libcxx/include/__cxx03/__random/is_valid.h

   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___CXX03___RANDOM_IS_VALID_H
  10 #define _LIBCPP___CXX03___RANDOM_IS_VALID_H
  11
  12 #include <__cxx03/__config>
  13 #include <__cxx03/__type_traits/enable_if.h>
  14 #include <__cxx03/__type_traits/integral_constant.h>
  15 #include <__cxx03/__type_traits/is_same.h>
  16 #include <__cxx03/__type_traits/is_unsigned.h>
  17 #include <__cxx03/__utility/declval.h>
  18 #include <__cxx03/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
  31 template <class>
  32 struct __libcpp_random_is_valid_realtype : false_type {};
  33 template <>
  34 struct __libcpp_random_is_valid_realtype<float> : true_type {};
  35 template <>
  36 struct __libcpp_random_is_valid_realtype<double> : true_type {};
  37 template <>
  38 struct __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
  46 template <class>
  47 struct __libcpp_random_is_valid_inttype : false_type {};
  48 template <>
  49 struct __libcpp_random_is_valid_inttype<int8_t> : true_type {}; // extension
  50 template <>
  51 struct __libcpp_random_is_valid_inttype<short> : true_type {};
  52 template <>
  53 struct __libcpp_random_is_valid_inttype<int> : true_type {};
  54 template <>
  55 struct __libcpp_random_is_valid_inttype<long> : true_type {};
  56 template <>
  57 struct __libcpp_random_is_valid_inttype<long long> : true_type {};
  58 template <>
  59 struct __libcpp_random_is_valid_inttype<uint8_t> : true_type {}; // extension
  60 template <>
  61 struct __libcpp_random_is_valid_inttype<unsigned short> : true_type {};
  62 template <>
  63 struct __libcpp_random_is_valid_inttype<unsigned int> : true_type {};
  64 template <>
  65 struct __libcpp_random_is_valid_inttype<unsigned long> : true_type {};
  66 template <>
  67 struct __libcpp_random_is_valid_inttype<unsigned long long> : true_type {};
  68
  69 #ifndef _LIBCPP_HAS_NO_INT128
  70 template <>
  71 struct __libcpp_random_is_valid_inttype<__int128_t> : true_type {}; // extension
  72 template <>
  73 struct __libcpp_random_is_valid_inttype<__uint128_t> : true_type {}; // extension
  74 #endif                                                               // _LIBCPP_HAS_NO_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
  84 template <class, class = void>
  85 struct __libcpp_random_is_valid_urng : false_type {};
  86 template <class _Gp>
  87 struct __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___CXX03___RANDOM_IS_VALID_H