libcxx/include/__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___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]/1.5:
  27 // The effect of instantiating a template that has a template type parameter
  28 // named IntType is undefined unless the corresponding template argument is
  29 // cv-unqualified and is one of short, int, long, long long, unsigned short,
  30 // unsigned int, unsigned long, or unsigned long long.
  31
  32 template<class> struct __libcpp_random_is_valid_inttype : false_type {};
  33 template<> struct __libcpp_random_is_valid_inttype<int8_t> : true_type {}; // extension
  34 template<> struct __libcpp_random_is_valid_inttype<short> : true_type {};
  35 template<> struct __libcpp_random_is_valid_inttype<int> : true_type {};
  36 template<> struct __libcpp_random_is_valid_inttype<long> : true_type {};
  37 template<> struct __libcpp_random_is_valid_inttype<long long> : true_type {};
  38 template<> struct __libcpp_random_is_valid_inttype<uint8_t> : true_type {}; // extension
  39 template<> struct __libcpp_random_is_valid_inttype<unsigned short> : true_type {};
  40 template<> struct __libcpp_random_is_valid_inttype<unsigned int> : true_type {};
  41 template<> struct __libcpp_random_is_valid_inttype<unsigned long> : true_type {};
  42 template<> struct __libcpp_random_is_valid_inttype<unsigned long long> : true_type {};
  43
  44 #ifndef _LIBCPP_HAS_NO_INT128
  45 template<> struct __libcpp_random_is_valid_inttype<__int128_t> : true_type {}; // extension
  46 template<> struct __libcpp_random_is_valid_inttype<__uint128_t> : true_type {}; // extension
  47 #endif // _LIBCPP_HAS_NO_INT128
  48
  49 // [rand.req.urng]/3:
  50 // A class G meets the uniform random bit generator requirements if G models
  51 // uniform_random_bit_generator, invoke_result_t<G&> is an unsigned integer type,
  52 // and G provides a nested typedef-name result_type that denotes the same type
  53 // as invoke_result_t<G&>.
  54 // (In particular, reject URNGs with signed result_types; our distributions cannot
  55 // handle such generator types.)
  56
  57 template<class, class = void> struct __libcpp_random_is_valid_urng : false_type {};
  58 template<class _Gp> struct __libcpp_random_is_valid_urng<_Gp, __enable_if_t<
  59     is_unsigned<typename _Gp::result_type>::value &&
  60     _IsSame<decltype(std::declval<_Gp&>()()), typename _Gp::result_type>::value
  61 > > : true_type {};
  62
  63 _LIBCPP_END_NAMESPACE_STD
  64
  65 #endif // _LIBCPP___RANDOM_IS_VALID_H