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Code Issues Projects Releases Packages Wiki Activity Actions 10

AK+LibRegex: Add Utf16View::code_point_at and use it in RegexStringView

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The current method of iterating through the string to access a code
point hurts performance quite badly for very large strings. The test262
test "RegExp/property-escapes/generated/Any.js" previously took 3 hours
to complete; this one change brings it down to under 10 seconds.
This commit is contained in:
Timothy Flynn 2021-08-01 18:56:52 -04:00 • committed by Andreas Kling
parent bed51d856a
commit 510bbcd8e0
Notes: sideshowbarker 2024-07-18 07:30:48 +09:00
3 changed files with 21 additions and 0 deletions
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17
AK/Utf16View.cpp
View file

@ -111,6 +111,23 @@ u16 Utf16View::code_unit_at(size_t index) const
return m_code_units[index];
}
u32 Utf16View::code_point_at(size_t index) const
{
VERIFY(index < length_in_code_units());
u32 code_point = code_unit_at(index);
if (!is_high_surrogate(code_point) && !is_low_surrogate(code_point))
return code_point;
if (is_low_surrogate(code_point) || (index + 1 == length_in_code_units()))
return code_point;
auto second = code_unit_at(index + 1);
if (!is_low_surrogate(second))
return code_point;
return decode_surrogate_pair(code_point, second);
}
size_t Utf16View::code_point_offset_of(size_t code_unit_offset) const
{
size_t code_point_offset = 0;

1
AK/Utf16View.h
View file

@ -87,6 +87,7 @@ public:
u16 const* data() const { return m_code_units.data(); }
u16 code_unit_at(size_t index) const;
u32 code_point_at(size_t index) const;
size_t code_point_offset_of(size_t code_unit_offset) const;
size_t code_unit_offset_of(size_t code_point_offset) const;

3
Userland/Libraries/LibRegex/RegexMatch.h
View file

@ -240,7 +240,10 @@ public:
return ch;
},
[&](Utf32View& view) -> u32 { return view[index]; },
[&](Utf16View& view) -> u32 { return view.code_point_at(index); },
[&](auto& view) -> u32 {
// FIXME: Iterating to the code point is inefficient, particularly for very large
// strings. Implement something like code_point_at to Utf8View.
size_t i = index;
for (auto it = view.begin(); it != view.end(); ++it, --i) {
if (i == 0)