"

 COPYRIGHT (c) 1996 by Claus Gittinger

	      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.

"

FilteringStream subclass:#FilteringLineStream

	instanceVariableNames:'lineBuffer lineFilter'

	classVariableNames:''

	poolDictionaries:''

	category:'Streams-Misc'

!

!FilteringLineStream class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1996 by Claus Gittinger

	      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

"

    A FilteringLineStream is much like a FilteringStream, but

    processes its input line-wise.

    A FilteringLineStream can be connected to some input

    (from which characters are read via the ReadStream protocol),

    and/or to some output (to which characters are written via

    the WriteStream protocol.

    The FilteringLineStream itself performs some filtering/processing

    on the elements as they arrive, optionally suppressing filtering

    (i.e. removing) some elements.

    [author:]

	Claus Gittinger

    [See also:]

	FilteringStream ReadStream WriteStream

"

!

examples

"

  pushing the contents of a stream onto another stream

  (here, the Transcript) without a need to read everyting into a

  buffer or to reinvent the read-loop:

    |in pusher|

    in := 'Makefile' asFilename readStream.

    pusher := FilteringLineStream readingFrom:in writingTo:Transcript.

    pusher filterUpToEnd

  filter all comments (starting with '#') from a Makefile:

    |in filter|

    in := 'Makefile' asFilename readStream.

    filter := FilteringLineStream readingFrom:in.

    filter filter:[:line | (line startsWith:'#') ifTrue:[line] ifFalse:[nil]].

    filter outputStream:Transcript.

    filter filterUpToEnd

  the inverse - remove all comments from the Makefile:

    |in filter|

    in := 'Makefile' asFilename readStream.

    filter := FilteringLineStream readingFrom:in.

    filter filter:[:line | (line startsWith:'#') ifTrue:[nil] ifFalse:[line]].

    filter outputStream:Transcript.

    filter filterUpToEnd

  feed a second filter from the first filters output;

  (the remains are all lines starting with '#' and ending with '-'):

    |in filter1 filter2|

    in := 'Makefile' asFilename readStream.

    filter1 := FilteringLineStream readingFrom:in.

    filter1 filter:[:line | (line startsWith:'#') ifTrue:[line] ifFalse:[nil]].

    filter2 := FilteringLineStream readingFrom:filter1.

    filter2 filter:[:line | (line endsWith:'-') ifTrue:[line] ifFalse:[nil]].

    filter2 outputStream:Transcript.

    filter2 filterUpToEnd

"

! !

!FilteringLineStream methodsFor:'access - pull-reading'!

filterUpToEnd

    "pull input from inputStream up to the end,

     push it filtered into the outputStream."

    [inputStream atEnd] whileFalse:[

	self nextPutLine:(inputStream nextLine)

    ].

    "Created: 11.1.1997 / 16:09:05 / cg"

! !

!FilteringLineStream methodsFor:'access - push-writing'!

cr

    "finish a line, push it filtered into the outputStream"

    |output|

    lineFilter isNil ifTrue:[

    ] ifFalse:[

    ].

    lineBuffer := ''.

    "Modified: 11.1.1997 / 16:32:40 / cg"

!

nextPut:something

    "collect a line and push it when a cr arrives"

    something == Character cr ifTrue:[

	self cr

    ] ifFalse:[

	lineBuffer isNil ifTrue:[lineBuffer := ''].

	lineBuffer := lineBuffer copyWith:something.

    ]

    "Created: 2.7.1996 / 20:54:38 / cg"

    "Modified: 2.7.1996 / 21:03:26 / cg"

!

nextPutAll:something

    "collect a line and push it when a cr arrives"

    lineBuffer isNil ifTrue:[

	lineBuffer := something

    ] ifFalse:[

	lineBuffer := lineBuffer , something.

    ]

    "Modified: 11.1.1997 / 16:31:28 / cg"

! !

!FilteringLineStream methodsFor:'accessing'!

filter

    "return the filter"

    ^ lineFilter

    "Created: 11.1.1997 / 16:13:15 / cg"

!

filter:aBlock

    "set the filter"

    lineFilter := aBlock

    "Created: 11.1.1997 / 16:13:25 / cg"

! !

!FilteringLineStream class methodsFor:'documentation'!

version

! !