Function applyToSubtree

packages/angular_devkit/schematics/src/rules/base.ts:168–184

(path: string, rules: Rule[])

}

export function applyToSubtree(path: string, rules: Rule[]): Rule {
  return (tree, context) => {
    const scoped = new ScopedTree(tree, path);

    return callRule(chain(rules), scoped, context).pipe(
      map((result) => {
        if (result === scoped) {
          return tree;
        } else {
          throw new SchematicsException(
            'Original tree must be returned from all rules when using "applyToSubtree".',
          );
        }
      }),
    );
  };
}