/* CompareUnaryOperator Copyright (C) 1998-1999 Jochen Hoenicke.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id$
 */

package net.sf.jode.expr;
import net.sf.jode.type.Type;
import net.sf.jode.decompiler.TabbedPrintWriter;

public class CompareUnaryOperator extends Operator {
    boolean objectType;
    Type compareType;

    public CompareUnaryOperator(Type type, int op) {
        super(Type.tBoolean, op);
        compareType = type;
        objectType = (type.isOfType(Type.tUObject));
	initOperands(1);
    }

    public int getPriority() {
        switch (getOperatorIndex()) {
        case 26:
        case 27:
            return 500;
        case 28:
        case 29:
        case 30:
        case 31: 
            return 550;
        }
        throw new RuntimeException("Illegal operator");
    }

    public Type getCompareType() {
	return compareType;
    }

    public void updateSubTypes() {
	subExpressions[0].setType(Type.tSubType(compareType));
    }

    public void updateType() {
    }

    public Expression simplify() {
        if (subExpressions[0] instanceof CompareToIntOperator) {

	    CompareToIntOperator cmpOp 
		= (CompareToIntOperator) subExpressions[0];

	    boolean negated = false;
	    int opIndex = getOperatorIndex();
	    if (cmpOp.allowsNaN && getOperatorIndex() > NOTEQUALS_OP) {
		if (cmpOp.greaterOnNaN ==
		    (opIndex == GREATEREQ_OP || opIndex == GREATER_OP)) {
		    negated = true;
		    opIndex ^= 1;
		}
	    }
            Expression newOp = new CompareBinaryOperator
                (cmpOp.compareType, opIndex, cmpOp.allowsNaN)
		.addOperand(cmpOp.subExpressions[1])
		.addOperand(cmpOp.subExpressions[0]);

	    if (negated)
		return newOp.negate().simplify();
	    return newOp.simplify();
        }
        if (subExpressions[0].getType().isOfType(Type.tBoolean)) {
            /* xx == false */
            if (getOperatorIndex() == EQUALS_OP)
                return subExpressions[0].negate().simplify();
            /* xx != false */
            if (getOperatorIndex() == NOTEQUALS_OP)
                return subExpressions[0].simplify();
	}
	return super.simplify();
    }

    public Expression negate() {
	if ((getType() != Type.tFloat && getType() != Type.tDouble)
	    || getOperatorIndex() <= NOTEQUALS_OP) {
            setOperatorIndex(getOperatorIndex() ^ 1);
            return this;
        } 
        return super.negate();
    }

    public boolean opEquals(Operator o) {
	return (o instanceof CompareUnaryOperator)
	    && o.getOperatorIndex() == getOperatorIndex();
    }

    public void dumpExpression(TabbedPrintWriter writer)
	throws java.io.IOException {
	subExpressions[0].dumpExpression(writer, getPriority()+1);
	writer.breakOp();
	writer.print(getOperatorString());
	writer.print(objectType?"null":"0");
    }
}