! A priority-daemons extension for Inform libraries 6/5. 
! This is a pain in the ass to install, because you have to delete
! a large chunk of parserm and stick in calls to this stuff. Probably
! worthwhile, though.

! This version does not support timers. That's because I never use timers.

! We keep a simple-ass data structure: an array of daemon objects, 
! no holes, sorted by priority from highest to lowest.

Constant MAX_DAEMONS = 32;

! Constant DAEMONDEBUG;

Property daemon_priority 0;

Global daemon_index = -1; ! used during daemon iteration 
Global performing_daemons = false;
Global num_daemons = 0;

Array daemon_list --> MAX_DAEMONS;

[ PerformDaemons   obj;

	performing_daemons = true;
	
	#ifdef DAEMONDEBUG;
	print "^[PerformDaemons: ", num_daemons, " active...]^";
	for (daemon_index = 0 : 
		daemon_index < num_daemons : 
		daemon_index++) {
		obj = daemon_list-->daemon_index;
		print "[", daemon_index, ": ", (object) obj, " (", obj.daemon_priority, ")]^";
	}
	#endif;

	for (daemon_index = 0 : 
		deadflag == 0 && daemon_index < num_daemons : 
		daemon_index++) {
		obj = daemon_list-->daemon_index;
		#ifdef DAEMONDEBUG;
		print "[Running daemon ", daemon_index, ": ", (object) obj, " (",
			obj.daemon_priority, ")]^";
		#endif;
		RunRoutines(obj, daemon);
	}
	
	#ifdef DAEMONDEBUG;
	print "[Daemons all finished.]^";
	#endif;

	performing_daemons = false;
	daemon_index = -1; ! always reset to -1 after use
];

[ StartDaemon obj   pri ix jx;

	if (num_daemons >= MAX_DAEMONS) {
		RunTimeError(4);
		return;
	}
	
	pri = obj.daemon_priority;
	
	for (ix=0 : ix<num_daemons : ix++) {
		jx = daemon_list-->ix;
		if (jx == obj) {
			return; ! already in daemon list
		}
		if (pri > jx.daemon_priority)
			break;
	}
	
	! now insert a daemon before object ix.
	
	for (jx=num_daemons-1 : jx >= ix : jx--) {
		daemon_list-->(jx+1) = daemon_list-->jx;
	}
	daemon_list-->ix = obj;
	
	if (daemon_index >= 0) {
		! if the executing daemon is on or after object ix, kick the index forward
		! so that it doesn't repeat itself.
		if (daemon_index >= ix)
			daemon_index++;
	}

	num_daemons++;
];

[ StopDaemon obj   ix jx;

	for (ix=0 : ix<num_daemons : ix++) {
		jx = daemon_list-->ix;
		if (jx == obj) {
			break; ! already in daemon list
		}
	}
	
	if (ix >= num_daemons)
		return; ! not running
		
	for (jx=ix : jx < num_daemons-1 : jx++) {
		daemon_list-->jx = daemon_list-->(jx+1);
	}
	daemon_list-->(num_daemons-1) = 0;
	
	if (daemon_index >= 0) {
		! if the executing daemon is after object ix, kick the index backward
		! so that it doesn't repeat itself. If it's equal, kick it backward
		! anyway so that the next executing daemon is ix.
		if (daemon_index >= ix)
			daemon_index--;
	}

	num_daemons--;
];