tor-browser

The Tor Browser
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match.cc (4727B)

      1 // Copyright 2017 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/match.h"
     16 
     17 #include <algorithm>
     18 #include <cstdint>
     19 
     20 #include "absl/base/config.h"
     21 #include "absl/base/internal/endian.h"
     22 #include "absl/base/optimization.h"
     23 #include "absl/numeric/bits.h"
     24 #include "absl/strings/ascii.h"
     25 #include "absl/strings/internal/memutil.h"
     26 #include "absl/strings/string_view.h"
     27 
     28 namespace absl {
     29 ABSL_NAMESPACE_BEGIN
     30 
     31 bool EqualsIgnoreCase(absl::string_view piece1,
     32                      absl::string_view piece2) noexcept {
     33  return (piece1.size() == piece2.size() &&
     34          0 == absl::strings_internal::memcasecmp(piece1.data(), piece2.data(),
     35                                                  piece1.size()));
     36  // memcasecmp uses absl::ascii_tolower().
     37 }
     38 
     39 bool StrContainsIgnoreCase(absl::string_view haystack,
     40                           absl::string_view needle) noexcept {
     41  while (haystack.size() >= needle.size()) {
     42    if (StartsWithIgnoreCase(haystack, needle)) return true;
     43    haystack.remove_prefix(1);
     44  }
     45  return false;
     46 }
     47 
     48 bool StrContainsIgnoreCase(absl::string_view haystack,
     49                           char needle) noexcept {
     50  char upper_needle = absl::ascii_toupper(static_cast<unsigned char>(needle));
     51  char lower_needle = absl::ascii_tolower(static_cast<unsigned char>(needle));
     52  if (upper_needle == lower_needle) {
     53    return StrContains(haystack, needle);
     54  } else {
     55    const char both_cstr[3] = {lower_needle, upper_needle, '\0'};
     56    return haystack.find_first_of(both_cstr) != absl::string_view::npos;
     57  }
     58 }
     59 
     60 bool StartsWithIgnoreCase(absl::string_view text,
     61                          absl::string_view prefix) noexcept {
     62  return (text.size() >= prefix.size()) &&
     63         EqualsIgnoreCase(text.substr(0, prefix.size()), prefix);
     64 }
     65 
     66 bool EndsWithIgnoreCase(absl::string_view text,
     67                        absl::string_view suffix) noexcept {
     68  return (text.size() >= suffix.size()) &&
     69         EqualsIgnoreCase(text.substr(text.size() - suffix.size()), suffix);
     70 }
     71 
     72 absl::string_view FindLongestCommonPrefix(absl::string_view a,
     73                                          absl::string_view b) {
     74  const absl::string_view::size_type limit = std::min(a.size(), b.size());
     75  const char* const pa = a.data();
     76  const char* const pb = b.data();
     77  absl::string_view::size_type count = (unsigned) 0;
     78 
     79  if (ABSL_PREDICT_FALSE(limit < 8)) {
     80    while (ABSL_PREDICT_TRUE(count + 2 <= limit)) {
     81      uint16_t xor_bytes = absl::little_endian::Load16(pa + count) ^
     82                           absl::little_endian::Load16(pb + count);
     83      if (ABSL_PREDICT_FALSE(xor_bytes != 0)) {
     84        if (ABSL_PREDICT_TRUE((xor_bytes & 0xff) == 0)) ++count;
     85        return absl::string_view(pa, count);
     86      }
     87      count += 2;
     88    }
     89    if (ABSL_PREDICT_TRUE(count != limit)) {
     90      if (ABSL_PREDICT_TRUE(pa[count] == pb[count])) ++count;
     91    }
     92    return absl::string_view(pa, count);
     93  }
     94 
     95  do {
     96    uint64_t xor_bytes = absl::little_endian::Load64(pa + count) ^
     97                         absl::little_endian::Load64(pb + count);
     98    if (ABSL_PREDICT_FALSE(xor_bytes != 0)) {
     99      count += static_cast<uint64_t>(absl::countr_zero(xor_bytes) >> 3);
    100      return absl::string_view(pa, count);
    101    }
    102    count += 8;
    103  } while (ABSL_PREDICT_TRUE(count + 8 < limit));
    104 
    105  count = limit - 8;
    106  uint64_t xor_bytes = absl::little_endian::Load64(pa + count) ^
    107                       absl::little_endian::Load64(pb + count);
    108  if (ABSL_PREDICT_TRUE(xor_bytes != 0)) {
    109    count += static_cast<uint64_t>(absl::countr_zero(xor_bytes) >> 3);
    110    return absl::string_view(pa, count);
    111  }
    112  return absl::string_view(pa, limit);
    113 }
    114 
    115 absl::string_view FindLongestCommonSuffix(absl::string_view a,
    116                                          absl::string_view b) {
    117  const absl::string_view::size_type limit = std::min(a.size(), b.size());
    118  if (limit == 0) return absl::string_view();
    119 
    120  const char* pa = a.data() + a.size() - 1;
    121  const char* pb = b.data() + b.size() - 1;
    122  absl::string_view::size_type count = (unsigned) 0;
    123  while (count < limit && *pa == *pb) {
    124    --pa;
    125    --pb;
    126    ++count;
    127  }
    128 
    129  return absl::string_view(++pa, count);
    130 }
    131 
    132 ABSL_NAMESPACE_END
    133 }  // namespace absl