moo/stix/kernel/Context.st

#class(#pointer) Context(Apex)
{
	#dcl sender ip sp ntmprs.

	#method sender
	{
		^self.sender
	}
}

#class(#pointer) MethodContext(Context)
{
	#dcl method receiver home origin.

	#method pc
	{
		^ip
	}

	#method pc: anInteger
	{
		ip := anInteger.
		"sp := sp - 1."  "whould this always work??? "
	}

	#method sp
	{
		^sp.

	}
	#method sp: anInteger
	{
		sp := anInteger.
	}

	#method pc: aPC sp: aSP
	{
		ip := aPC.
		sp := aSP.
		##sp := sp - 1.
	}

	#method isHandlerContext
	{
		^self.method primitive == 512
	}
}

#class(#pointer) BlockContext(Context)
{
	#dcl nargs source home origin.

	#method fork
	{
		"crate a new process in the runnable state"
		^self newProcess resume.
	}

	#method newProcess
	{
		"create a new process in the suspended state"
		<primitive: #_block_new_process>
		self primitiveFailed.
	}

	#method newProcessWith: anArray
	{
		"create a new process in the suspended state passing the elements
		 of anArray as block arguments"
		<primitive: #_block_new_process>
		self primitiveFailed.
	}

	#method value
	{
		<primitive: #_block_value>
		self primitiveFailed.
	}

	#method value: a 
	{
		<primitive: #_block_value>
		self primitiveFailed.
	}

	#method value: a value: b
	{
		<primitive: #_block_value>
		self primitiveFailed.
	}

	#method value: a value: b value: c
	{
		<primitive: #_block_value>
		self primitiveFailed.
	}

	#method ifTrue: aBlock
	{
		^(self value) ifTrue: aBlock.
	}

	#method ifFalse: aBlock
	{
		^(self value) ifFalse: aBlock.
	}

	#method ifTrue: trueBlock ifFalse: falseBlock
	{
		^(self value) ifTrue: trueBlock ifFalse: falseBlock
	}

	#method whileTrue: aBlock
	{
## http://stackoverflow.com/questions/2500483/is-there-a-way-in-a-message-only-language-to-define-a-whiletrue-message-without

## ----------------------------------------------------------------------------

##		^(self value) ifTrue: [aBlock value. self whileTrue: aBlock].

## ----------------------------------------------------------------------------

		## less block context before whileTrue: is recursively sent.
		## whileTrue: is sent in a method context.
		(self value) ifFalse: [^nil].
		aBlock value. 
		self whileTrue: aBlock.

## ----------------------------------------------------------------------------

## ----------------------------------------------------------------------------
"		| pc sp xsp |

		sp := thisContext sp.
		sp := sp - 1. ## decrement sp by 1 becuase thisContext pushed above affects the sp method
		pc := thisContext pc.
		self value ifFalse: [ ^nil "^self" ].
		aBlock value.
		##thisContext pc: pc - 3 sp: sp.
		##thisContext pc: pc + 2 sp: sp.   
		thisContext pc: pc + 1 sp: sp.   
		## this +2 or - 3 above is dependent on the byte code instruction size used for 'store'  
		## +2 to skip STORE_INTO_TEMP(pc) and POP_STACKTOP.
		## TODO: make it independent of the byte code size 
"
## ----------------------------------------------------------------------------

##        #<label>:
##		thisContext pc: #<label> sp: sp.
##
##		| pc |
##		pc := thisContext pc.
##		^self value ifTrue: [aBlock value. thisContext pc: pc]

## ----------------------------------------------------------------------------

##		self value ifTrue: [ aBlock value. thisContext restart. ].
	}

	#method whileTrue
	{
		(self value) ifFalse: [^nil].
		self whileTrue.
	}

	#method whileFalse: aBlock
	{
		(self value) ifTrue: [^nil].
		aBlock value. 
		self whileFalse: aBlock.
	}

	#method whileFalse
	{
		(self value) ifTrue: [^nil].
		self whileFalse.
	}

	#method pc
	{
		^ip
	}

	#method pc: anInteger
	{
		ip := anInteger.
	}
	
	#method sp
	{
		^sp
	}

	#method sp: anInteger
	{
		sp := anInteger.
	}

	#method restart
	{
		ip := source pc.
	}


	"------ TODO: -------------------------------------"
	#method on: anException do: anExceptionBlock
	{
		| handlerActive |
		<exception>
		handlerActive := true.

(thisContext basicAt: 9) dump.

		^self value.
	}

	#method ensure: aBlock
	{
		"##
		| complete returnValue |
		<ensure>

		returnValue := self valueNoContextSwitch.
		complete ifNil: [
			complete := true.
			aBlock value.
		].
		^returnValue. ##"
	}

	#method ifCurtailed: aBlock
	{
	}

	"------ TODO: -------------------------------------"
}

#class Exception(Object)
{
	#dcl signalContext handlerContext messageText.

	#method(#class) signal
	{
		self new signal
	}

	#method(#class) signal: text
	{
		self new signal: text
	}

	#method signal 
	{
		self.signalContext := thisContext.
		self isHandled
			ifTrue: [ self handle ]
			ifFalse: [ self notHandled ].
	}

	#method signal: text
	{
		self.messageText := text.
		self signal.
	}

	#method isHandled
	{
		^self handlerContext notNil
	}

	#method handle
	{
		self return: (self.handlerContext handlerBlock value: self)
	}

	#method notHandle
	{
'EXCEPTION NOT HANDLED' dump.
## TODO: debug the current process???? "
Processor activeProcess terminate.
	}

	#method handlerContext
	{
		(self.handlerContext notNil) ifTrue: [ ^self.handlerContext ].
		^self handlerContextStartingFrom: self.signalContext sender.
	}

	#method handlerContextStartingFrom: aContext
	{
		## Find exception handling context starting from a given context

		| ctx |

		ctx := aContext.
		[ ctx notNil ]
			whileTrue: [
				(ctx handles: self) ifTrue: [ ^self.handlerContext := ctx ].
				ctx := ctx sender
			].
		^nil
	}
	
	#method return: anObject
	{
		Processor return: anObject to: (self.handlerContext parent)
	}
}

#class NoSuchMessageException(Exception)
{
}