"

 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' }"

"{ NameSpace: Smalltalk }"

Object subclass:#UndoSupport

	instanceVariableNames:'actionPerformer transaction undoList redoList

		infoOfCurrentTransaction undoLimit'

	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

!

undoLimit

    ^ undoLimit

!

undoLimit:something

    undoLimit := something.

! !

!UndoSupport methodsFor:'initialization'!

actionPerformer:something

    actionPerformer := something.

!

initialize

    self resetHistories.

    "/ undoLimit := 1000.

!

resetHistories

    transaction := nil.

    undoList := OrderedCollection new.

    redoList := OrderedCollection new.

! !

!UndoSupport methodsFor:'queries'!

isInTransaction

    ^ transaction notNil

    "Created: / 30-04-2016 / 20:31:04 / cg"

!

transactionNotEmpty

    ^ transaction notEmptyOrNil

    "Created: / 30-04-2016 / 20:47:53 / cg"

! !

!UndoSupport methodsFor:'undo & again'!

addUndo:action

    transaction notNil ifTrue:[

        transaction add:action

    ].

!

addUndoFirst:action

    transaction notNil ifTrue:[

        transaction addFirst:action

    ].

    "Created: / 30-04-2016 / 20:50:53 / cg"

!

closeTransactionAndAddTo:anUndoList

    "at the end of an operation, check the individual undo actions

     and add them to the given undoList.

     (either individually or as a compound undo action).

     Check if the new action(s) can be combined with the previous undo action into one

     (this is done for individual keystrokes and character-deletions)"

    |anythingToUndo actionToAdd lastAction canCombine|

    anythingToUndo := false.

    transaction notEmptyOrNil ifTrue:[

        anythingToUndo := transaction size > 1

                          or:[ transaction first isRestoreSelectionAndCursor not].

    ].                    

    anythingToUndo ifTrue:[

        canCombine := false.

        anUndoList isEmpty ifTrue:[

            "/ nothing yet 

            anUndoList addAll:transaction

        ] ifFalse:[

            "/ append new actions

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

                actionToAdd := transaction first.

                lastAction := anUndoList last.

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

            ] ifFalse:[

                (infoOfCurrentTransaction isNil 

                and:[ transaction size == 2 

                and:[ transaction first isRestoreSelectionAndCursor 

                and:[ undoList contains:[:op | op isRestoreSelectionAndCursor] ]]]) ifTrue:[

                    actionToAdd := transaction second.

                    lastAction := anUndoList last.

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

                ] ifFalse:[

                    actionToAdd := (CompoundAction new actions:transaction).

                    actionToAdd info:infoOfCurrentTransaction.

                ].

            ].

            canCombine ifTrue:[

                lastAction combineWithNext:actionToAdd.

            ] ifFalse:[

                anUndoList add:actionToAdd.

                (undoLimit notNil and:[anUndoList size > undoLimit]) ifTrue:[

                    Transcript showCR:'forget old undo-action'.

                    anUndoList removeFirst.

                ].

            ].

        ].

    ].

    infoOfCurrentTransaction := nil.

    transaction := nil

    "Modified (comment): / 22-05-2017 / 12:48:07 / mawalch"

!

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.

!

isRestoreSelectionAndCursor

    ^ false.

! !

!UndoSupport class methodsFor:'documentation'!

version

    ^ '$Header$'

! !