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