_t<_OtherClosure>, _OtherClosure> 79 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator|(_Closure&& __c1, _OtherClosure&& __c2) noexcept( 80 is_nothrow_constructible_v<decay_t<_Closure>, _Closure> && 81 is_nothrow_constructible_v<decay_t<_OtherClosure>, _OtherClosure>) { 82 return __pipeable(std::__compose(std::forward<_OtherClosure>(__c2), std::forward<_Closure>(__c1))); 83 } 84 85 # if _LIBCPP_STD_VER >= 23 86 template <class _Tp> 87 requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> 88 class _LIBCPP_NO_SPECIALIZATIONS range_adaptor_closure : public __range_adaptor_closure<_Tp> {}; 89 # endif // _LIBCPP_STD_VER >= 23 90 91 } // namespace ranges 92 93 #endif // _LIBCPP_STD_VER >= 20 94 95 _LIBCPP_END_NAMESPACE_STD 96 97 _LIBCPP_POP_MACROS 98 99 #endif // _LIBCPP___RANGES_RANGE_ADAPTOR_H 100