test/std/containers/unord/unord.map/rehash.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <unordered_map>

// template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
//           class Alloc = allocator<pair<const Key, T>>>
// class unordered_map

// void rehash(size_type n);

#include <unordered_map>
#include <string>
#include <cassert>

#include "test_macros.h"
#include "min_allocator.h"

template <class C>
void rehash_postcondition(const C& c, size_t n)
{
    assert(c.bucket_count() >= c.size() / c.max_load_factor() && c.bucket_count() >= n);
}

template <class C>
void test(const C& c)
{
    assert(c.size() == 4);
    assert(c.at(1) == "one");
    assert(c.at(2) == "two");
    assert(c.at(3) == "three");
    assert(c.at(4) == "four");
}

int main(int, char**)
{
    {
        typedef std::unordered_map<int, std::string> C;
        typedef std::pair<int, std::string> P;
        P a[] =
        {
            P(1, "one"),
            P(2, "two"),
            P(3, "three"),
            P(4, "four"),
            P(1, "four"),
            P(2, "four"),
        };
        C c(a, a + sizeof(a)/sizeof(a[0]));
        test(c);
        assert(c.bucket_count() >= 5);
        c.rehash(3);
        rehash_postcondition(c, 3);
        LIBCPP_ASSERT(c.bucket_count() == 5);
        test(c);
        c.max_load_factor(2);
        c.rehash(3);
        rehash_postcondition(c, 3);
        LIBCPP_ASSERT(c.bucket_count() == 3);
        test(c);
        c.rehash(31);
        rehash_postcondition(c, 31);
        LIBCPP_ASSERT(c.bucket_count() == 31);
        test(c);
    }
#if TEST_STD_VER >= 11
    {
        typedef std::unordered_map<int, std::string, std::hash<int>, std::equal_to<int>,
                            min_allocator<std::pair<const int, std::string>>> C;
        typedef std::pair<int, std::string> P;
        P a[] =
        {
            P(1, "one"),
            P(2, "two"),
            P(3, "three"),
            P(4, "four"),
            P(1, "four"),
            P(2, "four"),
        };
        C c(a, a + sizeof(a)/sizeof(a[0]));
        test(c);
        assert(c.bucket_count() >= 5);
        c.rehash(3);
        rehash_postcondition(c, 3);
        LIBCPP_ASSERT(c.bucket_count() == 5);
        test(c);
        c.max_load_factor(2);
        c.rehash(3);
        rehash_postcondition(c, 3);
        LIBCPP_ASSERT(c.bucket_count() == 3);
        test(c);
        c.rehash(31);
        rehash_postcondition(c, 31);
        LIBCPP_ASSERT(c.bucket_count() == 31);
        test(c);
    }
#endif

  return 0;
}