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

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