Object subclass:#Transaction
	instanceVariableNames:'type text actions'
	classVariableNames:''
	poolDictionaries:''
	privateIn:UIObjectView::UndoHistory
!

!UIObjectView::UndoHistory::Transaction class methodsFor:'instance creation'!

type:aType text:aTextOrNil
    ^ self new type:aType text:aTextOrNil


! !

!UIObjectView::UndoHistory::Transaction methodsFor:'accessing'!

asString
    "returns printable string
    "
    |string|

    string := type asString.

    text notNil ifTrue:[^ string, '    ', text ]
               ifFalse:[^ string ]
!

text
    "returns text or nil assigned to transition
    "
    ^ text
!

type
    "returns type assigned to transition
    "
    ^ type
!

type:aType
    "change type assigned to transition
    "
    type := aType
! !

!UIObjectView::UndoHistory::Transaction methodsFor:'add & undo'!

add:anUndoBlock
    "add an undo action to the transition
    "
    actions isNil ifTrue:[
        actions := anUndoBlock
    ] ifFalse:[
        actions isCollection ifFalse:[
            |temp|

            temp := OrderedCollection new.
            temp add:actions.
            actions := temp.
        ].
        actions add:anUndoBlock.
    ]
!

undo
    "undo transition
    "
    actions notNil ifTrue:[
        actions isCollection ifFalse:[
            actions value
        ] ifTrue:[
            actions reverseDo:[:anUndoBlock| anUndoBlock value ]
        ]
    ]
! !

!UIObjectView::UndoHistory::Transaction methodsFor:'initialization'!

type:aType text:aTextOrNil
    "initialize transition
    "
    type := aType.
    text := aTextOrNil.
! !

!UIObjectView::UndoHistory::Transaction methodsFor:'testing'!

isEmpty
    "returns true if no undo action is registered
    "
    ^ actions isNil
!

notEmpty
    "returns true if any undo action is registered
    "
    ^ actions notNil
! !