Function injectAttributeImpl

packages/core/src/render3/di.ts:343–384

(tNode: TNode, attrNameToInject: string)

 * @publicApi
 */
export function injectAttributeImpl(tNode: TNode, attrNameToInject: string): string | null {
  ngDevMode && assertTNodeType(tNode, TNodeType.AnyContainer | TNodeType.AnyRNode);
  ngDevMode && assertDefined(tNode, 'expecting tNode');
  if (attrNameToInject === 'class') {
    return tNode.classes;
  }
  if (attrNameToInject === 'style') {
    return tNode.styles;
  }

  const attrs = tNode.attrs;
  if (attrs) {
    const attrsLength = attrs.length;
    let i = 0;
    while (i < attrsLength) {
      const value = attrs[i];

      // If we hit a `Bindings` or `Template` marker then we are done.
      if (isNameOnlyAttributeMarker(value)) break;

      // Skip namespaced attributes
      if (value === AttributeMarker.NamespaceURI) {
        // we skip the next two values
        // as namespaced attributes looks like
        // [..., AttributeMarker.NamespaceURI, 'http://someuri.com/test', 'test:exist',
        // 'existValue', ...]
        i = i + 2;
      } else if (typeof value === 'number') {
        // Skip to the first value of the marked attribute.
        i++;
        while (i < attrsLength && typeof attrs[i] === 'string') {
          i++;
        }
      } else if (value === attrNameToInject) {
        return attrs[i + 1] as string;
      } else {
        i = i + 2;
      }
    }
  }
  return null;
}

function notFoundValueOrThrow<T>(
  notFoundValue: T | null,