Quadcap Embeddable Database

com/quadcap/sql/SelectFromTable.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.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.util.Vector;

import java.sql.SQLException;

import com.quadcap.sql.meta.MetaCursor;

import com.quadcap.util.Debug;

/**
 * Table expression implementation of <b>TABLE</b> <i>table-name</i>.
 *
 * @author Stan Bailes
 */
public class SelectFromTable extends TableExpression 
    implements Externalizable 
{
    String                      tableName;
    Relation                    table           = null;

    /**
     * Default constructor (required for Externalizable)
     */
    public SelectFromTable() {}

    /**
     * Constructor from specified table name
     */
    public SelectFromTable(String tableName) {
        this.tableName = tableName;
    }

    /**
     * We are a table expression;
     */
    public int rank() { return 2; }

    /**
     * And to prove it, here's our cursor.
     */
    public Cursor getCursor(Session session, Cursor cursor)
        throws SQLException
    {
        if (table == null) {
            try {
                Database db = session.getDatabase();
                table = db.getRelation(tableName);
            } catch (IOException e) {
                throw DbException.wrapThrowable(e);
            }
            if (table == null) {
                Cursor c = MetaCursor.find(session, tableName);
                if (c != null) return c;

                throw new SQLException("No such table: " + tableName, "42000");
            }
        }
        return table.getCursor(session, where, null, cursor);
    }

    /**
     * Our cursor is even updateable; we are so cool
     */
    public boolean isUpdatable() {
        return true;
    }

    /**
     *  TableExpression.getBaseTables(): We *are* the base table!
     */
    public void getBaseTables(Vector v) {
        v.addElement(tableName);
    }

    /**
     * Externalizable.readExternal(): Read me from a stream.
     */
    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        this.tableName = (String)in.readObject();
        this.table = null;
    }
    
    /**
     * Externalizable.writeExternal(): Write me to a stream.
     */
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(tableName);
    }

    public String toString() {
        return tableName;
    }

    /**
     * Public accessor for table name
     */
    public String getTableName() {
        return tableName;
    }

    /**
     * Public 'setter' for table name
     */
    public void setTableName(String t) {
        tableName = t;
    }

    //#ifdef DEBUG
    public String name() { return tableName; }
    //#endif
}