"{ Package: 'cvut:stx/goodies/newcompiler' }"

Object subclass:#IRStackCount

	instanceVariableNames:'start position length'

	classVariableNames:''

	poolDictionaries:''

	category:'NewCompiler-Bytecode'

!

IRStackCount comment:'This keeps track of the stack count for the BytecodeGenerator.'

!

!IRStackCount class methodsFor:'instance creation'!

new

	^ super new startAt: 0

! !

!IRStackCount class methodsFor:'as yet unclassified'!

startAt: pos

	^ super new startAt: pos

! !

!IRStackCount methodsFor:'affecting'!

pop

	^ self pop: 1

!

pop: n

	(position _ position - n) "< 0 

		ifTrue: [self error: 'Parse stack underflow']"

!

push

	^ self push: 1

!

push: n

	(position _ position + n) > length 

		ifTrue: [length _ position]

! !

!IRStackCount methodsFor:'comparing'!

= other

	^ self class == other class 

	  and: [start = other start

	  and: [position = other position

	  and: [length = other size]]]

!

hash

	^ position hash bitXor: (length hash bitXor: start hash)

! !

!IRStackCount methodsFor:'error handling'!

errorStackOutOfSync: aStackCount 

	self error: 'stack not in sync!!'.

! !

!IRStackCount methodsFor:'initialize'!

startAt: pos

	start _ position _ length _ pos

! !

!IRStackCount methodsFor:'printing'!

printOn: aStream

	super printOn: aStream.

	aStream

		nextPutAll: ' start '; print: start;

		nextPutAll: ' stop '; print: position;

		nextPutAll: ' max '; print: length.

! !

!IRStackCount methodsFor:'results'!

length

	^length

!

linkTo: stackOrNil

	stackOrNil ifNil: [^ self class startAt: self position].

	^ self position = stackOrNil start

		ifTrue: [stackOrNil]

		ifFalse: [self errorStackOutOfSync: stackOrNil]

!

position

	^position

!

size

	^length

!

start

	^ start

! !

!IRStackCount class methodsFor:'documentation'!

version

!

version_CVS

!

version_SVN

! !