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;
017    
018    /**
019     * A function object that evaluates one argument, executing a block of code. It
020     * returns a single result.
021     * <p>
022     * A closure evaluates a single argument against some expression. For example, a
023     * "StringLength" closure might accept any object and return the length of the
024     * object's string form.
025     *
026     * @author Keith Donald
027     */
028    public interface Closure {
029    
030            /**
031             * Evaluate the function with the provided argument, returning the result.
032             *
033             * @param argument the argument
034             * @return the function return value
035             */
036            Object call(Object argument);
037    }