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ccdbb5941 Export of internal Abseil changes 01f5f81f9 Export of internal Abseil changes 2c92bdc7c Export of internal Abseil changes e7ebf9803 Export of internal Abseil changes 2eba343b5 Export of internal Abseil changes a8b03d90e Export of internal Abseil changes 1d31b5c36 Export of internal Abseil changes da3a87690 Export of internal Abseil changes 8faf20461 Exclude empty directories (#697) 2069dc796 Export of internal Abseil changes 4832bf6bf Added a BUILD file in root to expose license. (#695) af8f994af Export of internal Abseil changes 33caf1097 Export of internal Abseil changes cf1a02e2d Export of internal Abseil changes git-subtree-dir: third_party/abseil_cpp git-subtree-split: ccdbb5941f992fabda7eae3ce72f55efc17c826a
92 lines
3.4 KiB
C++
92 lines
3.4 KiB
C++
//
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// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#ifndef ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_
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#define ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_
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#include <utility>
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#include "absl/base/config.h"
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#include "absl/base/internal/fast_type_id.h"
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#include "absl/utility/utility.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace random_internal {
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// DistributionCaller provides an opportunity to overload the general
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// mechanism for calling a distribution, allowing for mock-RNG classes
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// to intercept such calls.
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template <typename URBG>
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struct DistributionCaller {
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// SFINAE to detect whether the URBG type includes a member matching
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// bool InvokeMock(base_internal::FastTypeIdType, void*, void*).
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//
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// These live inside BitGenRef so that they have friend access
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// to MockingBitGen. (see similar methods in DistributionCaller).
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template <template <class...> class Trait, class AlwaysVoid, class... Args>
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struct detector : std::false_type {};
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template <template <class...> class Trait, class... Args>
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struct detector<Trait, absl::void_t<Trait<Args...>>, Args...>
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: std::true_type {};
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template <class T>
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using invoke_mock_t = decltype(std::declval<T*>()->InvokeMock(
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std::declval<::absl::base_internal::FastTypeIdType>(),
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std::declval<void*>(), std::declval<void*>()));
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using HasInvokeMock = typename detector<invoke_mock_t, void, URBG>::type;
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// Default implementation of distribution caller.
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template <typename DistrT, typename... Args>
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static typename DistrT::result_type Impl(std::false_type, URBG* urbg,
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Args&&... args) {
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DistrT dist(std::forward<Args>(args)...);
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return dist(*urbg);
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}
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// Mock implementation of distribution caller.
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// The underlying KeyT must match the KeyT constructed by MockOverloadSet.
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template <typename DistrT, typename... Args>
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static typename DistrT::result_type Impl(std::true_type, URBG* urbg,
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Args&&... args) {
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using ResultT = typename DistrT::result_type;
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using ArgTupleT = std::tuple<absl::decay_t<Args>...>;
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using KeyT = ResultT(DistrT, ArgTupleT);
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ArgTupleT arg_tuple(std::forward<Args>(args)...);
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ResultT result;
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if (!urbg->InvokeMock(::absl::base_internal::FastTypeId<KeyT>(), &arg_tuple,
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&result)) {
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auto dist = absl::make_from_tuple<DistrT>(arg_tuple);
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result = dist(*urbg);
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}
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return result;
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}
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// Default implementation of distribution caller.
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template <typename DistrT, typename... Args>
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static typename DistrT::result_type Call(URBG* urbg, Args&&... args) {
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return Impl<DistrT, Args...>(HasInvokeMock{}, urbg,
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std::forward<Args>(args)...);
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}
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};
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} // namespace random_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_
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