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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___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H10#define _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H11 12#include <__algorithm/copy_n.h>13#include <__algorithm/upper_bound.h>14#include <__config>15#include <__cstddef/ptrdiff_t.h>16#include <__iterator/back_insert_iterator.h>17#include <__random/is_valid.h>18#include <__random/uniform_real_distribution.h>19#include <__vector/vector.h>20#include <initializer_list>21#include <iosfwd>22#include <numeric>23 24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)25# pragma GCC system_header26#endif27 28_LIBCPP_PUSH_MACROS29#include <__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33template <class _RealType = double>34class piecewise_constant_distribution {35 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,36 "RealType must be a supported floating-point type");37 38public:39 // types40 typedef _RealType result_type;41 42 class param_type {43 vector<result_type> __b_;44 vector<result_type> __densities_;45 vector<result_type> __areas_;46 47 public:48 typedef piecewise_constant_distribution distribution_type;49 50 _LIBCPP_HIDE_FROM_ABI param_type();51 template <class _InputIteratorB, class _InputIteratorW>52 _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);53#ifndef _LIBCPP_CXX03_LANG54 template <class _UnaryOperation>55 _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);56#endif // _LIBCPP_CXX03_LANG57 template <class _UnaryOperation>58 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);59 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;60 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);61 62 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }63 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }64 65 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {66 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;67 }68 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }69 70 private:71 _LIBCPP_HIDE_FROM_ABI void __init();72 73 friend class piecewise_constant_distribution;74 75 template <class _CharT, class _Traits, class _RT>76 friend basic_ostream<_CharT, _Traits>&77 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);78 79 template <class _CharT, class _Traits, class _RT>80 friend basic_istream<_CharT, _Traits>&81 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);82 };83 84private:85 param_type __p_;86 87public:88 // constructor and reset functions89 _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution() {}90 template <class _InputIteratorB, class _InputIteratorW>91 _LIBCPP_HIDE_FROM_ABI92 piecewise_constant_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)93 : __p_(__f_b, __l_b, __f_w) {}94 95#ifndef _LIBCPP_CXX03_LANG96 template <class _UnaryOperation>97 _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)98 : __p_(__bl, __fw) {}99#endif // _LIBCPP_CXX03_LANG100 101 template <class _UnaryOperation>102 _LIBCPP_HIDE_FROM_ABI103 piecewise_constant_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)104 : __p_(__nw, __xmin, __xmax, __fw) {}105 106 _LIBCPP_HIDE_FROM_ABI explicit piecewise_constant_distribution(const param_type& __p) : __p_(__p) {}107 108 _LIBCPP_HIDE_FROM_ABI void reset() {}109 110 // generating functions111 template <class _URNG>112 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {113 return (*this)(__g, __p_);114 }115 template <class _URNG>116 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);117 118 // property functions119 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }120 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }121 122 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }123 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }124 125 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }126 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }127 128 friend _LIBCPP_HIDE_FROM_ABI bool129 operator==(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {130 return __x.__p_ == __y.__p_;131 }132 friend _LIBCPP_HIDE_FROM_ABI bool133 operator!=(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {134 return !(__x == __y);135 }136 137 template <class _CharT, class _Traits, class _RT>138 friend basic_ostream<_CharT, _Traits>&139 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);140 141 template <class _CharT, class _Traits, class _RT>142 friend basic_istream<_CharT, _Traits>&143 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);144};145 146template <class _RealType>147typename piecewise_constant_distribution<_RealType>::param_type&148piecewise_constant_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {149 // These can throw150 __b_.reserve(__rhs.__b_.size());151 __densities_.reserve(__rhs.__densities_.size());152 __areas_.reserve(__rhs.__areas_.size());153 154 // These can not throw155 __b_ = __rhs.__b_;156 __densities_ = __rhs.__densities_;157 __areas_ = __rhs.__areas_;158 return *this;159}160 161template <class _RealType>162void piecewise_constant_distribution<_RealType>::param_type::__init() {163 // __densities_ contains non-normalized areas164 result_type __total_area = std::accumulate(__densities_.begin(), __densities_.end(), result_type());165 for (size_t __i = 0; __i < __densities_.size(); ++__i)166 __densities_[__i] /= __total_area;167 // __densities_ contains normalized areas168 __areas_.assign(__densities_.size(), result_type());169 std::partial_sum(__densities_.begin(), __densities_.end() - 1, __areas_.begin() + 1);170 // __areas_ contains partial sums of normalized areas: [0, __densities_ - 1]171 __densities_.back() = 1 - __areas_.back(); // correct round off error172 for (size_t __i = 0; __i < __densities_.size(); ++__i)173 __densities_[__i] /= (__b_[__i + 1] - __b_[__i]);174 // __densities_ now contains __densities_175}176 177template <class _RealType>178piecewise_constant_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(1, 1.0), __areas_(1, 0.0) {179 __b_[1] = 1;180}181 182template <class _RealType>183template <class _InputIteratorB, class _InputIteratorW>184piecewise_constant_distribution<_RealType>::param_type::param_type(185 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)186 : __b_(__f_b, __l_b) {187 if (__b_.size() < 2) {188 __b_.resize(2);189 __b_[0] = 0;190 __b_[1] = 1;191 __densities_.assign(1, 1.0);192 __areas_.assign(1, 0.0);193 } else {194 __densities_.reserve(__b_.size() - 1);195 std::copy_n(__f_w, __b_.size() - 1, std::back_inserter(__densities_));196 __init();197 }198}199 200#ifndef _LIBCPP_CXX03_LANG201 202template <class _RealType>203template <class _UnaryOperation>204piecewise_constant_distribution<_RealType>::param_type::param_type(205 initializer_list<result_type> __bl, _UnaryOperation __fw)206 : __b_(__bl.begin(), __bl.end()) {207 if (__b_.size() < 2) {208 __b_.resize(2);209 __b_[0] = 0;210 __b_[1] = 1;211 __densities_.assign(1, 1.0);212 __areas_.assign(1, 0.0);213 } else {214 __densities_.reserve(__b_.size() - 1);215 for (size_t __i = 0; __i < __b_.size() - 1; ++__i)216 __densities_.push_back(__fw((__b_[__i + 1] + __b_[__i]) * .5));217 __init();218 }219}220 221#endif // _LIBCPP_CXX03_LANG222 223template <class _RealType>224template <class _UnaryOperation>225piecewise_constant_distribution<_RealType>::param_type::param_type(226 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)227 : __b_(__nw == 0 ? 2 : __nw + 1) {228 size_t __n = __b_.size() - 1;229 result_type __d = (__xmax - __xmin) / __n;230 __densities_.reserve(__n);231 for (size_t __i = 0; __i < __n; ++__i) {232 __b_[__i] = __xmin + __i * __d;233 __densities_.push_back(__fw(__b_[__i] + __d * .5));234 }235 __b_[__n] = __xmax;236 __init();237}238 239template <class _RealType>240template <class _URNG>241_RealType piecewise_constant_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {242 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");243 typedef uniform_real_distribution<result_type> _Gen;244 result_type __u = _Gen()(__g);245 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;246 return (__u - __p.__areas_[__k]) / __p.__densities_[__k] + __p.__b_[__k];247}248 249template <class _CharT, class _Traits, class _RT>250_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&251operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x) {252 __save_flags<_CharT, _Traits> __lx(__os);253 typedef basic_ostream<_CharT, _Traits> _OStream;254 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);255 _CharT __sp = __os.widen(' ');256 __os.fill(__sp);257 size_t __n = __x.__p_.__b_.size();258 __os << __n;259 for (size_t __i = 0; __i < __n; ++__i)260 __os << __sp << __x.__p_.__b_[__i];261 __n = __x.__p_.__densities_.size();262 __os << __sp << __n;263 for (size_t __i = 0; __i < __n; ++__i)264 __os << __sp << __x.__p_.__densities_[__i];265 __n = __x.__p_.__areas_.size();266 __os << __sp << __n;267 for (size_t __i = 0; __i < __n; ++__i)268 __os << __sp << __x.__p_.__areas_[__i];269 return __os;270}271 272template <class _CharT, class _Traits, class _RT>273_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&274operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x) {275 typedef piecewise_constant_distribution<_RT> _Eng;276 typedef typename _Eng::result_type result_type;277 __save_flags<_CharT, _Traits> __lx(__is);278 typedef basic_istream<_CharT, _Traits> _Istream;279 __is.flags(_Istream::dec | _Istream::skipws);280 size_t __n;281 __is >> __n;282 vector<result_type> __b(__n);283 for (size_t __i = 0; __i < __n; ++__i)284 __is >> __b[__i];285 __is >> __n;286 vector<result_type> __densities(__n);287 for (size_t __i = 0; __i < __n; ++__i)288 __is >> __densities[__i];289 __is >> __n;290 vector<result_type> __areas(__n);291 for (size_t __i = 0; __i < __n; ++__i)292 __is >> __areas[__i];293 if (!__is.fail()) {294 swap(__x.__p_.__b_, __b);295 swap(__x.__p_.__densities_, __densities);296 swap(__x.__p_.__areas_, __areas);297 }298 return __is;299}300 301_LIBCPP_END_NAMESPACE_STD302 303_LIBCPP_POP_MACROS304 305#endif // _LIBCPP___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H306