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/is_class.h> 23 #include <__type_traits/is_nothrow_constructible.h> 24 #include <__type_traits/remove_cvref.h> 25 #include <__utility/forward.h> 26 #include <__utility/move.h> 27 28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 29 # pragma GCC system_header 30 #endif 31 32 _LIBCPP_PUSH_MACROS 33 #include <__undef_macros> 34 35 _LIBCPP_BEGIN_NAMESPACE_STD 36 37 #if _LIBCPP_STD_VER >= 20 38 39 namespace ranges { 40 41 // CRTP base that one can derive from in order to be considered a range adaptor closure 42 // by the library. When deriving from this class, a pipe operator will be provided to 43 // make the following hold: 44 // - `x | f` is equivalent to `f(x)` 45 // - `f1 | f2` is an adaptor closure `g` such that `g(x)` is equivalent to `f2(f1(x))` 46 template <class _Tp> 47 requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> 48 struct __range_adaptor_closure; 49 50 // Type that wraps an arbitrary function object and makes it into a range adaptor closure, 51 // i.e. something that can be called via the `x | f` notation. 52 template <class _Fn> 53 struct __range_adaptor_closure_t : _Fn, __range_adaptor_closure<__range_adaptor_closure_t<_Fn>> { __range_adaptor_closure_t__range_adaptor_closure_t54 _LIBCPP_HIDE_FROM_ABI constexpr explicit __range_adaptor_closure_t(_Fn&& __f) : _Fn(std::move(__f)) {} 55 }; 56 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(__range_adaptor_closure_t); 57 58 template <class _Tp> 59 _Tp __derived_from_range_adaptor_closure(__range_adaptor_closure<_Tp>*); 60 61 template <class _Tp> 62 concept _RangeAdaptorClosure = !ranges::range<remove_cvref_t<_Tp>> && requires { 63 // Ensure that `remove_cvref_t<_Tp>` is derived from `__range_adaptor_closure<remove_cvref_t<_Tp>>` and isn't derived 64 // from `__range_adaptor_closure<U>` for any other type `U`. 65 { ranges::__derived_from_range_adaptor_closure((remove_cvref_t<_Tp>*)nullptr) } -> same_as<remove_cvref_t<_Tp>>; 66 }; 67 68 template <ranges::range _Range, _RangeAdaptorClosure _Closure> 69 requires invocable<_Closure, _Range> 70 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) 71 operator|(_Range&& __range, _Closure&& __closure) noexcept(is_nothrow_invocable_v<_Closure, _Range>) { 72 return std::invoke(std::forward<_Closure>(__closure), std::forward<_Range>(__range)); 73 } 74 75 template <_RangeAdaptorClosure _Closure, _RangeAdaptorClosure _OtherClosure> 76 requires constructible_from<decay_t<_Closure>, _Closure> && constructible_from<decay_t<_OtherClosure>, _OtherClosure> 77 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator|(_Closure&& __c1, _OtherClosure&& __c2) noexcept( 78 is_nothrow_constructible_v<decay_t<_Closure>, _Closure> && 79 is_nothrow_constructible_v<decay_t<_OtherClosure>, _OtherClosure>) { 80 return __range_adaptor_closure_t(std::__compose(std::forward<_OtherClosure>(__c2), std::forward<_Closure>(__c1))); 81 } 82 83 template <class _Tp> 84 requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> 85 struct __range_adaptor_closure {}; 86 87 # if _LIBCPP_STD_VER >= 23 88 template <class _Tp> 89 requires is_class_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>> 90 class range_adaptor_closure : public __range_adaptor_closure<_Tp> {}; 91 # endif // _LIBCPP_STD_VER >= 23 92 93 } // namespace ranges 94 95 #endif // _LIBCPP_STD_VER >= 20 96 97 _LIBCPP_END_NAMESPACE_STD 98 99 _LIBCPP_POP_MACROS 100 101 #endif // _LIBCPP___RANGES_RANGE_ADAPTOR_H 102