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.AMultipleCommand; 21 import com.google.clearsilver.jsilver.syntax.node.AOptimizedMultipleCommand; 22 23 /** 24 * Visitor that can be applied to the AST to optimize it by replacing nodes with more efficient 25 * implementations than the default SableCC generated versions. 26 */ 27 public class SyntaxTreeOptimizer extends DepthFirstAdapter { 28 29 /** 30 * Replace AMultipleCommand nodes with AOptimizedMultipleCommands, which iterates over children 31 * faster. 32 */ 33 @Override caseAMultipleCommand(AMultipleCommand originalNode)34 public void caseAMultipleCommand(AMultipleCommand originalNode) { 35 // Recurse through child nodes first. Because the optimised node doesn't 36 // handle replacement, go leaves-first. 37 super.caseAMultipleCommand(originalNode); 38 // Replace this node with the optimized version. 39 originalNode.replaceBy(new AOptimizedMultipleCommand(originalNode)); 40 } 41 42 } 43