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A full SQL database system with JDBC driver that can be embedded in a Java application or operate as a stand-alone server with clients connecting via TCP/IP.

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/**
 * com.mckoi.database.AbstractQueryContext  25 Mar 2002
 *
 * Mckoi SQL Database ( http://www.mckoi.com/database )
 * Copyright (C) 2000, 2001, 2002  Diehl and Associates, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * Version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License Version 2 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * Version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Change Log:
 * 
 * 
 */

package com.mckoi.database;

import java.util.HashMap;

/**
 * An abstract implementation of QueryContext
 *
 * @author Tobias Downer
 */

public abstract class AbstractQueryContext implements QueryContext {

  /**
   * Any marked tables that are made during the evaluation of a query plan.
   * (String) -> (Table)
   */
  private HashMap marked_tables;


  /**
   * Marks a table in a query plan.
   */
  public void addMarkedTable(String mark_name, Table table) {
    if (marked_tables == null) {
      marked_tables = new HashMap();
    }
    marked_tables.put(mark_name, table);
  }

  /**
   * Returns a table that was marked in a query plan or null if no mark was
   * found.
   */
  public Table getMarkedTable(String mark_name) {
    if (marked_tables == null) {
      return null;
    }
    return (Table) marked_tables.get(mark_name);
  }

  /**
   * Put a Table into the cache.
   */
  public void putCachedNode(long id, Table table) {
    if (marked_tables == null) {
      marked_tables = new HashMap();
    }
    marked_tables.put(new Long(id), table);
  }

  /**
   * Returns a cached table or null if it isn't cached.
   */
  public Table getCachedNode(long id) {
    if (marked_tables == null) {
      return null;
    }
    return (Table) marked_tables.get(new Long(id));
  }

  /**
   * Clears the cache of any cached tables.
   */
  public void clearCache() {
    if (marked_tables != null) {
      marked_tables.clear();
    }
  }

}