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 */
017package org.apache.activemq.filter;
018
019import java.util.List;
020
021/**
022 * Function call expression that evaluates to a boolean value.  Selector parsing requires BooleanExpression objects for
023 * Boolean expressions, such as operands to AND, and as the final result of a selector.  This provides that interface
024 * for function call expressions that resolve to Boolean values.
025 * <p/>
026 * If a function can return different types at evaluation-time, the function implementation needs to decide whether it
027 * supports casting to Boolean at parse-time.
028 *
029 * @see    FunctionCallExpression#createFunctionCall
030 */
031
032public class BooleanFunctionCallExpr extends FunctionCallExpression implements BooleanExpression {
033    /**
034     * Constructs a function call expression with the named filter function and arguments, which returns a boolean
035     * result.
036     *
037     * @param    func_name - Name of the filter function to be called when evaluated.
038     * @param    args - List of argument expressions passed to the function.
039     */
040
041    public BooleanFunctionCallExpr(String func_name, List<Expression> args)
042            throws invalidFunctionExpressionException {
043        super(func_name, args);
044    }
045
046
047    /**
048     * Evaluate the function call expression, in the given context, and return an indication of whether the
049     * expression "matches" (i.e.&nbsp;evaluates to true).
050     *
051     * @param    message_ctx - message context against which the expression will be evaluated.
052     * @return the boolean evaluation of the function call expression.
053     */
054
055    public boolean matches(MessageEvaluationContext message_ctx) throws javax.jms.JMSException {
056        Boolean result;
057
058        result = (Boolean) evaluate(message_ctx);
059
060        if (result != null)
061            return result.booleanValue();
062
063        return false;
064    }
065}
066