Key.java :  » Database-ORM » TJDO » com » triactive » jdo » store » Java Open Source

/*
 * Copyright 2002 (C) TJDO.
 * All rights reserved.
 *
 * This software is distributed under the terms of the TJDO License version 1.0.
 * See the terms of the TJDO License in the documentation provided with this software.
 *
 * $Id: Key.java,v 1.4 2003/04/16 03:26:58 jackknifebarber Exp $
 */

package com.triactive.jdo.store;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import javax.jdo.JDOFatalInternalException;


abstract class Key
{
    protected BaseTable table;
    protected ArrayList columns = new ArrayList();


    protected Key(BaseTable table)
    {
        this.table = table;
    }


    protected void assertSameTable(Column col)
    {
        if (!table.equals(col.getTable()))
            throw new JDOFatalInternalException("Cannot add " + col + " as key column for " + table);
    }


    public BaseTable getTable()
    {
        return table;
    }


    public List getColumns()
    {
        return Collections.unmodifiableList(columns);
    }


    public String getColumnList()
    {
        return getColumnList(columns);
    }


    public boolean startsWith(Key k)
    {
        int kSize = k.columns.size();

        return kSize <= columns.size() && k.columns.equals(columns.subList(0, kSize));
    }


    protected static void setMinSize(List list, int size)
    {
        while (list.size() < size)
            list.add(null);
    }


    public static String getColumnList(Collection cols)
    {
        StringBuffer s = new StringBuffer("(");
        Iterator i = cols.iterator();

        while (i.hasNext())
        {
            Column col = (Column)i.next();

            if (col == null)
                s.append('?');
            else
                s.append(col.getName());

            if (i.hasNext())
                s.append(',');
        }

        s.append(')');

        return s.toString();
    }
}