001    /*
002     * Copyright 2002-2004 the original author or authors.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not
005     * use this file except in compliance with the License. You may obtain a copy of
006     * the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
012     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
013     * License for the specific language governing permissions and limitations under
014     * the License.
015     */
016    package org.springframework.rules.closure.support;
017    
018    import org.springframework.rules.closure.Closure;
019    import org.springframework.rules.constraint.Constraint;
020    
021    /**
022     * Only execute the specified closure if a provided constraint is also true.
023     *
024     * @author Keith Donald
025     */
026    public class IfBlock extends Block {
027            private static final long serialVersionUID = 1L;
028    
029            /**
030             * Block of code to execute if object passes test.
031             */
032            private Closure closure;
033    
034            /**
035             * Constraint to test against.
036             */
037            private Constraint constraint;
038    
039            /**
040             * Constructor.
041             *
042             * @param constraint Constraint to test against.
043             * @param closure closure to be executed if object passes the test.
044             */
045            public IfBlock(Constraint constraint, Closure closure) {
046                    this.constraint = constraint;
047                    this.closure = closure;
048            }
049    
050            /**
051             * Only invoke the wrapped closure against the provided argument if the
052             * constraint permits, else take no action.
053             */
054            protected void handle(Object argument) {
055                    if (constraint.test(argument)) {
056                            closure.call(argument);
057                    }
058            }
059    
060    }