bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/combinators/Selection.java

   1 /*******************************************************************************
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   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
   8  *
   9  * Contributors:
  10  *     VTT Technical Research Centre of Finland - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.layer0.genericrelation.combinators;
  13
  14 import gnu.trove.list.array.TIntArrayList;
  15
  16 import java.util.ArrayList;
  17 import java.util.List;
  18
  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;
  24
  25 /**
  26  * Selects tuples from the relation by fixing certain fields.
  27  * Also projects the relation to unfixed fields.
  28  *
  29  * Do not use this class directly, because relations have often
  30  * optimized selection methods, but use IRelation.select method.
  31  */
  32 public class Selection extends AbstractRelation {
  33
  34         AbstractRelation base;
  35         int baseLength;
  36         int[] constantPositions;
  37         int[] variablePositions;
  38         Object[] constants;
  39
  40         public Selection(AbstractRelation base, String bindingPattern,
  41                         Object[] constants) {
  42                 this.base = base;
  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;
  50                         }
  51                 constantPositions = constantPositionArray.toArray();
  52                 variablePositions = variablePositionsArray.toArray();
  53                 this.constants = constants;
  54         }
  55
  56         @Override
  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);
  65         }
  66
  67         @Override
  68         public boolean isRealizable() {
  69                 return base.isRealizable();
  70         }
  71
  72         @Override
  73         public List<Object[]> realize(ReadGraph g) throws DatabaseException {
  74                 ArrayList<Object[]> result = new ArrayList<Object[]>();
  75                 loop:
  76                 for(Object[] tuple : base.realize(g)) {
  77                         for(int i=0;i<constantPositions.length;++i)
  78                                 if(!constants[i].equals(tuple[constantPositions[i]]))
  79                                         continue loop;
  80                         Object[] temp = new Object[variablePositions.length];
  81                         for(int i=0;i<variablePositions.length;++i)
  82                                 temp[i] = tuple[variablePositions[i]];
  83                         result.add(temp);
  84                 }
  85                 return result;
  86         }
  87
  88         @Override
  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];
  96                 }
  97                 int j = 0;
  98                 for(int i=0;i<variablePositions.length;++i) {
  99                         char c = baseBindingPattern[variablePositions[i]] = bindingPattern.charAt(i);
 100                         if(c == 'b')
 101                                 baseConstants[constantPositions[i]] = givenConstants[j++];
 102                 }
 103                 assert(j == givenConstants.length);
 104                 return base.select(new String(baseBindingPattern), constants);
 105         }
 106
 107         @SuppressWarnings("unchecked")
 108     @Override
 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]];
 114                 return result;
 115         }
 116
 117 }