-\section pf_flexml_bypassing Bypassing the XML parser with your own C functions
-<b>NOTE THAT THIS DOCUMENTATION, WHILE STILL WORKING, IS STRONGLY DEPRECATED</b>
-
-So you want to bypass the XML files parser, uh? Maybe doing some parameter
-sweep experiments on your simulations or so? This is possible, and
-it's not even really difficult (well. Such a brutal idea could be
-harder to implement). Here is how it goes.
-
-For this, you have to first remember that the XML parsing in SimGrid is done
-using a tool called FleXML. Given a DTD, this gives a flex-based parser. If
-you want to bypass the parser, you need to provide some code mimicking what
-it does and replacing it in its interactions with the SURF code. So, let's
-have a look at these interactions.
-
-FleXML parser are close to classical SAX parsers. It means that a
-well-formed SimGrid platform XML file might result in the following
-"events":
-
- - start "platform_description" with attribute version="4"
- - start "host" with attributes id="host1" power="1.0"
- - end "host"
- - start "host" with attributes id="host2" power="2.0"
- - end "host"
- - start "link" with ...
- - end "link"
- - start "route" with ...
- - start "link_ctn" with ...
- - end "link_ctn"
- - end "route"
- - end "platform_description"
-
-The communication from the parser to the SURF code uses two means:
-Attributes get copied into some global variables, and a surf-provided
-function gets called by the parser for each event. For example, the event
- - start "host" with attributes id="host1" power="1.0"
-
-let the parser do something roughly equivalent to:
-\verbatim
- strcpy(A_host_id,"host1");
- A_host_power = 1.0;
- STag_host();
-\endverbatim
-
-In SURF, we attach callbacks to the different events by initializing the
-pointer functions to some the right surf functions. Since there can be
-more than one callback attached to the same event (if more than one
-model is in use, for example), they are stored in a dynar. Example in
-host_ptask_L07.c:
-\verbatim
- /* Adding callback functions */
- surf_parse_reset_parser();
- surfxml_add_callback(STag_surfxml_host_cb_list, &parse_cpu_init);
- surfxml_add_callback(STag_surfxml_prop_cb_list, &parse_properties);
- surfxml_add_callback(STag_surfxml_link_cb_list, &parse_link_init);
- surfxml_add_callback(STag_surfxml_route_cb_list, &parse_route_set_endpoints);
- surfxml_add_callback(ETag_surfxml_link_c_ctn_cb_list, &parse_route_elem);
- surfxml_add_callback(ETag_surfxml_route_cb_list, &parse_route_set_route);
-
- /* Parse the file */
- surf_parse_open(file);
- xbt_assert(!surf_parse(), "Parse error in %s", file);
- surf_parse_close();
-\endverbatim
-
-So, to bypass the FleXML parser, you need to write your own version of the
-surf_parse function, which should do the following:
- - Fill the A_<tag>_<attribute> variables with the wanted values
- - Call the corresponding STag_<tag>_fun function to simulate tag start
- - Call the corresponding ETag_<tag>_fun function to simulate tag end
- - (do the same for the next set of values, and loop)
-
-Then, tell SimGrid that you want to use your own "parser" instead of the stock one:
-\verbatim
- surf_parse = surf_parse_bypass_environment;
- MSG_create_environment(NULL);
- surf_parse = surf_parse_bypass_application;
- MSG_launch_application(NULL);
-\endverbatim
-
-A set of macros are provided at the end of
-include/surf/surfxml_parse.h to ease the writing of the bypass
-functions. An example of this trick is distributed in the file
-examples/msg/masterslave/masterslave_bypass.c
-
-
