001    /**
002     * Copyright 2005-2013 The Kuali Foundation
003     *
004     * Licensed under the Educational Community License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.opensource.org/licenses/ecl2.php
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,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.kuali.rice.krms.framework.engine.expression;
017    
018    import java.util.List;
019    
020    import org.kuali.rice.krms.api.engine.ExecutionEnvironment;
021    import org.kuali.rice.krms.api.engine.expression.ComparisonOperatorService;
022    import org.kuali.rice.krms.framework.engine.Function;
023    
024    /**
025     * An implementation of {@link Expression} which invokes a {@link Function} with the results of the invocation of the given
026     * List of {@link Expression}s (of the given {@link ExecutionEnvironment}).
027     * @author Kuali Rice Team (rice.collab@kuali.org)
028     * 
029     */
030    public final class FunctionExpression implements Expression<Object> {
031    
032            private final Function function;
033        private final String [] parameterTypes;
034            private final List<Expression<? extends Object>> parameters;
035        private final ComparisonOperatorService comparisonOperatorService;
036    
037        /**
038         * Create a FunctionExpression with the given values.
039         * @param function {@link Function} to be invoked using the invoked results of the given List of {@link Expression}s
040         * @param parameterTypes the full class names for the function's parameter types in sequential order
041         * @param parameters List of {@link Expression}s to be invoked whose results (of the given {@link ExecutionEnvironment})
042         * @param comparisonOperatorService -- TODO:
043         * will be used to invoke the given {@link Function}.
044         */
045            public FunctionExpression(Function function, String[] parameterTypes,
046                            List<Expression<? extends Object>> parameters,
047                ComparisonOperatorService comparisonOperatorService) {
048                    this.function = function;
049            this.parameterTypes = parameterTypes;
050                    this.parameters = parameters;
051            this.comparisonOperatorService = comparisonOperatorService;
052            }
053    
054            @Override
055            public Object invoke(ExecutionEnvironment environment) {
056            Object[] argumentValues = new Object[parameters.size()];
057    
058            int argValIndex = 0;
059    
060                    for (Expression<? extends Object> argument : parameters) {
061                            Object argumentValue = argument.invoke(environment);
062                String expectedArgumentType = parameterTypes[argValIndex];
063    
064                argumentValue = ComparisonOperatorServiceUtils.coerceIfNeeded(argumentValue, expectedArgumentType, comparisonOperatorService);
065    
066                argumentValues[argValIndex] = argumentValue;
067                argValIndex += 1;
068                    }
069    
070                    return function.invoke(argumentValues);
071            }
072    
073    
074    }