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"
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COPYRIGHT (c) 2009 by eXept Software AG
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All Rights Reserved
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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"{ Package: 'stx:libbasic2' }"
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Stream subclass:#SelectingReadStream
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instanceVariableNames:'selectBlock hasReadAhead readAhead inStream'
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classVariableNames:''
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poolDictionaries:''
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2366
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category:'Streams-Misc'
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2362
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!
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!SelectingReadStream class methodsFor:'documentation'!
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2908
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copyright
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"
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COPYRIGHT (c) 2009 by eXept Software AG
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All Rights Reserved
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This software is furnished under a license and may be used
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only in accordance with the terms of that license and with the
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inclusion of the above copyright notice. This software may not
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be provided or otherwise made available to, or used by, any
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other person. No title to or ownership of the software is
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hereby transferred.
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"
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!
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documentation
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"
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A stream which only delivers elements for which a select block returns true
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from an underlying stream.
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Needs readAhead for proper atEnd handling.
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[Author:]
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Claus Gittinger
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[instance variables:]
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hasReadAhead - because nil is a valid read-element,
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this is used to know if readAhead is valid.
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"
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!
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examples
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"
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|s|
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s := SelectingReadStream
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on:#(1 2 3 4 5 6 7 8) readStream
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selecting:[:each | each even].
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s upToEnd
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"
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! !
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!SelectingReadStream class methodsFor:'instance creation'!
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on:aStream selecting:aBlock
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^ self basicNew on:aStream selecting:aBlock
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! !
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!SelectingReadStream methodsFor:'instance creation'!
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on:aStream selecting:aBlock
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inStream := aStream.
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selectBlock := aBlock.
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hasReadAhead := false.
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! !
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!SelectingReadStream methodsFor:'queries'!
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atEnd
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|el|
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hasReadAhead ifTrue:[^ false].
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[
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inStream atEnd ifTrue:[
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^ true
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].
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el := inStream next.
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(selectBlock value:el)
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] whileFalse.
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readAhead := el.
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hasReadAhead := true.
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^ false.
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!
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contentsSpecies
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"return a class of which instances will be returned, when
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parts of the collection are asked for.
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(see upTo-kind of methods in Stream)"
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^ inStream contentsSpecies.
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! !
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!SelectingReadStream methodsFor:'reading'!
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next
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|el|
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hasReadAhead ifTrue:[
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hasReadAhead := false.
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^ readAhead
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].
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[
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inStream atEnd ifTrue:[
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^ self pastEndRead
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].
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el := inStream next.
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(selectBlock value:el)
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] whileFalse.
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^ el
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! !
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!SelectingReadStream class methodsFor:'documentation'!
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version_CVS
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^ '$Header: /cvs/stx/stx/libbasic2/SelectingReadStream.st,v 1.5 2014-04-30 18:20:55 cg Exp $'
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! !
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