Ink 渲染器

commitUpdate(
  node: DOMElement,
  _type: ElementNames,
  oldProps: Props,
  newProps: Props,
): void {
  const props = diff(oldProps, newProps)
  const style = diff(oldProps['style'] as Styles, newProps['style'] as Styles)

  if (props) {
    for (const [key, value] of Object.entries(props)) {
      // Event handlers stored separately — never mark dirty
      // (handler identity changes don't affect pixels)
      if (EVENT_HANDLER_PROPS.has(key)) {
        setEventHandler(node, key, value); continue
      }
      setAttribute(node, key, value)   // marks dirty
    }
  }
  // Apply only the changed style keys to the Yoga node
  if (style) applyStyles(node.yogaNode, style)
}

export type LayoutNode = {
  // Tree manipulation
  insertChild(child: LayoutNode, index: number): void
  removeChild(child: LayoutNode): void

  // Trigger flexbox computation
  calculateLayout(width?: number, height?: number): void
  setMeasureFunc(fn: LayoutMeasureFunc): void

  // Read results (only valid after calculateLayout)
  getComputedLeft(): number
  getComputedTop(): number
  getComputedWidth(): number
  getComputedHeight(): number

  // Style setters (each corresponds to a CSS Flexbox property)
  setFlexDirection(dir: LayoutFlexDirection): void
  setPositionType(type: LayoutPositionType): void
  setOverflow(overflow: LayoutOverflow): void

  // WASM memory management
  free(): void
  freeRecursive(): void
}

// Calculate yoga index BEFORE modifying childNodes.
// DOM index ≠ yoga index: ink-progress, ink-link, ink-virtual-text
// have no yogaNodes, so their slots don't exist in the yoga tree.
let yogaIndex = 0
if (newChildNode.yogaNode && node.yogaNode) {
  for (let i = 0; i < index; i++) {
    if (node.childNodes[i]?.yogaNode) {
      yogaIndex++
    }
  }
}

intern(styles: AnsiCode[]): number {
  const key = styles.length === 0
    ? ''
    : styles.map(s => s.code).join('\0')
  let id = this.ids.get(key)
  if (id === undefined) {
    const rawId = this.styles.length
    this.styles.push(styles)
    // Bit 0 = "visible on space" (background, inverse, underline, etc.)
    // Even IDs = fg-only styles.  Odd IDs = styles that paint space cells.
    // diffEach uses a single bitmask check to skip invisible spaces.
    id = (rawId << 1) |
      (styles.length > 0 && hasVisibleSpaceEffect(styles) ? 1 : 0)
    this.ids.set(key, id)
  }
  return id
}

// const enum is inlined at compile time — no runtime object, no property access
export const enum CellWidth {
  Narrow    = 0,  // standard single-column character
  Wide      = 1,  // CJK/emoji — actual char, 2 visual cols
  SpacerTail= 2,  // second col of a wide char — skip in renderer
  SpacerHead= 3,  // wide char at line end that continues on next row
}