"

 COPYRIGHT (c) 2004 by eXept Software AG

              All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

"{ Package: 'stx:libbasic2' }"

Object subclass:#UndoSupport

	instanceVariableNames:'actionPerformer transaction undoList redoList

	classVariableNames:''

	poolDictionaries:''

	category:'Views-Text'

!

Object subclass:#CompoundAction

	instanceVariableNames:'actions userFriendlyInfo'

	classVariableNames:''

	poolDictionaries:''

	privateIn:UndoSupport

!

!UndoSupport class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 2004 by eXept Software AG

              All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    Framework for undo & redo.

    See concrete usage in EditTextView.

    [author:]

         (cg@betti)

    [instance variables:]

    [class variables:]

    [see also:]

"

!

examples

"

    See usage in EditTextView

"

! !

!UndoSupport class methodsFor:'instance creation'!

for:anActionPerformer

    ^ self new actionPerformer:anActionPerformer.

!

new

    ^ self basicNew initialize.

! !

!UndoSupport methodsFor:'accessing'!

actionInfo:aString

    infoOfCurrentTransaction := aString

! !

!UndoSupport methodsFor:'initialization'!

actionPerformer:something

    actionPerformer := something.

!

initialize

    self resetHistories.

!

resetHistories

    transaction := nil.

    undoList := OrderedCollection new.

    redoList := OrderedCollection new.

! !

!UndoSupport methodsFor:'undo & again'!

addUndo:action

    transaction notNil ifTrue:[

        transaction add:action

    ].

!

closeTransactionAndAddTo:aList

    |actionToAdd lastAction canCombine|

    transaction notEmptyOrNil ifTrue:[

        canCombine := false.

        (transaction size == 1 and:[infoOfCurrentTransaction isNil]) ifTrue:[

            actionToAdd := transaction first.

            aList notEmpty ifTrue:[

                lastAction := aList last.

                canCombine := lastAction perform:#canCombineWithNext: with:actionToAdd ifNotUnderstood:false.

            ].

        ] ifFalse:[

            actionToAdd := (CompoundAction new actions:transaction).

            actionToAdd info:infoOfCurrentTransaction.

        ].

        canCombine ifTrue:[

            lastAction combineWithNext:actionToAdd.

        ] ifFalse:[

            aList add:actionToAdd.

        ].

    ].

    infoOfCurrentTransaction := nil.

    transaction := nil

!

executeActionFrom:doList addUndoTo:unDoList

    |action previousTransaction|

    doList notEmptyOrNil ifTrue:[

        action := doList removeLast.

        previousTransaction := transaction.

        [

            transaction := OrderedCollection new.

            action executeIn:actionPerformer.

            self closeTransactionAndAddTo:unDoList.

        ] ensure:[

            transaction := previousTransaction.

        ]

    ]

!

hasRedoAction

    ^ redoList size > 0

!

hasUndoAction

    ^ undoList size > 0

!

lastRedoAction

    ^ redoList removeLast

!

lastUndoAction

    ^ undoList removeLast

!

nonUndoableDo:aBlock

    |prev|

    prev := transaction.

    transaction := nil.

    aBlock 

        ensure:[

            transaction := prev.

        ].

!

redo

    self executeActionFrom:redoList addUndoTo:undoList

!

redoActionInfo

    ^ redoList last info

!

undo

    self executeActionFrom:undoList addUndoTo:redoList

!

undoActionInfo

    ^ undoList last info

!

undoableDo:aBlock

    self undoableDo:aBlock info:nil.

!

undoableDo:aBlock info:aString

    transaction notNil ifTrue:[

        infoOfCurrentTransaction := infoOfCurrentTransaction ? aString.

        aBlock value.

    ] ifFalse:[

        transaction := OrderedCollection new.

        infoOfCurrentTransaction := aString.

        aBlock 

            ensure:[  

                self closeTransactionAndAddTo:undoList.

            ].

    ].

! !

!UndoSupport::CompoundAction methodsFor:'accessing'!

info

    ^ userFriendlyInfo

!

info:aString

    userFriendlyInfo := aString

! !

!UndoSupport::CompoundAction methodsFor:'adding'!

actions:aCollection

    actions := aCollection

!

add:action

    actions isNil ifTrue:[

        actions := OrderedCollection new.

    ].

    actions add:action

! !

!UndoSupport::CompoundAction methodsFor:'execution'!

executeIn:editor 

    actions reverseDo:[:each | each executeIn:editor ]

! !

!UndoSupport::CompoundAction methodsFor:'queries'!

canCombineWithNext:nextAction

    ^ false.

! !

!UndoSupport class methodsFor:'documentation'!

version

! !