"{ Encoding: utf8 }"

"

 COPYRIGHT (c) 2018 by eXept Software AG

              All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

"{ Package: 'stx:libbasic2' }"

"{ NameSpace: Smalltalk }"

PeekableStream subclass:#MultiReadStream

	instanceVariableNames:'streamStack'

	classVariableNames:''

	poolDictionaries:''

	category:'Streams-Misc'

!

!MultiReadStream class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 2018 by eXept Software AG

              All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    Stacked streams. 

    At any time, another stream can be stacked onto a stream stack. 

    Making this stream's contents to be returned before the rest. 

    To the stream reader, this looks like a single stream delivering the

    embedded stream contents sequentially.

    Useful when reading files which include each other, 

    or to handle define-macro expansion in a c-parser.

    [Author:]

        Claus Gittinger

    [instance variables:]

"

    "Created: / 21-05-2010 / 14:34:48 / cg"

!

examples

"

    |s|

    s := MultiReadStream on:('abcd' readStream).

    self assert:(s peek == $a).

    self assert:(s next == $a).

    s pushInputStream:('1234' readStream).

    self assert:(s next == $1).

    self assert:(s next == $2).

    s pushInputStream:('aa' readStream).

    self assert:(s next == $a).

    self assert:(s next == $a).

    self assert:(s atEnd not).

    self assert:(s next == $3).

    self assert:(s next == $4).

    self assert:(s next == $b).

    self assert:(s next == $c).

    self assert:(s next == $d).

    self assert:(s atEnd).

    self assert:(s peek == nil).

    self assert:(s next == nil).

"

    "Created: / 21-05-2010 / 14:27:53 / cg"

! !

!MultiReadStream class methodsFor:'instance creation'!

on:aReadStream

    ^ self basicNew pushInputStream:aReadStream

    "Created: / 21-05-2010 / 14:26:03 / cg"

! !

!MultiReadStream methodsFor:'accessing'!

readStream

    ^ self

    "Created: / 21-05-2010 / 14:51:05 / cg"

! !

!MultiReadStream methodsFor:'obsolete positioning'!

position0Based

    <resource: #obsolete>

    ^ self position

    "Created: / 21-05-2010 / 14:52:40 / cg"

!

position1Based

    <resource: #obsolete>

    ^ self position + 1

    "Created: / 21-05-2010 / 14:52:40 / cg"

! !

!MultiReadStream methodsFor:'private'!

checkCurrentStreamAtEnd

    [streamStack size > 1 and:[streamStack last atEnd]] whileTrue:[

        "keep the last stream, so that the #position kludge will work"

        self popInputStream

    ].

    "Created: / 21-05-2010 / 14:30:20 / cg"

! !

!MultiReadStream methodsFor:'queries'!

atEnd

    self checkCurrentStreamAtEnd.

    ^ streamStack isEmptyOrNil or:[streamStack last atEnd]

    "Created: / 21-05-2010 / 14:31:48 / cg"

!

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)"

    streamStack isEmptyOrNil ifTrue:[^ super contentsSpecies].

    ^ streamStack first contentsSpecies

    "Created: / 21-05-2010 / 14:44:26 / cg"

!

position

    "/ that's debatable !!

    "/ the code below only makes sense, if we see the multiStream as some kind of

    "/ macro-expanding c-define stream

    streamStack isEmptyOrNil ifTrue:[

        "we assume we are at the beginning"

        ^ 0

    ].

    ^ streamStack first position

    "Created: / 21-05-2010 / 14:52:40 / cg"

! !

!MultiReadStream methodsFor:'reading'!

next

    self checkCurrentStreamAtEnd.

    streamStack isEmptyOrNil ifTrue:[^ self pastEndRead].

    ^ streamStack last next

    "Created: / 21-05-2010 / 14:31:23 / cg"

!

peek

    self checkCurrentStreamAtEnd.

    streamStack isEmptyOrNil ifTrue:[^ self pastEndRead].

    ^ streamStack last peek

    "Created: / 21-05-2010 / 14:29:06 / cg"

! !

!MultiReadStream methodsFor:'stream stacking'!

popInputStream

    streamStack removeLast

    "Created: / 21-05-2010 / 14:25:30 / cg"

!

pushInputStream:aReadStream

    streamStack isNil ifTrue:[

        streamStack := OrderedCollection new.

    ].

    streamStack add:aReadStream

    "Created: / 21-05-2010 / 14:25:17 / cg"

! !

!MultiReadStream class methodsFor:'documentation'!

version_CVS

    ^ '$Header$'

! !