Function isMonotonicNonDecreasingFiniteX

src/core/createRenderCoordinator.ts:672–711

(data: ReadonlyArray<DataPoint>, isTuple: boolean)

const monotonicXCache = new WeakMap<ReadonlyArray<DataPoint>, boolean>();

const isMonotonicNonDecreasingFiniteX = (data: ReadonlyArray<DataPoint>, isTuple: boolean): boolean => {
  const cached = monotonicXCache.get(data);
  if (cached !== undefined) return cached;

  let prevX = Number.NEGATIVE_INFINITY;

  if (isTuple) {
    const tupleData = data as ReadonlyArray<TuplePoint>;
    for (let i = 0; i < tupleData.length; i++) {
      const x = tupleData[i][0];
      if (!Number.isFinite(x)) {
        monotonicXCache.set(data, false);
        return false;
      }
      if (x < prevX) {
        monotonicXCache.set(data, false);
        return false;
      }
      prevX = x;
    }
    monotonicXCache.set(data, true);
    return true;
  }

  const objectData = data as ReadonlyArray<ObjectPoint>;
  for (let i = 0; i < objectData.length; i++) {
    const x = objectData[i].x;
    if (!Number.isFinite(x)) {
      monotonicXCache.set(data, false);
      return false;
    }
    if (x < prevX) {
      monotonicXCache.set(data, false);
      return false;
    }
    prevX = x;
  }
  monotonicXCache.set(data, true);
  return true;
};

const lowerBoundXTuple = (data: ReadonlyArray<TuplePoint>, xTarget: number): number => {
  let lo = 0;