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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_PIECEWISE_CONSTANT_DISTRIBUTION_H10#define _LIBCPP___CXX03___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H11 12#include <__cxx03/__algorithm/upper_bound.h>13#include <__cxx03/__config>14#include <__cxx03/__random/is_valid.h>15#include <__cxx03/__random/uniform_real_distribution.h>16#include <__cxx03/iosfwd>17#include <__cxx03/numeric>18#include <__cxx03/vector>19 20#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)21# pragma GCC system_header22#endif23 24_LIBCPP_PUSH_MACROS25#include <__cxx03/__undef_macros>26 27_LIBCPP_BEGIN_NAMESPACE_STD28 29template <class _RealType = double>30class _LIBCPP_TEMPLATE_VIS piecewise_constant_distribution {31 static_assert(__libcpp_random_is_valid_realtype<_RealType>::value,32 "RealType must be a supported floating-point type");33 34public:35 // types36 typedef _RealType result_type;37 38 class _LIBCPP_TEMPLATE_VIS param_type {39 vector<result_type> __b_;40 vector<result_type> __densities_;41 vector<result_type> __areas_;42 43 public:44 typedef piecewise_constant_distribution distribution_type;45 46 _LIBCPP_HIDE_FROM_ABI param_type();47 template <class _InputIteratorB, class _InputIteratorW>48 _LIBCPP_HIDE_FROM_ABI param_type(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w);49 template <class _UnaryOperation>50 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw);51 _LIBCPP_HIDE_FROM_ABI param_type(param_type const&) = default;52 _LIBCPP_HIDE_FROM_ABI param_type& operator=(const param_type& __rhs);53 54 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __b_; }55 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __densities_; }56 57 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {58 return __x.__densities_ == __y.__densities_ && __x.__b_ == __y.__b_;59 }60 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }61 62 private:63 _LIBCPP_HIDE_FROM_ABI void __init();64 65 friend class piecewise_constant_distribution;66 67 template <class _CharT, class _Traits, class _RT>68 friend basic_ostream<_CharT, _Traits>&69 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);70 71 template <class _CharT, class _Traits, class _RT>72 friend basic_istream<_CharT, _Traits>&73 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);74 };75 76private:77 param_type __p_;78 79public:80 // constructor and reset functions81 _LIBCPP_HIDE_FROM_ABI piecewise_constant_distribution() {}82 template <class _InputIteratorB, class _InputIteratorW>83 _LIBCPP_HIDE_FROM_ABI84 piecewise_constant_distribution(_InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)85 : __p_(__f_b, __l_b, __f_w) {}86 87 template <class _UnaryOperation>88 _LIBCPP_HIDE_FROM_ABI89 piecewise_constant_distribution(size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)90 : __p_(__nw, __xmin, __xmax, __fw) {}91 92 _LIBCPP_HIDE_FROM_ABI explicit piecewise_constant_distribution(const param_type& __p) : __p_(__p) {}93 94 _LIBCPP_HIDE_FROM_ABI void reset() {}95 96 // generating functions97 template <class _URNG>98 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {99 return (*this)(__g, __p_);100 }101 template <class _URNG>102 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);103 104 // property functions105 _LIBCPP_HIDE_FROM_ABI vector<result_type> intervals() const { return __p_.intervals(); }106 _LIBCPP_HIDE_FROM_ABI vector<result_type> densities() const { return __p_.densities(); }107 108 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }109 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }110 111 _LIBCPP_HIDE_FROM_ABI result_type min() const { return __p_.__b_.front(); }112 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__b_.back(); }113 114 friend _LIBCPP_HIDE_FROM_ABI bool115 operator==(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {116 return __x.__p_ == __y.__p_;117 }118 friend _LIBCPP_HIDE_FROM_ABI bool119 operator!=(const piecewise_constant_distribution& __x, const piecewise_constant_distribution& __y) {120 return !(__x == __y);121 }122 123 template <class _CharT, class _Traits, class _RT>124 friend basic_ostream<_CharT, _Traits>&125 operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x);126 127 template <class _CharT, class _Traits, class _RT>128 friend basic_istream<_CharT, _Traits>&129 operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x);130};131 132template <class _RealType>133typename piecewise_constant_distribution<_RealType>::param_type&134piecewise_constant_distribution<_RealType>::param_type::operator=(const param_type& __rhs) {135 // These can throw136 __b_.reserve(__rhs.__b_.size());137 __densities_.reserve(__rhs.__densities_.size());138 __areas_.reserve(__rhs.__areas_.size());139 140 // These can not throw141 __b_ = __rhs.__b_;142 __densities_ = __rhs.__densities_;143 __areas_ = __rhs.__areas_;144 return *this;145}146 147template <class _RealType>148void piecewise_constant_distribution<_RealType>::param_type::__init() {149 // __densities_ contains non-normalized areas150 result_type __total_area = std::accumulate(__densities_.begin(), __densities_.end(), result_type());151 for (size_t __i = 0; __i < __densities_.size(); ++__i)152 __densities_[__i] /= __total_area;153 // __densities_ contains normalized areas154 __areas_.assign(__densities_.size(), result_type());155 std::partial_sum(__densities_.begin(), __densities_.end() - 1, __areas_.begin() + 1);156 // __areas_ contains partial sums of normalized areas: [0, __densities_ - 1]157 __densities_.back() = 1 - __areas_.back(); // correct round off error158 for (size_t __i = 0; __i < __densities_.size(); ++__i)159 __densities_[__i] /= (__b_[__i + 1] - __b_[__i]);160 // __densities_ now contains __densities_161}162 163template <class _RealType>164piecewise_constant_distribution<_RealType>::param_type::param_type() : __b_(2), __densities_(1, 1.0), __areas_(1, 0.0) {165 __b_[1] = 1;166}167 168template <class _RealType>169template <class _InputIteratorB, class _InputIteratorW>170piecewise_constant_distribution<_RealType>::param_type::param_type(171 _InputIteratorB __f_b, _InputIteratorB __l_b, _InputIteratorW __f_w)172 : __b_(__f_b, __l_b) {173 if (__b_.size() < 2) {174 __b_.resize(2);175 __b_[0] = 0;176 __b_[1] = 1;177 __densities_.assign(1, 1.0);178 __areas_.assign(1, 0.0);179 } else {180 __densities_.reserve(__b_.size() - 1);181 for (size_t __i = 0; __i < __b_.size() - 1; ++__i, ++__f_w)182 __densities_.push_back(*__f_w);183 __init();184 }185}186 187template <class _RealType>188template <class _UnaryOperation>189piecewise_constant_distribution<_RealType>::param_type::param_type(190 size_t __nw, result_type __xmin, result_type __xmax, _UnaryOperation __fw)191 : __b_(__nw == 0 ? 2 : __nw + 1) {192 size_t __n = __b_.size() - 1;193 result_type __d = (__xmax - __xmin) / __n;194 __densities_.reserve(__n);195 for (size_t __i = 0; __i < __n; ++__i) {196 __b_[__i] = __xmin + __i * __d;197 __densities_.push_back(__fw(__b_[__i] + __d * .5));198 }199 __b_[__n] = __xmax;200 __init();201}202 203template <class _RealType>204template <class _URNG>205_RealType piecewise_constant_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {206 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");207 typedef uniform_real_distribution<result_type> _Gen;208 result_type __u = _Gen()(__g);209 ptrdiff_t __k = std::upper_bound(__p.__areas_.begin(), __p.__areas_.end(), __u) - __p.__areas_.begin() - 1;210 return (__u - __p.__areas_[__k]) / __p.__densities_[__k] + __p.__b_[__k];211}212 213template <class _CharT, class _Traits, class _RT>214_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&215operator<<(basic_ostream<_CharT, _Traits>& __os, const piecewise_constant_distribution<_RT>& __x) {216 __save_flags<_CharT, _Traits> __lx(__os);217 typedef basic_ostream<_CharT, _Traits> _OStream;218 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);219 _CharT __sp = __os.widen(' ');220 __os.fill(__sp);221 size_t __n = __x.__p_.__b_.size();222 __os << __n;223 for (size_t __i = 0; __i < __n; ++__i)224 __os << __sp << __x.__p_.__b_[__i];225 __n = __x.__p_.__densities_.size();226 __os << __sp << __n;227 for (size_t __i = 0; __i < __n; ++__i)228 __os << __sp << __x.__p_.__densities_[__i];229 __n = __x.__p_.__areas_.size();230 __os << __sp << __n;231 for (size_t __i = 0; __i < __n; ++__i)232 __os << __sp << __x.__p_.__areas_[__i];233 return __os;234}235 236template <class _CharT, class _Traits, class _RT>237_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&238operator>>(basic_istream<_CharT, _Traits>& __is, piecewise_constant_distribution<_RT>& __x) {239 typedef piecewise_constant_distribution<_RT> _Eng;240 typedef typename _Eng::result_type result_type;241 __save_flags<_CharT, _Traits> __lx(__is);242 typedef basic_istream<_CharT, _Traits> _Istream;243 __is.flags(_Istream::dec | _Istream::skipws);244 size_t __n;245 __is >> __n;246 vector<result_type> __b(__n);247 for (size_t __i = 0; __i < __n; ++__i)248 __is >> __b[__i];249 __is >> __n;250 vector<result_type> __densities(__n);251 for (size_t __i = 0; __i < __n; ++__i)252 __is >> __densities[__i];253 __is >> __n;254 vector<result_type> __areas(__n);255 for (size_t __i = 0; __i < __n; ++__i)256 __is >> __areas[__i];257 if (!__is.fail()) {258 swap(__x.__p_.__b_, __b);259 swap(__x.__p_.__densities_, __densities);260 swap(__x.__p_.__areas_, __areas);261 }262 return __is;263}264 265_LIBCPP_END_NAMESPACE_STD266 267_LIBCPP_POP_MACROS268 269#endif // _LIBCPP___CXX03___RANDOM_PIECEWISE_CONSTANT_DISTRIBUTION_H270