[SynopticScenes::] Scenes.

To compile the main/synoptic/scenes submodule.

@ Our inventory |inv| already contains a list |inv->scene_nodes| of all packages
in the tree with type |_instance| which are of the kind |K_scene|. (These do not
have ID numbers here because they already have |instance_id| values by virtue
of being instances.)

=
void SynopticScenes::compile(inter_tree *I, pipeline_step *step, tree_inventory *inv) {
	if (InterNodeList::array_len(inv->scene_nodes) > 0)
		InterNodeList::array_sort(inv->scene_nodes, MakeSynopticModuleStage::module_order);
	@<Define SHOWSCENESTATUS function@>;
	@<Define DETECTSCENECHANGE function@>;
}

@<Define SHOWSCENESTATUS function@> =
	inter_name *iname = HierarchyLocations::iname(I, SHOWSCENESTATUS_HL);
	Synoptic::begin_function(I, iname);
	for (int i=0; i<InterNodeList::array_len(inv->scene_nodes); i++) {
		inter_package *pack =
			PackageInstruction::at_this_head(inv->scene_nodes->list[i].node);
		inter_symbol *ssf_s = Metadata::required_symbol(pack, I"^scene_status_fn");
		Produce::inv_call_symbol(I, ssf_s);
	}
	Synoptic::end_function(I, step, iname);

@ There is one argument, |chs|: the number of iterations so far. Iterations
occur because each set of scene changes could change the circumstances in such
a way that other scene changes are now required (through external conditions,
not through anchors); we don't want this to lock up, so we will cap recursion.
Within the function, a second local variable, |ch|, is a flag indicating
whether any change in status has or has not occurred.

@d MAX_SCENE_CHANGE_ITERATION 20

@<Define DETECTSCENECHANGE function@> =
	inter_name *iname = HierarchyLocations::iname(I, DETECTSCENECHANGE_HL);
	Synoptic::begin_function(I, iname);
	inter_symbol *chs_s = Synoptic::local(I, I"chs", NULL);
	inter_symbol *Again_l = Produce::reserve_label(I, I".Again");
	inter_symbol *CScene_l = Produce::reserve_label(I, I".CScene");
	Produce::place_label(I, Again_l);
	for (int i=0; i<InterNodeList::array_len(inv->scene_nodes); i++) {
		inter_package *pack =
			PackageInstruction::at_this_head(inv->scene_nodes->list[i].node);
		inter_symbol *scf_s = Metadata::required_symbol(pack, I"^scene_change_fn");
		Produce::inv_primitive(I, IF_BIP);
		Produce::down(I);
			Produce::inv_call_symbol(I, scf_s);
			Produce::code(I);
			Produce::down(I);
				Produce::inv_primitive(I, JUMP_BIP);
				Produce::down(I);
					Produce::lab(I, CScene_l);
				Produce::up(I);				
			Produce::up(I);
		Produce::up(I);
	}
	Produce::rfalse(I);

	Produce::place_label(I, CScene_l);

	Produce::inv_primitive(I, IF_BIP);
	Produce::down(I);
		Produce::inv_primitive(I, GT_BIP);
		Produce::down(I);
			Produce::val_symbol(I, K_value, chs_s);
			Produce::val(I, K_value,
				InterValuePairs::number((inter_ti) MAX_SCENE_CHANGE_ITERATION));
		Produce::up(I);
		Produce::code(I);
		Produce::down(I);
			Produce::inv_primitive(I, PRINT_BIP);
			Produce::down(I);
				Produce::val_text(I, I">--> The scene change machinery is stuck.\n");
			Produce::up(I);
			Produce::rtrue(I);
		Produce::up(I);
	Produce::up(I);
	Produce::inv_primitive(I, PREINCREMENT_BIP);
	Produce::down(I);
		Produce::ref_symbol(I, K_value, chs_s);
	Produce::up(I);
	Produce::inv_primitive(I, JUMP_BIP);
	Produce::down(I);
		Produce::lab(I, Again_l);
	Produce::up(I);				
	Synoptic::end_function(I, step, iname);