    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    }