1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/strings/internal/resize_uninitialized.h"
16
17 #include "gtest/gtest.h"
18
19 namespace {
20
21 int resize_call_count = 0;
22
23 // A mock string class whose only purpose is to track how many times its
24 // resize() method has been called.
25 struct resizable_string {
size__anon743226790111::resizable_string26 size_t size() const { return 0; }
capacity__anon743226790111::resizable_string27 size_t capacity() const { return 0; }
operator []__anon743226790111::resizable_string28 char& operator[](size_t) {
29 static char c = '\0';
30 return c;
31 }
resize__anon743226790111::resizable_string32 void resize(size_t) { resize_call_count += 1; }
reserve__anon743226790111::resizable_string33 void reserve(size_t) {}
34 };
35
36 int resize_default_init_call_count = 0;
37
38 // A mock string class whose only purpose is to track how many times its
39 // resize() and __resize_default_init() methods have been called.
40 struct resize_default_init_string {
size__anon743226790111::resize_default_init_string41 size_t size() const { return 0; }
capacity__anon743226790111::resize_default_init_string42 size_t capacity() const { return 0; }
operator []__anon743226790111::resize_default_init_string43 char& operator[](size_t) {
44 static char c = '\0';
45 return c;
46 }
resize__anon743226790111::resize_default_init_string47 void resize(size_t) { resize_call_count += 1; }
__resize_default_init__anon743226790111::resize_default_init_string48 void __resize_default_init(size_t) { resize_default_init_call_count += 1; }
reserve__anon743226790111::resize_default_init_string49 void reserve(size_t) {}
50 };
51
TEST(ResizeUninit,WithAndWithout)52 TEST(ResizeUninit, WithAndWithout) {
53 resize_call_count = 0;
54 resize_default_init_call_count = 0;
55 {
56 resizable_string rs;
57
58 EXPECT_EQ(resize_call_count, 0);
59 EXPECT_EQ(resize_default_init_call_count, 0);
60 EXPECT_FALSE(
61 absl::strings_internal::STLStringSupportsNontrashingResize(&rs));
62 EXPECT_EQ(resize_call_count, 0);
63 EXPECT_EQ(resize_default_init_call_count, 0);
64 absl::strings_internal::STLStringResizeUninitialized(&rs, 237);
65 EXPECT_EQ(resize_call_count, 1);
66 EXPECT_EQ(resize_default_init_call_count, 0);
67 absl::strings_internal::STLStringResizeUninitializedAmortized(&rs, 1000);
68 EXPECT_EQ(resize_call_count, 2);
69 EXPECT_EQ(resize_default_init_call_count, 0);
70 }
71
72 resize_call_count = 0;
73 resize_default_init_call_count = 0;
74 {
75 resize_default_init_string rus;
76
77 EXPECT_EQ(resize_call_count, 0);
78 EXPECT_EQ(resize_default_init_call_count, 0);
79 EXPECT_TRUE(
80 absl::strings_internal::STLStringSupportsNontrashingResize(&rus));
81 EXPECT_EQ(resize_call_count, 0);
82 EXPECT_EQ(resize_default_init_call_count, 0);
83 absl::strings_internal::STLStringResizeUninitialized(&rus, 237);
84 EXPECT_EQ(resize_call_count, 0);
85 EXPECT_EQ(resize_default_init_call_count, 1);
86 absl::strings_internal::STLStringResizeUninitializedAmortized(&rus, 1000);
87 EXPECT_EQ(resize_call_count, 0);
88 EXPECT_EQ(resize_default_init_call_count, 2);
89 }
90 }
91
TEST(ResizeUninit,Amortized)92 TEST(ResizeUninit, Amortized) {
93 std::string str;
94 size_t prev_cap = str.capacity();
95 int cap_increase_count = 0;
96 for (int i = 0; i < 1000; ++i) {
97 absl::strings_internal::STLStringResizeUninitializedAmortized(&str, i);
98 size_t new_cap = str.capacity();
99 if (new_cap > prev_cap) ++cap_increase_count;
100 prev_cap = new_cap;
101 }
102 EXPECT_LT(cap_increase_count, 50);
103 }
104
105 } // namespace
106