Quadcap Embeddable Database

com/quadcap/sql/VectorExpression.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 antlr.RecognitionException;

import com.quadcap.sql.types.Value;

import com.quadcap.util.Debug;

/**
 * This might be a vector (row value constructor) or a cursor (table value
 * constructor)
 *
 * @author Stan Bailes
 */
public class VectorExpression extends TableExpression 
    implements Externalizable 
{
    Vector                              expressions     = new Vector();
    int                                 rank            = 1;

    public VectorExpression() {}

    public void addElement(Expression expression) throws RecognitionException {
        if (expressions.size() == 0) {
            // determine rank
            rank = expression.rank() + 1;
        } else {
            if (expression.rank() != rank-1) {
                throw new RecognitionException(
                    "Mismatched ranks in table expression");
            }
        }
        expressions.addElement(expression);
    }
    
    public int rank() { return rank; }

    public boolean isUpdatable() { return false; }

    public void getBaseTables(Vector v) {}

    public int size() { return expressions.size(); }

    public final Expression get(int i) {
        return (Expression)expressions.get(i);
    }

    public Row getValues(Session session, Cursor cursor) throws SQLException {
        if (rank == 1) {
            Row values = new Row();
            for (int i = 0; i < expressions.size(); i++) {
                Expression e = (Expression)expressions.elementAt(i);
                values.addElement(e.getValue(session, cursor));
            }
            return values;
        } else if (rank == 2) {
            Expression e = (Expression)expressions.elementAt(0);
            return e.getValues(session, cursor);
        }
        return null;
    }

    public Cursor getCursor(Session session, Cursor cursor)
        throws SQLException
    {
        if (rank == 1) {
            Vector v = new Vector();
            v.addElement(getValues(session, cursor));
            return new StaticCursor(session, v);
        } else if (rank == 2) {
            Vector cursorVec = new Vector();
            for (int i = 0; i < expressions.size(); i++) {
                Expression e = (Expression)expressions.elementAt(i);
                cursorVec.addElement(e.getValues(session, cursor));
            }
            return new StaticCursor(session, cursorVec);
        } else {
            return null;
        }
    }

    public void invert() {
        throw new RuntimeException("Can't invert vector expression");
    }

    public void visitSubExpressions(ExpressionVisitor ev) {
        for (int i = 0; i < expressions.size(); i++) {
            Expression ex = (Expression)expressions.elementAt(i);
            ev.visit(ex);
        }
    }

    public String toString() {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < expressions.size(); i++) {
            if (i > 0) sb.append(", ");
            sb.append(expressions.elementAt(i).toString());
        }
        return sb.toString();
    }

    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        expressions = (Vector)in.readObject();
    }
    
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(expressions);
    }

    /**
     * Return the (one-based) parameter from this VectorExpression which
     * is assumed to be a simple list of parameterized expressions
     */
    public Value getParameter(Session session, int pos) {
        try {
            if (rank == 2) {
                VectorExpression v = (VectorExpression)expressions.get(0);
                Expression e = v.get(pos-1);
                return e.getValue(session, null);
            }
        } catch (Throwable t) {}
        return null;
    }

    //#ifdef DEBUG
    public String name() { return "[]"; }
    //#endif
}