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LibJS: Implement the Intl.Segmenter FindBoundary AO
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@ -4,7 +4,10 @@
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/BinarySearch.h>
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#include <AK/Utf16View.h>
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#include <LibJS/Runtime/Intl/Segmenter.h>
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#include <LibUnicode/CharacterTypes.h>
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namespace JS::Intl {
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@ -40,4 +43,73 @@ StringView Segmenter::segmenter_granularity_string() const
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}
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}
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// 18.8.1 FindBoundary ( segmenter, string, startIndex, direction ), https://tc39.es/ecma402/#sec-findboundary
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double find_boundary(Segmenter const& segmenter, Utf16View const& string, double start_index, Direction direction, Optional<Vector<size_t>>& boundaries_cache)
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{
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// 1. Let locale be segmenter.[[Locale]].
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auto const& locale = segmenter.locale();
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// 2. Let granularity be segmenter.[[SegmenterGranularity]].
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auto granularity = segmenter.segmenter_granularity();
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// 3. Let len be the length of string.
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auto length = string.length_in_code_units();
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// Non-standard, populate boundaries cache
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if (!boundaries_cache.has_value()) {
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switch (granularity) {
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case Segmenter::SegmenterGranularity::Grapheme:
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boundaries_cache = Unicode::find_grapheme_segmentation_boundaries(string);
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break;
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case Segmenter::SegmenterGranularity::Word:
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boundaries_cache = Unicode::find_word_segmentation_boundaries(string);
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break;
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case Segmenter::SegmenterGranularity::Sentence:
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boundaries_cache = Unicode::find_sentence_segmentation_boundaries(string);
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break;
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default:
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VERIFY_NOT_REACHED();
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}
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}
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(void)locale; // TODO: Support locale-sensitive boundaries
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// 4. If direction is before, then
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if (direction == Direction::Before) {
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// a. Assert: startIndex ≥ 0.
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VERIFY(start_index >= 0);
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// b. Assert: startIndex < len.
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VERIFY(start_index < length);
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// 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.
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size_t boundary_index;
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binary_search(*boundaries_cache, start_index, &boundary_index);
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// d. If a boundary is found, return the count of code units in string preceding it.
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if (boundary_index < boundaries_cache->size())
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return boundaries_cache->at(boundary_index);
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// e. Return 0.
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return 0;
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}
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// 5. Assert: direction is after.
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VERIFY(direction == Direction::After);
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// 6. If len is 0 or startIndex ≥ len, return +∞.
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if (length == 0 || start_index >= length)
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return INFINITY;
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// 7. Search string for the first segmentation boundary that follows the code unit at index startIndex, using locale locale and text element granularity granularity.
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size_t boundary_index;
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binary_search(*boundaries_cache, start_index, &boundary_index);
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++boundary_index;
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// 8. If a boundary is found, return the count of code units in string preceding it.
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if (boundary_index < boundaries_cache->size())
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return boundaries_cache->at(boundary_index);
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// 9. Return len.
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return length;
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}
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}
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@ -36,4 +36,10 @@ private:
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SegmenterGranularity m_segmenter_granularity { SegmenterGranularity::Grapheme }; // [[SegmenterGranularity]]
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};
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enum class Direction {
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Before,
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After,
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};
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double find_boundary(Segmenter const&, Utf16View const&, double start_index, Direction, Optional<Vector<size_t>>& boundaries_cache);
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}
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@ -25,11 +25,15 @@ public:
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Utf16View segments_string() const { return m_segments_string.view(); }
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Optional<Vector<size_t>>& boundaries_cache() const { return m_boundaries_cache; }
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private:
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virtual void visit_edges(Cell::Visitor&) override;
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Segmenter& m_segments_segmenter; // [[SegmentsSegmenter]]
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Utf16String m_segments_string; // [[SegmentsString]]
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mutable Optional<Vector<size_t>> m_boundaries_cache;
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};
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}
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