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// 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 <algorithm>
#include <cstdlib>
#include "absl/strings/ascii.h"
#include "absl/strings/internal/memutil.h"
#include "benchmark/benchmark.h"
// We fill the haystack with aaaaaaaaaaaaaaaaaa...aaaab.
// That gives us:
// - an easy search: 'b'
// - a medium search: 'ab'. That means every letter is a possible match.
// - a pathological search: 'aaaaaa.......aaaaab' (half as many a's as haytack)
namespace {
constexpr int kHaystackSize = 10000;
constexpr int64_t kHaystackSize64 = kHaystackSize;
const char* MakeHaystack() {
char* haystack = new char[kHaystackSize];
for (int i = 0; i < kHaystackSize - 1; ++i) haystack[i] = 'a';
haystack[kHaystackSize - 1] = 'b';
return haystack;
}
const char* const kHaystack = MakeHaystack();
bool case_eq(const char a, const char b) {
return absl::ascii_tolower(a) == absl::ascii_tolower(b);
}
void BM_Searchcase(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
kHaystack + kHaystackSize - 1,
kHaystack + kHaystackSize, case_eq));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_Searchcase);
void BM_SearchcaseMedium(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
kHaystack + kHaystackSize - 2,
kHaystack + kHaystackSize, case_eq));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_SearchcaseMedium);
void BM_SearchcasePathological(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
kHaystack + kHaystackSize / 2,
kHaystack + kHaystackSize, case_eq));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_SearchcasePathological);
char* memcasechr(const char* s, int c, size_t slen) {
c = absl::ascii_tolower(c);
for (; slen; ++s, --slen) {
if (absl::ascii_tolower(*s) == c) return const_cast<char*>(s);
}
return nullptr;
}
const char* memcasematch(const char* phaystack, size_t haylen,
const char* pneedle, size_t neelen) {
if (0 == neelen) {
return phaystack; // even if haylen is 0
}
if (haylen < neelen) return nullptr;
const char* match;
const char* hayend = phaystack + haylen - neelen + 1;
while ((match = static_cast<char*>(
memcasechr(phaystack, pneedle[0], hayend - phaystack)))) {
if (absl::strings_internal::memcasecmp(match, pneedle, neelen) == 0)
return match;
else
phaystack = match + 1;
}
return nullptr;
}
void BM_Memcasematch(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize, "b", 1));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_Memcasematch);
void BM_MemcasematchMedium(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize, "ab", 2));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_MemcasematchMedium);
void BM_MemcasematchPathological(benchmark::State& state) {
for (auto _ : state) {
benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize,
kHaystack + kHaystackSize / 2,
kHaystackSize - kHaystackSize / 2));
}
state.SetBytesProcessed(kHaystackSize64 * state.iterations());
}
BENCHMARK(BM_MemcasematchPathological);
} // namespace
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