//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//==============================================================================
// NOTICE: This file has been modified by Green Hills Software, Inc.  Such
// modifications are subject to copyright by Green Hills Software, Inc.  See the
// "Green Hills Software Modifications" section in the LICENSE.txt included with
// this distribution for more information.
//==============================================================================

#ifndef _LIBCPP___RANDOM_IS_VALID_H
#define _LIBCPP___RANDOM_IS_VALID_H

#include <__config>
#include <cstdint>
#include <type_traits>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

#if defined(__ghs__)
  #pragma ghs start_cxx_lib_header
  #pragma ghs startdata
  #if defined(__ghs_max_pack_value)
    #pragma pack (push, __ghs_max_pack_value)
  #endif
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

// [rand.req.genl]/1.5:
// The effect of instantiating a template that has a template type parameter
// named IntType is undefined unless the corresponding template argument is
// cv-unqualified and is one of short, int, long, long long, unsigned short,
// unsigned int, unsigned long, or unsigned long long.

template<class> struct __libcpp_random_is_valid_inttype : false_type {};
template<> struct __libcpp_random_is_valid_inttype<int8_t> : true_type {}; // extension
template<> struct __libcpp_random_is_valid_inttype<short> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<int> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<long> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<long long> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<uint8_t> : true_type {}; // extension
template<> struct __libcpp_random_is_valid_inttype<unsigned short> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<unsigned int> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<unsigned long> : true_type {};
template<> struct __libcpp_random_is_valid_inttype<unsigned long long> : true_type {};

#ifndef _LIBCPP_HAS_NO_INT128
template<> struct __libcpp_random_is_valid_inttype<__int128_t> : true_type {}; // extension
template<> struct __libcpp_random_is_valid_inttype<__uint128_t> : true_type {}; // extension
#endif // _LIBCPP_HAS_NO_INT128

// [rand.req.urng]/3:
// A class G meets the uniform random bit generator requirements if G models
// uniform_random_bit_generator, invoke_result_t<G&> is an unsigned integer type,
// and G provides a nested typedef-name result_type that denotes the same type
// as invoke_result_t<G&>.
// (In particular, reject URNGs with signed result_types; our distributions cannot
// handle such generator types.)

template<class, class = void> struct __libcpp_random_is_valid_urng : false_type {};
template<class _Gp> struct __libcpp_random_is_valid_urng<_Gp, __enable_if_t<
    is_unsigned<typename _Gp::result_type>::value &&
    _IsSame<decltype(declval<_Gp&>()()), typename _Gp::result_type>::value
> > : true_type {};

_LIBCPP_END_NAMESPACE_STD

#if defined(__ghs__)
  #if defined(__ghs_max_pack_value)
    #pragma pack(pop)
  #endif
  #pragma ghs enddata
  #pragma ghs end_cxx_lib_header
#endif

#endif // _LIBCPP___RANDOM_IS_VALID_H