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Diffstat (limited to 'third_party/abseil_cpp/absl/random/internal/distribution_caller.h')
-rw-r--r-- | third_party/abseil_cpp/absl/random/internal/distribution_caller.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/random/internal/distribution_caller.h b/third_party/abseil_cpp/absl/random/internal/distribution_caller.h new file mode 100644 index 000000000000..fc81b787ebe2 --- /dev/null +++ b/third_party/abseil_cpp/absl/random/internal/distribution_caller.h @@ -0,0 +1,92 @@ +// +// Copyright 2018 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_DISTRIBUTION_CALLER_H_ +#define ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_ + +#include <utility> + +#include "absl/base/config.h" +#include "absl/base/internal/fast_type_id.h" +#include "absl/utility/utility.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace random_internal { + +// DistributionCaller provides an opportunity to overload the general +// mechanism for calling a distribution, allowing for mock-RNG classes +// to intercept such calls. +template <typename URBG> +struct DistributionCaller { + // SFINAE to detect whether the URBG type includes a member matching + // bool InvokeMock(base_internal::FastTypeIdType, void*, void*). + // + // These live inside BitGenRef so that they have friend access + // to MockingBitGen. (see similar methods in DistributionCaller). + template <template <class...> class Trait, class AlwaysVoid, class... Args> + struct detector : std::false_type {}; + template <template <class...> class Trait, class... Args> + struct detector<Trait, absl::void_t<Trait<Args...>>, Args...> + : std::true_type {}; + + template <class T> + using invoke_mock_t = decltype(std::declval<T*>()->InvokeMock( + std::declval<::absl::base_internal::FastTypeIdType>(), + std::declval<void*>(), std::declval<void*>())); + + using HasInvokeMock = typename detector<invoke_mock_t, void, URBG>::type; + + // Default implementation of distribution caller. + template <typename DistrT, typename... Args> + static typename DistrT::result_type Impl(std::false_type, URBG* urbg, + Args&&... args) { + DistrT dist(std::forward<Args>(args)...); + return dist(*urbg); + } + + // Mock implementation of distribution caller. + // The underlying KeyT must match the KeyT constructed by MockOverloadSet. + template <typename DistrT, typename... Args> + static typename DistrT::result_type Impl(std::true_type, URBG* urbg, + Args&&... args) { + using ResultT = typename DistrT::result_type; + using ArgTupleT = std::tuple<absl::decay_t<Args>...>; + using KeyT = ResultT(DistrT, ArgTupleT); + + ArgTupleT arg_tuple(std::forward<Args>(args)...); + ResultT result; + if (!urbg->InvokeMock(::absl::base_internal::FastTypeId<KeyT>(), &arg_tuple, + &result)) { + auto dist = absl::make_from_tuple<DistrT>(arg_tuple); + result = dist(*urbg); + } + return result; + } + + // Default implementation of distribution caller. + template <typename DistrT, typename... Args> + static typename DistrT::result_type Call(URBG* urbg, Args&&... args) { + return Impl<DistrT, Args...>(HasInvokeMock{}, urbg, + std::forward<Args>(args)...); + } +}; + +} // namespace random_internal +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_ |