Function stringWidth

ui-tui/packages/clawcodex-ink/src/ink/stringWidth.ts:290–333

const WIDTH_CACHE_LIMIT = 8192

export const stringWidth: (str: string) => number = str => {
  if (!str) {
    return 0
  }

  // ASCII fast-path detection — for short ASCII, skip the cache.
  if (str.length <= 64) {
    let asciiOnly = true

    for (let i = 0; i < str.length; i++) {
      const code = str.charCodeAt(i)

      if (code >= 127 || code === 0x1b) {
        asciiOnly = false

        break
      }
    }

    if (asciiOnly) {
      return rawStringWidth(str)
    }
  }

  const cached = widthCache.get(str)

  if (cached !== undefined) {
    // True LRU: refresh recency by re-inserting (Map iteration is insertion order).
    widthCache.delete(str)
    widthCache.set(str, cached)

    return cached
  }

  const w = rawStringWidth(str)

  if (widthCache.size >= WIDTH_CACHE_LIMIT) {
    widthCache.delete(widthCache.keys().next().value!)
  }

  widthCache.set(str, w)

  return w
}

export function widthCacheSize(): number {
  return widthCache.size