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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___CXX03___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H10#define _LIBCPP___CXX03___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H11 12#include <__cxx03/__assert>13#include <__cxx03/__config>14#include <__cxx03/__random/bernoulli_distribution.h>15#include <__cxx03/__random/gamma_distribution.h>16#include <__cxx03/__random/is_valid.h>17#include <__cxx03/__random/poisson_distribution.h>18#include <__cxx03/iosfwd>19#include <__cxx03/limits>20 21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)22# pragma GCC system_header23#endif24 25_LIBCPP_PUSH_MACROS26#include <__cxx03/__undef_macros>27 28_LIBCPP_BEGIN_NAMESPACE_STD29 30template <class _IntType = int>31class _LIBCPP_TEMPLATE_VIS negative_binomial_distribution {32 static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");33 34public:35 // types36 typedef _IntType result_type;37 38 class _LIBCPP_TEMPLATE_VIS param_type {39 result_type __k_;40 double __p_;41 42 public:43 typedef negative_binomial_distribution distribution_type;44 45 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __k = 1, double __p = 0.5) : __k_(__k), __p_(__p) {}46 47 _LIBCPP_HIDE_FROM_ABI result_type k() const { return __k_; }48 _LIBCPP_HIDE_FROM_ABI double p() const { return __p_; }49 50 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {51 return __x.__k_ == __y.__k_ && __x.__p_ == __y.__p_;52 }53 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }54 };55 56private:57 param_type __p_;58 59public:60 // constructor and reset functions61 _LIBCPP_HIDE_FROM_ABI explicit negative_binomial_distribution(result_type __k = 1, double __p = 0.5)62 : __p_(__k, __p) {}63 _LIBCPP_HIDE_FROM_ABI explicit negative_binomial_distribution(const param_type& __p) : __p_(__p) {}64 _LIBCPP_HIDE_FROM_ABI void reset() {}65 66 // generating functions67 template <class _URNG>68 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {69 return (*this)(__g, __p_);70 }71 template <class _URNG>72 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);73 74 // property functions75 _LIBCPP_HIDE_FROM_ABI result_type k() const { return __p_.k(); }76 _LIBCPP_HIDE_FROM_ABI double p() const { return __p_.p(); }77 78 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }79 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }80 81 _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }82 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::max(); }83 84 friend _LIBCPP_HIDE_FROM_ABI bool85 operator==(const negative_binomial_distribution& __x, const negative_binomial_distribution& __y) {86 return __x.__p_ == __y.__p_;87 }88 friend _LIBCPP_HIDE_FROM_ABI bool89 operator!=(const negative_binomial_distribution& __x, const negative_binomial_distribution& __y) {90 return !(__x == __y);91 }92};93 94template <class _IntType>95template <class _URNG>96_IntType negative_binomial_distribution<_IntType>::operator()(_URNG& __urng, const param_type& __pr) {97 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");98 result_type __k = __pr.k();99 double __p = __pr.p();100 // When the number of bits in _IntType is small, we are too likely to101 // overflow __f below to use this technique.102 if (__k <= 21 * __p && sizeof(_IntType) > 1) {103 bernoulli_distribution __gen(__p);104 result_type __f = 0;105 result_type __s = 0;106 while (__s < __k) {107 if (__gen(__urng))108 ++__s;109 else110 ++__f;111 }112 _LIBCPP_ASSERT_INTERNAL(__f >= 0,113 "std::negative_binomial_distribution should never produce negative values. "114 "This is almost certainly a signed integer overflow issue on __f.");115 return __f;116 }117 return poisson_distribution<result_type>(gamma_distribution<double>(__k, (1 - __p) / __p)(__urng))(__urng);118}119 120template <class _CharT, class _Traits, class _IntType>121_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&122operator<<(basic_ostream<_CharT, _Traits>& __os, const negative_binomial_distribution<_IntType>& __x) {123 __save_flags<_CharT, _Traits> __lx(__os);124 typedef basic_ostream<_CharT, _Traits> _OStream;125 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);126 _CharT __sp = __os.widen(' ');127 __os.fill(__sp);128 return __os << __x.k() << __sp << __x.p();129}130 131template <class _CharT, class _Traits, class _IntType>132_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&133operator>>(basic_istream<_CharT, _Traits>& __is, negative_binomial_distribution<_IntType>& __x) {134 typedef negative_binomial_distribution<_IntType> _Eng;135 typedef typename _Eng::result_type result_type;136 typedef typename _Eng::param_type param_type;137 __save_flags<_CharT, _Traits> __lx(__is);138 typedef basic_istream<_CharT, _Traits> _Istream;139 __is.flags(_Istream::dec | _Istream::skipws);140 result_type __k;141 double __p;142 __is >> __k >> __p;143 if (!__is.fail())144 __x.param(param_type(__k, __p));145 return __is;146}147 148_LIBCPP_END_NAMESPACE_STD149 150_LIBCPP_POP_MACROS151 152#endif // _LIBCPP___CXX03___RANDOM_NEGATIVE_BINOMIAL_DISTRIBUTION_H153