001    /*
002     * Cumulus4j - Securing your data in the cloud - http://cumulus4j.org
003     * Copyright (C) 2011 NightLabs Consulting GmbH
004     *
005     * This program is free software: you can redistribute it and/or modify
006     * it under the terms of the GNU Affero General Public License as
007     * published by the Free Software Foundation, either version 3 of the
008     * License, or (at your option) any later version.
009     *
010     * This program is distributed in the hope that it will be useful,
011     * but WITHOUT ANY WARRANTY; without even the implied warranty of
012     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013     * GNU Affero General Public License for more details.
014     *
015     * You should have received a copy of the GNU Affero General Public License
016     * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017     */
018    package org.cumulus4j.store.query.method;
019    
020    import java.util.Set;
021    
022    import org.cumulus4j.store.model.DataEntry;
023    import org.cumulus4j.store.query.QueryEvaluator;
024    import org.cumulus4j.store.query.eval.InvokeExpressionEvaluator;
025    import org.cumulus4j.store.query.eval.ResultDescriptor;
026    import org.datanucleus.query.expression.Expression;
027    
028    /**
029     * Interface for the evaluator for a method.
030     */
031    public interface MethodEvaluator
032    {
033            /**
034             * Method to evaluate the provided method invocation invoking on a PrimaryExpression.
035             * @param queryEval Query evaluator
036             * @param invokeExprEval Evaluator for the InvokeExpression that this is processing
037             * @param invokedExpr Expression on which we are invoking the method
038             * @param resultDesc Result descriptor
039             * @return those {@link DataEntry#getDataEntryID() dataEntryID}s that match the query
040             * criteria for the specified <code>resultSymbol</code> or <code>null</code>, if the symbol is not supported
041             */
042            Set<Long> evaluate(QueryEvaluator queryEval, InvokeExpressionEvaluator invokeExprEval, Expression invokedExpr, 
043                            ResultDescriptor resultDesc);
044    
045            /**
046             * Whether this evaluator requires a comparison argument to perform its evaluation.
047             * @return True if needing the comparison argument
048             */
049            boolean requiresComparisonArgument();
050    
051            /**
052             * Method to set any argument to be compared with (when evaluating method invocation and comparison).
053             * Should be set prior to call of evaluate(...).
054             * @param obj The compared argument
055             */
056            void setCompareToArgument(Object obj);
057    }