public RegExpLanguageHost.Lookbehind supportsLookbehind(RegExpGroup group) {
    final RegExpLanguageHost host = findRegExpHost(group);
    if (host == null) {
      return RegExpLanguageHost.Lookbehind.FULL;
    }
    return host.supportsLookbehind(group);
  }
public RegExpLanguageHost.Lookbehind supportsLookbehind(RegExpGroup group)