A Guide to Using ACT Data Structures

Act files are read in automatically when the library is initialized as:

Act::Init (&argc, &argv);

where argc and argv are the usual command-line options to main(). This should be the first function call before any other ACT functions are used. When this call is executed, the file provided in the command-line is read in and processed to create the internal act data structures. Typically, the next step is to create an Act pointer to the data structure:

Act *a;
a = new Act (argv[1]);

Once the act pointer has been created, a process (provided in the command-line arguments) within the file can be accessed and expanded:

Process *p = a->findProcess (argv[2]);
p = p->Expand (ActNamespace::Global(), p->CurScope(), 0, NULL);

The languages body can be accessed from the process pointer:

act_languages *lang;
lang = p->getlang();

A language body can be accessed from the languages pointer. For example, for the chp body:

act_chp *chp;
chp = lang->getchp();

Finally, to get a pointer to the actual object that stores the chp data structure:

act_chp_lang_t *chp_lang;
chp_lang = chp->c;

The act_chp_lang_t object is an object of the act_chp_lang structure (definition in lang.h). It contains an integer type, which says what type of ACT_CHP token it is. Two other members label and space are typically NULL. The final member u is an object that contains the actual CHP statement. For example, any given u can be a loop, doloop, assignment statement, communication action, etc. Each of these have their own structure and the object is a union of these. One of the possibilities: a comma or semicolon separated list of statements is stored as a list_t linked list semi_comma.cmd.

The linked list list_t contains elements of type list_item_t. See list.h or list.c for details. This is used to store lists of statements. To get the actual statement stored in the list of statements, call list_value on the required listitem_t of the list:

act_chp_lang_t *c; // contains the overall chp body
act_chp_lang_t *stmt;
list_t *stmt_list;
listitem_t *li;

stmt_list = c->u.semi_comma.cmd; // returns the linked list

for (li = list_first (stmt_list); li; li = list_next (li)) {

stmt = (act_chp_lang_t *)(list_value(li));
// do something here

}