1 package org.apache.commons.ognl;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import org.apache.commons.ognl.enhance.ExpressionAccessor;
23
24 /**
25 * JJTree interface for AST nodes, as modified to handle the OGNL operations getValue and setValue. JJTree's original
26 * comment: All AST nodes must implement this interface. It provides basic machinery for constructing the parent and
27 * child relationships between nodes.
28 *
29 * @author Luke Blanshard (blanshlu@netscape.net)
30 * @author Drew Davidson (drew@ognl.org)
31 */
32 public interface Node
33 extends JavaSource
34 {
35
36 /**
37 * This method is called after the node has been made the current node. It indicates that child nodes can now be
38 * added to it.
39 */
40 void jjtOpen();
41
42 /**
43 * This method is called after all the child nodes have been added.
44 */
45 void jjtClose();
46
47 /**
48 * This pair of methods are used to inform the node of its parent.
49 */
50 void jjtSetParent( Node n );
51
52 Node jjtGetParent();
53
54 /**
55 * This method tells the node to add its argument to the node's list of children.
56 */
57 void jjtAddChild( Node n, int i );
58
59 /**
60 * This method returns a child node. The children are numbered from zero, left to right.
61 */
62 Node jjtGetChild( int i );
63
64 /** Return the number of children the node has. */
65 int jjtGetNumChildren();
66
67 // OGNL additions to Node:
68
69 /**
70 * Extracts the value from the given source object that is appropriate for this node within the given context.
71 */
72 Object getValue( OgnlContext context, Object source )
73 throws OgnlException;
74
75 /**
76 * Sets the given value in the given target as appropriate for this node within the given context.
77 */
78 void setValue( OgnlContext context, Object target, Object value )
79 throws OgnlException;
80
81 /**
82 * Gets the compiled bytecode enhanced expression accessor for getting/setting values.
83 *
84 * @return The accessor for this node, or null if none has been compiled for it.
85 */
86 ExpressionAccessor getAccessor();
87
88 /**
89 * Sets a new compiled accessor for this node expression.
90 *
91 * @param accessor The compiled representation of this node.
92 */
93 void setAccessor( ExpressionAccessor accessor );
94
95
96 /**
97 * Supports the Visitor pattern. The method which corresponds to
98 * the runtime type of this Node will be called.
99 *
100 * @param visitor The visitor to accept.
101 * @param data The second parameter to pass through to visitor.visit
102 * @param <R> The return type of the visitor.visit method.
103 * @param <P> The type of the second parameter type.
104 * @return the value returned by visitor.visit
105 * @throws NullPointerException if visitor is null
106 * @throws RuntimeException if visitor.visit throws an exception.
107 */
108 <R, P> R accept( NodeVisitor<? extends R, ? super P> visitor, P data )
109 throws OgnlException;
110
111 }