Function utf8ByteOffsetToStringIndex

packages/tui/src/editor-zed.ts:228–243

(text: string, byteOffset: number)

}

function utf8ByteOffsetToStringIndex(text: string, byteOffset: number) {
  if (byteOffset <= 0) return 0

  let bytes = 0
  for (let index = 0; index < text.length; ) {
    const codePoint = text.codePointAt(index)
    if (codePoint === undefined) return text.length

    const nextIndex = index + (codePoint > 0xffff ? 2 : 1)
    bytes += utf8.encode(text.slice(index, nextIndex)).length
    if (bytes >= byteOffset) return nextIndex
    index = nextIndex
  }

  return text.length
}

function offsetsToSelection(text: string, startOffset: number, endOffset: number) {
  const start = Math.max(0, Math.min(startOffset, text.length))