"{ Encoding: utf8 }"

"{ Package: 'stx:libbasic2' }"

"{ NameSpace: Smalltalk }"

IteratorStream subclass:#RecursiveSeriesStream

	instanceVariableNames:'lastValue endValue'

	classVariableNames:''

	poolDictionaries:''

	category:'Streams'

!

!RecursiveSeriesStream class methodsFor:'documentation'!

documentation

"

    documentation to be added.

    class:

        <a short class summary here, describing what instances represent>

    responsibilities:    

        <describing what my main role is>

    collaborators:    

        <describing with whom and how I talk to>

    API:

        <public api and main messages>

    example:

        <a one-line examples on how to use - can also be in a separate example method>

    implementation:

        <implementation points>

    [author:]

        cg

    [instance variables:]

    [class variables:]

    [see also:]

"

!

example

"

        |collatz|

        collatz := [:n | RecursiveSeriesStream on:[:n | n even ifTrue:[n/2] ifFalse:[n*3+1]] startValue:n].

        (collatz[20]) next:20.  

        (collatz[24]) next:20.  

        (collatz[25]) next:30.   

"

!

example2

"

        |max bits collatz newNums|

        newNums := OrderedCollection new.        

        bits := SortedCollection new.

        max := 2.

        1 to:100000 do:[:n0 |

            newNums removeAll.    

            collatz startValue:n0.

            [

                |n|

                n := collatz next.

                newNums add:n.

                n <= max

            ] whileFalse.

            bits addAll:newNums.

            [bits notEmpty and:[bits first <= (max+1)]] whileTrue:[max := max max:(bits first). bits removeFirst].

        ].

        self halt.

"

! !

!RecursiveSeriesStream class methodsFor:'instance creation'!

on:aBlock startValue:startValue

    ^ self basicNew initialize iterator:aBlock startValue:startValue

! !

!RecursiveSeriesStream methodsFor:'accessing'!

atEnd

    ^ lastValue = endValue

!

endValue:something

    "define a stop value"

    endValue := something.

!

iterator:aOneArgBlock startValue:startValue

    iterator := aOneArgBlock.

    lastValue := startValue.

!

startValue:startValue

    lastValue := startValue.

! !

!RecursiveSeriesStream methodsFor:'reading'!

next

    "return the next element from the stream by evaluating the nextBlock"

    |prevValue|

    prevValue := lastValue.

    lastValue := iterator value:lastValue.

    ^ prevValue

! !

!RecursiveSeriesStream class methodsFor:'documentation'!

version_CVS

    ^ '$Header$'

! !