[squeak-dev] The Trunk: Collections-topa.726.mcz

Levente Uzonyi leves at caesar.elte.hu
Tue Dec 6 19:08:19 UTC 2016


Is there any use of these lists? I mean besides process scheduling.
I can't imagine a use-case where I would use a LinkedList instead of an 
OrderedCollection (or another data structure).
I would also get rid of the current Stack implementation.

Levente

On Tue, 6 Dec 2016, Tobias Pape wrote:

>
> On 06.12.2016, at 19:11, Chris Muller <asqueaker at gmail.com> wrote:
>
>> More specifically, will existing instances work or is there some
>> conversion needed?
>
> As far as I can tell, no work needed.
>
>
>> 
>> On Tue, Dec 6, 2016 at 12:10 PM, Chris Muller <asqueaker at gmail.com> wrote:
>>> 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.!
>>>> 
>>>> 
>>


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