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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_LINEAR_DISTRIBUTION_H10#define _LIBCPP___RANDOM_PIECEWISE_LINEAR_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/comparison.h>20#include <__vector/vector.h>21#include <cmath>22#include <initializer_list>23#include <iosfwd>24 25#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)26# pragma GCC system_header27#endif28 29_LIBCPP_PUSH_MACROS30#include <__undef_macros>31 32_LIBCPP_BEGIN_NAMESPACE_STD33 34template <class _RealType = double>35class piecewise_linear_distribution {36 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,37 "RealType must be a supported floating-point type");38 39public:40 // types41 typedef _RealType result_type;42 43 class param_type {44 vector<result_type> __b_;45 vector<result_type> __densities_;46 vector<result_type> __areas_;47 48 public:49 typedef piecewise_linear_distribution distribution_type;50 51 _LIBCPP_HIDE_FROM_ABI param_type();52 template <class _InputIteratorB, class _InputIteratorW>53 _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);54#ifndef _LIBCPP_CXX03_LANG55 template <class _UnaryOperation>56 _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<result_type> __bl, _UnaryOperation __fw);57#endif // _LIBCPP_CXX03_LANG58 template <class _UnaryOperation>59 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);60 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;61 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);62 63 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }64 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }65 66 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {67 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;68 }69 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }70 71 private:72 _LIBCPP_HIDE_FROM_ABI void __init();73 74 friend class piecewise_linear_distribution;75 76 template <class _CharT, class _Traits, class _RT>77 friend basic_ostream<_CharT, _Traits>&78 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);79 80 template <class _CharT, class _Traits, class _RT>81 friend basic_istream<_CharT, _Traits>&82 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);83 };84 85private:86 param_type __p_;87 88public:89 // constructor and reset functions90 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution() {}91 template <class _InputIteratorB, class _InputIteratorW>92 _LIBCPP_HIDE_FROM_ABI93 piecewise_linear_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)94 : __p_(__f_b, __l_b, __f_w) {}95 96#ifndef _LIBCPP_CXX03_LANG97 template <class _UnaryOperation>98 _LIBCPP_HIDE_FROM_ABI piecewise_linear_distribution(initializer_list<result_type> __bl, _UnaryOperation __fw)99 : __p_(__bl, __fw) {}100#endif // _LIBCPP_CXX03_LANG101 102 template <class _UnaryOperation>103 _LIBCPP_HIDE_FROM_ABI104 piecewise_linear_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)105 : __p_(__nw, __xmin, __xmax, __fw) {}106 107 _LIBCPP_HIDE_FROM_ABI explicit piecewise_linear_distribution(const param_type& __p) : __p_(__p) {}108 109 _LIBCPP_HIDE_FROM_ABI void reset() {}110 111 // generating functions112 template <class _URNG>113 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {114 return (*this)(__g, __p_);115 }116 template <class _URNG>117 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);118 119 // property functions120 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }121 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }122 123 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }124 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }125 126 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }127 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }128 129 friend _LIBCPP_HIDE_FROM_ABI bool130 operator==(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {131 return __x.__p_ == __y.__p_;132 }133 friend _LIBCPP_HIDE_FROM_ABI bool134 operator!=(const piecewise_linear_distribution& __x, const piecewise_linear_distribution& __y) {135 return !(__x == __y);136 }137 138 template <class _CharT, class _Traits, class _RT>139 friend basic_ostream<_CharT, _Traits>&140 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x);141 142 template <class _CharT, class _Traits, class _RT>143 friend basic_istream<_CharT, _Traits>&144 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x);145};146 147template <class _RealType>148typename piecewise_linear_distribution<_RealType>::param_type&149piecewise_linear_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {150 // These can throw151 __b_.reserve(__rhs.__b_.size());152 __densities_.reserve(__rhs.__densities_.size());153 __areas_.reserve(__rhs.__areas_.size());154 155 // These can not throw156 __b_ = __rhs.__b_;157 __densities_ = __rhs.__densities_;158 __areas_ = __rhs.__areas_;159 return *this;160}161 162template <class _RealType>163void piecewise_linear_distribution<_RealType>::param_type::__init() {164 __areas_.assign(__densities_.size() - 1, result_type());165 result_type __sp = 0;166 for (size_t __i = 0; __i < __areas_.size(); ++__i) {167 __areas_[__i] = (__densities_[__i + 1] + __densities_[__i]) * (__b_[__i + 1] - __b_[__i]) * .5;168 __sp += __areas_[__i];169 }170 for (size_t __i = __areas_.size(); __i > 1;) {171 --__i;172 __areas_[__i] = __areas_[__i - 1] / __sp;173 }174 __areas_[0] = 0;175 for (size_t __i = 1; __i < __areas_.size(); ++__i)176 __areas_[__i] += __areas_[__i - 1];177 for (size_t __i = 0; __i < __densities_.size(); ++__i)178 __densities_[__i] /= __sp;179}180 181template <class _RealType>182piecewise_linear_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(2, 1.0), __areas_(1, 0.0) {183 __b_[1] = 1;184}185 186template <class _RealType>187template <class _InputIteratorB, class _InputIteratorW>188piecewise_linear_distribution<_RealType>::param_type::param_type(189 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)190 : __b_(__f_b, __l_b) {191 if (__b_.size() < 2) {192 __b_.resize(2);193 __b_[0] = 0;194 __b_[1] = 1;195 __densities_.assign(2, 1.0);196 __areas_.assign(1, 0.0);197 } else {198 __densities_.reserve(__b_.size());199 std::copy_n(__f_w, __b_.size(), std::back_inserter(__densities_));200 __init();201 }202}203 204#ifndef _LIBCPP_CXX03_LANG205 206template <class _RealType>207template <class _UnaryOperation>208piecewise_linear_distribution<_RealType>::param_type::param_type(209 initializer_list<result_type> __bl, _UnaryOperation __fw)210 : __b_(__bl.begin(), __bl.end()) {211 if (__b_.size() < 2) {212 __b_.resize(2);213 __b_[0] = 0;214 __b_[1] = 1;215 __densities_.assign(2, 1.0);216 __areas_.assign(1, 0.0);217 } else {218 __densities_.reserve(__b_.size());219 for (size_t __i = 0; __i < __b_.size(); ++__i)220 __densities_.push_back(__fw(__b_[__i]));221 __init();222 }223}224 225#endif // _LIBCPP_CXX03_LANG226 227template <class _RealType>228template <class _UnaryOperation>229piecewise_linear_distribution<_RealType>::param_type::param_type(230 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)231 : __b_(__nw == 0 ? 2 : __nw + 1) {232 size_t __n = __b_.size() - 1;233 result_type __d = (__xmax - __xmin) / __n;234 __densities_.reserve(__b_.size());235 for (size_t __i = 0; __i < __n; ++__i) {236 __b_[__i] = __xmin + __i * __d;237 __densities_.push_back(__fw(__b_[__i]));238 }239 __b_[__n] = __xmax;240 __densities_.push_back(__fw(__b_[__n]));241 __init();242}243 244template <class _RealType>245template <class _URNG>246_RealType piecewise_linear_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {247 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");248 typedef uniform_real_distribution<result_type> _Gen;249 result_type __u = _Gen()(__g);250 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;251 __u -= __p.__areas_[__k];252 const result_type __dk = __p.__densities_[__k];253 const result_type __dk1 = __p.__densities_[__k + 1];254 const result_type __deltad = __dk1 - __dk;255 const result_type __bk = __p.__b_[__k];256 if (__deltad == 0)257 return __u / __dk + __bk;258 const result_type __bk1 = __p.__b_[__k + 1];259 const result_type __deltab = __bk1 - __bk;260 return (__bk * __dk1 - __bk1 * __dk + std::sqrt(__deltab * (__deltab * __dk * __dk + 2 * __deltad * __u))) / __deltad;261}262 263template <class _CharT, class _Traits, class _RT>264_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&265operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_linear_distribution<_RT>& __x) {266 __save_flags<_CharT, _Traits> __lx(__os);267 typedef basic_ostream<_CharT, _Traits> _OStream;268 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);269 _CharT __sp = __os.widen(' ');270 __os.fill(__sp);271 size_t __n = __x.__p_.__b_.size();272 __os << __n;273 for (size_t __i = 0; __i < __n; ++__i)274 __os << __sp << __x.__p_.__b_[__i];275 __n = __x.__p_.__densities_.size();276 __os << __sp << __n;277 for (size_t __i = 0; __i < __n; ++__i)278 __os << __sp << __x.__p_.__densities_[__i];279 __n = __x.__p_.__areas_.size();280 __os << __sp << __n;281 for (size_t __i = 0; __i < __n; ++__i)282 __os << __sp << __x.__p_.__areas_[__i];283 return __os;284}285 286template <class _CharT, class _Traits, class _RT>287_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&288operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_linear_distribution<_RT>& __x) {289 typedef piecewise_linear_distribution<_RT> _Eng;290 typedef typename _Eng::result_type result_type;291 __save_flags<_CharT, _Traits> __lx(__is);292 typedef basic_istream<_CharT, _Traits> _Istream;293 __is.flags(_Istream::dec | _Istream::skipws);294 size_t __n;295 __is >> __n;296 vector<result_type> __b(__n);297 for (size_t __i = 0; __i < __n; ++__i)298 __is >> __b[__i];299 __is >> __n;300 vector<result_type> __densities(__n);301 for (size_t __i = 0; __i < __n; ++__i)302 __is >> __densities[__i];303 __is >> __n;304 vector<result_type> __areas(__n);305 for (size_t __i = 0; __i < __n; ++__i)306 __is >> __areas[__i];307 if (!__is.fail()) {308 swap(__x.__p_.__b_, __b);309 swap(__x.__p_.__densities_, __densities);310 swap(__x.__p_.__areas_, __areas);311 }312 return __is;313}314 315_LIBCPP_END_NAMESPACE_STD316 317_LIBCPP_POP_MACROS318 319#endif // _LIBCPP___RANDOM_PIECEWISE_LINEAR_DISTRIBUTION_H320