Function checkStylingMap

packages/core/src/render3/instructions/styling.ts:279–338

(
  keyValueArraySet: (keyValueArray: KeyValueArray<any>, key: string, value: any) => void,
  stringParser: (styleKeyValueArray: KeyValueArray<any>, text: string) => void,
  value: any | NO_CHANGE,
  isClassBased: boolean,
)

 * @param isClassBased `true` if `class` change (`false` if `style`)
 */
export function checkStylingMap(
  keyValueArraySet: (keyValueArray: KeyValueArray<any>, key: string, value: any) => void,
  stringParser: (styleKeyValueArray: KeyValueArray<any>, text: string) => void,
  value: any | NO_CHANGE,
  isClassBased: boolean,
): void {
  const tView = getTView();
  const bindingIndex = incrementBindingIndex(2);
  if (tView.firstUpdatePass) {
    stylingFirstUpdatePass(tView, null, bindingIndex, isClassBased);
  }
  const lView = getLView();
  if (value !== NO_CHANGE && bindingUpdated(lView, bindingIndex, value)) {
    // `getSelectedIndex()` should be here (rather than in instruction) so that it is guarded by the
    // if so as not to read unnecessarily.
    const tNode = tView.data[getSelectedIndex()] as TNode;
    if (hasStylingInputShadow(tNode, isClassBased) && !isInHostBindings(tView, bindingIndex)) {
      if (ngDevMode) {
        // verify that if we are shadowing then `TData` is appropriately marked so that we skip
        // processing this binding in styling resolution.
        const tStylingKey = tView.data[bindingIndex];
        assertEqual(
          Array.isArray(tStylingKey) ? tStylingKey[1] : tStylingKey,
          false,
          "Styling linked list shadow input should be marked as 'false'",
        );
      }
      // VE does not concatenate the static portion like we are doing here.
      // Instead VE just ignores the static completely if dynamic binding is present.
      // Because of locality we have already set the static portion because we don't know if there
      // is a dynamic portion until later. If we would ignore the static portion it would look like
      // the binding has removed it. This would confuse `[ngStyle]`/`[ngClass]` to do the wrong
      // thing as it would think that the static portion was removed. For this reason we
      // concatenate it so that `[ngStyle]`/`[ngClass]`  can continue to work on changed.
      let staticPrefix = isClassBased ? tNode.classesWithoutHost : tNode.stylesWithoutHost;
      ngDevMode &&
        isClassBased === false &&
        staticPrefix !== null &&
        assertEqual(staticPrefix.endsWith(';'), true, "Expecting static portion to end with ';'");
      if (staticPrefix !== null) {
        // We want to make sure that falsy values of `value` become empty strings.
        value = concatStringsWithSpace(staticPrefix, value ? value : '');
      }
      // Given `<div [style] my-dir>` such that `my-dir` has `@Input('style')`.
      // This takes over the `[style]` binding. (Same for `[class]`)
      setDirectiveInputsWhichShadowsStyling(tView, tNode, lView, value, isClassBased);
    } else {
      updateStylingMap(
        tView,
        tNode,
        lView,
        lView[RENDERER],
        lView[bindingIndex + 1],
        (lView[bindingIndex + 1] = toStylingKeyValueArray(keyValueArraySet, stringParser, value)),
        isClassBased,
        bindingIndex,
      );
    }