package luan.impl;

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


final class LenExpr extends UnaryOpExpr {

	LenExpr(LuanElement el,Expr op) {
		super(el,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;
		}
		luan.push(el,null);
		try {
			if( !(o instanceof LuanTable) )
				throw luan.exception( "attempt to get length of a " + Luan.type(o) + " value" );
			LuanTable t = (LuanTable)o;
			return t.length(luan);
		} finally {
			luan.pop();
		}
	}
}