Function addreturn

src/lua/lua_environment.cpp:146–156

** Try to compile line on the stack as 'return ;'; on return, stack ** has either compiled chunk or original line (if compilation failed). */

** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn(lua_State *L)
{
	const char *line = lua_tostring(L, -1);  /* original line */
	const char *retline = lua_pushfstring(L, "return %s;", line);
	int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
	if (status == LUA_OK)
		lua_remove(L, -2); /* remove modified line */
	else
		lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
	return status;
}

/*
** Read a line and try to load (compile) it first as an expression (by