// 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 #include #include #include "absl/meta/type_traits.h" namespace absl { inline namespace lts_2019_08_08 { template class uniform_int_distribution; template 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 absl::enable_if_t< absl::conjunction< std::is_integral, absl::disjunction, std::is_same>>::value, IntType> uniform_lower_bound(Tag, IntType a, IntType) { return a + 1; } template typename absl::enable_if_t< absl::conjunction< std::is_floating_point, absl::disjunction, std::is_same>>::value, FloatType> uniform_lower_bound(Tag, FloatType a, FloatType b) { return std::nextafter(a, b); } template typename absl::enable_if_t< absl::disjunction, std::is_same>::value, NumType> uniform_lower_bound(Tag, NumType a, NumType) { return a; } template typename absl::enable_if_t< absl::conjunction< std::is_integral, absl::disjunction, std::is_same>>::value, IntType> uniform_upper_bound(Tag, IntType, IntType b) { return b - 1; } template typename absl::enable_if_t< absl::conjunction< std::is_floating_point, absl::disjunction, std::is_same>>::value, FloatType> uniform_upper_bound(Tag, FloatType, FloatType b) { return b; } template typename absl::enable_if_t< absl::conjunction< std::is_integral, absl::disjunction, std::is_same>>::value, IntType> uniform_upper_bound(Tag, IntType, IntType b) { return b; } template typename absl::enable_if_t< absl::conjunction< std::is_floating_point, absl::disjunction, std::is_same>>::value, FloatType> uniform_upper_bound(Tag, FloatType, FloatType b) { return std::nextafter(b, (std::numeric_limits::max)()); } template using UniformDistribution = typename std::conditional::value, absl::uniform_int_distribution, absl::uniform_real_distribution>::type; template struct UniformDistributionWrapper : public UniformDistribution { explicit UniformDistributionWrapper(NumType lo, NumType hi) : UniformDistribution( uniform_lower_bound(TagType{}, lo, hi), uniform_upper_bound(TagType{}, lo, hi)) {} }; } // namespace random_internal } // inline namespace lts_2019_08_08 } // namespace absl #endif // ABSL_RANDOM_INTERNAL_UNIFORM_HELPER_H_