view src/luan/interp/UnmExpr.java @ 112:f5af13062b10

fix previous rev git-svn-id: https://luan-java.googlecode.com/svn/trunk@113 21e917c8-12df-6dd8-5cb6-c86387c605b9
author fschmidt@gmail.com <fschmidt@gmail.com@21e917c8-12df-6dd8-5cb6-c86387c605b9>
date Fri, 23 May 2014 22:52:39 +0000
parents 6ca02b188dba
children
line wrap: on
line source

package luan.interp;

import luan.Luan;
import luan.LuanFunction;
import luan.LuanException;
import luan.LuanSource;
import luan.LuanBit;


// unary minus
final class UnmExpr extends UnaryOpExpr {

	UnmExpr(LuanSource.Element se,Expr op) {
		super(se,op);
	}

	@Override public Object eval(LuanStateImpl luan) throws LuanException {
		Object o = op.eval(luan);
		Number n = Luan.toNumber(o);
		if( n != null )
			return -n.doubleValue();
		LuanBit bit = luan.bit(se);
		LuanFunction fn = bit.getHandlerFunction("__unm",o);
		if( fn != null ) {
			return Luan.first(bit.call(fn,"__unm",new Object[]{o}));
		}
		throw bit.exception("attempt to perform arithmetic on a "+Luan.type(o)+" value");
	}
}