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The JS string_length intrinsic built [...str_out(s)], a whole expanded copy of the string, just to count its Chars. Replace it with a string_length helper that walks the string with the existing Char-width decoder (char_len) and a counter, so counting is O(n) time and O(1) space. Resolves bendlang#1612.
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Thanks for the clean patch. We're closing this one: the JS backend is Bend's reference runtime, and we don't want JS-only performance changes there (see #1644). The current |
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Resolves #1612.
The JS
string_lengthintrinsic was[...str_out($0)].length, which builds a whole expanded copy of the string just to count its Chars — O(n) temporary storage, including a second representation of every supplementary character.Replace it with a
string_length(s)helper that walks the string with the existing Char-width decoder (char_len) and a counter: O(n) time, O(1) space. This reuses the samechar_lenthe runtime already trusts (e.g.string_contains), so it counts a packed U32 Char (4 UTF-16 units) as one Char and an astral scalar (2 units) as one Char, exactly as before.Verified equivalence against the previous
[...str_out(s)].lengthfor ASCII, astral, and packed-U32-Char strings.