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