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___RANDOM_IS_VALID_H
10#define _LIBCPP___RANDOM_IS_VALID_H
11
12#include <__config>
13#include <__type_traits/enable_if.h>
14#include <__type_traits/integral_constant.h>
15#include <__type_traits/is_same.h>
16#include <__type_traits/is_unsigned.h>
17#include <__utility/declval.h>
18#include <cstdint>
19
20#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21# pragma GCC system_header
22#endif
23
24_LIBCPP_BEGIN_NAMESPACE_STD
25
26// [rand.req.genl]/1.4:
27// The effect of instantiating a template that has a template type parameter
28// named RealType is undefined unless the corresponding template argument is
29// cv-unqualified and is one of float, double, or long double.
30
31template <class>
32struct __libcpp_random_is_valid_realtype : false_type {};
33template <>
34struct __libcpp_random_is_valid_realtype<float> : true_type {};
35template <>
36struct __libcpp_random_is_valid_realtype<double> : true_type {};
37template <>
38struct __libcpp_random_is_valid_realtype<long double> : true_type {};
39
40// [rand.req.genl]/1.5:
41// The effect of instantiating a template that has a template type parameter
42// named IntType is undefined unless the corresponding template argument is
43// cv-unqualified and is one of short, int, long, long long, unsigned short,
44// unsigned int, unsigned long, or unsigned long long.
45
46template <class>
47struct __libcpp_random_is_valid_inttype : false_type {};
48template <>
49struct __libcpp_random_is_valid_inttype<int8_t> : true_type {}; // extension
50template <>
51struct __libcpp_random_is_valid_inttype<short> : true_type {};
52template <>
53struct __libcpp_random_is_valid_inttype<int> : true_type {};
54template <>
55struct __libcpp_random_is_valid_inttype<long> : true_type {};
56template <>
57struct __libcpp_random_is_valid_inttype<long long> : true_type {};
58template <>
59struct __libcpp_random_is_valid_inttype<uint8_t> : true_type {}; // extension
60template <>
61struct __libcpp_random_is_valid_inttype<unsigned short> : true_type {};
62template <>
63struct __libcpp_random_is_valid_inttype<unsigned int> : true_type {};
64template <>
65struct __libcpp_random_is_valid_inttype<unsigned long> : true_type {};
66template <>
67struct __libcpp_random_is_valid_inttype<unsigned long long> : true_type {};
68
69#if _LIBCPP_HAS_INT128
70template <>
71struct __libcpp_random_is_valid_inttype<__int128_t> : true_type {}; // extension
72template <>
73struct __libcpp_random_is_valid_inttype<__uint128_t> : true_type {}; // extension
74#endif // _LIBCPP_HAS_INT128
75
76// [rand.req.urng]/3:
77// A class G meets the uniform random bit generator requirements if G models
78// uniform_random_bit_generator, invoke_result_t<G&> is an unsigned integer type,
79// and G provides a nested typedef-name result_type that denotes the same type
80// as invoke_result_t<G&>.
81// (In particular, reject URNGs with signed result_types; our distributions cannot
82// handle such generator types.)
83
84template <class, class = void>
85struct __libcpp_random_is_valid_urng : false_type {};
86template <class _Gp>
87struct __libcpp_random_is_valid_urng<
88 _Gp,
89 __enable_if_t< is_unsigned<typename _Gp::result_type>::value &&
90 _IsSame<decltype(std::declval<_Gp&>()()), typename _Gp::result_type>::value > > : true_type {};
91
92_LIBCPP_END_NAMESPACE_STD
93
94#endif // _LIBCPP___RANDOM_IS_VALID_H
95