Smalltalk createPackage: 'Axxord-Axon'!
Object subclass: #Axon
	instanceVariableNames: 'factory'
	package: 'Axxord-Axon'!
!Axon commentStamp!
I represent a pub-sub based on a key (called 'aspect').
I manage aspect-block subscriptions (called 'interests') as well as run blocks of dirtied interests.
The interest objects are responsible of decision if the change of an aspect is relevant for them.
Interest object must be subclasses of `AxonInterest`.

My subclasses must provide implementation for:

 - add:
 - do:
 - clean!

!Axon methodsFor: 'accessing'!

addInterest: anInterest
	self
		add: (anInterest flag; yourself);
		dirty: true
! !

!Axon methodsFor: 'change-update'!

changed: anAspect
	| needsToRun |
	needsToRun := false.
	self do: [ :each |
		(each accepts: anAspect) ifTrue: [
			each flag.
			needsToRun := true ]].
	self dirty: needsToRun
!

changedAll
	| needsToRun |
	needsToRun := false.
	self do: [ :each |
		each flag.
		needsToRun := true ].
	self dirty: needsToRun
! !

!Axon methodsFor: 'primitive ops'!

add: anInterest
	self subclassResponsibility
!

clean
	self subclassResponsibility
!

do: aBlock
	self subclassResponsibility
! !

!Axon methodsFor: 'private'!

dirty: aBoolean
	aBoolean ifTrue: [[ self run ] fork]
!

run
	[
		| needsClean |
	    needsClean := false.
		self do: [ :each |
			each isFlagged ifTrue: [ each run ].
	        each isClosed ifTrue: [ needsClean := true ]
		].
    	needsClean ifTrue: [ self clean ]
	] on: Error do: [ self dirty: true ]
! !

Axon subclass: #SimpleAxon
	instanceVariableNames: 'queue'
	package: 'Axxord-Axon'!

!SimpleAxon methodsFor: 'initialization'!

initialize
    super initialize.
	queue := OrderedCollection new
! !

!SimpleAxon methodsFor: 'primitive ops'!

add: aSubscription
	queue add: aSubscription.
!

clean
	queue := queue reject: [ :each | each isClosed ]
!

do: aBlock
	queue do: aBlock
! !

Object subclass: #AxonInterest
	instanceVariableNames: 'flagged'
	package: 'Axxord-Axon'!

!AxonInterest methodsFor: 'accessing'!

flag
	flagged := true
! !

!AxonInterest methodsFor: 'action'!

close
	self subclassResponsibility
!

enact
	self subclassResponsibility
!

run
	[ flagged := false. self enact ]
    on: AxonOff do: [ self close ]
! !

!AxonInterest methodsFor: 'initialization'!

initialize
	super initialize.
    flagged := false.
! !

!AxonInterest methodsFor: 'testing'!

accepts: anAspect
    "Should return true if change for anAspect is relevant for this AxonInterest"
    self subclassResponsibility
!

isClosed
	self subclassResponsibility
!

isFlagged
	^flagged
! !

AxonInterest subclass: #PluggableInterest
	instanceVariableNames: 'acceptBlock enactBlock'
	package: 'Axxord-Axon'!

!PluggableInterest methodsFor: 'accessing'!

accept: aBlock enact: anotherBlock
	acceptBlock := aBlock.
    enactBlock := anotherBlock
! !

!PluggableInterest methodsFor: 'action'!

close
	acceptBlock := nil.
	enactBlock := nil
!

enact
	enactBlock value
! !

!PluggableInterest methodsFor: 'initialization'!

initialize
	super initialize.
    self close
! !

!PluggableInterest methodsFor: 'testing'!

accepts: anAspect
    ^ acceptBlock value: anAspect
!

isClosed
	^ acceptBlock isNil
! !

Error subclass: #AxonOff
	instanceVariableNames: ''
	package: 'Axxord-Axon'!
!AxonOff commentStamp!
Signal me from the subscription block to unsubscribe it.!