/*
 * BooleanExpression.java
 *
 * Copyright (c) 1996 Chuck McManis, All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies.
 *
 * CHUCK MCMANIS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
 * SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. CHUCK MCMANIS
 * SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT
 * OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

package basic;
import java.io.PrintStream;

/**
 * This class implements Boolean expression parsing and evaluation.
 * unlike normal arithmetic expressions, boolean expressions are only
 * true or false.
 */
class BooleanExpression extends Expression {

    BooleanExpression(int t, Expression a, Expression b) throws BASICSyntaxError {
        super(t, a, b);
    }

    BooleanExpression(int t, Expression a) throws BASICSyntaxError {
        super(t, a);
    }

    double value(Program pgm) throws BASICRuntimeError {
        if (! (arg1.isString() || arg2.isString()))
            return super.value(pgm);

        switch (oper) {
            case OP_EQ:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) == 0) ? 1 : 0;
            case OP_NE:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) != 0) ? 1 : 0;
            case OP_LT:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) < 0) ? 1 : 0;
            case OP_LE:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) <= 0) ? 1 : 0;
            case OP_GT:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) > 0) ? 1 : 0;
            case OP_GE:
                return (arg1.stringValue(pgm).compareTo(arg2.stringValue(pgm)) >= 0) ? 1 : 0;
            default:
                return super.value(pgm);
        }
    }

}