TurtleDB
A mini distributed database system
src/ca/uqac/dim/turtledb/QueryVisitor.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 public abstract class QueryVisitor
00021 {
00022   public abstract void visit(Projection r) throws VisitorException;
00023   
00024   public abstract void visit(Selection r) throws VisitorException;
00025   
00026   public abstract void visit(Table r) throws VisitorException;
00027   
00028   public abstract void visit(VariableTable r) throws VisitorException;
00029   
00030   public abstract void visit(Union r) throws VisitorException;
00031   
00032   public abstract void visit(Intersection r) throws VisitorException;
00033   
00034   public abstract void visit(Join r) throws VisitorException;
00035   
00036   public abstract void visit(Product r) throws VisitorException;
00037   
00042   public class VisitorException extends Exception
00043   {
00044     protected String m_message = "VisitorException";
00045     private static final long serialVersionUID = 1L;
00046     
00047     public VisitorException(String msg)
00048     {
00049       m_message = msg;
00050     }
00051     
00052     @Override
00053     public String toString()
00054     {
00055       return m_message;
00056     }
00057     
00058   }
00059 }