// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/strings/str_replace.h"
#include <cstring>
#include <string>
#include "benchmark/benchmark.h"
#include "absl/base/internal/raw_logging.h"
namespace {
std::string* big_string;
std::string* after_replacing_the;
std::string* after_replacing_many;
struct Replacement {
const char* needle;
const char* replacement;
} replacements[] = {
{"the", "box"}, //
{"brown", "quick"}, //
{"jumped", "liquored"}, //
{"dozen", "brown"}, //
{"lazy", "pack"}, //
{"liquor", "shakes"}, //
};
// Here, we set up a string for use in global-replace benchmarks.
// We started with a million blanks, and then deterministically insert
// 10,000 copies each of two pangrams. The result is a string that is
// 40% blank space and 60% these words. 'the' occurs 18,247 times and
// all the substitutions together occur 49,004 times.
//
// We then create "after_replacing_the" to be a string that is a result of
// replacing "the" with "box" in big_string.
//
// And then we create "after_replacing_many" to be a string that is result
// of preferring several substitutions.
void SetUpStrings() {
if (big_string == nullptr) {
size_t r = 0;
big_string = new std::string(1000 * 1000, ' ');
for (std::string phrase : {"the quick brown fox jumped over the lazy dogs",
"pack my box with the five dozen liquor jugs"}) {
for (int i = 0; i < 10 * 1000; ++i) {
r = r * 237 + 41; // not very random.
memcpy(&(*big_string)[r % (big_string->size() - phrase.size())],
phrase.data(), phrase.size());
}
}
// big_string->resize(50);
// OK, we've set up the string, now let's set up expectations - first by
// just replacing "the" with "box"
after_replacing_the = new std::string(*big_string);
for (size_t pos = 0;
(pos = after_replacing_the->find("the", pos)) != std::string::npos;) {
memcpy(&(*after_replacing_the)[pos], "box", 3);
}
// And then with all the replacements.
after_replacing_many = new std::string(*big_string);
for (size_t pos = 0;;) {
size_t next_pos = static_cast<size_t>(-1);
const char* needle_string = nullptr;
const char* replacement_string = nullptr;
for (const auto& r : replacements) {
auto needlepos = after_replacing_many->find(r.needle, pos);
if (needlepos != std::string::npos && needlepos < next_pos) {
next_pos = needlepos;
needle_string = r.needle;
replacement_string = r.replacement;
}
}
if (next_pos > after_replacing_many->size()) break;
after_replacing_many->replace(next_pos, strlen(needle_string),
replacement_string);
next_pos += strlen(replacement_string);
pos = next_pos;
}
}
}
void BM_StrReplaceAllOneReplacement(benchmark::State& state) {
SetUpStrings();
std::string src = *big_string;
for (auto _ : state) {
std::string dest = absl::StrReplaceAll(src, {{"the", "box"}});
ABSL_RAW_CHECK(dest == *after_replacing_the,
"not benchmarking intended behavior");
}
}
BENCHMARK(BM_StrReplaceAllOneReplacement);
void BM_StrReplaceAll(benchmark::State& state) {
SetUpStrings();
std::string src = *big_string;
for (auto _ : state) {
std::string dest = absl::StrReplaceAll(src, {{"the", "box"},
{"brown", "quick"},
{"jumped", "liquored"},
{"dozen", "brown"},
{"lazy", "pack"},
{"liquor", "shakes"}});
ABSL_RAW_CHECK(dest == *after_replacing_many,
"not benchmarking intended behavior");
}
}
BENCHMARK(BM_StrReplaceAll);
} // namespace
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