recordenumerationimpl.java

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/*
 *  MicroEmulator
 *  Copyright (C) 2001-2005 Bartek Teodorczyk <[e-mail]>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package com.barteo.emulator.util;

import java.util.Enumeration;
import java.util.Vector;

import javax.microedition.rms.InvalidRecordIDException;
import javax.microedition.rms.RecordComparator;
import javax.microedition.rms.RecordEnumeration;
import javax.microedition.rms.RecordFilter;
import javax.microedition.rms.RecordListener;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;
import javax.microedition.rms.RecordStoreNotOpenException;


public class RecordEnumerationImpl implements RecordEnumeration
{
	private RecordStoreImpl recordStoreImpl;
	private RecordFilter filter;
	private RecordComparator comparator;
	private boolean keepUpdated;

	private Vector enumerationRecords = new Vector();
	private int currentRecord;    
    
	private RecordListener recordListener = new RecordListener() 
    {
        public void recordAdded(RecordStore recordStore, int recordId)
        {
            rebuild();
        }

        public void recordChanged(RecordStore recordStore, int recordId)
        {
            rebuild();
        }

        public void recordDeleted(RecordStore recordStore, int recordId)
        {
            rebuild();
        }
    };


    public RecordEnumerationImpl(RecordStoreImpl recordStoreImpl, RecordFilter filter, RecordComparator comparator, boolean keepUpdated)
    {
    	this.recordStoreImpl = recordStoreImpl;
        this.filter = filter;
        this.comparator = comparator;
        this.keepUpdated = keepUpdated;

        rebuild();

        if (keepUpdated) {
        	recordStoreImpl.addRecordListener(recordListener);
        }
    }


    public int numRecords()
    {
        return enumerationRecords.size();
    }


    public byte[] nextRecord() 
    		throws InvalidRecordIDException, RecordStoreNotOpenException, RecordStoreException
    {
        if (!recordStoreImpl.isOpen()) {
            throw new RecordStoreNotOpenException();
        }

        if (currentRecord >= numRecords()) {
            throw new InvalidRecordIDException();
        }

        byte[] result = ((EnumerationRecord) enumerationRecords
                .elementAt(currentRecord)).value;
        currentRecord++;

        return result;
    }


    public int nextRecordId() 
    		throws InvalidRecordIDException
    {
        if (currentRecord >= numRecords()) {
            throw new InvalidRecordIDException();
        }

        int result = ((EnumerationRecord) enumerationRecords
                .elementAt(currentRecord)).recordId;
        currentRecord++;

        return result;
    }


    public byte[] previousRecord() 
    		throws InvalidRecordIDException, RecordStoreNotOpenException, RecordStoreException
    {
        if (!recordStoreImpl.isOpen()) {
            throw new RecordStoreNotOpenException();
        }
        if (currentRecord < 0) {
            throw new InvalidRecordIDException();
        }

        byte[] result = ((EnumerationRecord) enumerationRecords
                .elementAt(currentRecord)).value;
        currentRecord--;

        return result;
    }


    public int previousRecordId() 
    		throws InvalidRecordIDException
    {
        if (currentRecord < 0) {
            throw new InvalidRecordIDException();
        }

        int result = ((EnumerationRecord) enumerationRecords
                .elementAt(currentRecord)).recordId;
        currentRecord--;

        return result;
    }


    public boolean hasNextElement()
    {
        if (currentRecord == numRecords()) {
            return false;
        } else {
            return true;
        }
    }


    public boolean hasPreviousElement()
    {
        if (currentRecord == 0) {
            return false;
        } else {
            return true;
        }
    }


    public void reset()
    {
        currentRecord = 0;
    }


    public void rebuild()
    {
        enumerationRecords.removeAllElements();

        int position;
        for (Enumeration e = recordStoreImpl.records.keys(); e.hasMoreElements();) {
            Object key = e.nextElement();
            if (filter != null && !filter.matches((byte[]) recordStoreImpl.records.get(key))) {
                continue;
            }
            byte[] tmp_data = (byte[]) recordStoreImpl.records.get(key);
            // here should be better sorting
            if (comparator != null) {
                for (position = 0; position < enumerationRecords.size(); position++) {
                    if (comparator.compare(tmp_data, (byte[]) enumerationRecords.elementAt(position)) == RecordComparator.FOLLOWS) {
                        break;
                    }
                }
            } else {
                position = enumerationRecords.size();
            }
            enumerationRecords.insertElementAt(
                    new EnumerationRecord(((Integer) key).intValue(), tmp_data), position);
        }
        currentRecord = 0;
    }


    public void keepUpdated(boolean keepUpdated)
    {
        if (keepUpdated) {
            if (!this.keepUpdated) {
                rebuild();
                recordStoreImpl.addRecordListener(recordListener);
            }
        } else {
        	recordStoreImpl.removeRecordListener(recordListener);
        }

        this.keepUpdated = keepUpdated;
    }


    public boolean isKeptUpdated()
    {
        return keepUpdated;
    }


    public void destroy()
    {
    }


    class EnumerationRecord
    {
        int recordId;

        byte[] value;

        
        EnumerationRecord(int recordId, byte[] value)
        {
            this.recordId = recordId;
            this.value = value;
        }
    }    

}