Quadcap Embeddable Database

com/quadcap/sql/MultiSet.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

import java.util.Hashtable;
import java.util.Iterator;
import java.util.Enumeration;

import com.quadcap.sql.io.ObjectInputStream;
import com.quadcap.sql.io.ObjectOutputStream;

import com.quadcap.sql.index.Btree;

import com.quadcap.util.Debug;
import com.quadcap.util.Util;

/**
 * Implement a multi-valued map over a Btree.
 *
 * @author Stan Bailes
 */
public class MultiSet {
    Btree                               map;

    public MultiSet(Btree map) {
        this.map = map;
    }
    
    public void put(String a, String b) throws IOException {
        //Debug.println("put(" + a + ", " + b + ")");
        byte[] ba = bytes(a);
        Hashtable t = map(map.get(ba));
        t.put(b, b);
        map.set(ba, bytes(t));
    }

    public void delete(String a, String b) throws IOException {
        //Debug.println("delete(" + a + ", " + b + ")");
        byte[] ba = bytes(a);
        Hashtable t = map(map.get(ba));
        t.remove(b);
        map.set(ba, bytes(t));
    }

    public void rename(String oldN, String newN, MultiSet rev) throws IOException {
        byte[] oldK = bytes(oldN);
        byte[] oldB = map.get(bytes(oldN));
        if (oldB != null && rev != null) {
            Iterator iter = map(oldB).keySet().iterator();
            while (iter.hasNext()) {
                String nam = iter.next().toString();
                rev.delete(nam, oldN);
                rev.put(nam, newN);
            }
            map.delete(oldK);
            map.set(bytes(newN), oldB);
        }
    }

    public Enumeration get(String key) throws IOException {
        Hashtable t = map(map.get(bytes(key)));
        return t.keys();
    }

    static byte[] bytes(Hashtable t) {
        try {
            ObjectOutputStream os = new ObjectOutputStream(null);
            os.writeInt(t.size());
            Enumeration e = t.keys();
            while (e.hasMoreElements()) {
                os.writeObject(e.nextElement().toString());
            }
            return os.toByteArray();
        } catch (IOException e) {
            Debug.print(e);
            throw new RuntimeException(e.toString());
        }
    }

    static Hashtable map(byte[] b) {
        Hashtable t = new Hashtable();
        if (b != null) {
            try {
                ByteArrayInputStream bis = new ByteArrayInputStream(b);
                ObjectInputStream is = new ObjectInputStream(bis);
                int len = is.readInt();
                for (int i = 0; i < len; i++) {
                    String s = (String)is.readObject();
                    t.put(s, s);
                }
            } catch (Exception e) {
                Debug.print(e);
                throw new RuntimeException(e.toString());
            }
        }
        return t;
    }

    static byte[] bytes(String s) {
        return Util.bytes(s);
    }
    
    public void delete(String a) throws IOException {
        map.delete(bytes(a));
    }

    //#ifdef DEBUG
    public void display(PrintWriter w) throws IOException {
        map.display(w);
    }
    //#endif

}