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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___RANDOM_DISCRETE_DISTRIBUTION_H
10#define _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
11
12#include <__algorithm/upper_bound.h>
13#include <__config>
14#include <__random/is_valid.h>
15#include <__random/uniform_real_distribution.h>
16#include <__vector/vector.h>
17#include <initializer_list>
18#include <iosfwd>
19#include <numeric>
20
21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22# pragma GCC system_header
23#endif
24
25_LIBCPP_PUSH_MACROS
26#include <__undef_macros>
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30template <class _IntType = int>
31class 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 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#ifndef _LIBCPP_CXX03_LANG
50 _LIBCPP_HIDE_FROM_ABI param_type(initializer_list<double> __wl) : __p_(__wl.begin(), __wl.end()) { __init(); }
51#endif // _LIBCPP_CXX03_LANG
52 template <class _UnaryOperation>
53 _LIBCPP_HIDE_FROM_ABI param_type(size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw);
54
55 _LIBCPP_HIDE_FROM_ABI vector<double> probabilities() const;
56
57 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
58 return __x.__p_ == __y.__p_;
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 discrete_distribution;
66
67 template <class _CharT, class _Traits, class _IT>
68 friend basic_ostream<_CharT, _Traits>&
69 operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x);
70
71 template <class _CharT, class _Traits, class _IT>
72 friend basic_istream<_CharT, _Traits>&
73 operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x);
74 };
75
76private:
77 param_type __p_;
78
79public:
80 // constructor and reset functions
81 _LIBCPP_HIDE_FROM_ABI discrete_distribution() {}
82 template <class _InputIterator>
83 _LIBCPP_HIDE_FROM_ABI discrete_distribution(_InputIterator __f, _InputIterator __l) : __p_(__f, __l) {}
84#ifndef _LIBCPP_CXX03_LANG
85 _LIBCPP_HIDE_FROM_ABI discrete_distribution(initializer_list<double> __wl) : __p_(__wl) {}
86#endif // _LIBCPP_CXX03_LANG
87 template <class _UnaryOperation>
88 _LIBCPP_HIDE_FROM_ABI discrete_distribution(size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw)
89 : __p_(__nw, __xmin, __xmax, __fw) {}
90 _LIBCPP_HIDE_FROM_ABI explicit discrete_distribution(const param_type& __p) : __p_(__p) {}
91 _LIBCPP_HIDE_FROM_ABI void reset() {}
92
93 // generating functions
94 template <class _URNG>
95 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
96 return (*this)(__g, __p_);
97 }
98 template <class _URNG>
99 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
100
101 // property functions
102 _LIBCPP_HIDE_FROM_ABI vector<double> probabilities() const { return __p_.probabilities(); }
103
104 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
105 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
106
107 _LIBCPP_HIDE_FROM_ABI result_type min() const { return 0; }
108 _LIBCPP_HIDE_FROM_ABI result_type max() const { return __p_.__p_.size(); }
109
110 friend _LIBCPP_HIDE_FROM_ABI bool operator==(const discrete_distribution& __x, const discrete_distribution& __y) {
111 return __x.__p_ == __y.__p_;
112 }
113 friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const discrete_distribution& __x, const discrete_distribution& __y) {
114 return !(__x == __y);
115 }
116
117 template <class _CharT, class _Traits, class _IT>
118 friend basic_ostream<_CharT, _Traits>&
119 operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x);
120
121 template <class _CharT, class _Traits, class _IT>
122 friend basic_istream<_CharT, _Traits>&
123 operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x);
124};
125
126template <class _IntType>
127template <class _UnaryOperation>
128discrete_distribution<_IntType>::param_type::param_type(
129 size_t __nw, double __xmin, double __xmax, _UnaryOperation __fw) {
130 if (__nw > 1) {
131 __p_.reserve(__nw - 1);
132 double __d = (__xmax - __xmin) / __nw;
133 double __d2 = __d / 2;
134 for (size_t __k = 0; __k < __nw; ++__k)
135 __p_.push_back(__fw(__xmin + __k * __d + __d2));
136 __init();
137 }
138}
139
140template <class _IntType>
141void discrete_distribution<_IntType>::param_type::__init() {
142 if (!__p_.empty()) {
143 if (__p_.size() > 1) {
144 double __s = std::accumulate(__p_.begin(), __p_.end(), 0.0);
145 for (vector<double>::iterator __i = __p_.begin(), __e = __p_.end(); __i < __e; ++__i)
146 *__i /= __s;
147 vector<double> __t(__p_.size() - 1);
148 std::partial_sum(__p_.begin(), __p_.end() - 1, __t.begin());
149 swap(__p_, __t);
150 } else {
151 __p_.clear();
152 __p_.shrink_to_fit();
153 }
154 }
155}
156
157template <class _IntType>
158vector<double> discrete_distribution<_IntType>::param_type::probabilities() const {
159 size_t __n = __p_.size();
160 vector<double> __p(__n + 1);
161 std::adjacent_difference(__p_.begin(), __p_.end(), __p.begin());
162 if (__n > 0)
163 __p[__n] = 1 - __p_[__n - 1];
164 else
165 __p[0] = 1;
166 return __p;
167}
168
169template <class _IntType>
170template <class _URNG>
171_IntType discrete_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p) {
172 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
173 uniform_real_distribution<double> __gen;
174 return static_cast<_IntType>(std::upper_bound(__p.__p_.begin(), __p.__p_.end(), __gen(__g)) - __p.__p_.begin());
175}
176
177template <class _CharT, class _Traits, class _IT>
178_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
179operator<<(basic_ostream<_CharT, _Traits>& __os, const discrete_distribution<_IT>& __x) {
180 __save_flags<_CharT, _Traits> __lx(__os);
181 typedef basic_ostream<_CharT, _Traits> _OStream;
182 __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
183 _CharT __sp = __os.widen(' ');
184 __os.fill(__sp);
185 size_t __n = __x.__p_.__p_.size();
186 __os << __n;
187 for (size_t __i = 0; __i < __n; ++__i)
188 __os << __sp << __x.__p_.__p_[__i];
189 return __os;
190}
191
192template <class _CharT, class _Traits, class _IT>
193_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
194operator>>(basic_istream<_CharT, _Traits>& __is, discrete_distribution<_IT>& __x) {
195 __save_flags<_CharT, _Traits> __lx(__is);
196 typedef basic_istream<_CharT, _Traits> _Istream;
197 __is.flags(_Istream::dec | _Istream::skipws);
198 size_t __n;
199 __is >> __n;
200 vector<double> __p(__n);
201 for (size_t __i = 0; __i < __n; ++__i)
202 __is >> __p[__i];
203 if (!__is.fail())
204 swap(__x.__p_.__p_, __p);
205 return __is;
206}
207
208_LIBCPP_END_NAMESPACE_STD
209
210_LIBCPP_POP_MACROS
211
212#endif // _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H