Function migrateScreenPools

src/ink/screen.ts:554–587

(
  screen: Screen,
  charPool: CharPool,
  hyperlinkPool: HyperlinkPool,
)

 * O(width * height) but only called occasionally (e.g., between conversation turns).
 */
export function migrateScreenPools(
  screen: Screen,
  charPool: CharPool,
  hyperlinkPool: HyperlinkPool,
): void {
  const oldCharPool = screen.charPool
  const oldHyperlinkPool = screen.hyperlinkPool
  if (oldCharPool === charPool && oldHyperlinkPool === hyperlinkPool) return

  const size = screen.width * screen.height
  const cells = screen.cells

  // Re-intern chars and hyperlinks in a single pass, stride by 2
  for (let ci = 0; ci < size << 1; ci += 2) {
    // Re-intern charId (word0)
    const oldCharId = cells[ci]!
    cells[ci] = charPool.intern(oldCharPool.get(oldCharId))

    // Re-intern hyperlinkId (packed in word1)
    const word1 = cells[ci + 1]!
    const oldHyperlinkId = (word1 >>> HYPERLINK_SHIFT) & HYPERLINK_MASK
    if (oldHyperlinkId !== 0) {
      const oldStr = oldHyperlinkPool.get(oldHyperlinkId)
      const newHyperlinkId = hyperlinkPool.intern(oldStr)
      // Repack word1 with new hyperlinkId, preserving styleId and width
      const styleId = word1 >>> STYLE_SHIFT
      const width = word1 & WIDTH_MASK
      cells[ci + 1] = packWord1(styleId, newHyperlinkId, width)
    }
  }

  screen.charPool = charPool
  screen.hyperlinkPool = hyperlinkPool
}

/**
 * Get a Cell view at the given position. Returns a new object each call -