Function parseCSI

src/ink/termio/parser.ts:87–240

Parse a raw CSI sequence (e.g., "\x1b[31m") into an action

(rawSequence: string)

/** Parse a raw CSI sequence (e.g., "\x1b[31m") into an action */
function parseCSI(rawSequence: string): Action | null {
  const inner = rawSequence.slice(2)
  if (inner.length === 0) return null

  const finalByte = inner.charCodeAt(inner.length - 1)
  const beforeFinal = inner.slice(0, -1)

  let privateMode = ''
  let paramStr = beforeFinal
  let intermediate = ''

  if (beforeFinal.length > 0 && '?>='.includes(beforeFinal[0]!)) {
    privateMode = beforeFinal[0]!
    paramStr = beforeFinal.slice(1)
  }

  const intermediateMatch = paramStr.match(/([^0-9;:]+)$/)
  if (intermediateMatch) {
    intermediate = intermediateMatch[1]!
    paramStr = paramStr.slice(0, -intermediate.length)
  }

  const params = parseCSIParams(paramStr)
  const p0 = params[0] ?? 1
  const p1 = params[1] ?? 1

  // SGR (Select Graphic Rendition)
  if (finalByte === CSI.SGR && privateMode === '') {
    return { type: 'sgr', params: paramStr }
  }

  // Cursor movement
  if (finalByte === CSI.CUU) {
    return {
      type: 'cursor',
      action: { type: 'move', direction: 'up', count: p0 },
    }
  }
  if (finalByte === CSI.CUD) {
    return {
      type: 'cursor',
      action: { type: 'move', direction: 'down', count: p0 },
    }
  }
  if (finalByte === CSI.CUF) {
    return {
      type: 'cursor',
      action: { type: 'move', direction: 'forward', count: p0 },
    }
  }
  if (finalByte === CSI.CUB) {
    return {
      type: 'cursor',
      action: { type: 'move', direction: 'back', count: p0 },
    }
  }
  if (finalByte === CSI.CNL) {
    return { type: 'cursor', action: { type: 'nextLine', count: p0 } }