1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jxpath;
18
19 import java.io.Serializable;
20
21 /**
22 * Variables provide access to a global set of values accessible via XPath.
23 * XPath can reference variables using the <code>"$varname"</code> syntax.
24 * To use a custom implementation of this interface, pass it to
25 * {@link JXPathContext#setVariables JXPathContext.setVariables()}
26 *
27 * @author Dmitri Plotnikov
28 * @version $Revision: 652925 $ $Date: 2008-05-03 00:05:41 +0200 (Sa, 03 Mai 2008) $
29 */
30 public interface Variables extends Serializable {
31
32 /**
33 * Returns true if the specified variable is declared.
34 * @param varName variable name
35 * @return boolean
36 */
37 boolean isDeclaredVariable(String varName);
38
39 /**
40 * Returns the value of the specified variable.
41 * @param varName variable name
42 * @return Object value
43 * @throws IllegalArgumentException if there is no such variable.
44 */
45 Object getVariable(String varName);
46
47 /**
48 * Defines a new variable with the specified value or modifies
49 * the value of an existing variable.
50 * May throw UnsupportedOperationException.
51 * @param varName variable name
52 * @param value to declare
53 */
54 void declareVariable(String varName, Object value);
55
56 /**
57 * Removes an existing variable. May throw UnsupportedOperationException.
58 *
59 * @param varName is a variable name without the "$" sign
60 */
61 void undeclareVariable(String varName);
62 }