public final AntlrPilarParser.annotation_return annotation()
      throws RecognitionException {
    AntlrPilarParser.annotation_return retval = new AntlrPilarParser.annotation_return();
    retval.start = input.LT(1);
    int annotation_StartIndex = input.index();
    Object root_0 = null;

    Token t = null;
    Token ID32 = null;
    AntlrPilarParser.annotationParams_return annotationParams33 = null;

    Object t_tree = null;
    Object ID32_tree = null;
    RewriteRuleTokenStream stream_171 = new RewriteRuleTokenStream(adaptor,
        "token 171");
    RewriteRuleTokenStream stream_ID = new RewriteRuleTokenStream(adaptor,
        "token ID");
    RewriteRuleSubtreeStream stream_annotationParams = new RewriteRuleSubtreeStream(
        adaptor, "rule annotationParams");
    try {
      if (state.backtracking > 0 && alreadyParsedRule(input, 15)) {
        return retval;
      }
      // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:2: (t= '@' ID ( annotationParams )? -> ^( ANNOTATION[$t] ID ^( OPTION ( annotationParams )? ) ) )
      // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:4: t= '@' ID ( annotationParams )?
      {
        t = (Token) match(input, 171, FOLLOW_171_in_annotation1447);
        if (state.failed) return retval;
        if (state.backtracking == 0) stream_171.add(t);

        ID32 = (Token) match(input, ID, FOLLOW_ID_in_annotation1449);
        if (state.failed) return retval;
        if (state.backtracking == 0) stream_ID.add(ID32);

        // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:13: ( annotationParams )?
        int alt9 = 2;
        alt9 = dfa9.predict(input);
        switch (alt9) {
          case 1:
          // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:0:0: annotationParams
          {
            pushFollow(FOLLOW_annotationParams_in_annotation1451);
            annotationParams33 = annotationParams();

            state._fsp--;
            if (state.failed) return retval;
            if (state.backtracking == 0)
              stream_annotationParams.add(annotationParams33.getTree());

          }
            break;

        }

        // AST REWRITE
        // elements: annotationParams, ID
        // token labels: 
        // rule labels: retval
        // token list labels: 
        // rule list labels: 
        // wildcard labels: 
        if (state.backtracking == 0) {
          retval.tree = root_0;
          RewriteRuleSubtreeStream stream_retval = new RewriteRuleSubtreeStream(
              adaptor, "rule retval", retval != null ? retval.tree : null);

          root_0 = (Object) adaptor.nil();
          // 228:41: -> ^( ANNOTATION[$t] ID ^( OPTION ( annotationParams )? ) )
          {
            // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:44: ^( ANNOTATION[$t] ID ^( OPTION ( annotationParams )? ) )
            {
              Object root_1 = (Object) adaptor.nil();
              root_1 = (Object) adaptor.becomeRoot(
                  (Object) adaptor.create(ANNOTATION, t),
                  root_1);

              adaptor.addChild(root_1, stream_ID.nextNode());
              // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:64: ^( OPTION ( annotationParams )? )
              {
                Object root_2 = (Object) adaptor.nil();
                root_2 = (Object) adaptor.becomeRoot(
                    (Object) adaptor.create(OPTION, "OPTION"),
                    root_2);

                // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:228:73: ( annotationParams )?
                if (stream_annotationParams.hasNext()) {
                  adaptor.addChild(root_2, stream_annotationParams.nextTree());

                }
                stream_annotationParams.reset();

                adaptor.addChild(root_1, root_2);
              }

              adaptor.addChild(root_0, root_1);
            }

          }

          retval.tree = root_0;
        }
      }

      retval.stop = input.LT(-1);

      if (state.backtracking == 0) {

        retval.tree = (Object) adaptor.rulePostProcessing(root_0);
        adaptor.setTokenBoundaries(retval.tree, retval.start, retval.stop);
      }
    } catch (RecognitionException re) {
      reportError(re);
      recover(input, re);
      retval.tree = (Object) adaptor.errorNode(
          input,
          retval.start,
          input.LT(-1),
          re);

    } finally {
      if (state.backtracking > 0) {
        memoize(input, 15, annotation_StartIndex);
      }
    }
    return retval;
  }