131 lines
4.5 KiB
C++
131 lines
4.5 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/strings/match.h"
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#include <algorithm>
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#include <cstdint>
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#include "absl/base/internal/endian.h"
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#include "absl/numeric/bits.h"
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#include "absl/strings/ascii.h"
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#include "absl/strings/internal/memutil.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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bool EqualsIgnoreCase(absl::string_view piece1,
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absl::string_view piece2) noexcept {
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return (piece1.size() == piece2.size() &&
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0 == absl::strings_internal::memcasecmp(piece1.data(), piece2.data(),
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piece1.size()));
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// memcasecmp uses absl::ascii_tolower().
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}
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bool StrContainsIgnoreCase(absl::string_view haystack,
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absl::string_view needle) noexcept {
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while (haystack.size() >= needle.size()) {
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if (StartsWithIgnoreCase(haystack, needle)) return true;
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haystack.remove_prefix(1);
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}
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return false;
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}
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bool StrContainsIgnoreCase(absl::string_view haystack,
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char needle) noexcept {
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char upper_needle = absl::ascii_toupper(static_cast<unsigned char>(needle));
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char lower_needle = absl::ascii_tolower(static_cast<unsigned char>(needle));
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if (upper_needle == lower_needle) {
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return StrContains(haystack, needle);
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} else {
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const char both_cstr[3] = {lower_needle, upper_needle, '\0'};
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return haystack.find_first_of(both_cstr) != absl::string_view::npos;
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}
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}
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bool StartsWithIgnoreCase(absl::string_view text,
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absl::string_view prefix) noexcept {
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return (text.size() >= prefix.size()) &&
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EqualsIgnoreCase(text.substr(0, prefix.size()), prefix);
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}
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bool EndsWithIgnoreCase(absl::string_view text,
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absl::string_view suffix) noexcept {
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return (text.size() >= suffix.size()) &&
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EqualsIgnoreCase(text.substr(text.size() - suffix.size()), suffix);
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}
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absl::string_view FindLongestCommonPrefix(absl::string_view a,
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absl::string_view b) {
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const absl::string_view::size_type limit = std::min(a.size(), b.size());
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const char* const pa = a.data();
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const char* const pb = b.data();
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absl::string_view::size_type count = (unsigned) 0;
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if (ABSL_PREDICT_FALSE(limit < 8)) {
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while (ABSL_PREDICT_TRUE(count + 2 <= limit)) {
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uint16_t xor_bytes = absl::little_endian::Load16(pa + count) ^
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absl::little_endian::Load16(pb + count);
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if (ABSL_PREDICT_FALSE(xor_bytes != 0)) {
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if (ABSL_PREDICT_TRUE((xor_bytes & 0xff) == 0)) ++count;
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return absl::string_view(pa, count);
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}
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count += 2;
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}
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if (ABSL_PREDICT_TRUE(count != limit)) {
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if (ABSL_PREDICT_TRUE(pa[count] == pb[count])) ++count;
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}
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return absl::string_view(pa, count);
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}
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do {
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uint64_t xor_bytes = absl::little_endian::Load64(pa + count) ^
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absl::little_endian::Load64(pb + count);
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if (ABSL_PREDICT_FALSE(xor_bytes != 0)) {
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count += static_cast<uint64_t>(absl::countr_zero(xor_bytes) >> 3);
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return absl::string_view(pa, count);
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}
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count += 8;
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} while (ABSL_PREDICT_TRUE(count + 8 < limit));
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count = limit - 8;
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uint64_t xor_bytes = absl::little_endian::Load64(pa + count) ^
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absl::little_endian::Load64(pb + count);
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if (ABSL_PREDICT_TRUE(xor_bytes != 0)) {
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count += static_cast<uint64_t>(absl::countr_zero(xor_bytes) >> 3);
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return absl::string_view(pa, count);
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}
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return absl::string_view(pa, limit);
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}
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absl::string_view FindLongestCommonSuffix(absl::string_view a,
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absl::string_view b) {
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const absl::string_view::size_type limit = std::min(a.size(), b.size());
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if (limit == 0) return absl::string_view();
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const char* pa = a.data() + a.size() - 1;
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const char* pb = b.data() + b.size() - 1;
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absl::string_view::size_type count = (unsigned) 0;
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while (count < limit && *pa == *pb) {
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--pa;
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--pb;
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++count;
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}
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return absl::string_view(++pa, count);
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}
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ABSL_NAMESPACE_END
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} // namespace absl
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