1 // Copyright 2018 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/str_replace.h"
16
17 #include <cstring>
18 #include <string>
19
20 #include "benchmark/benchmark.h"
21 #include "absl/base/internal/raw_logging.h"
22
23 namespace {
24
25 std::string* big_string;
26 std::string* after_replacing_the;
27 std::string* after_replacing_many;
28
29 struct Replacement {
30 const char* needle;
31 const char* replacement;
32 } replacements[] = {
33 {"the", "box"}, //
34 {"brown", "quick"}, //
35 {"jumped", "liquored"}, //
36 {"dozen", "brown"}, //
37 {"lazy", "pack"}, //
38 {"liquor", "shakes"}, //
39 };
40
41 // Here, we set up a string for use in global-replace benchmarks.
42 // We started with a million blanks, and then deterministically insert
43 // 10,000 copies each of two pangrams. The result is a string that is
44 // 40% blank space and 60% these words. 'the' occurs 18,247 times and
45 // all the substitutions together occur 49,004 times.
46 //
47 // We then create "after_replacing_the" to be a string that is a result of
48 // replacing "the" with "box" in big_string.
49 //
50 // And then we create "after_replacing_many" to be a string that is result
51 // of preferring several substitutions.
SetUpStrings()52 void SetUpStrings() {
53 if (big_string == nullptr) {
54 size_t r = 0;
55 big_string = new std::string(1000 * 1000, ' ');
56 for (std::string phrase : {"the quick brown fox jumped over the lazy dogs",
57 "pack my box with the five dozen liquor jugs"}) {
58 for (int i = 0; i < 10 * 1000; ++i) {
59 r = r * 237 + 41; // not very random.
60 memcpy(&(*big_string)[r % (big_string->size() - phrase.size())],
61 phrase.data(), phrase.size());
62 }
63 }
64 // big_string->resize(50);
65 // OK, we've set up the std::string, now let's set up expectations - first by
66 // just replacing "the" with "box"
67 after_replacing_the = new std::string(*big_string);
68 for (size_t pos = 0;
69 (pos = after_replacing_the->find("the", pos)) != std::string::npos;) {
70 memcpy(&(*after_replacing_the)[pos], "box", 3);
71 }
72 // And then with all the replacements.
73 after_replacing_many = new std::string(*big_string);
74 for (size_t pos = 0;;) {
75 size_t next_pos = static_cast<size_t>(-1);
76 const char* needle_string = nullptr;
77 const char* replacement_string = nullptr;
78 for (const auto& r : replacements) {
79 auto needlepos = after_replacing_many->find(r.needle, pos);
80 if (needlepos != std::string::npos && needlepos < next_pos) {
81 next_pos = needlepos;
82 needle_string = r.needle;
83 replacement_string = r.replacement;
84 }
85 }
86 if (next_pos > after_replacing_many->size()) break;
87 after_replacing_many->replace(next_pos, strlen(needle_string),
88 replacement_string);
89 next_pos += strlen(replacement_string);
90 pos = next_pos;
91 }
92 }
93 }
94
BM_StrReplaceAllOneReplacement(benchmark::State & state)95 void BM_StrReplaceAllOneReplacement(benchmark::State& state) {
96 SetUpStrings();
97 std::string src = *big_string;
98 for (auto _ : state) {
99 std::string dest = absl::StrReplaceAll(src, {{"the", "box"}});
100 ABSL_RAW_CHECK(dest == *after_replacing_the,
101 "not benchmarking intended behavior");
102 }
103 }
104 BENCHMARK(BM_StrReplaceAllOneReplacement);
105
BM_StrReplaceAll(benchmark::State & state)106 void BM_StrReplaceAll(benchmark::State& state) {
107 SetUpStrings();
108 std::string src = *big_string;
109 for (auto _ : state) {
110 std::string dest = absl::StrReplaceAll(src, {{"the", "box"},
111 {"brown", "quick"},
112 {"jumped", "liquored"},
113 {"dozen", "brown"},
114 {"lazy", "pack"},
115 {"liquor", "shakes"}});
116 ABSL_RAW_CHECK(dest == *after_replacing_many,
117 "not benchmarking intended behavior");
118 }
119 }
120 BENCHMARK(BM_StrReplaceAll);
121
122 } // namespace
123