Function markDuplicates

packages/core/src/render3/styling/style_binding_list.ts:387–424

* Marks `TStyleValue`s as duplicates if another style binding in the list has the same * `TStyleValue`. * * NOTE: this function is intended to be called twice once with `isPrevDir` set to `true` and once * with it set to `false` to search both the previous as well as next items in the list. *

(
  tData: TData,
  tStylingKey: TStylingKeyPrimitive,
  index: number,
  isPrevDir: boolean,
)

 *        - `false` for next (higher priority).
 */
function markDuplicates(
  tData: TData,
  tStylingKey: TStylingKeyPrimitive,
  index: number,
  isPrevDir: boolean,
) {
  const tStylingAtIndex = tData[index + 1] as TStylingRange;
  const isMap = tStylingKey === null;
  let cursor = isPrevDir
    ? getTStylingRangePrev(tStylingAtIndex)
    : getTStylingRangeNext(tStylingAtIndex);
  let foundDuplicate = false;
  // We keep iterating as long as we have a cursor
  // AND either:
  // - we found what we are looking for, OR
  // - we are a map in which case we have to continue searching even after we find what we were
  //   looking for since we are a wild card and everything needs to be flipped to duplicate.
  while (cursor !== 0 && (foundDuplicate === false || isMap)) {
    ngDevMode && assertIndexInRange(tData, cursor);
    const tStylingValueAtCursor = tData[cursor] as TStylingKey;
    const tStyleRangeAtCursor = tData[cursor + 1] as TStylingRange;
    if (isStylingMatch(tStylingValueAtCursor, tStylingKey)) {
      foundDuplicate = true;
      tData[cursor + 1] = isPrevDir
        ? setTStylingRangeNextDuplicate(tStyleRangeAtCursor)
        : setTStylingRangePrevDuplicate(tStyleRangeAtCursor);
    }
    cursor = isPrevDir
      ? getTStylingRangePrev(tStyleRangeAtCursor)
      : getTStylingRangeNext(tStyleRangeAtCursor);
  }
  if (foundDuplicate) {
    // if we found a duplicate, than mark ourselves.
    tData[index + 1] = isPrevDir
      ? setTStylingRangePrevDuplicate(tStylingAtIndex)
      : setTStylingRangeNextDuplicate(tStylingAtIndex);
  }
}

/**
 * Determines if two `TStylingKey`s are a match.