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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-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___CXX03___RANDOM_DISCRETE_DISTRIBUTION_H
10#define _LIBCPP___CXX03___RANDOM_DISCRETE_DISTRIBUTION_H
11
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/cstddef>
17#include <__cxx03/iosfwd>
18#include <__cxx03/numeric>
19#include <__cxx03/vector>
20
21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22# pragma GCC system_header
23#endif
24
25_LIBCPP_PUSH_MACROS
26#include <__cxx03/__undef_macros>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30template <class _IntType = int>
31class _LIBCPP_TEMPLATE_VIS discrete_distribution {
32 static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
33
34public:
35 // types
36 typedef _IntType result_type;
37
38 class _LIBCPP_TEMPLATE_VIS param_type {
39 vector<double> __p_;
40
41 public:
42 typedef discrete_distribution distribution_type;
43
44 _LIBCPP_HIDE_FROM_ABI param_type() {}
45 template <class _InputIterator>
46 _LIBCPP_HIDE_FROM_ABI param_type(_InputIterator __f, _InputIterator __l) : __p_(__f, __l) {
47 __init();
48 }
49 template <class _UnaryOperation>
50 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw);
51
52 _LIBCPP_HIDE_FROM_ABI vector<double> probabilities() const;
53
54 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
55 return __x.__p_ == __y.__p_;
56 }
57 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
58
59 private:
60 _LIBCPP_HIDE_FROM_ABI void __init();
61
62 friend class discrete_distribution;
63
64 template <class _CharT, class _Traits, class _IT>
65 friend basic_ostream<_CharT, _Traits>&
66 operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x);
67
68 template <class _CharT, class _Traits, class _IT>
69 friend basic_istream<_CharT, _Traits>&
70 operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x);
71 };
72
73private:
74 param_type __p_;
75
76public:
77 // constructor and reset functions
78 _LIBCPP_HIDE_FROM_ABI discrete_distribution() {}
79 template <class _InputIterator>
80 _LIBCPP_HIDE_FROM_ABI discrete_distribution(_InputIterator __f, _InputIterator __l) : __p_(__f, __l) {}
81 template <class _UnaryOperation>
82 _LIBCPP_HIDE_FROM_ABI discrete_distribution(size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw)
83 : __p_(__nw, __xmin, __xmax, __fw) {}
84 _LIBCPP_HIDE_FROM_ABI explicit discrete_distribution(const param_type& __p) : __p_(__p) {}
85 _LIBCPP_HIDE_FROM_ABI void reset() {}
86
87 // generating functions
88 template <class _URNG>
89 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
90 return (*this)(__g, __p_);
91 }
92 template <class _URNG>
93 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
94
95 // property functions
96 _LIBCPP_HIDE_FROM_ABI vector<double> probabilities() const { return __p_.probabilities(); }
97
98 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
99 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
100
101 _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }
102 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__p_.size(); }
103
104 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const discrete_distribution& __x, const discrete_distribution& __y) {
105 return __x.__p_ == __y.__p_;
106 }
107 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const discrete_distribution& __x, const discrete_distribution& __y) {
108 return !(__x == __y);
109 }
110
111 template <class _CharT, class _Traits, class _IT>
112 friend basic_ostream<_CharT, _Traits>&
113 operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x);
114
115 template <class _CharT, class _Traits, class _IT>
116 friend basic_istream<_CharT, _Traits>&
117 operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x);
118};
119
120template <class _IntType>
121template <class _UnaryOperation>
122discrete_distribution<_IntType>::param_type::param_type(
123 size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw) {
124 if (__nw > 1) {
125 __p_.reserve(__nw - 1);
126 double __d = (__xmax - __xmin) / __nw;
127 double __d2 = __d / 2;
128 for (size_t __k = 0; __k < __nw; ++__k)
129 __p_.push_back(__fw(__xmin + __k * __d + __d2));
130 __init();
131 }
132}
133
134template <class _IntType>
135void discrete_distribution<_IntType>::param_type::__init() {
136 if (!__p_.empty()) {
137 if (__p_.size() > 1) {
138 double __s = std::accumulate(__p_.begin(), __p_.end(), 0.0);
139 for (vector<double>::iterator __i = __p_.begin(), __e = __p_.end(); __i < __e; ++__i)
140 *__i /= __s;
141 vector<double> __t(__p_.size() - 1);
142 std::partial_sum(__p_.begin(), __p_.end() - 1, __t.begin());
143 swap(__p_, __t);
144 } else {
145 __p_.clear();
146 __p_.shrink_to_fit();
147 }
148 }
149}
150
151template <class _IntType>
152vector<double> discrete_distribution<_IntType>::param_type::probabilities() const {
153 size_t __n = __p_.size();
154 vector<double> __p(__n + 1);
155 std::adjacent_difference(__p_.begin(), __p_.end(), __p.begin());
156 if (__n > 0)
157 __p[__n] = 1 - __p_[__n - 1];
158 else
159 __p[0] = 1;
160 return __p;
161}
162
163template <class _IntType>
164template <class _URNG>
165_IntType discrete_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p) {
166 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
167 uniform_real_distribution<double> __gen;
168 return static_cast<_IntType>(std::upper_bound(__p.__p_.begin(), __p.__p_.end(), __gen(__g)) - __p.__p_.begin());
169}
170
171template <class _CharT, class _Traits, class _IT>
172_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
173operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x) {
174 __save_flags<_CharT, _Traits> __lx(__os);
175 typedef basic_ostream<_CharT, _Traits> _OStream;
176 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
177 _CharT __sp = __os.widen(' ');
178 __os.fill(__sp);
179 size_t __n = __x.__p_.__p_.size();
180 __os << __n;
181 for (size_t __i = 0; __i < __n; ++__i)
182 __os << __sp << __x.__p_.__p_[__i];
183 return __os;
184}
185
186template <class _CharT, class _Traits, class _IT>
187_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
188operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x) {
189 __save_flags<_CharT, _Traits> __lx(__is);
190 typedef basic_istream<_CharT, _Traits> _Istream;
191 __is.flags(_Istream::dec | _Istream::skipws);
192 size_t __n;
193 __is >> __n;
194 vector<double> __p(__n);
195 for (size_t __i = 0; __i < __n; ++__i)
196 __is >> __p[__i];
197 if (!__is.fail())
198 swap(__x.__p_.__p_, __p);
199 return __is;
200}
201
202_LIBCPP_END_NAMESPACE_STD
203
204_LIBCPP_POP_MACROS
205
206#endif // _LIBCPP___CXX03___RANDOM_DISCRETE_DISTRIBUTION_H
207

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source code of libcxx/include/__cxx03/__random/discrete_distribution.h