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LibJS: Use iterative text segmentation algorithms for Intl.Segmenter

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This uses the find-next and find-previous APIs instead of storing all
indices as a vector.
This commit is contained in:
Timothy Flynn 2023-02-15 10:03:14 -05:00 • committed by Linus Groh
parent 9a7b3c145f
commit 7cb956d17b
5 changed files with 43 additions and 38 deletions
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67
Userland/Libraries/LibJS/Runtime/Intl/Segmenter.cpp
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@ -1,10 +1,10 @@
/*
* Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BinarySearch.h>
#include <AK/Utf16View.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Intl/Segmenter.h>
@ -92,11 +92,39 @@ ThrowCompletionOr<NonnullGCPtr<Object>> create_segment_data_object(VM& vm, Segme
return result;
}
static Optional<size_t> find_previous_boundary_index(Utf16View const& string, size_t index, Segmenter::SegmenterGranularity granularity)
{
switch (granularity) {
case Segmenter::SegmenterGranularity::Grapheme:
return Unicode::previous_grapheme_segmentation_boundary(string, index);
case Segmenter::SegmenterGranularity::Word:
return Unicode::previous_word_segmentation_boundary(string, index);
case Segmenter::SegmenterGranularity::Sentence:
return Unicode::previous_sentence_segmentation_boundary(string, index);
}
VERIFY_NOT_REACHED();
}
static Optional<size_t> find_next_boundary_index(Utf16View const& string, size_t index, Segmenter::SegmenterGranularity granularity)
{
switch (granularity) {
case Segmenter::SegmenterGranularity::Grapheme:
return Unicode::next_grapheme_segmentation_boundary(string, index);
case Segmenter::SegmenterGranularity::Word:
return Unicode::next_word_segmentation_boundary(string, index);
case Segmenter::SegmenterGranularity::Sentence:
return Unicode::next_sentence_segmentation_boundary(string, index);
}
VERIFY_NOT_REACHED();
}
// 18.8.1 FindBoundary ( segmenter, string, startIndex, direction ), https://tc39.es/ecma402/#sec-findboundary
double find_boundary(Segmenter const& segmenter, Utf16View const& string, double start_index, Direction direction, Optional<Vector<size_t>>& boundaries_cache)
double find_boundary(Segmenter const& segmenter, Utf16View const& string, double start_index, Direction direction)
{
// 1. Let locale be segmenter.[[Locale]].
auto const& locale = segmenter.locale();
// FIXME: Support locale-sensitive boundaries
// 2. Let granularity be segmenter.[[SegmenterGranularity]].
auto granularity = segmenter.segmenter_granularity();
@ -104,24 +132,6 @@ double find_boundary(Segmenter const& segmenter, Utf16View const& string, double
// 3. Let len be the length of string.
auto length = string.length_in_code_units();
// Non-standard, populate boundaries cache
if (!boundaries_cache.has_value()) {
switch (granularity) {
case Segmenter::SegmenterGranularity::Grapheme:
boundaries_cache = Unicode::find_grapheme_segmentation_boundaries(string);
break;
case Segmenter::SegmenterGranularity::Word:
boundaries_cache = Unicode::find_word_segmentation_boundaries(string);
break;
case Segmenter::SegmenterGranularity::Sentence:
boundaries_cache = Unicode::find_sentence_segmentation_boundaries(string);
break;
default:
VERIFY_NOT_REACHED();
}
}
(void)locale; // TODO: Support locale-sensitive boundaries
// 4. If direction is before, then
if (direction == Direction::Before) {
// a. Assert: startIndex ≥ 0.
@ -130,12 +140,11 @@ double find_boundary(Segmenter const& segmenter, Utf16View const& string, double
VERIFY(start_index < length);
// c. Search string for the last segmentation boundary that is preceded by at most startIndex code units from the beginning, using locale locale and text element granularity granularity.
size_t boundary_index;
binary_search(*boundaries_cache, start_index, &boundary_index);
auto boundary_index = find_previous_boundary_index(string, static_cast<size_t>(start_index) + 1, granularity);
// d. If a boundary is found, return the count of code units in string preceding it.
if (boundary_index < boundaries_cache->size())
return boundaries_cache->at(boundary_index);
if (boundary_index.has_value())
return static_cast<double>(*boundary_index);
// e. Return 0.
return 0;
@ -149,13 +158,11 @@ double find_boundary(Segmenter const& segmenter, Utf16View const& string, double
return INFINITY;
// 7. Search string for the first segmentation boundary that follows the code unit at index startIndex, using locale locale and text element granularity granularity.
size_t boundary_index;
binary_search(*boundaries_cache, start_index, &boundary_index);
++boundary_index;
auto boundary_index = find_next_boundary_index(string, static_cast<size_t>(start_index), granularity);
// 8. If a boundary is found, return the count of code units in string preceding it.
if (boundary_index < boundaries_cache->size())
return boundaries_cache->at(boundary_index);
if (boundary_index.has_value())
return static_cast<double>(*boundary_index);
// 9. Return len.
return length;