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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_EXPONENTIAL_DISTRIBUTION_H10#define _LIBCPP___CXX03___RANDOM_EXPONENTIAL_DISTRIBUTION_H11 12#include <__cxx03/__config>13#include <__cxx03/__random/generate_canonical.h>14#include <__cxx03/__random/is_valid.h>15#include <__cxx03/__random/uniform_real_distribution.h>16#include <__cxx03/cmath>17#include <__cxx03/iosfwd>18#include <__cxx03/limits>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 exponential_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 result_type __lambda_;40 41 public:42 typedef exponential_distribution distribution_type;43 44 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __lambda = 1) : __lambda_(__lambda) {}45 46 _LIBCPP_HIDE_FROM_ABI result_type lambda() const { return __lambda_; }47 48 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {49 return __x.__lambda_ == __y.__lambda_;50 }51 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }52 };53 54private:55 param_type __p_;56 57public:58 // constructors and reset functions59 _LIBCPP_HIDE_FROM_ABI explicit exponential_distribution(result_type __lambda = 1) : __p_(param_type(__lambda)) {}60 _LIBCPP_HIDE_FROM_ABI explicit exponential_distribution(const param_type& __p) : __p_(__p) {}61 _LIBCPP_HIDE_FROM_ABI void reset() {}62 63 // generating functions64 template <class _URNG>65 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {66 return (*this)(__g, __p_);67 }68 template <class _URNG>69 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);70 71 // property functions72 _LIBCPP_HIDE_FROM_ABI result_type lambda() const { return __p_.lambda(); }73 74 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }75 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }76 77 _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }78 _LIBCPP_HIDE_FROM_ABI result_type max() const { return numeric_limits<result_type>::infinity(); }79 80 friend _LIBCPP_HIDE_FROM_ABI bool81 operator==(const exponential_distribution& __x, const exponential_distribution& __y) {82 return __x.__p_ == __y.__p_;83 }84 friend _LIBCPP_HIDE_FROM_ABI bool85 operator!=(const exponential_distribution& __x, const exponential_distribution& __y) {86 return !(__x == __y);87 }88};89 90template <class _RealType>91template <class _URNG>92_RealType exponential_distribution<_RealType>::operator()(_URNG& __g, const param_type& __p) {93 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");94 return -std::log(result_type(1) - std::generate_canonical<result_type, numeric_limits<result_type>::digits>(__g)) /95 __p.lambda();96}97 98template <class _CharT, class _Traits, class _RealType>99_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&100operator<<(basic_ostream<_CharT, _Traits>& __os, const exponential_distribution<_RealType>& __x) {101 __save_flags<_CharT, _Traits> __lx(__os);102 typedef basic_ostream<_CharT, _Traits> _OStream;103 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);104 return __os << __x.lambda();105}106 107template <class _CharT, class _Traits, class _RealType>108_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&109operator>>(basic_istream<_CharT, _Traits>& __is, exponential_distribution<_RealType>& __x) {110 typedef exponential_distribution<_RealType> _Eng;111 typedef typename _Eng::result_type result_type;112 typedef typename _Eng::param_type param_type;113 __save_flags<_CharT, _Traits> __lx(__is);114 typedef basic_istream<_CharT, _Traits> _Istream;115 __is.flags(_Istream::dec | _Istream::skipws);116 result_type __lambda;117 __is >> __lambda;118 if (!__is.fail())119 __x.param(param_type(__lambda));120 return __is;121}122 123_LIBCPP_END_NAMESPACE_STD124 125_LIBCPP_POP_MACROS126 127#endif // _LIBCPP___CXX03___RANDOM_EXPONENTIAL_DISTRIBUTION_H128