Method calc_

src/core/context/values.js:556–617

* The used value calculation algorithm. * * @param {IContextPropUsed } used * @param {boolean} refreshParent * @return {T|undefined} The used value. * @private * @template T

(used, refreshParent)

   * @template T
   */
  calc_(used, refreshParent) {
    devAssert(this.isConnected_());

    const {depValues, prop} = used;
    const {compute, defaultValue, key} = prop;

    const inputValues = this.inputsByKey_?.get(key)?.values;

    // Calculate parent value.
    const recursive = calcRecursive(prop, inputValues);

    // Refresh parent if requested.
    if (refreshParent || recursive != Boolean(used.parentContextNode)) {
      const newParentContextNode = recursive
        ? findParent(this.contextNode_, hasInput, prop, /* includeSelf */ false)
        : null;
      this.updateParentContextNode_(used, newParentContextNode);
    }

    // If no parent node is found, use the default value.
    const parentValue = isDefined(used.parentValue)
      ? used.parentValue
      : recursive && !used.parentContextNode
        ? defaultValue
        : undefined;

    // Calculate the "used" value.
    let newValue = undefined;
    const ready =
      depValues.every(isDefined) && (!recursive || isDefined(parentValue));
    if (ready) {
      const {node} = this.contextNode_;
      if (inputValues && !compute) {
        newValue = inputValues[0];
      } else if (isRecursive(prop)) {
        if (inputValues || depValues.length > 0) {
          // The node specifies its own input values and they need to be
          // recomputed with parent and dep values.
          newValue = callRecursiveCompute(
            compute,
            node,
            inputValues || EMPTY_ARRAY,
            parentValue,
            depValues
          );
        } else if (isDefined(parentValue)) {
          // The node doesn't specify its own value, but parent is available.
          // Since parent is available, it means that the node is recursive.
          newValue = parentValue;
        }
      } else if (compute) {
        newValue = callCompute(
          compute,
          node,
          inputValues || EMPTY_ARRAY,
          depValues
        );
      }