THUAI6/CAPI/cpp/grpc/include/absl/container/btree_test.h

// 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_CONTAINER_BTREE_TEST_H_
#define ABSL_CONTAINER_BTREE_TEST_H_

#include <algorithm>
#include <cassert>
#include <random>
#include <string>
#include <utility>
#include <vector>

#include "absl/container/btree_map.h"
#include "absl/container/btree_set.h"
#include "absl/container/flat_hash_set.h"
#include "absl/strings/cord.h"
#include "absl/time/time.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace container_internal
    {

        // Like remove_const but propagates the removal through std::pair.
        template<typename T>
        struct remove_pair_const
        {
            using type = typename std::remove_const<T>::type;
        };
        template<typename T, typename U>
        struct remove_pair_const<std::pair<T, U>>
        {
            using type = std::pair<typename remove_pair_const<T>::type, typename remove_pair_const<U>::type>;
        };

        // Utility class to provide an accessor for a key given a value. The default
        // behavior is to treat the value as a pair and return the first element.
        template<typename K, typename V>
        struct KeyOfValue
        {
            struct type
            {
                const K& operator()(const V& p) const
                {
                    return p.first;
                }
            };
        };

        // Partial specialization of KeyOfValue class for when the key and value are
        // the same type such as in set<> and btree_set<>.
        template<typename K>
        struct KeyOfValue<K, K>
        {
            struct type
            {
                const K& operator()(const K& k) const
                {
                    return k;
                }
            };
        };

        inline char* GenerateDigits(char buf[16], unsigned val, unsigned maxval)
        {
            assert(val <= maxval);
            constexpr unsigned kBase = 64;  // avoid integer division.
            unsigned p = 15;
            buf[p--] = 0;
            while (maxval > 0)
            {
                buf[p--] = ' ' + (val % kBase);
                val /= kBase;
                maxval /= kBase;
            }
            return buf + p + 1;
        }

        template<typename K>
        struct Generator
        {
            int maxval;
            explicit Generator(int m) :
                maxval(m)
            {
            }
            K operator()(int i) const
            {
                assert(i <= maxval);
                return K(i);
            }
        };

        template<>
        struct Generator<absl::Time>
        {
            int maxval;
            explicit Generator(int m) :
                maxval(m)
            {
            }
            absl::Time operator()(int i) const
            {
                return absl::FromUnixMillis(i);
            }
        };

        template<>
        struct Generator<std::string>
        {
            int maxval;
            explicit Generator(int m) :
                maxval(m)
            {
            }
            std::string operator()(int i) const
            {
                char buf[16];
                return GenerateDigits(buf, i, maxval);
            }
        };

        template<>
        struct Generator<Cord>
        {
            int maxval;
            explicit Generator(int m) :
                maxval(m)
            {
            }
            Cord operator()(int i) const
            {
                char buf[16];
                return Cord(GenerateDigits(buf, i, maxval));
            }
        };

        template<typename T, typename U>
        struct Generator<std::pair<T, U>>
        {
            Generator<typename remove_pair_const<T>::type> tgen;
            Generator<typename remove_pair_const<U>::type> ugen;

            explicit Generator(int m) :
                tgen(m),
                ugen(m)
            {
            }
            std::pair<T, U> operator()(int i) const
            {
                return std::make_pair(tgen(i), ugen(i));
            }
        };

        // Generate n values for our tests and benchmarks. Value range is [0, maxval].
        inline std::vector<int> GenerateNumbersWithSeed(int n, int maxval, int seed)
        {
            // NOTE: Some tests rely on generated numbers not changing between test runs.
            // We use std::minstd_rand0 because it is well-defined, but don't use
            // std::uniform_int_distribution because platforms use different algorithms.
            std::minstd_rand0 rng(seed);

            std::vector<int> values;
            absl::flat_hash_set<int> unique_values;
            if (values.size() < n)
            {
                for (int i = values.size(); i < n; i++)
                {
                    int value;
                    do
                    {
                        value = static_cast<int>(rng()) % (maxval + 1);
                    } while (!unique_values.insert(value).second);

                    values.push_back(value);
                }
            }
            return values;
        }

        // Generates n values in the range [0, maxval].
        template<typename V>
        std::vector<V> GenerateValuesWithSeed(int n, int maxval, int seed)
        {
            const std::vector<int> nums = GenerateNumbersWithSeed(n, maxval, seed);
            Generator<V> gen(maxval);
            std::vector<V> vec;

            vec.reserve(n);
            for (int i = 0; i < n; i++)
            {
                vec.push_back(gen(nums[i]));
            }

            return vec;
        }

    }  // namespace container_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_CONTAINER_BTREE_TEST_H_