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LibUnicode: Perform code point case conversion lookups in constant time

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Similar to commit 0652cc4, we now generate 2-stage lookup tables for
case conversion information. Only about 1500 code points are actually
cased. This means that case information is rather highly compressible,
as the blocks we break the code points into will generally all have no
casing information at all.

In total, this change:

    * Does not change the size of libunicode.so (which is nice because,
      generally, the 2-stage lookup tables are expected to trade a bit
      of size for performance).

    * Reduces the runtime of the new benchmark test case added here from
      1.383s to 1.127s (about an 18.5% improvement).
This commit is contained in:
Timothy Flynn 2023-07-26 12:54:05 -04:00 • committed by Andreas Kling
parent 0ee133af90
commit 456211932f
3 changed files with 149 additions and 57 deletions
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32
Userland/Libraries/LibUnicode/UnicodeUtils.cpp
View file

@ -147,7 +147,7 @@ static bool is_followed_by_combining_dot_above(Utf8View const& string, size_t in
return false;
}
static SpecialCasing const* find_matching_special_case(u32 code_point, Utf8View const& string, Optional<StringView> locale, size_t index, size_t byte_length)
static Optional<SpecialCasing const&> find_matching_special_case(u32 code_point, Utf8View const& string, Optional<StringView> locale, size_t index, size_t byte_length)
{
auto requested_locale = Locale::None;
@ -158,11 +158,11 @@ static SpecialCasing const* find_matching_special_case(u32 code_point, Utf8View
auto special_casings = special_case_mapping(code_point);
for (auto const* special_casing : special_casings) {
if (special_casing->locale != Locale::None && special_casing->locale != requested_locale)
for (auto const& special_casing : special_casings) {
if (special_casing.locale != Locale::None && special_casing.locale != requested_locale)
continue;
switch (special_casing->condition) {
switch (special_casing.condition) {
case Condition::None:
return special_casing;
@ -193,20 +193,20 @@ static SpecialCasing const* find_matching_special_case(u32 code_point, Utf8View
}
}
return nullptr;
return {};
}
template<CaseFoldingStatus... StatusFilter>
static CaseFolding const* find_matching_case_folding(u32 code_point)
static Optional<CaseFolding const&> find_matching_case_folding(u32 code_point)
{
auto case_foldings = case_folding_mapping(code_point);
for (auto const* case_folding : case_foldings) {
if (((case_folding->status == StatusFilter) || ...))
for (auto const& case_folding : case_foldings) {
if (((case_folding.status == StatusFilter) || ...))
return case_folding;
}
return nullptr;
return {};
}
#endif
@ -222,8 +222,8 @@ ErrorOr<void> build_lowercase_string([[maybe_unused]] Utf8View code_points, [[ma
u32 code_point = *it;
byte_length = it.underlying_code_point_length_in_bytes();
auto const* special_casing = find_matching_special_case(code_point, code_points, locale, index, byte_length);
if (!special_casing) {
auto special_casing = find_matching_special_case(code_point, code_points, locale, index, byte_length);
if (!special_casing.has_value()) {
TRY(builder.try_append_code_point(to_unicode_lowercase(code_point)));
continue;
}
@ -249,8 +249,8 @@ ErrorOr<void> build_uppercase_string([[maybe_unused]] Utf8View code_points, [[ma
u32 code_point = *it;
byte_length = it.underlying_code_point_length_in_bytes();
auto const* special_casing = find_matching_special_case(code_point, code_points, locale, index, byte_length);
if (!special_casing) {
auto special_casing = find_matching_special_case(code_point, code_points, locale, index, byte_length);
if (!special_casing.has_value()) {
TRY(builder.try_append_code_point(to_unicode_uppercase(code_point)));
continue;
}
@ -287,8 +287,8 @@ ErrorOr<void> build_titlecase_string([[maybe_unused]] Utf8View code_points, [[ma
};
auto append_code_point_as_titlecase = [&](auto code_point, auto code_point_offset, auto code_point_length) -> ErrorOr<void> {
auto const* special_casing = find_matching_special_case(code_point, code_points, locale, code_point_offset, code_point_length);
if (!special_casing) {
auto special_casing = find_matching_special_case(code_point, code_points, locale, code_point_offset, code_point_length);
if (!special_casing.has_value()) {
TRY(builder.try_append_code_point(to_unicode_titlecase(code_point)));
return {};
}
@ -350,7 +350,7 @@ Utf32View casefold_code_point(u32 const& code_point)
// CaseFolding.txt in the Unicode Character Database.
using enum CaseFoldingStatus;
if (auto const* case_folding = find_matching_case_folding<Common, Full>(code_point))
if (auto case_folding = find_matching_case_folding<Common, Full>(code_point); case_folding.has_value())
return Utf32View { case_folding->mapping, case_folding->mapping_size };
#endif