1/*
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.clearsilver.jsilver.syntax;
18
19import com.google.clearsilver.jsilver.syntax.analysis.DepthFirstAdapter;
20import com.google.clearsilver.jsilver.syntax.node.ASequenceExpression;
21import com.google.clearsilver.jsilver.syntax.node.PExpression;
22
23import java.util.LinkedList;
24
25/**
26 * Simple optimizer to simplify expression sequences which only have a single element. This
27 * optimization should be run as early as possible because it simplifies the syntax tree (and some
28 * later optimizations may rely on the simplified structure).
29 */
30public class SequenceOptimizer extends DepthFirstAdapter {
31
32  /**
33   * Removes sequence expressions with only one element.
34   */
35  @Override
36  public void caseASequenceExpression(ASequenceExpression originalNode) {
37    super.caseASequenceExpression(originalNode);
38    LinkedList<PExpression> args = originalNode.getArgs();
39    if (args.size() == 1) {
40      originalNode.replaceBy(args.getFirst());
41    }
42  }
43}
44