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 17 package com.google.clearsilver.jsilver.syntax; 18 19 import com.google.clearsilver.jsilver.syntax.analysis.DepthFirstAdapter; 20 import com.google.clearsilver.jsilver.syntax.node.ASequenceExpression; 21 import com.google.clearsilver.jsilver.syntax.node.PExpression; 22 23 import 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 */ 30 public class SequenceOptimizer extends DepthFirstAdapter { 31 32 /** 33 * Removes sequence expressions with only one element. 34 */ 35 @Override caseASequenceExpression(ASequenceExpression originalNode)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