Is this backward compatible?

On Tue, Dec 6, 2016 at 7:31 AM,  <commits at source.squeak.org> wrote:
> Tobias Pape uploaded a new version of Collections to project The Trunk:
> http://source.squeak.org/trunk/Collections-topa.726.mcz
>
> ==================== Summary ====================
>
> Name: Collections-topa.726
> Author: topa
> Time: 6 December 2016, 2:31:08.021296 pm
> UUID: 8409fe6a-d5ea-4d4e-ac78-243182dd1fd7
> Ancestors: Collections-topa.725
>
> Adopt improved (ie, actually working) Linked List from our relatives.
>
> =============== Diff against Collections-topa.725 ===============
>
> Item was added:
> + ----- Method: Link>>asLink (in category 'converting') -----
> + asLink
> +
> +       ^ self!
>
> Item was changed:
>   ----- Method: Link>>nextLink (in category 'accessing') -----
>   nextLink
> -       "Answer the link to which the receiver points."
>
> +       ^ nextLink!
> -       ^nextLink!
>
> Item was changed:
>   ----- Method: Link>>nextLink: (in category 'accessing') -----
>   nextLink: aLink
>         "Store the argument, aLink, as the link to which the receiver refers.
>         Answer aLink."
>
> +       ^ nextLink := aLink!
> -       ^nextLink := aLink!
>
> Item was changed:
>   SequenceableCollection subclass: #LinkedList
>         instanceVariableNames: 'firstLink lastLink'
>         classVariableNames: ''
>         poolDictionaries: ''
>         category: 'Collections-Sequenceable'!
>
> + !LinkedList commentStamp: 'topa 12/6/2016 14:17' prior: 0!
> + I represent a collection of links, which are containers for other objects. Using the message sequence addFirst:/removeLast causes the receiver to behave as a stack; using addLast:/removeFirst causes the receiver to behave as a queue.
> +
> + If you attempt to add any object into a LinkedList that is not a Link, it will automatically be wrapped by a ValueLink. A LinkedList therefore behaves very much like any collection, except that certain calls such as atIndex: are linear rather than constant time.!
> - !LinkedList commentStamp: '<historical>' prior: 0!
> - I represent a collection of links, which are containers for other objects. Using the message sequence addFirst:/removeLast causes the receiver to behave as a stack; using addLast:/removeFirst causes the receiver to behave as a queue.!
>
> Item was added:
> + ----- Method: LinkedList class>>new: (in category 'instance creation') -----
> + new: anInt
> +       "LinkedList don't need capacity"
> +       ^self new!
>
> Item was added:
> + ----- Method: LinkedList class>>new:streamContents: (in category 'stream creation') -----
> + new: size streamContents: aBlock
> +       ^ self withAll: (super new: size streamContents: aBlock)!
>
> Item was added:
> + ----- Method: LinkedList class>>newFrom: (in category 'instance creation') -----
> + newFrom: aCollection
> +       "Answer an instance with same elements as aCollection."
> +       ^self new
> +               addAll: aCollection;
> +               yourself!
>
> Item was changed:
>   ----- Method: LinkedList>>add: (in category 'adding') -----
> + add: aLinkOrObject
> - add: aLink
>         "Add aLink to the end of the receiver's list. Answer aLink."
>
> +       ^self addLast: aLinkOrObject!
> -       ^self addLast: aLink!
>
> Item was changed:
>   ----- Method: LinkedList>>add:after: (in category 'adding') -----
> + add: link after: otherLinkOrObject
> - add: link after: otherLink
> -
>         "Add otherLink  after link in the list. Answer aLink."
>
> +       | otherLink |
> +       otherLink := self linkAt: (self indexOf: otherLinkOrObject).
> +       ^ self add: link afterLink: otherLink!
> -       | savedLink |
> -       lastLink == otherLink ifTrue: [^ self addLast: link].
> -       savedLink := otherLink nextLink.
> -       otherLink nextLink: link.
> -       link nextLink:  savedLink.
> -       ^link.!
>
> Item was added:
> + ----- Method: LinkedList>>add:afterLink: (in category 'adding') -----
> + add: aLinkOrObject afterLink: otherLink
> +
> +       "Add otherLink  after link in the list. Answer aLink."
> +
> +       | savedLink aLink |
> +       lastLink == otherLink ifTrue: [^ self addLast: aLinkOrObject].
> +       savedLink := otherLink nextLink.
> +       aLink := aLinkOrObject asLink.
> +       otherLink nextLink: aLink.
> +       aLink nextLink:  savedLink.
> +       ^aLink.!
>
> Item was changed:
>   ----- Method: LinkedList>>add:before: (in category 'adding') -----
> + add: link before: otherLinkOrObject
> +       "Add otherLink  after link in the list. Answer aLink."
> - add: link before: otherLink
>
> +       | otherLink |
> +       otherLink := self linkAt: (self indexOf: otherLinkOrObject).
> +       ^ self add: link beforeLink: otherLink!
> -       | aLink |
> -       firstLink == otherLink ifTrue: [^ self addFirst: link].
> -       aLink := firstLink.
> -       [aLink == nil] whileFalse: [
> -               aLink nextLink == otherLink ifTrue: [
> -                       link nextLink: aLink nextLink.
> -                       aLink nextLink: link.
> -                       ^ link
> -               ].
> -                aLink := aLink nextLink.
> -       ].
> -       ^ self errorNotFound: otherLink!
>
> Item was added:
> + ----- Method: LinkedList>>add:beforeLink: (in category 'adding') -----
> + add: aLinkOrObject beforeLink: otherLink
> +
> +       | currentLink|
> +
> +       firstLink == otherLink ifTrue: [^ self addFirst: aLinkOrObject].
> +
> +       currentLink := firstLink.
> +       [currentLink == nil] whileFalse: [
> +               currentLink nextLink == otherLink ifTrue: [
> +                       | aLink |
> +                       aLink := aLinkOrObject asLink.
> +                       aLink nextLink: currentLink nextLink.
> +                       currentLink nextLink: aLink.
> +                       ^ aLink
> +               ].
> +                currentLink := currentLink nextLink.
> +       ].
> +       ^ self errorNotFound: otherLink!
>
> Item was changed:
>   ----- Method: LinkedList>>addFirst: (in category 'adding') -----
> + addFirst: aLinkOrObject
> - addFirst: aLink
>         "Add aLink to the beginning of the receiver's list. Answer aLink."
> +       |aLink|
> +       aLink := aLinkOrObject asLink.
> -
>         self isEmpty ifTrue: [lastLink := aLink].
>         aLink nextLink: firstLink.
>         firstLink := aLink.
>         ^aLink!
>
> Item was changed:
>   ----- Method: LinkedList>>addLast: (in category 'adding') -----
> + addLast: aLinkOrObject
> - addLast: aLink
>         "Add aLink to the end of the receiver's list. Answer aLink."
> +       |aLink|
> +       aLink := aLinkOrObject asLink.
> -
>         self isEmpty
>                 ifTrue: [firstLink := aLink]
>                 ifFalse: [lastLink nextLink: aLink].
>         lastLink := aLink.
>         ^aLink!
>
> Item was changed:
>   ----- Method: LinkedList>>at: (in category 'accessing') -----
>   at: index
>
> +       ^(self linkAt: index) value!
> -       | i |
> -       i := 0.
> -       self do: [:link |
> -               (i := i + 1) = index ifTrue: [^ link]].
> -       ^ self errorSubscriptBounds: index!
>
> Item was added:
> + ----- Method: LinkedList>>at:put: (in category 'accessing') -----
> + at: index put: anObject
> +
> +       ^self at: index putLink: (self linkOf: anObject ifAbsent: [anObject asLink])!
>
> Item was added:
> + ----- Method: LinkedList>>at:putLink: (in category 'accessing') -----
> + at: index putLink: aLink
> +       | previousLink nextLink |
> +       "Please don't put a link which is already in the list, or you will create an infinite loop"
> +       (self validIndex: index) ifFalse: [^ self errorOutOfBounds].
> +
> +       index = 1 ifTrue: [
> +               aLink nextLink: self firstLink nextLink.
> +               firstLink := aLink.
> +               aLink nextLink ifNil: [lastLink := aLink].
> +               ^ aLink].
> +
> +       previousLink := self linkAt: index - 1.
> +       nextLink := previousLink nextLink nextLink.
> +
> +       nextLink
> +               ifNil: [aLink nextLink: self lastLink]
> +               ifNotNil: [:link |aLink nextLink: link].
> +
> +       previousLink nextLink: aLink.
> +
> +       nextLink ifNil: [
> +               lastLink := aLink.
> +               aLink nextLink: nil].
> +
> +       ^ aLink!
>
> Item was added:
> + ----- Method: LinkedList>>collect: (in category 'enumerating') -----
> + collect: aBlock
> +       "Evaluate aBlock with each of the receiver's elements as the argument.
> +       Collect the resulting values into a collection like the receiver. Answer
> +       the new collection."
> +
> +       | aLink newCollection |
> +       newCollection := self class new.
> +       aLink := firstLink.
> +       [aLink == nil] whileFalse:
> +               [newCollection add: (aBlock value: aLink value).
> +                aLink := aLink nextLink].
> +       ^ newCollection!
>
> Item was added:
> + ----- Method: LinkedList>>collect:thenSelect: (in category 'enumerating') -----
> + collect: collectBlock thenSelect: selectBlock
> +       "Optimized version of SequenceableCollection>>#collect:#thenSelect:"
> +
> +       | newCollection newElement |
> +       newCollection := self class new.
> +       self
> +               do: [ :each |
> +                       newElement := collectBlock value: each.
> +                       (selectBlock value: newElement)
> +                               ifTrue: [ newCollection add: newElement ] ].
> +       ^ newCollection!
>
> Item was added:
> + ----- Method: LinkedList>>copyWith: (in category 'copying') -----
> + copyWith: newElement
> +       ^self copy add: newElement; yourself!
>
> Item was added:
> + ----- Method: LinkedList>>copyWithout: (in category 'copying') -----
> + copyWithout: oldElement
> +       |newInst|
> +       newInst := self class new.
> +       self do: [:each | each = oldElement ifFalse: [newInst add: each]].
> +       ^newInst!
>
> Item was changed:
>   ----- Method: LinkedList>>do: (in category 'enumerating') -----
>   do: aBlock
>
>         | aLink |
>         aLink := firstLink.
>         [aLink == nil] whileFalse:
> +               [aBlock value: aLink value.
> -               [aBlock value: aLink.
>                  aLink := aLink nextLink]!
>
> Item was changed:
>   ----- Method: LinkedList>>first (in category 'accessing') -----
>   first
>         "Answer the first link. Create an error notification if the receiver is
>         empty."
>
> +       ^ self firstLink value!
> -       self emptyCheck.
> -       ^firstLink!
>
> Item was added:
> + ----- Method: LinkedList>>firstLink (in category 'accessing') -----
> + firstLink
> +       "Answer the first link. Create an error notification if the receiver is
> +       empty."
> +
> +       self emptyCheck.
> +       ^firstLink!
>
> Item was added:
> + ----- Method: LinkedList>>indexOf:startingAt:ifAbsent: (in category 'private') -----
> + indexOf: anElement startingAt: start ifAbsent: exceptionBlock
> +       "Answer the index of the first occurence of anElement after start
> +       within the receiver. If the receiver does not contain anElement,
> +       answer the      result of evaluating the argument, exceptionBlock."
> +
> +       |currentLink index|
> +       currentLink := self linkAt: start ifAbsent: [nil].
> +       index := start.
> +       [currentLink isNil ]
> +               whileFalse: [currentLink value = anElement value ifTrue: [^index].
> +                                       currentLink := currentLink nextLink.
> +                                       index := index +1].
> +       ^exceptionBlock value!
>
> Item was changed:
>   ----- Method: LinkedList>>isEmpty (in category 'testing') -----
>   isEmpty
>
> +       ^ firstLink isNil!
> -       ^firstLink == nil!
>
> Item was changed:
>   ----- Method: LinkedList>>last (in category 'accessing') -----
>   last
>         "Answer the last link. Create an error notification if the receiver is
>         empty."
>
> +
> +       ^self lastLink value!
> -       self emptyCheck.
> -       ^lastLink!
>
> Item was added:
> + ----- Method: LinkedList>>lastLink (in category 'accessing') -----
> + lastLink
> +       "Answer the last link. Create an error notification if the receiver is
> +       empty."
> +
> +       self emptyCheck.
> +       ^lastLink!
>
> Item was added:
> + ----- Method: LinkedList>>linkAt: (in category 'private') -----
> + linkAt: index
> +
> +       ^self linkAt: index ifAbsent: [ self errorSubscriptBounds: index]!
>
> Item was added:
> + ----- Method: LinkedList>>linkAt:ifAbsent: (in category 'private') -----
> + linkAt: index ifAbsent: errorBlock
> +
> +       | i |
> +       i := 0.
> +       self linksDo: [:link | (i := i + 1) = index ifTrue: [^ link]].
> +       ^ errorBlock value!
>
> Item was added:
> + ----- Method: LinkedList>>linkOf: (in category 'private') -----
> + linkOf: anObject
> +
> +       ^ self
> +               linkOf: anObject
> +               ifAbsent: [self error: 'No such element']!
>
> Item was added:
> + ----- Method: LinkedList>>linkOf:ifAbsent: (in category 'private') -----
> + linkOf: anObject ifAbsent: errorBlock
> +
> +       self    linksDo: [:link | link value = anObject value ifTrue: [^ link]].
> +       ^ errorBlock value!
>
> Item was added:
> + ----- Method: LinkedList>>linksDo: (in category 'enumerating') -----
> + linksDo: aBlock
> +
> +       | aLink |
> +       aLink := firstLink.
> +       [aLink == nil] whileFalse:
> +               [aBlock value: aLink.
> +                aLink := aLink nextLink]!
>
> Item was changed:
>   ----- Method: LinkedList>>postCopy (in category 'copying') -----
>   postCopy
>         | aLink |
>         super postCopy.
> +       firstLink ifNotNil: [
> -       firstLink isNil ifFalse: [
>                 aLink := firstLink := firstLink copy.
>                 [aLink nextLink isNil] whileFalse: [aLink nextLink: (aLink := aLink nextLink copy)].
>                 lastLink := aLink].!
>
> Item was changed:
>   ----- Method: LinkedList>>remove:ifAbsent: (in category 'removing') -----
> + remove: aLinkOrObject ifAbsent: aBlock
> +       "Remove aLink from the receiver. If it is not there, answer the result of evaluating aBlock."
> +
> +       | link |
> +       link := self linkOf: aLinkOrObject ifAbsent: [^aBlock value].
> +       self removeLink: link ifAbsent: [^aBlock value].
> +       ^aLinkOrObject!
> - remove: aLink ifAbsent: aBlock
> -       "Remove aLink from the receiver. If it is not there, answer the result of
> -       evaluating aBlock."
> -
> -       | tempLink |
> -       aLink == firstLink
> -               ifTrue: [firstLink := aLink nextLink.
> -                               aLink == lastLink
> -                                       ifTrue: [lastLink := nil]]
> -               ifFalse: [tempLink := firstLink.
> -                               [tempLink == nil ifTrue: [^aBlock value].
> -                                tempLink nextLink == aLink]
> -                                       whileFalse: [tempLink := tempLink nextLink].
> -                               tempLink nextLink: aLink nextLink.
> -                               aLink == lastLink
> -                                       ifTrue: [lastLink := tempLink]].
> -       aLink nextLink: nil.
> -       ^aLink!
>
> Item was added:
> + ----- Method: LinkedList>>removeAllSuchThat: (in category 'removing') -----
> + removeAllSuchThat: aBlock
> +       "Evaluate aBlock for each element and remove all that elements from
> +       the receiver for that aBlock evaluates to true.  For LinkedLists, it's safe to use do:."
> +
> +       self do: [:each | (aBlock value: each) ifTrue: [self remove: each]]!
>
> Item was changed:
>   ----- Method: LinkedList>>removeFirst (in category 'removing') -----
>   removeFirst
>         "Remove the first element and answer it. If the receiver is empty, create
>         an error notification."
>
>         | oldLink |
>         self emptyCheck.
>         oldLink := firstLink.
>         firstLink == lastLink
>                 ifTrue: [firstLink := nil. lastLink := nil]
>                 ifFalse: [firstLink := oldLink nextLink].
>         oldLink nextLink: nil.
> +       ^oldLink value!
> -       ^oldLink!
>
> Item was changed:
>   ----- Method: LinkedList>>removeLast (in category 'removing') -----
>   removeLast
>         "Remove the receiver's last element and answer it. If the receiver is
>         empty, create an error notification."
>
>         | oldLink aLink |
>         self emptyCheck.
>         oldLink := lastLink.
>         firstLink == lastLink
>                 ifTrue: [firstLink := nil. lastLink := nil]
>                 ifFalse: [aLink := firstLink.
>                                 [aLink nextLink == oldLink] whileFalse:
>                                         [aLink := aLink nextLink].
>                                  aLink nextLink: nil.
>                                  lastLink := aLink].
>         oldLink nextLink: nil.
> +       ^oldLink value!
> -       ^oldLink!
>
> Item was added:
> + ----- Method: LinkedList>>removeLink: (in category 'removing') -----
> + removeLink: aLink
> +       ^self removeLink: aLink ifAbsent: [self error: 'no such method!!']!
>
> Item was added:
> + ----- Method: LinkedList>>removeLink:ifAbsent: (in category 'removing') -----
> + removeLink: aLink ifAbsent: aBlock
> +       "Remove aLink from the receiver. If it is not there, answer the result of
> +       evaluating aBlock."
> +
> +       | tempLink |
> +       aLink == firstLink
> +               ifTrue: [firstLink := aLink nextLink.
> +                               aLink == lastLink
> +                                       ifTrue: [lastLink := nil]]
> +               ifFalse: [tempLink := firstLink.
> +                               [tempLink == nil ifTrue: [^aBlock value].
> +                                tempLink nextLink == aLink]
> +                                       whileFalse: [tempLink := tempLink nextLink].
> +                               tempLink nextLink: aLink nextLink.
> +                               aLink == lastLink
> +                                       ifTrue: [lastLink := tempLink]].
> +       "Not nilling the link enables us to delete while iterating"
> +       "aLink nextLink: nil."
> +       ^aLink!
>
> Item was added:
> + ----- Method: LinkedList>>select: (in category 'enumerating') -----
> + select: aBlock
> +       "Reimplemennt #select: for speedup on linked lists.
> +       The super implemention accesses the linkes by index, thus causing an O(n^2)"
> +
> +       | newCollection |
> +       newCollection := self class new.
> +       self do: [:each | (aBlock value: each) ifTrue: [newCollection add: each]].
> +       ^newCollection!
>
> Item was added:
> + ----- Method: LinkedList>>select:thenCollect: (in category 'enumerating') -----
> + select: selectBlock thenCollect: collectBlock
> +       "Optimized version of SequenceableCollection>>#select:thenCollect:"
> +
> +       | newCollection |
> +       newCollection := self class new.
> +       self    do: [ :each | (selectBlock value: each) ifTrue: [newCollection add: (collectBlock value: each)]].
> +       ^ newCollection!
>
> Item was added:
> + ----- Method: LinkedList>>swap:with: (in category 'accessing') -----
> + swap: ix1 with: ix2
> +       "Reimplemented, super would create an infinite loop"
> +       | minIx maxIx link1Prev link2Prev link1 link2 link1Next link2Next newLink2Next |
> +       ((self validIndex: ix1) and: [self validIndex: ix2])    ifFalse: [^ self errorOutOfBounds].
> +
> +       "Get edge case out of the way"
> +       ix1 = ix2 ifTrue: [^ self ].
> +
> +       "Sort indexes to make boundary-checks easier"
> +       minIx := ix1 min: ix2.
> +       maxIx := ix2 max: ix1.
> +
> +       link1Prev := (minIx = 1) ifFalse: [self linkAt: minIx -1].
> +       link1 := link1Prev ifNotNil: [ link1Prev nextLink]
> +                               ifNil: [self linkAt: minIx].
> +       link1Next := link1 nextLink.
> +       link2Prev := self linkAt: maxIx -1.
> +       link2 := link2Prev nextLink.
> +       link2Next := link2 nextLink.
> +
> +       "Link at start being swapped"
> +       link1 = firstLink ifTrue: [firstLink := link2.] ifFalse: [link1Prev nextLink: link2].
> +       "Link at end being swapped"
> +       link2 = lastLink ifTrue: [lastLink := link1] ifFalse: [].
> +       "Links  being swapped adjacent"
> +       newLink2Next := (link1 nextLink = link2) ifTrue: [link1] ifFalse: [link2Prev nextLink: link1.
> +               link1Next].
> +       link1 nextLink: link2Next.
> +       link2 nextLink: newLink2Next.
> +       !
>
> Item was added:
> + ----- Method: LinkedList>>validIndex: (in category 'private') -----
> + validIndex: index
> +
> +        ^ index > 0 and: [index <= self size]!
>
> Item was added:
> + ----- Method: Object>>asLink (in category '*collections') -----
> + asLink
> +
> +       ^ ValueLink value: self!
>
> Item was added:
> + Link subclass: #ValueLink
> +       instanceVariableNames: 'value'
> +       classVariableNames: ''
> +       poolDictionaries: ''
> +       category: 'Collections-Support'!
> +
> + !ValueLink commentStamp: 'HenrikSperreJohansen 10/18/2009 15:57' prior: 0!
> + A ValueLink is a Link containing a Value.
> + Adding an object to a LinkedList which is not a Link will create a ValueLink containing that object.
> +
> +
> + value - The object this link points to.!
>
> Item was added:
> + ----- Method: ValueLink class>>value: (in category 'instance creation') -----
> + value: aValue
> +
> +       ^self new value: aValue!
>
> Item was added:
> + ----- Method: ValueLink>>= (in category 'comparing') -----
> + = anotherObject
> +
> +       ^self species == anotherObject species
> +       and: [self value = anotherObject value
> +       and: [self nextLink == anotherObject nextLink]]!
>
> Item was added:
> + ----- Method: ValueLink>>hash (in category 'comparing') -----
> + hash
> +
> +       ^self value hash bitXor: self nextLink identityHash
> + !
>
> Item was added:
> + ----- Method: ValueLink>>printOn: (in category 'printing') -----
> + printOn: aStream
> +
> +       super printOn: aStream.
> +       aStream nextPut: $(.
> +       value printOn: aStream.
> +       aStream nextPut: $)
> + !
>
> Item was added:
> + ----- Method: ValueLink>>value (in category 'accessing') -----
> + value
> +
> +       ^ value!
>
> Item was added:
> + ----- Method: ValueLink>>value: (in category 'accessing') -----
> + value: anObject
> +
> +       value := anObject.!
>
>