001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.jxpath;
018
019 import java.io.Serializable;
020
021 /**
022 * Variables provide access to a global set of values accessible via XPath.
023 * XPath can reference variables using the <code>"$varname"</code> syntax.
024 * To use a custom implementation of this interface, pass it to
025 * {@link JXPathContext#setVariables JXPathContext.setVariables()}
026 *
027 * @author Dmitri Plotnikov
028 * @version $Revision: 652925 $ $Date: 2008-05-02 17:05:41 -0500 (Fri, 02 May 2008) $
029 */
030 public interface Variables extends Serializable {
031
032 /**
033 * Returns true if the specified variable is declared.
034 * @param varName variable name
035 * @return boolean
036 */
037 boolean isDeclaredVariable(String varName);
038
039 /**
040 * Returns the value of the specified variable.
041 * @param varName variable name
042 * @return Object value
043 * @throws IllegalArgumentException if there is no such variable.
044 */
045 Object getVariable(String varName);
046
047 /**
048 * Defines a new variable with the specified value or modifies
049 * the value of an existing variable.
050 * May throw UnsupportedOperationException.
051 * @param varName variable name
052 * @param value to declare
053 */
054 void declareVariable(String varName, Object value);
055
056 /**
057 * Removes an existing variable. May throw UnsupportedOperationException.
058 *
059 * @param varName is a variable name without the "$" sign
060 */
061 void undeclareVariable(String varName);
062 }