1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// <unordered_map>
10
11// template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
12// class Alloc = allocator<pair<const Key, T>>>
13// class unordered_map
14
15// void rehash(size_type n);
16
17#include <unordered_map>
18#include <string>
19#include <cassert>
20
21#include "test_macros.h"
22#include "min_allocator.h"
23
24template <class C>
25void rehash_postcondition(const C& c, std::size_t n)
26{
27 assert(c.bucket_count() >= c.size() / c.max_load_factor() && c.bucket_count() >= n);
28}
29
30template <class C>
31void test(const C& c)
32{
33 assert(c.size() == 4);
34 assert(c.at(1) == "one");
35 assert(c.at(2) == "two");
36 assert(c.at(3) == "three");
37 assert(c.at(4) == "four");
38}
39
40int main(int, char**)
41{
42 {
43 typedef std::unordered_map<int, std::string> C;
44 typedef std::pair<int, std::string> P;
45 P a[] =
46 {
47 P(1, "one"),
48 P(2, "two"),
49 P(3, "three"),
50 P(4, "four"),
51 P(1, "four"),
52 P(2, "four"),
53 };
54 C c(a, a + sizeof(a)/sizeof(a[0]));
55 test(c);
56 assert(c.bucket_count() >= 5);
57 c.rehash(n: 3);
58 rehash_postcondition(c, n: 3);
59 LIBCPP_ASSERT(c.bucket_count() == 5);
60 test(c);
61 c.max_load_factor(z: 2);
62 c.rehash(n: 3);
63 rehash_postcondition(c, n: 3);
64 LIBCPP_ASSERT(c.bucket_count() == 3);
65 test(c);
66 c.rehash(n: 31);
67 rehash_postcondition(c, n: 31);
68 LIBCPP_ASSERT(c.bucket_count() == 31);
69 test(c);
70 }
71#if TEST_STD_VER >= 11
72 {
73 typedef std::unordered_map<int, std::string, std::hash<int>, std::equal_to<int>,
74 min_allocator<std::pair<const int, std::string>>> C;
75 typedef std::pair<int, std::string> P;
76 P a[] =
77 {
78 P(1, "one"),
79 P(2, "two"),
80 P(3, "three"),
81 P(4, "four"),
82 P(1, "four"),
83 P(2, "four"),
84 };
85 C c(a, a + sizeof(a)/sizeof(a[0]));
86 test(c);
87 assert(c.bucket_count() >= 5);
88 c.rehash(3);
89 rehash_postcondition(c, 3);
90 LIBCPP_ASSERT(c.bucket_count() == 5);
91 test(c);
92 c.max_load_factor(2);
93 c.rehash(3);
94 rehash_postcondition(c, 3);
95 LIBCPP_ASSERT(c.bucket_count() == 3);
96 test(c);
97 c.rehash(31);
98 rehash_postcondition(c, 31);
99 LIBCPP_ASSERT(c.bucket_count() == 31);
100 test(c);
101 }
102#endif
103
104 return 0;
105}
106

source code of libcxx/test/std/containers/unord/unord.map/rehash.pass.cpp