libcxx/include/__random/shuffle_order_engine.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_SHUFFLE_ORDER_ENGINE_H
  10 #define _LIBCPP___RANDOM_SHUFFLE_ORDER_ENGINE_H
  11
  12 #include <__algorithm/equal.h>
  13 #include <__config>
  14 #include <__random/is_seed_sequence.h>
  15 #include <__type_traits/enable_if.h>
  16 #include <__type_traits/integral_constant.h>
  17 #include <__type_traits/is_convertible.h>
  18 #include <__utility/move.h>
  19 #include <cstddef>
  20 #include <cstdint>
  21 #include <iosfwd>
  22
  23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  24 #  pragma GCC system_header
  25 #endif
  26
  27 _LIBCPP_PUSH_MACROS
  28 #include <__undef_macros>
  29
  30 _LIBCPP_BEGIN_NAMESPACE_STD
  31
  32 template <uint64_t _Xp, uint64_t _Yp>
  33 struct __ugcd
  34 {
  35     static _LIBCPP_CONSTEXPR const uint64_t value = __ugcd<_Yp, _Xp % _Yp>::value;
  36 };
  37
  38 template <uint64_t _Xp>
  39 struct __ugcd<_Xp, 0>
  40 {
  41     static _LIBCPP_CONSTEXPR const uint64_t value = _Xp;
  42 };
  43
  44 template <uint64_t _Np, uint64_t _Dp>
  45 class __uratio
  46 {
  47     static_assert(_Dp != 0, "__uratio divide by 0");
  48     static _LIBCPP_CONSTEXPR const uint64_t __gcd = __ugcd<_Np, _Dp>::value;
  49 public:
  50     static _LIBCPP_CONSTEXPR const uint64_t num = _Np / __gcd;
  51     static _LIBCPP_CONSTEXPR const uint64_t den = _Dp / __gcd;
  52
  53     typedef __uratio<num, den> type;
  54 };
  55
  56 template<class _Engine, size_t __k>
  57 class _LIBCPP_TEMPLATE_VIS shuffle_order_engine
  58 {
  59     static_assert(0 < __k, "shuffle_order_engine invalid parameters");
  60 public:
  61     // types
  62     typedef typename _Engine::result_type result_type;
  63
  64 private:
  65     _Engine __e_;
  66     result_type __v_[__k];
  67     result_type __y_;
  68
  69 public:
  70     // engine characteristics
  71     static _LIBCPP_CONSTEXPR const size_t table_size = __k;
  72
  73 #ifdef _LIBCPP_CXX03_LANG
  74     static const result_type _Min = _Engine::_Min;
  75     static const result_type _Max = _Engine::_Max;
  76 #else
  77     static _LIBCPP_CONSTEXPR const result_type _Min = _Engine::min();
  78     static _LIBCPP_CONSTEXPR const result_type _Max = _Engine::max();
  79 #endif
  80     static_assert(_Min < _Max, "shuffle_order_engine invalid parameters");
  81     _LIBCPP_INLINE_VISIBILITY
  82     static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
  83     _LIBCPP_INLINE_VISIBILITY
  84     static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
  85
  86     static _LIBCPP_CONSTEXPR const unsigned long long _Rp = _Max - _Min + 1ull;
  87
  88     // constructors and seeding functions
  89     _LIBCPP_INLINE_VISIBILITY
  90     shuffle_order_engine() {__init();}
  91     _LIBCPP_INLINE_VISIBILITY
  92     explicit shuffle_order_engine(const _Engine& __e)
  93         : __e_(__e) {__init();}
  94 #ifndef _LIBCPP_CXX03_LANG
  95     _LIBCPP_INLINE_VISIBILITY
  96     explicit shuffle_order_engine(_Engine&& __e)
  97         : __e_(_VSTD::move(__e)) {__init();}
  98 #endif // _LIBCPP_CXX03_LANG
  99     _LIBCPP_INLINE_VISIBILITY
 100     explicit shuffle_order_engine(result_type __sd) : __e_(__sd) {__init();}
 101     template<class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, shuffle_order_engine>::value &&
 102                                         !is_convertible<_Sseq, _Engine>::value, int> = 0>
 103         _LIBCPP_INLINE_VISIBILITY
 104         explicit shuffle_order_engine(_Sseq& __q)
 105          : __e_(__q) {__init();}
 106     _LIBCPP_INLINE_VISIBILITY
 107     void seed() {__e_.seed(); __init();}
 108     _LIBCPP_INLINE_VISIBILITY
 109     void seed(result_type __sd) {__e_.seed(__sd); __init();}
 110     template<class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, shuffle_order_engine>::value, int> = 0>
 111         _LIBCPP_INLINE_VISIBILITY
 112         void
 113         seed(_Sseq& __q) {__e_.seed(__q); __init();}
 114
 115     // generating functions
 116     _LIBCPP_INLINE_VISIBILITY
 117     result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
 118     _LIBCPP_INLINE_VISIBILITY
 119     void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
 120
 121     // property functions
 122     _LIBCPP_INLINE_VISIBILITY
 123     const _Engine& base() const _NOEXCEPT {return __e_;}
 124
 125 private:
 126     template<class _Eng, size_t _Kp>
 127     friend
 128     bool
 129     operator==(
 130         const shuffle_order_engine<_Eng, _Kp>& __x,
 131         const shuffle_order_engine<_Eng, _Kp>& __y);
 132
 133     template<class _Eng, size_t _Kp>
 134     friend
 135     bool
 136     operator!=(
 137         const shuffle_order_engine<_Eng, _Kp>& __x,
 138         const shuffle_order_engine<_Eng, _Kp>& __y);
 139
 140     template <class _CharT, class _Traits,
 141               class _Eng, size_t _Kp>
 142     friend
 143     basic_ostream<_CharT, _Traits>&
 144     operator<<(basic_ostream<_CharT, _Traits>& __os,
 145                const shuffle_order_engine<_Eng, _Kp>& __x);
 146
 147     template <class _CharT, class _Traits,
 148               class _Eng, size_t _Kp>
 149     friend
 150     basic_istream<_CharT, _Traits>&
 151     operator>>(basic_istream<_CharT, _Traits>& __is,
 152                shuffle_order_engine<_Eng, _Kp>& __x);
 153
 154     _LIBCPP_INLINE_VISIBILITY
 155     void __init()
 156     {
 157         for (size_t __i = 0; __i < __k; ++__i)
 158             __v_[__i] = __e_();
 159         __y_ = __e_();
 160     }
 161
 162     _LIBCPP_INLINE_VISIBILITY
 163     result_type __eval(false_type) {return __eval2(integral_constant<bool, __k & 1>());}
 164     _LIBCPP_INLINE_VISIBILITY
 165     result_type __eval(true_type) {return __eval(__uratio<__k, _Rp>());}
 166
 167     _LIBCPP_INLINE_VISIBILITY
 168     result_type __eval2(false_type) {return __eval(__uratio<__k/2, 0x8000000000000000ull>());}
 169     _LIBCPP_INLINE_VISIBILITY
 170     result_type __eval2(true_type) {return __evalf<__k, 0>();}
 171
 172     template <uint64_t _Np, uint64_t _Dp, __enable_if_t<(__uratio<_Np, _Dp>::num > 0xFFFFFFFFFFFFFFFFull / (_Max - _Min)), int> = 0>
 173         _LIBCPP_INLINE_VISIBILITY
 174         result_type
 175         __eval(__uratio<_Np, _Dp>)
 176             {return __evalf<__uratio<_Np, _Dp>::num, __uratio<_Np, _Dp>::den>();}
 177
 178     template <uint64_t _Np, uint64_t _Dp, __enable_if_t<__uratio<_Np, _Dp>::num <= 0xFFFFFFFFFFFFFFFFull / (_Max - _Min), int> = 0>
 179         _LIBCPP_INLINE_VISIBILITY
 180         result_type
 181         __eval(__uratio<_Np, _Dp>)
 182         {
 183             const size_t __j = static_cast<size_t>(__uratio<_Np, _Dp>::num * (__y_ - _Min)
 184                                                    / __uratio<_Np, _Dp>::den);
 185             __y_ = __v_[__j];
 186             __v_[__j] = __e_();
 187             return __y_;
 188         }
 189
 190     template <uint64_t __n, uint64_t __d>
 191         _LIBCPP_INLINE_VISIBILITY
 192         result_type __evalf()
 193         {
 194             const double __fp = __d == 0 ?
 195                 __n / (2. * 0x8000000000000000ull) :
 196                 __n / (double)__d;
 197             const size_t __j = static_cast<size_t>(__fp * (__y_ - _Min));
 198             __y_ = __v_[__j];
 199             __v_[__j] = __e_();
 200             return __y_;
 201         }
 202 };
 203
 204 template<class _Engine, size_t __k>
 205     _LIBCPP_CONSTEXPR const size_t shuffle_order_engine<_Engine, __k>::table_size;
 206
 207 template<class _Eng, size_t _Kp>
 208 _LIBCPP_HIDE_FROM_ABI bool
 209 operator==(
 210     const shuffle_order_engine<_Eng, _Kp>& __x,
 211     const shuffle_order_engine<_Eng, _Kp>& __y)
 212 {
 213     return __x.__y_ == __y.__y_ && _VSTD::equal(__x.__v_, __x.__v_ + _Kp, __y.__v_) &&
 214            __x.__e_ == __y.__e_;
 215 }
 216
 217 template<class _Eng, size_t _Kp>
 218 inline _LIBCPP_INLINE_VISIBILITY
 219 bool
 220 operator!=(
 221     const shuffle_order_engine<_Eng, _Kp>& __x,
 222     const shuffle_order_engine<_Eng, _Kp>& __y)
 223 {
 224     return !(__x == __y);
 225 }
 226
 227 template <class _CharT, class _Traits,
 228           class _Eng, size_t _Kp>
 229 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 230 operator<<(basic_ostream<_CharT, _Traits>& __os,
 231            const shuffle_order_engine<_Eng, _Kp>& __x)
 232 {
 233     __save_flags<_CharT, _Traits> __lx(__os);
 234     typedef basic_ostream<_CharT, _Traits> _Ostream;
 235     __os.flags(_Ostream::dec | _Ostream::left);
 236     _CharT __sp = __os.widen(' ');
 237     __os.fill(__sp);
 238     __os << __x.__e_ << __sp << __x.__v_[0];
 239     for (size_t __i = 1; __i < _Kp; ++__i)
 240         __os << __sp << __x.__v_[__i];
 241     return __os << __sp << __x.__y_;
 242 }
 243
 244 template <class _CharT, class _Traits,
 245           class _Eng, size_t _Kp>
 246 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 247 operator>>(basic_istream<_CharT, _Traits>& __is,
 248            shuffle_order_engine<_Eng, _Kp>& __x)
 249 {
 250     typedef typename shuffle_order_engine<_Eng, _Kp>::result_type result_type;
 251     __save_flags<_CharT, _Traits> __lx(__is);
 252     typedef basic_istream<_CharT, _Traits> _Istream;
 253     __is.flags(_Istream::dec | _Istream::skipws);
 254     _Eng __e;
 255     result_type __vp[_Kp+1];
 256     __is >> __e;
 257     for (size_t __i = 0; __i < _Kp+1; ++__i)
 258         __is >> __vp[__i];
 259     if (!__is.fail())
 260     {
 261         __x.__e_ = __e;
 262         for (size_t __i = 0; __i < _Kp; ++__i)
 263             __x.__v_[__i] = __vp[__i];
 264         __x.__y_ = __vp[_Kp];
 265     }
 266     return __is;
 267 }
 268
 269 _LIBCPP_END_NAMESPACE_STD
 270
 271 _LIBCPP_POP_MACROS
 272
 273 #endif // _LIBCPP___RANDOM_SHUFFLE_ORDER_ENGINE_H