package luan.interp;

import luan.Lua;
import luan.LuaNumber;
import luan.LuaFunction;
import luan.LuaException;


final class LtExpr extends BinaryOpExpr {

	LtExpr(Expr op1,Expr op2) {
		super(op1,op2);
	}

	@Override public Object eval(LuaStateImpl lua) throws LuaException {
		Object o1 = op1.eval(lua);
		Object o2 = op2.eval(lua);
		if( o1 instanceof LuaNumber && o2 instanceof LuaNumber ) {
			LuaNumber n1 = (LuaNumber)o1;
			LuaNumber n2 = (LuaNumber)o2;
			return n1.compareTo(n2) < 0;
		}
		if( o1 instanceof String && o2 instanceof String ) {
			String s1 = (String)o1;
			String s2 = (String)o2;
			return s1.compareTo(s2) < 0;
		}
		LuaFunction fn = lua.getBinHandler("__lt",o1,o2);
		if( fn != null )
			return Lua.toBoolean( Utils.first(fn.call(lua,o1,o2)) );
		throw new LuaException( "attempt to compare " + Lua.type(o1) + " with " + Lua.type(o2) );
	}
}