tvl-depot/absl/random/internal/uniform_helper.h
Abseil Team 36d37ab992 Export of internal Abseil changes.
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1224e58a45e4d016b18f5a6cf5762ba33027017a by CJ Johnson <johnsoncj@google.com>:

Unifies the growth factor of InlinedVector's mutating members to max(2 * capacity, req_capacity). In doing so, LegacyNextCapacityFrom(...) is removed thus removing a loop from several callsites.

PiperOrigin-RevId: 259920301

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945fc0bf27b67ea77d39144dcb6a483dc879ceda by Laramie Leavitt <lar@google.com>:

Cleanup header guards which do not reflect the correct style.

PiperOrigin-RevId: 259881520

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8c7d0532ba9a9aabfd57f67552572b2b1bedda97 by Derek Mauro <dmauro@google.com>:

Move log_severity sources to the new log_severity target.

PiperOrigin-RevId: 259837015
GitOrigin-RevId: 1224e58a45e4d016b18f5a6cf5762ba33027017a
Change-Id: Id19506c3b8db71a0d4391ee917bfef3e802d550d
2019-07-25 18:02:32 -04:00

150 lines
5 KiB
C++

// 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_