package luan.impl;

import luan.Luan;
import luan.LuanTable;
import luan.LuanFunction;
import luan.LuanException;


final class LenExpr extends UnaryOpExpr {

	LenExpr(Expr op) {
		super(op);
	}

	@Override public Object eval(LuanStateImpl luan) throws LuanException {
		Object o = op.eval(luan);
		if( o instanceof String ) {
			String s = (String)o;
			return s.length();
		}
		if( o instanceof byte[] ) {
			byte[] a = (byte[])o;
			return a.length;
		}
		if( !(o instanceof LuanTable) )
			throw new LuanException(luan, "attempt to get length of a " + Luan.type(o) + " value" );
		LuanTable t = (LuanTable)o;
		return t.length(luan);
	}
}