1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
|
// Copyright 2019 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef ABSL_RANDOM_INTERNAL_UNIFORM_HELPER_H_
#define ABSL_RANDOM_INTERNAL_UNIFORM_HELPER_H_
#include <cmath>
#include <limits>
#include <type_traits>
#include "absl/meta/type_traits.h"
namespace absl {
template <typename IntType>
class uniform_int_distribution;
template <typename RealType>
class uniform_real_distribution;
// Interval tag types which specify whether the interval is open or closed
// on either boundary.
namespace random_internal {
struct IntervalClosedClosedT {};
struct IntervalClosedOpenT {};
struct IntervalOpenClosedT {};
struct IntervalOpenOpenT {};
} // namespace random_internal
namespace random_internal {
// The functions
// uniform_lower_bound(tag, a, b)
// and
// uniform_upper_bound(tag, a, b)
// are used as implementation-details for absl::Uniform().
//
// Conceptually,
// [a, b] == [uniform_lower_bound(IntervalClosedClosed, a, b),
// uniform_upper_bound(IntervalClosedClosed, a, b)]
// (a, b) == [uniform_lower_bound(IntervalOpenOpen, a, b),
// uniform_upper_bound(IntervalOpenOpen, a, b)]
// [a, b) == [uniform_lower_bound(IntervalClosedOpen, a, b),
// uniform_upper_bound(IntervalClosedOpen, a, b)]
// (a, b] == [uniform_lower_bound(IntervalOpenClosed, a, b),
// uniform_upper_bound(IntervalOpenClosed, a, b)]
//
template <typename IntType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_integral<IntType>,
absl::disjunction<std::is_same<Tag, IntervalOpenClosedT>,
std::is_same<Tag, IntervalOpenOpenT>>>::value,
IntType>
uniform_lower_bound(Tag, IntType a, IntType) {
return a + 1;
}
template <typename FloatType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_floating_point<FloatType>,
absl::disjunction<std::is_same<Tag, IntervalOpenClosedT>,
std::is_same<Tag, IntervalOpenOpenT>>>::value,
FloatType>
uniform_lower_bound(Tag, FloatType a, FloatType b) {
return std::nextafter(a, b);
}
template <typename NumType, typename Tag>
typename absl::enable_if_t<
absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
std::is_same<Tag, IntervalClosedOpenT>>::value,
NumType>
uniform_lower_bound(Tag, NumType a, NumType) {
return a;
}
template <typename IntType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_integral<IntType>,
absl::disjunction<std::is_same<Tag, IntervalClosedOpenT>,
std::is_same<Tag, IntervalOpenOpenT>>>::value,
IntType>
uniform_upper_bound(Tag, IntType, IntType b) {
return b - 1;
}
template <typename FloatType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_floating_point<FloatType>,
absl::disjunction<std::is_same<Tag, IntervalClosedOpenT>,
std::is_same<Tag, IntervalOpenOpenT>>>::value,
FloatType>
uniform_upper_bound(Tag, FloatType, FloatType b) {
return b;
}
template <typename IntType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_integral<IntType>,
absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
std::is_same<Tag, IntervalOpenClosedT>>>::value,
IntType>
uniform_upper_bound(Tag, IntType, IntType b) {
return b;
}
template <typename FloatType, typename Tag>
typename absl::enable_if_t<
absl::conjunction<
std::is_floating_point<FloatType>,
absl::disjunction<std::is_same<Tag, IntervalClosedClosedT>,
std::is_same<Tag, IntervalOpenClosedT>>>::value,
FloatType>
uniform_upper_bound(Tag, FloatType, FloatType b) {
return std::nextafter(b, (std::numeric_limits<FloatType>::max)());
}
template <typename NumType>
using UniformDistribution =
typename std::conditional<std::is_integral<NumType>::value,
absl::uniform_int_distribution<NumType>,
absl::uniform_real_distribution<NumType>>::type;
template <typename TagType, typename NumType>
struct UniformDistributionWrapper : public UniformDistribution<NumType> {
explicit UniformDistributionWrapper(NumType lo, NumType hi)
: UniformDistribution<NumType>(
uniform_lower_bound<NumType>(TagType{}, lo, hi),
uniform_upper_bound<NumType>(TagType{}, lo, hi)) {}
};
} // namespace random_internal
} // namespace absl
#endif // ABSL_RANDOM_INTERNAL_UNIFORM_HELPER_H_
|
