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LibJS: Implement the Intl.Segmenter FindBoundary AO

This commit is contained in:
Idan Horowitz 2022-01-30 20:39:26 +02:00
parent b1d19b5917
commit cea6c81c77
3 changed files with 82 additions and 0 deletions

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@ -4,7 +4,10 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BinarySearch.h>
#include <AK/Utf16View.h>
#include <LibJS/Runtime/Intl/Segmenter.h>
#include <LibUnicode/CharacterTypes.h>
namespace JS::Intl {
@ -40,4 +43,73 @@ StringView Segmenter::segmenter_granularity_string() const
}
}
// 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)
{
// 1. Let locale be segmenter.[[Locale]].
auto const& locale = segmenter.locale();
// 2. Let granularity be segmenter.[[SegmenterGranularity]].
auto granularity = segmenter.segmenter_granularity();
// 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.
VERIFY(start_index >= 0);
// b. Assert: startIndex < len.
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);
// 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);
// e. Return 0.
return 0;
}
// 5. Assert: direction is after.
VERIFY(direction == Direction::After);
// 6. If len is 0 or startIndex ≥ len, return +∞.
if (length == 0 || start_index >= length)
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;
// 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);
// 9. Return len.
return length;
}
}