/*
 * Load the file KhPol_knots_data if it wasn't already loaded.
 */

global(KHPOL_KNOTS_DATA);

/*
 * Check whether a file exists of not
 */
file_exists(filename) =
	extern(concat(["test -e ", filename, " && echo 1 || echo 0"]));

/*
 * Load file2load or file2load.gz (whatever exists) or print loaded_msg if
 * it's already been done, depending on the value of loaded_var.
 */
load_data_file(file2load, loaded_var, loaded_msg) =
{
	if (eval(loaded_var) == "Loaded",
		/* Nothing to worry about, print the message and relax */
		print(loaded_msg);
		,
		/* Ok, it's our first time here. Try to load the file then */
		if (file_exists(file2load),
			read(file2load);
			,
			if (file_exists(concat(file2load, ".gz")),
				extern(concat(["zcat ", file2load, ".gz"]));
				,
				error("Neither file ", file2load, " nor ",
						file2load, ".gz exist!");
			);
		);
		eval(concat(loaded_var, " = \"Loaded\""));
	);
}

load_data_file("KhPol_knots_data", "KHPOL_KNOTS_DATA",  \
	"Khovanov polynomials for knots with up to 13 crossings already loaded!");