1 /*******************************************************************************
2 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
4 * All rights reserved. This program and the accompanying materials
5 * are made available under the terms of the Eclipse Public License v1.0
6 * which accompanies this distribution, and is available at
7 * http://www.eclipse.org/legal/epl-v10.html
10 * VTT Technical Research Centre of Finland - initial API and implementation
11 *******************************************************************************/
12 package org.simantics.db.layer0.genericrelation.combinators;
14 import gnu.trove.list.array.TIntArrayList;
16 import java.util.ArrayList;
17 import java.util.List;
19 import org.simantics.db.ReadGraph;
20 import org.simantics.db.exception.DatabaseException;
21 import org.simantics.db.layer0.adapter.GenericRelation;
22 import org.simantics.db.layer0.genericrelation.AbstractRelation;
23 import org.simantics.utils.datastructures.Pair;
26 * Selects tuples from the relation by fixing certain fields.
27 * Also projects the relation to unfixed fields.
29 * Do not use this class directly, because relations have often
30 * optimized selection methods, but use IRelation.select method.
32 public class Selection extends AbstractRelation {
34 AbstractRelation base;
36 int[] constantPositions;
37 int[] variablePositions;
40 public Selection(AbstractRelation base, String bindingPattern,
43 TIntArrayList constantPositionArray = new TIntArrayList();
44 TIntArrayList variablePositionsArray = new TIntArrayList();
45 baseLength = bindingPattern.length();
46 for(int i=0;i<baseLength;++i)
47 switch(bindingPattern.charAt(i)) {
48 case 'b': constantPositionArray.add(i); break;
49 case 'v': variablePositionsArray.add(i); break;
51 constantPositions = constantPositionArray.toArray();
52 variablePositions = variablePositionsArray.toArray();
53 this.constants = constants;
57 public boolean contains(ReadGraph g, Object[] tuple) throws DatabaseException {
58 assert(tuple.length == variablePositions.length);
59 Object[] temp = new Object[baseLength];
60 for(int i=0;i<constantPositions.length;++i)
61 temp[constantPositions[i]] = constants[i];
62 for(int i=0;i<variablePositions.length;++i)
63 temp[variablePositions[i]] = tuple[i];
64 return base.contains(g, temp);
68 public boolean isRealizable() {
69 return base.isRealizable();
73 public List<Object[]> realize(ReadGraph g) throws DatabaseException {
74 ArrayList<Object[]> result = new ArrayList<Object[]>();
76 for(Object[] tuple : base.realize(g)) {
77 for(int i=0;i<constantPositions.length;++i)
78 if(!constants[i].equals(tuple[constantPositions[i]]))
80 Object[] temp = new Object[variablePositions.length];
81 for(int i=0;i<variablePositions.length;++i)
82 temp[i] = tuple[variablePositions[i]];
89 public GenericRelation select(String bindingPattern, Object[] givenConstants) {
90 assert(bindingPattern.length() == variablePositions.length);
91 char[] baseBindingPattern = new char[baseLength];
92 Object[] baseConstants = new Object[baseLength];
93 for(int i=0;i<constantPositions.length;++i) {
94 baseBindingPattern[constantPositions[i]] = 'b';
95 baseConstants[constantPositions[i]] = constants[i];
98 for(int i=0;i<variablePositions.length;++i) {
99 char c = baseBindingPattern[variablePositions[i]] = bindingPattern.charAt(i);
101 baseConstants[constantPositions[i]] = givenConstants[j++];
103 assert(j == givenConstants.length);
104 return base.select(new String(baseBindingPattern), constants);
107 @SuppressWarnings("unchecked")
109 public Pair<String, String>[] getFields() {
110 Pair<String, String>[] baseFields = base.getFields();
111 Pair<String, String>[] result = new Pair[variablePositions.length];
112 for(int i=0;i<variablePositions.length;++i)
113 result[i] = baseFields[variablePositions[i]];