File size: 734 Bytes
064bfd6 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | import { stringWidth } from './stringWidth.js'
// During streaming, text grows but completed lines are immutable.
// Caching stringWidth per-line avoids re-measuring hundreds of
// unchanged lines on every token (~50x reduction in stringWidth calls).
const cache = new Map<string, number>()
const MAX_CACHE_SIZE = 4096
export function lineWidth(line: string): number {
const cached = cache.get(line)
if (cached !== undefined) return cached
const width = stringWidth(line)
// Evict when cache grows too large (e.g. after many different responses).
// Simple full-clear is fine — the cache repopulates in one frame.
if (cache.size >= MAX_CACHE_SIZE) {
cache.clear()
}
cache.set(line, width)
return width
}
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