Java tutorial
package org.apache.commons.ognl; /* * 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. */ import org.apache.commons.ognl.enhance.ExpressionAccessor; /** * JJTree interface for AST nodes, as modified to handle the OGNL operations getValue and setValue. JJTree's original * comment: All AST nodes must implement this interface. It provides basic machinery for constructing the parent and * child relationships between nodes. */ public interface Node extends JavaSource { /** * This method is called after the node has been made the current node. It indicates that child nodes can now be * added to it. */ void jjtOpen(); /** * This method is called after all the child nodes have been added. */ void jjtClose(); /** * This pair of methods are used to inform the node of its parent. */ void jjtSetParent(Node n); Node jjtGetParent(); /** * This method tells the node to add its argument to the node's list of children. */ void jjtAddChild(Node n, int i); /** * This method returns a child node. The children are numbered from zero, left to right. */ Node jjtGetChild(int i); /** Return the number of children the node has. */ int jjtGetNumChildren(); // OGNL additions to Node: /** * Extracts the value from the given source object that is appropriate for this node within the given context. */ Object getValue(OgnlContext context, Object source) throws OgnlException; /** * Sets the given value in the given target as appropriate for this node within the given context. */ void setValue(OgnlContext context, Object target, Object value) throws OgnlException; /** * Gets the compiled bytecode enhanced expression accessor for getting/setting values. * * @return The accessor for this node, or null if none has been compiled for it. */ ExpressionAccessor getAccessor(); /** * Sets a new compiled accessor for this node expression. * * @param accessor The compiled representation of this node. */ void setAccessor(ExpressionAccessor accessor); /** * Supports the Visitor pattern. The method which corresponds to * the runtime type of this Node will be called. * * @param visitor The visitor to accept. * @param data The second parameter to pass through to visitor.visit * @param <R> The return type of the visitor.visit method. * @param <P> The type of the second parameter type. * @return the value returned by visitor.visit * @throws NullPointerException if visitor is null * @throws RuntimeException if visitor.visit throws an exception. */ <R, P> R accept(NodeVisitor<? extends R, ? super P> visitor, P data) throws OgnlException; }