/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*
*/
package org.hibernate.hql.internal.ast.util;
import java.util.Stack;
import antlr.collections.AST;
/**
* A visitor for traversing an AST tree.
*
* @author Steve Ebersole
* @author Philip R. "Pib" Burns.
* @author Strong Liu
*
*/
public class NodeTraverser {
public static interface VisitationStrategy {
public void visit( AST node );
}
private final VisitationStrategy strategy;
public NodeTraverser( VisitationStrategy strategy ) {
this.strategy = strategy;
}
/**
* Traverse the AST tree depth first.
*
* @param ast
* Root node of subtree to traverse.
*
* <p>
* Note that the AST passed in is not visited itself. Visitation
* starts with its children.
* </p>
*/
public void traverseDepthFirst( AST ast ) {
if ( ast == null ) {
throw new IllegalArgumentException(
"node to traverse cannot be null!" );
}
visitDepthFirst( ast.getFirstChild() );
}
private void visitDepthFirst(AST ast){
if(ast==null){
return;
}
Stack stack = new Stack();
if ( ast != null ) {
stack.push( ast );
while (!stack.empty()) {
ast = (AST) stack.pop();
strategy.visit( ast );
if ( ast.getNextSibling() != null )
stack.push( ast.getNextSibling() );
if ( ast.getFirstChild() != null )
stack.push( ast.getFirstChild() );
}
}
}
}