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AK: Implement case-insensitive StringUtils::matches() without allocs

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Previously this would create new to_lowercase()'d strings from the
needle and the haystack. This generated a huge amount of malloc
traffic in some programs.
This commit is contained in:
Andreas Kling 2021-04-17 00:33:38 +02:00
parent f7139d9422
commit 1f684c8123
Notes: sideshowbarker 2024-07-18 19:32:44 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/1f684c81234
1 changed files with 8 additions and 10 deletions
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18
AK/StringUtils.cpp
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@ -54,22 +54,20 @@ bool matches(const StringView& str, const StringView& mask, CaseSensitivity case
return true;
}
if (case_sensitivity == CaseSensitivity::CaseInsensitive) {
const String str_lower = String(str).to_lowercase();
const String mask_lower = String(mask).to_lowercase();
return matches(str_lower, mask_lower, CaseSensitivity::CaseSensitive, match_spans);
}
const char* string_ptr = str.characters_without_null_termination();
const char* string_start = str.characters_without_null_termination();
const char* string_end = string_ptr + str.length();
const char* mask_ptr = mask.characters_without_null_termination();
const char* mask_end = mask_ptr + mask.length();
auto matches_one = [](char ch, char p) {
auto matches_one = [](char ch, char p, CaseSensitivity case_sensitivity) {
if (p == '?')
return true;
return p == ch && ch != 0;
if (ch == 0)
return false;
if (case_sensitivity == CaseSensitivity::CaseSensitive)
return p == ch;
return tolower(p) == tolower(ch);
};
while (string_ptr < string_end && mask_ptr < mask_end) {
auto string_start_ptr = string_ptr;
@ -79,7 +77,7 @@ bool matches(const StringView& str, const StringView& mask, CaseSensitivity case
record_span(string_ptr - string_start, string_end - string_ptr);
return true;
}
while (string_ptr < string_end && !matches(string_ptr, mask_ptr + 1))
while (string_ptr < string_end && !matches(string_ptr, mask_ptr + 1, case_sensitivity))
++string_ptr;
record_span(string_start_ptr - string_start, string_ptr - string_start_ptr);
--string_ptr;
@ -88,7 +86,7 @@ bool matches(const StringView& str, const StringView& mask, CaseSensitivity case
record_span(string_ptr - string_start, 1);
break;
default:
if (!matches_one(*string_ptr, *mask_ptr))
if (!matches_one(*string_ptr, *mask_ptr, case_sensitivity))
return false;
break;
}