VIM: first_autopat / last_autopat

first_autopat and last_autopat are both arrays that store a pointers to AutoPat structs for each event:

static AutoPat *first_autopat[NUM_EVENTS] = {NULL, … };
static AutoPat *last_autopat [NUM_EVENTS] = {NULL, … };

An AutoPat has the member next which points to another AutoPat or NULL. This allows to create a linked list.

An AutoPat also has the member to a (linked list) of AutoCmd. Each AutoCmd stores a command (char_u *cmd). These commands are executed if the AutoPat that the AutoCmd hangs on matches the conditions stored in the AutoPat.

Each element of the last_autopat array points to tha last AutoPat in an event's linked list of AutoPat.

The general design of these linked lists is depicted in the following graphic: