Method _cacheChildrenWithExternalReferences

src/material/icon/icon.ts:419–442

* Caches the children of an SVG element that have `url()` * references that we need to prefix with the current path.

(element: SVGElement)

   * references that we need to prefix with the current path.
   */
  private _cacheChildrenWithExternalReferences(element: SVGElement) {
    const elementsWithFuncIri = element.querySelectorAll(funcIriAttributeSelector);
    const elements = (this._elementsWithExternalReferences =
      this._elementsWithExternalReferences || new Map());

    for (let i = 0; i < elementsWithFuncIri.length; i++) {
      funcIriAttributes.forEach(attr => {
        const elementWithReference = elementsWithFuncIri[i];
        const value = elementWithReference.getAttribute(attr);
        const match = value ? value.match(funcIriPattern) : null;

        if (match) {
          let attributes = elements.get(elementWithReference);

          if (!attributes) {
            attributes = [];
            elements.set(elementWithReference, attributes);
          }

          attributes!.push({name: attr, value: match[1]});
        }
      });
    }
  }

  /** Sets a new SVG icon with a particular name. */
  private _updateSvgIcon(rawName: string | undefined) {