Function diffLinesUnified2

packages/utils/src/diff/diffLines.ts:122–175

(
  aLinesDisplay: Array<string>,
  bLinesDisplay: Array<string>,
  aLinesCompare: Array<string>,
  bLinesCompare: Array<string>,
  options?: DiffOptions,
)

// Compare the pair of comparison arrays line-by-line.
// Format the corresponding lines in the pair of displayable arrays.
export function diffLinesUnified2(
  aLinesDisplay: Array<string>,
  bLinesDisplay: Array<string>,
  aLinesCompare: Array<string>,
  bLinesCompare: Array<string>,
  options?: DiffOptions,
): string {
  if (isEmptyString(aLinesDisplay) && isEmptyString(aLinesCompare)) {
    aLinesDisplay = []
    aLinesCompare = []
  }
  if (isEmptyString(bLinesDisplay) && isEmptyString(bLinesCompare)) {
    bLinesDisplay = []
    bLinesCompare = []
  }

  if (
    aLinesDisplay.length !== aLinesCompare.length
    || bLinesDisplay.length !== bLinesCompare.length
  ) {
    // Fall back to diff of display lines.
    return diffLinesUnified(aLinesDisplay, bLinesDisplay, options)
  }

  const [diffs, truncated] = diffLinesRaw(
    aLinesCompare,
    bLinesCompare,
    options,
  )

  // Replace comparison lines with displayable lines.
  let aIndex = 0
  let bIndex = 0
  diffs.forEach((diff: Diff) => {
    switch (diff[0]) {
      case DIFF_DELETE:
        diff[1] = aLinesDisplay[aIndex]
        aIndex += 1
        break

      case DIFF_INSERT:
        diff[1] = bLinesDisplay[bIndex]
        bIndex += 1
        break

      default:
        diff[1] = bLinesDisplay[bIndex]
        aIndex += 1
        bIndex += 1
    }
  })

  return printDiffLines(diffs, truncated, normalizeDiffOptions(options))
}

// Compare two arrays of strings line-by-line.
export function diffLinesRaw(