Quadcap Embeddable Database

com/quadcap/sql/QuantifiedCompare.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.types.Op;
import com.quadcap.sql.types.Type;
import com.quadcap.sql.types.TypeBoolean;
import com.quadcap.sql.types.Value;
import com.quadcap.sql.types.ValueBoolean;

import com.quadcap.util.Debug;

/**
 * Expression implemented quantified comparisons: <b>ALL</b>, <b>ANY</b>.
 *
 * @author Stan Bailes
 */
public class QuantifiedCompare extends Expression implements Externalizable {
    Expression                          e               = null;
    int                                 op              = 0;
    int                                 quant           = 0;
    Expression                          q               = null;
    boolean                             not             = false;
    ValueBoolean                        value           = null;

    public QuantifiedCompare() {}
    
    public QuantifiedCompare(Expression e, int op, int quant, Expression q) {
        this.e = e;
        this.op = op;
        this.quant = quant;
        this.q = q;
    }

    public int rank() { return 1; }

    public void invert() { not = !not; }

    static boolean compare(int op, Row a, Row b) throws SQLException {
        boolean eq = true;
        for (int i = 1; eq && i <= a.size(); i++) {
            Value va = a.item(i);
            Value vb = b.item(i);
            eq = Value.boolOp(op, va, vb);
        }
        return eq;
    }

    public Type getType(Session session, Cursor cursor) {
        return TypeBoolean.typeBoolean;
    }

    public Value getValue(Session session, Cursor cursor)
        throws SQLException
    {
        Cursor qcursor = q.getCursor(session, cursor);
        try {
            Row row = e.getValues(session, cursor);
            boolean res = false;

            if (quant == Op.ALL) {
                res = true;
                while (res && qcursor.next()) {
                    Row crow = qcursor.getRow();
                    res = compare(op, row, crow);
                }
            } else if (quant == Op.ANY) {
                while (!res && qcursor.next()) {
                    Row crow = qcursor.getRow();
                    res = compare(op, row, crow);
                }
            } else {
                throw new SQLException("bad quantifier: " + quant, "42000");
            }
            return new ValueBoolean(not ^ res);
        } finally {
            qcursor.close();
        }
    }

    public void visitSubExpressions(ExpressionVisitor ev) {
        ev.visit(e);
        ev.visit(q);
    }

    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        e = (Expression)in.readObject();
        op = in.read();
        quant = in.read();
        q = (Expression)in.readObject();
        not = in.read() == 1;
    }
    
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(e);
        out.write(op);
        out.write(quant);
        out.writeObject(q);
        out.write(not ? 1 : 0);
    }

    public String toString() {
        StringBuffer sb = new StringBuffer(e.toString());
        sb.append(' ');
        sb.append(Op.toString(op));
        sb.append(' ');
        sb.append(Op.toString(quant));
        sb.append(' ');
        sb.append(q.toString());
        return sb.toString();
    }
}