"{ Package: 'stx:goodies/xtreams/core' }"

"{ NameSpace: Xtreams }"

WriteStream subclass:#PositionWriteStream

	instanceVariableNames:'buffer'

	classVariableNames:''

	poolDictionaries:'XtreamsPool'

	category:'Xtreams-Core'

!

PositionWriteStream comment:'Wraps a non-positionable stream and provides positioning capability by buffering written elements. Buffering strategy can be configured via different Buffer classes.

Instance Variables

	buffer  <Buffer> holds written elements

'

!

!PositionWriteStream methodsFor:'accessing'!

insert: anInteger from: aSequenceableCollection at: startIndex

	^buffer insert: anInteger from: aSequenceableCollection at: startIndex

!

write: anInteger from: aSequenceableCollection at: startIndex

	| toFlush bufferFlush |

	(buffer hasFixedWriteSpace not or: [buffer writeSize >= anInteger ]) ifTrue: [

		buffer write: anInteger from: aSequenceableCollection at: startIndex.

		^anInteger ].

	toFlush := buffer readSize + anInteger - buffer cacheSize.

	bufferFlush := toFlush min: buffer readSize.

	destination write: bufferFlush from: buffer.

	(toFlush > bufferFlush) ifTrue: [

		toFlush := toFlush - bufferFlush.

		destination write: toFlush from: aSequenceableCollection at: startIndex ].

	buffer write: anInteger - toFlush from: aSequenceableCollection at: startIndex + toFlush.

	^anInteger

! !

!PositionWriteStream methodsFor:'initialize-release'!

buffer

	^buffer

!

buffer: aBuffer

	buffer recycle.

	buffer := aBuffer

!

close

	super close.

	buffer recycle.

	buffer := nil

!

contentsSpecies

	^destination contentsSpecies

!

flush

	buffer ifNil: [^self].

	destination write: buffer.

	buffer clear

!

on: aDestination

	buffer := Buffer new: DefaultBufferSize class: aDestination contentsSpecies.

	super on: aDestination

! !

!PositionWriteStream methodsFor:'printing'!

streamingPrintOn: aStream

	super streamingPrintOn: aStream.

	aStream

		write: ' buffered: ';

		print: buffer writeSize.

	buffer writeSize isZero ifTrue: [^self].

	aStream

		cr; tab;

		print: buffer contentsPast

! !

!PositionWriteStream methodsFor:'seeking'!

++ anInteger

	| skipped |

	anInteger < 0 ifTrue: [ ^self -- anInteger negated ].

	skipped := buffer writeSkip: anInteger.

	skipped = anInteger ifTrue: [^anInteger].

	[destination ++ (anInteger - skipped)] on: Incomplete do: [:incomplete |

		(Incomplete count: incomplete count + skipped) raise].

	^anInteger

!

-- anInteger

	| skipped |

	anInteger < 0 ifTrue: [ ^self ++ anInteger negated ].

	skipped := (buffer writeSkip: anInteger negated) negated.

	skipped = anInteger ifTrue: [^anInteger].

	(Incomplete count: skipped) raise

!

available

	^buffer writeSize

!

length

	^buffer activeSize

!

position

	^buffer writePosition

!

position: aPosition

	| startPosition delta |

	aPosition < 0 ifTrue: [Incomplete zero raise].

	startPosition := buffer writePosition.

	delta := aPosition - startPosition.

	^[      self ++ delta. aPosition

	] on: Incomplete do: [ :ex |

		(Incomplete count: startPosition + ex count) raise ]

! !

!PositionWriteStream methodsFor:'testing'!

isPositionable

	^true

! !

!PositionWriteStream methodsFor:'transforming'!

positioning

	^self

! !

!PositionWriteStream class methodsFor:'documentation'!

version_SVN

    ^ '$Id$'

! !