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.Collection;
021    import java.util.HashMap;
022    import java.util.HashSet;
023    import java.util.Map;
024    import java.util.Set;
025    
026    import javax.jdo.Query;
027    
028    import org.cumulus4j.store.crypto.CryptoContext;
029    import org.cumulus4j.store.model.ClassMeta;
030    import org.cumulus4j.store.model.FieldMeta;
031    import org.cumulus4j.store.model.IndexEntry;
032    import org.cumulus4j.store.model.IndexEntryFactory;
033    import org.cumulus4j.store.model.IndexValue;
034    import org.cumulus4j.store.query.QueryEvaluator;
035    import org.cumulus4j.store.query.eval.InvokeExpressionEvaluator;
036    import org.cumulus4j.store.query.eval.PrimaryExpressionResolver;
037    import org.cumulus4j.store.query.eval.ResultDescriptor;
038    import org.datanucleus.query.expression.Expression;
039    import org.datanucleus.query.expression.PrimaryExpression;
040    
041    /**
042     * Evaluator for "Map.isEmpty()".
043     */
044    public class MapIsEmptyEvaluator extends AbstractMethodEvaluator {
045    
046            /* (non-Javadoc)
047             * @see org.cumulus4j.store.query.method.MethodEvaluator#evaluate(org.cumulus4j.store.query.QueryEvaluator, org.cumulus4j.store.query.eval.InvokeExpressionEvaluator, org.datanucleus.query.expression.Expression, org.cumulus4j.store.query.eval.ResultDescriptor)
048             */
049            @Override
050            public Set<Long> evaluate(QueryEvaluator queryEval,
051                            InvokeExpressionEvaluator invokeExprEval, Expression invokedExpr,
052                            ResultDescriptor resultDesc) {
053                    if (invokeExprEval.getExpression().getArguments().size() != 0)
054                            throw new IllegalStateException("isEmpty(...) expects no argument, but there are " +
055                                            invokeExprEval.getExpression().getArguments().size());
056    
057                    if (invokedExpr instanceof PrimaryExpression) {
058                            return new MapIsEmptyResolver(queryEval, (PrimaryExpression) invokedExpr, resultDesc.isNegated()).query();
059                    }
060                    else {
061                            if (!invokeExprEval.getLeft().getResultSymbols().contains(resultDesc.getSymbol()))
062                                    return null;
063                            return queryMapIsEmpty(queryEval, resultDesc.getFieldMeta(), resultDesc.isNegated());
064                    }
065            }
066    
067            private Set<Long> queryMapIsEmpty(
068                            QueryEvaluator queryEval,
069                            FieldMeta fieldMeta,
070                            boolean negate
071            ) {
072                    CryptoContext cryptoContext = queryEval.getCryptoContext();
073                    IndexEntryFactory indexEntryFactory = queryEval.getStoreManager().getIndexFactoryRegistry().getIndexEntryFactoryForContainerSize();
074    
075                    Query q = queryEval.getPersistenceManagerForIndex().newQuery(indexEntryFactory.getIndexEntryClass());
076                    q.setFilter(
077                                    "this.keyStoreRefID == :keyStoreRefID && this.fieldMeta == :fieldMeta && " +
078                                    (negate ? "this.indexKey != 0" : "this.indexKey == 0")
079                    );
080                    Map<String, Object> params = new HashMap<String, Object>(3);
081                    params.put("keyStoreRefID", cryptoContext.getKeyStoreRefID());
082                    params.put("fieldMeta", fieldMeta);
083    
084                    @SuppressWarnings("unchecked")
085                    Collection<? extends IndexEntry> indexEntries = (Collection<? extends IndexEntry>) q.executeWithMap(params);
086    
087                    Set<Long> result = new HashSet<Long>();
088                    for (IndexEntry indexEntry : indexEntries) {
089                            IndexValue indexValue = queryEval.getEncryptionHandler().decryptIndexEntry(cryptoContext, indexEntry);
090                            result.addAll(indexValue.getDataEntryIDs());
091                    }
092                    q.closeAll();
093                    return result;
094            }
095    
096            private class MapIsEmptyResolver extends PrimaryExpressionResolver
097            {
098                    private boolean negate;
099    
100                    public MapIsEmptyResolver(
101                                    QueryEvaluator queryEvaluator, PrimaryExpression primaryExpression,
102                                    boolean negate
103                    )
104                    {
105                            super(queryEvaluator, primaryExpression);
106                            this.negate = negate;
107                    }
108    
109                    @Override
110                    protected Set<Long> queryEnd(FieldMeta fieldMeta, ClassMeta classMeta) {
111                            return queryMapIsEmpty(queryEvaluator, fieldMeta, negate);
112                    }
113            }
114    }