libcxx/include/__algorithm/shuffle.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___ALGORITHM_SHUFFLE_H
  10 #define _LIBCPP___ALGORITHM_SHUFFLE_H
  11
  12 #include <__algorithm/iterator_operations.h>
  13 #include <__config>
  14 #include <__cstddef/ptrdiff_t.h>
  15 #include <__iterator/iterator_traits.h>
  16 #include <__random/uniform_int_distribution.h>
  17 #include <__utility/forward.h>
  18 #include <__utility/move.h>
  19 #include <__utility/swap.h>
  20 #include <cstdint>
  21
  22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  23 #  pragma GCC system_header
  24 #endif
  25
  26 _LIBCPP_PUSH_MACROS
  27 #include <__undef_macros>
  28
  29 _LIBCPP_BEGIN_NAMESPACE_STD
  30
  31 class _LIBCPP_EXPORTED_FROM_ABI __libcpp_debug_randomizer {
  32 public:
  33   _LIBCPP_HIDE_FROM_ABI __libcpp_debug_randomizer() {
  34     __state_ = __seed();
  35     __inc_   = __state_ + 0xda3e39cb94b95bdbULL;
  36     __inc_   = (__inc_ << 1) | 1;
  37   }
  38   typedef uint_fast32_t result_type;
  39
  40   static const result_type _Min = 0;
  41   static const result_type _Max = 0xFFFFFFFF;
  42
  43   _LIBCPP_HIDE_FROM_ABI result_type operator()() {
  44     uint_fast64_t __oldstate = __state_;
  45     __state_                 = __oldstate * 6364136223846793005ULL + __inc_;
  46     return __oldstate >> 32;
  47   }
  48
  49   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR result_type min() { return _Min; }
  50   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR result_type max() { return _Max; }
  51
  52 private:
  53   uint_fast64_t __state_;
  54   uint_fast64_t __inc_;
  55   _LIBCPP_HIDE_FROM_ABI static uint_fast64_t __seed() {
  56 #ifdef _LIBCPP_DEBUG_RANDOMIZE_UNSPECIFIED_STABILITY_SEED
  57     return _LIBCPP_DEBUG_RANDOMIZE_UNSPECIFIED_STABILITY_SEED;
  58 #else
  59     static char __x;
  60     return reinterpret_cast<uintptr_t>(&__x);
  61 #endif
  62   }
  63 };
  64
  65 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) || defined(_LIBCPP_BUILDING_LIBRARY)
  66 class _LIBCPP_EXPORTED_FROM_ABI __rs_default;
  67
  68 _LIBCPP_EXPORTED_FROM_ABI __rs_default __rs_get();
  69
  70 class _LIBCPP_EXPORTED_FROM_ABI __rs_default {
  71   static unsigned __c_;
  72
  73   __rs_default();
  74
  75 public:
  76   typedef uint_fast32_t result_type;
  77
  78   static const result_type _Min = 0;
  79   static const result_type _Max = 0xFFFFFFFF;
  80
  81   __rs_default(const __rs_default&);
  82   ~__rs_default();
  83
  84   result_type operator()();
  85
  86   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR result_type min() { return _Min; }
  87   static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR result_type max() { return _Max; }
  88
  89   friend _LIBCPP_EXPORTED_FROM_ABI __rs_default __rs_get();
  90 };
  91
  92 _LIBCPP_EXPORTED_FROM_ABI __rs_default __rs_get();
  93
  94 template <class _RandomAccessIterator>
  95 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX14 void
  96 random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last) {
  97   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
  98   typedef uniform_int_distribution<ptrdiff_t> _Dp;
  99   typedef typename _Dp::param_type _Pp;
 100   difference_type __d = __last - __first;
 101   if (__d > 1) {
 102     _Dp __uid;
 103     __rs_default __g = __rs_get();
 104     for (--__last, (void)--__d; __first < __last; ++__first, (void)--__d) {
 105       difference_type __i = __uid(__g, _Pp(0, __d));
 106       if (__i != difference_type(0))
 107         swap(*__first, *(__first + __i));
 108     }
 109   }
 110 }
 111
 112 template <class _RandomAccessIterator, class _RandomNumberGenerator>
 113 _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX14 void
 114 random_shuffle(_RandomAccessIterator __first,
 115                _RandomAccessIterator __last,
 116 #  ifndef _LIBCPP_CXX03_LANG
 117                _RandomNumberGenerator&& __rand)
 118 #  else
 119                _RandomNumberGenerator& __rand)
 120 #  endif
 121 {
 122   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
 123   difference_type __d = __last - __first;
 124   if (__d > 1) {
 125     for (--__last; __first < __last; ++__first, (void)--__d) {
 126       difference_type __i = __rand(__d);
 127       if (__i != difference_type(0))
 128         swap(*__first, *(__first + __i));
 129     }
 130   }
 131 }
 132 #endif
 133
 134 template <class _AlgPolicy, class _RandomAccessIterator, class _Sentinel, class _UniformRandomNumberGenerator>
 135 _LIBCPP_HIDE_FROM_ABI _RandomAccessIterator
 136 __shuffle(_RandomAccessIterator __first, _Sentinel __last_sentinel, _UniformRandomNumberGenerator&& __g) {
 137   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
 138   typedef uniform_int_distribution<ptrdiff_t> _Dp;
 139   typedef typename _Dp::param_type _Pp;
 140
 141   auto __original_last = _IterOps<_AlgPolicy>::next(__first, __last_sentinel);
 142   auto __last          = __original_last;
 143   difference_type __d  = __last - __first;
 144   if (__d > 1) {
 145     _Dp __uid;
 146     for (--__last, (void)--__d; __first < __last; ++__first, (void)--__d) {
 147       difference_type __i = __uid(__g, _Pp(0, __d));
 148       if (__i != difference_type(0))
 149         _IterOps<_AlgPolicy>::iter_swap(__first, __first + __i);
 150     }
 151   }
 152
 153   return __original_last;
 154 }
 155
 156 template <class _RandomAccessIterator, class _UniformRandomNumberGenerator>
 157 _LIBCPP_HIDE_FROM_ABI void
 158 shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last, _UniformRandomNumberGenerator&& __g) {
 159   (void)std::__shuffle<_ClassicAlgPolicy>(
 160       std::move(__first), std::move(__last), std::forward<_UniformRandomNumberGenerator>(__g));
 161 }
 162
 163 _LIBCPP_END_NAMESPACE_STD
 164
 165 _LIBCPP_POP_MACROS
 166
 167 #endif // _LIBCPP___ALGORITHM_SHUFFLE_H