Quadcap Embeddable Database

com/quadcap/sql/BinaryExpression.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.Enumeration;
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.Value;

import com.quadcap.util.Debug;

/**
 * Expression class for all binary ops.
 *
 * @author Stan Bailes
 */
public class BinaryExpression extends Expression implements Externalizable {
    Expression                          e       = null;
    Expression                          f       = null;
    int                                 op      = -1;
    boolean                             not     = false;

    /**
     * Default constructor
     */
    public BinaryExpression() {}

    /**
     * Parser's constructor:  A binary expression node consists of an opcode and two
     * "child" expressions.
     */
    public BinaryExpression(int op, Expression e, Expression f) {
        this.op = op;
        this.e = e;
        this.f = f;
    }

    public int rank() { return 0; }

    public Type getType(Session session, Cursor cursor) throws SQLException {
        return e.getType(session, cursor);              // XXX not quite...
    }

    public Value getValue(Session session, Cursor cursor) throws SQLException {
        Value eval = e.getValue(session, cursor);
        Value fval = f.getValue(session, cursor);
        Value ret = Value.binop(op, eval, fval);
        if (not) {
            ret = ret.unop(Op.NOT);
        }
        return ret;
    }
    
    public void invert() {
        not = !not;
    }

    public String toString() {
        String n = not ? "not " : "";
        return n + e + " " + Op.toString(op) + " " + f;
    }

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

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