Abseil Common Libraries (C++) (grcp 依赖)
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85 lines
2.6 KiB
85 lines
2.6 KiB
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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_MOCKING_BIT_GEN_BASE_H_ |
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#define ABSL_RANDOM_INTERNAL_MOCKING_BIT_GEN_BASE_H_ |
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#include <string> |
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#include <typeinfo> |
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#include "absl/random/random.h" |
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#include "absl/strings/str_cat.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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class MockingBitGenBase { |
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template <typename> |
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friend struct DistributionCaller; |
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using generator_type = absl::BitGen; |
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public: |
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// URBG interface |
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using result_type = generator_type::result_type; |
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static constexpr result_type(min)() { return (generator_type::min)(); } |
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static constexpr result_type(max)() { return (generator_type::max)(); } |
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result_type operator()() { return gen_(); } |
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virtual ~MockingBitGenBase() = default; |
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protected: |
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// CallImpl is the type-erased virtual dispatch. |
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// The type of dist is always distribution<T>, |
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// The type of result is always distribution<T>::result_type. |
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virtual bool CallImpl(const std::type_info& distr_type, void* dist_args, |
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void* result) = 0; |
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template <typename DistrT, typename ArgTupleT> |
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static const std::type_info& GetTypeId() { |
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return typeid(std::pair<absl::decay_t<DistrT>, absl::decay_t<ArgTupleT>>); |
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} |
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// Call the generating distribution function. |
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// Invoked by DistributionCaller<>::Call<DistT>. |
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// DistT is the distribution type. |
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template <typename DistrT, typename... Args> |
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typename DistrT::result_type Call(Args&&... args) { |
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using distr_result_type = typename DistrT::result_type; |
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using ArgTupleT = std::tuple<absl::decay_t<Args>...>; |
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ArgTupleT arg_tuple(std::forward<Args>(args)...); |
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auto dist = absl::make_from_tuple<DistrT>(arg_tuple); |
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distr_result_type result{}; |
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bool found_match = |
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CallImpl(GetTypeId<DistrT, ArgTupleT>(), &arg_tuple, &result); |
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if (!found_match) { |
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result = dist(gen_); |
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} |
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return result; |
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} |
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private: |
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generator_type gen_; |
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}; // namespace random_internal |
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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_MOCKING_BIT_GEN_BASE_H_
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