"{ Package: 'stx:goodies' }"
SequenceableCollection subclass:#ReindexedCollection
instanceVariableNames:'sequence interval'
classVariableNames:''
poolDictionaries:''
category:'Collections-Sequenceable'
!
!ReindexedCollection class methodsFor:'documentation'!
documentation
"
ReindexedCollection is a wrapper around a sequenceable collection that remaps the indices
with in linear algorithm.
The elements in the ReindexedCollection are elements in the sequenceable collection at
some start to some stop at some step.
See class side examples.
[Instance Variables:]
sequence <SequenceableCollection> the sequence that will be reindexed.
interval <Interval> the object that describes indicies of interest in the sequence.
"
!
examples
"
|coll|
coll := (1 to:10) asOrderedCollection from:8.
coll.
coll size.
coll at:1.
coll do:[:each | Transcript showCR:each].
|coll|
coll := (1 to:10) asOrderedCollection from:3 to:8.
coll.
coll size.
coll at:1.
coll do:[:each | Transcript showCR:each].
|coll|
coll := (1 to:10) asOrderedCollection to:4.
coll.
coll size.
coll at:1.
coll last.
coll do:[:each | Transcript showCR:each].
"
! !
!ReindexedCollection class methodsFor:'instance creation'!
on: aSequence from: start
"Create a reindexedCollection on aSequence from start to the end of aSequence"
^ self
on: aSequence
from: start
to: aSequence size
by: 1
!
on: aSequence from: start by: step
"Create a reindexedCollection on aSequence start to the end of aSequence
if step is positive, else
from start to the beginning of the sequence if step is negative."
^ self
on: aSequence
from: start
to: (step > 0
ifTrue: [aSequence size]
ifFalse: [1])
by: step
!
on: aSequence from: start to: stop
"Create a reindexedCollection on aSequence from start to stop by 1
(or -1 if start is greater than stop)"
^ self
on: aSequence
from: start
to: stop
by: (start <= stop
ifTrue: [1]
ifFalse: [-1])
!
on: aSequence from: start to: stop by: step
"Create a reindexedCollection on aSequence from start to stop by step"
^ self new
initialize: aSequence
from: start
to: stop
by: step
!
on: aSequence to: stop
"Create a reindexedCollection on aSequence from 1 to stop by 1"
^ self
on: aSequence
from: 1
to: stop
by: 1
!
on: aSequence to: stop by: step
"Create a reindexedCollection on aSequence from 1 to stop (if step is
positive) or the end to stop (if
step is negative). Note: if step is not 1 or -1, there is a chance that the
index specified by stop may
not be in the interval."
^ self
on: aSequence
from: (step > 0
ifTrue: [1]
ifFalse: [aSequence size])
to: stop
by: step
!
on: aSequence with: anInterval
"Create a reindexedCollection on aSequence"
^ self new initialize: aSequence with: anInterval
! !
!ReindexedCollection methodsFor:'accessing'!
at: index
"Answer the value of an indexable field in the sequence instance variable. "
^ sequence at: (interval at: index)
!
at: index put: value
"Store the argument value in the indexable field of the sequence
instance variable indicated by index.
Answer the value that was stored."
^ sequence at: (interval at: index) put: value
!
size
"Answer how many elements the receiver contains."
^ interval size
!
slide
"slide by 1"
self slide: 1
!
slide: anIncrement
"given an increment, adjust the reindex map by sliding it that far"
interval := interval + anIncrement
! !
!ReindexedCollection methodsFor:'adding & removing'!
add: anObject
self shouldNotImplement
! !
!ReindexedCollection methodsFor:'initialization'!
initialize: aSequence from: start to: stop by: step
sequence := aSequence.
interval := Interval from: start to: stop by: step
!
initialize: aSequence with: anInterval
sequence := aSequence.
interval := anInterval
! !
!ReindexedCollection methodsFor:'queries'!
species
"Answer the preferred class for reconstructing the receiver, that is, the sequence."
^ sequence species
! !
!ReindexedCollection class methodsFor:'documentation'!
version
^ '$Header: /cvs/stx/stx/libbasic2/ReindexedCollection.st,v 1.1 2003-05-04 17:09:14 cg Exp $'
! !