THUAI6/CAPI/cpp/grpc/include/absl/random/internal/sequence_urbg.h

// Copyright 2017 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_SEQUENCE_URBG_H_
#define ABSL_RANDOM_INTERNAL_SEQUENCE_URBG_H_

#include <cstdint>
#include <cstring>
#include <limits>
#include <type_traits>
#include <vector>

#include "absl/base/config.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace random_internal
    {

        // `sequence_urbg` is a simple random number generator which meets the
        // requirements of [rand.req.urbg], and is solely for testing absl
        // distributions.
        class sequence_urbg
        {
        public:
            using result_type = uint64_t;

            static constexpr result_type(min)()
            {
                return (std::numeric_limits<result_type>::min)();
            }
            static constexpr result_type(max)()
            {
                return (std::numeric_limits<result_type>::max)();
            }

            sequence_urbg(std::initializer_list<result_type> data) :
                i_(0),
                data_(data)
            {
            }
            void reset()
            {
                i_ = 0;
            }

            result_type operator()()
            {
                return data_[i_++ % data_.size()];
            }

            size_t invocations() const
            {
                return i_;
            }

        private:
            size_t i_;
            std::vector<result_type> data_;
        };

    }  // namespace random_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_RANDOM_INTERNAL_SEQUENCE_URBG_H_