| // 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_ |