1	import Base
2	import ./machine.bend as M
3	
4	# Bevy NextState::set_if_different preserves an existing forced same target.
5	# Equality is the same closed erased V comparator used by apply/conditions.
6	def forced_pending_generic(-V:Data,same:Bool,prior:V,value:V) -> M.Pending<V>:
7	  match same:
8	    case True{}:M.Queued{prior,False{}}
9	    case False{}:M.Queued{value,True{}}
10	def forced_pending(~V:Data,same:Bool,prior:V,value:V) -> M.Pending<V>:
11	  forced_pending_generic(V,same,prior,value)
12	
13	def conditional_pending_generic(-V:Data,same:V -> V -> Bool,pending:M.Pending<V>,+value:V) -> M.Pending<V>:
14	  match pending:
15	    case M.Queued{+prior,False{}}:forced_pending_generic(V,same(prior,value),prior,value)
16	    case _:M.Queued{value,True{}}
17	def conditional_pending(~V:Data,~same:V -> V -> Bool,pending:M.Pending<V>,+value:V) -> M.Pending<V>:
18	  conditional_pending_generic(V,same,pending,value)
19	
20	def conditional_generic(-S:Data,-K:Data,-V:Data,same:V -> V -> Bool,slot:M.Slot<S,K,V>,value:V) -> M.Slot<S,K,V>:
21	  match slot:
22	    case M.Missing{}:M.Missing{}
23	    case M.Present{current,pending,previous,changed}:M.Present{current,conditional_pending_generic(V,same,pending,value),previous,changed}
24	def conditional(~S:Data,~K:Data,~V:Data,~same:V -> V -> Bool,slot:M.Slot<S,K,V>,value:V) -> M.Slot<S,K,V>:
25	  conditional_generic(S,K,V,same,slot,value)
26	
27	def queue_generic(-S:Data,-K:Data,-V:Data,same:V -> V -> Bool,slot:M.Slot<S,K,V>,value:V,skipSame:Bool) -> M.Slot<S,K,V>:
28	  match skipSame:
29	    case False{}:M.queue_generic(S,K,V,slot,value,False{})
30	    case True{}:conditional_generic(S,K,V,same,slot,value)
31	def queue(~S:Data,~K:Data,~V:Data,~same:V -> V -> Bool,slot:M.Slot<S,K,V>,value:V,skipSame:Bool) -> M.Slot<S,K,V>:
32	  queue_generic(S,K,V,same,slot,value,skipSame)