LibWeb: Avoid O(n²) behavior in NamedNodeMap::supported_property_names#8901
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LibWeb: Avoid O(n²) behavior in NamedNodeMap::supported_property_names#8901officialasishkumar wants to merge 1 commit intoLadybirdBrowser:masterfrom
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The function deduplicates attribute names in order. The previous implementation used Vector::contains_slow() inside the loop, making the overall complexity O(n²) in the number of attributes. Replace the in-place linear search with a HashTable<FlyString> that tracks which names have already been appended. Each set() call is O(1) amortized, reducing the total deduplication step from O(n²) to O(n). The pre-allocated hash table is initialised to the same capacity as the attribute list so reallocation is avoided in the common case where every attribute name is unique. Fixes LadybirdBrowser#7980.
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NamedNodeMap::supported_property_namesdeduplicates attribute names whilepreserving order. The previous loop called
Vector::contains_slow()onnamesat every iteration, which is O(n) in the size ofnames. With nattributes the deduplication step is therefore O(n²).
Replace the linear scan with a
HashTable<FlyString>that tracks whichnames have already been appended.
HashTable::set()returnsHashSetResult::InsertedNewEntryfor first-seen names andHashSetResult::KeptExistingEntryfor duplicates, so a single O(1)amortized call replaces the previous O(n) scan.
The hash table is pre-allocated to the same capacity as the attribute
list to avoid reallocation in the typical case where all attribute names
are unique.
Fixes #7980.