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    
018    package org.apache.commons.jexl2;
019    
020    
021    /**
022     * Represents a single JEXL expression.
023     * <p>
024     * This simple interface provides access to the underlying expression through
025     * {@link Expression#getExpression()}.
026     * </p>
027     *
028     * <p>
029     * An expression is different than a script - it is simply a reference of
030     * an expression.
031     * </p>
032     *
033     * @since 1.0
034     * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
035     * @version $Id: Expression.java 884175 2009-11-25 16:23:41Z henrib $
036     */
037    public interface Expression {
038        /**
039         * Evaluates the expression with the variables contained in the
040         * supplied {@link JexlContext}.
041         *
042         * @param context A JexlContext containing variables.
043         * @return The result of this evaluation
044         * @throws JexlException on any error
045         */
046        Object evaluate(JexlContext context);
047    
048        /**
049         * Returns the JEXL expression this Expression was created with.
050         *
051         * @return The JEXL expression to be evaluated
052         */
053        String getExpression();
054    
055        /**
056         * Returns the JEXL expression by reconstructing it from the parsed tree.
057         * @return the JEXL expression
058         */
059        String dump();
060    }