"{ Package: 'stx:libbasic2' }"

PeekableStream subclass:#CollectingReadStream

	instanceVariableNames:'collectBlock inStream'

	classVariableNames:''

	poolDictionaries:''

	category:'Streams-Misc'

!

!CollectingReadStream class methodsFor:'documentation'!

documentation

"

    A stream which evaluates collectBlock for every element

    read from an underlying stream, providing the result from

    the evaluation as read-elements.

    Useful to process a readStream, for tracing or diverting to another

    processing stage.

    [Author:]

        Claus Gittinger

"

!

examples

"

                                                            [exBegin]

    |s|

    s := CollectingReadStream 

            on:#(1 2 3 4 5 6 7 8) readStream

            collecting:[:each | each squared].

    s upToEnd  

                                                            [exEnd]

                                                            [exBegin]

    |s|

    s := (#(1 2 3 4 5 6 7 8) readStream 

            selecting:[:n | n odd])

                collecting:[:n | n squared].

    s upToEnd    

                                                            [exEnd]

"

! !

!CollectingReadStream class methodsFor:'instance creation'!

diverting:aStream to:anotherStream

    ^ self on:aStream collecting:[:el | anotherStream nextPut:el. el].

    "

     |s|

     s := CollectingReadStream 

            diverting:#(1 2 3 4 5 6 7 8) readStream

            to:Transcript.

     s upToEnd  

    "

!

on:aStream collecting:aBlock

    ^ self basicNew on:aStream collecting:aBlock

    "

     |s|

     s := CollectingReadStream 

            on:#(1 2 3 4 5 6 7 8) readStream

            collecting:[:each | each squared].

     s upToEnd  

    "

! !

!CollectingReadStream methodsFor:'instance creation'!

on:aStream collecting:aBlock

    inStream := aStream.

    collectBlock := aBlock.

! !

!CollectingReadStream methodsFor:'queries'!

atEnd

    ^ inStream atEnd

!

contentsSpecies

    "return a class of which instances will be returned, when

     parts of the collection are asked for. 

     (see upTo-kind of methods in Stream)"

    ^ inStream contentsSpecies.

! !

!CollectingReadStream methodsFor:'stream protocol'!

next

    inStream atEnd ifTrue:[

        ^ self pastEndRead

    ].

    ^ collectBlock value:(inStream next)

!

nextOrNil

    |ch|

    ch := inStream nextOrNil.

    ch notNil ifTrue:[

        collectBlock value:ch

    ].

    ^ ch

    "Created: / 26-10-2011 / 17:29:01 / cg"

!

nextPeek

    self next.

    ^ self peek

    "Created: / 26-10-2011 / 17:25:16 / cg"

!

peek

    ^ inStream peek

    "Created: / 26-10-2011 / 17:24:59 / cg"

!

peekOrNil

    ^ inStream peekOrNil

    "Created: / 26-10-2011 / 17:25:32 / cg"

!

position

    ^ inStream position

    "Created: / 26-10-2011 / 17:25:08 / cg"

!

position0Based

    <resource: #obsolete>

    ^ inStream position

    "Created: / 26-10-2011 / 17:23:56 / cg"

!

position1Based

    <resource: #obsolete>

    ^ inStream position + 1

    "Created: / 26-10-2011 / 17:22:42 / cg"

!

readStream

    ^ self

    "Created: / 26-10-2011 / 17:25:43 / cg"

! !

!CollectingReadStream class methodsFor:'documentation'!

version_CVS

    ^ '$Header: /cvs/stx/stx/libbasic2/CollectingReadStream.st,v 1.6 2014-04-30 18:19:37 cg Exp $'

! !