| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| */ |
| package org.apache.directory.shared.ldap.filter; |
| |
| |
| import java.util.List; |
| |
| |
| /** |
| * Filter expression tree node visitor interface. Note that this is a variation |
| * of the extrinsic visitor variation. It has the following advantages over the |
| * standard visitor pattern: |
| * <ul> |
| * <li>Visitor takes responsibility that a visitor can visit a node</li> |
| * <li>Each visitor knows which types of concrete classes it can visit</li> |
| * <li>New visitors can be created without changing the node class</li> |
| * <li>New node classes can be added without having to change old visitors</li> |
| * <li>Visitation order can be controled in every respect:</li> |
| * <ul> |
| * <li>Visitation rejection with canVisit() and/or getOrder()</li> |
| * <li>Recursive visitation ordering with isPrefix()</li> |
| * <li>Child visitation ordering with getOrder()</li> |
| * </ul> |
| * </ul> |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| * @version $Revision$ |
| */ |
| public interface FilterVisitor |
| { |
| /** |
| * Visits a filter expression AST using a specific visitation order. |
| * |
| * @param node the node to visit |
| * @return node the resulting modified node |
| */ |
| Object visit( ExprNode node ); |
| |
| |
| /** |
| * Checks to see if a node can be visited. |
| * |
| * @param node the node to be visited |
| * @return whether or node the node should be visited |
| */ |
| boolean canVisit( ExprNode node ); |
| |
| |
| /** |
| * Determines whether the visitation order is prefix or postfix. |
| * |
| * @return true if the visitation is in prefix order, false otherwise. |
| */ |
| boolean isPrefix(); |
| |
| |
| /** |
| * Get the array of children to visit sequentially to determine the order of |
| * child visitations. Some children may not be returned at all if canVisit() |
| * returns false on them. |
| * |
| * @param node the parent branch node |
| * @param children the child node array |
| * @return the new reordered array of children |
| */ |
| List<ExprNode> getOrder( BranchNode node, List<ExprNode> children ); |
| } |