TurtleDB
A mini distributed database system
src/ca/uqac/dim/turtledb/BinaryRelation.java
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00001 /*-------------------------------------------------------------------------
00002     Simple distributed database engine
00003     Copyright (C) 2012  Sylvain Hallé
00004 
00005     This program is free software: you can redistribute it and/or modify
00006     it under the terms of the GNU General Public License as published by
00007     the Free Software Foundation, either version 3 of the License, or
00008     (at your option) any later version.
00009 
00010     This program is distributed in the hope that it will be useful,
00011     but WITHOUT ANY WARRANTY; without even the implied warranty of
00012     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013     GNU General Public License for more details.
00014 
00015     You should have received a copy of the GNU General Public License
00016     along with this program.  If not, see <http://www.gnu.org/licenses/>.
00017  -------------------------------------------------------------------------*/
00018 package ca.uqac.dim.turtledb;
00019 
00020 import ca.uqac.dim.turtledb.QueryVisitor.VisitorException;
00021 
00026 public abstract class BinaryRelation extends Relation
00027 {
00028   protected Relation m_left;
00029   protected Relation m_right;
00030   
00031   public void setLeft(Relation r)
00032   {
00033     m_left = r;
00034   }
00035   
00036   public void setRight(Relation r)
00037   {
00038     m_right = r;
00039   }
00040   
00041   public Relation getLeft()
00042   {
00043     return m_left;
00044   }
00045   
00046   public Relation getRight()
00047   {
00048     return m_right;
00049   }
00050 
00051   protected void acceptBinary(QueryVisitor v) throws VisitorException
00052   {
00053     m_left.accept(v);
00054     m_right.accept(v);
00055   }
00056 
00057   @Override
00058   public int tupleCount()
00059   {
00060     return m_left.tupleCount() + m_right.tupleCount();
00061   }
00062   
00063   protected abstract class BinaryRelationStreamIterator extends RelationStreamIterator
00064   {
00065     
00066   }
00067   
00068   protected class BinaryRelationCacheIterator extends RelationCacheIterator
00069   {
00070     protected Table m_intermediateLeft;
00071     protected Table m_intermediateRight;
00072     
00073     @Override
00074     protected void getIntermediateResult()
00075     {
00076       RelationIterator it = null;
00077       it = m_left.cacheIterator();
00078       m_intermediateLeft = new Table(m_left.getSchema());
00079       while (it.hasNext())
00080       {
00081         Tuple t = it.next();
00082         m_intermediateLeft.put(t);
00083       }
00084       it = m_right.cacheIterator();
00085       m_intermediateRight = new Table(m_right.getSchema());
00086       while (it.hasNext())
00087       {
00088         Tuple t = it.next();
00089         m_intermediateRight.put(t);
00090       }
00091       m_intermediateRight = new Table(m_right.getSchema());
00092     }
00093   }
00094 
00095 }