str_replace_benchmark.cc
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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 
16 
17 #include <cstring>
18 #include <string>
19 
20 #include "benchmark/benchmark.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.
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 
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 
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
#define ABSL_RAW_CHECK(condition, message)
Definition: raw_logging.h:57
std::string StrReplaceAll(absl::string_view s, strings_internal::FixedMapping replacements)
Definition: str_replace.cc:70


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autogenerated on Mon Feb 28 2022 21:31:20