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| 1 | //===----------------------------------------------------------------------===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #ifndef _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |
| 10 | #define _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |
| 11 | |
| 12 | #include <__config> |
| 13 | #include <__type_traits/invoke.h> |
| 14 | #include <__type_traits/remove_cvref.h> |
| 15 | |
| 16 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| 17 | # pragma GCC system_header |
| 18 | #endif |
| 19 | |
| 20 | #if _LIBCPP_STD_VER >= 20 |
| 21 | |
| 22 | _LIBCPP_PUSH_MACROS |
| 23 | # include <__undef_macros> |
| 24 | |
| 25 | _LIBCPP_BEGIN_NAMESPACE_STD |
| 26 | |
| 27 | // Range versions of random algorithms (e.g. `std::shuffle`) are less constrained than their classic counterparts. |
| 28 | // Range algorithms only require the given generator to satisfy the `std::uniform_random_bit_generator` concept. |
| 29 | // Classic algorithms require the given generator to meet the uniform random bit generator requirements; these |
| 30 | // requirements include satisfying `std::uniform_random_bit_generator` and add a requirement for the generator to |
| 31 | // provide a nested `result_type` typedef (see `[rand.req.urng]`). |
| 32 | // |
| 33 | // To be able to reuse classic implementations, make the given generator meet the classic requirements by wrapping |
| 34 | // it into an adaptor type that forwards all of its interface and adds the required typedef. |
| 35 | template <class _Gen> |
| 36 | class _ClassicGenAdaptor { |
| 37 | private: |
| 38 | // The generator is not required to be copyable or movable, so it has to be stored as a reference. |
| 39 | _Gen& __gen_; |
| 40 | |
| 41 | public: |
| 42 | using result_type = invoke_result_t<_Gen&>; |
| 43 | |
| 44 | _LIBCPP_HIDE_FROM_ABI static constexpr auto min() { return __remove_cvref_t<_Gen>::min(); } |
| 45 | _LIBCPP_HIDE_FROM_ABI static constexpr auto max() { return __remove_cvref_t<_Gen>::max(); } |
| 46 | |
| 47 | _LIBCPP_HIDE_FROM_ABI constexpr explicit _ClassicGenAdaptor(_Gen& __g) : __gen_(__g) {} |
| 48 | |
| 49 | _LIBCPP_HIDE_FROM_ABI constexpr auto operator()() const { return __gen_(); } |
| 50 | }; |
| 51 | |
| 52 | _LIBCPP_END_NAMESPACE_STD |
| 53 | |
| 54 | _LIBCPP_POP_MACROS |
| 55 | |
| 56 | #endif // _LIBCPP_STD_VER >= 20 |
| 57 | |
| 58 | #endif // _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |
| 59 |
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