"{ Encoding: utf8 }"

"

 COPYRIGHT (c) 1989 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.

"

"{ Package: 'stx:libbasic' }"

"{ NameSpace: Smalltalk }"

PositionableStream subclass:#WriteStream

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'Streams'

!

!WriteStream class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1989 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

"

    Streams for writing into.

    WriteStreams are especially useful, if big strings are to be constructed

    from pieces - create a writeStream, add the pieces (with #nextPut: or

    #nextPutAll:) and finally fetch the concatenated string via #contents.

    This is much better than constructing the big string by concatenating via

    the comma (,) operator, since less intermediate garbage objects are created.

    This implementation currently DOES change the

    identity of the streamed-upon collection IF it cannot grow easily.

    Collections which cannot grow easily are for example: Array, ByteArray and String.

    Thus it is slightly incompatible to ST-80 since 'aStream contents' does

    not always return the original collection. This may change.

    [caveat:]

        Basing capabilities like readability/writability/positionability/peekability on inheritance makes

        the class hierarchy ugly and leads to strange and hard to teach redefinitions (aka. NonPositionableStream

        below PositionableStream or ExternalReadStream under WriteStream)

    [author:]

        Claus Gittinger

    [see also:]

        CharacterWriteStream (if streaming for a unicode string)

"

!

examples

"

								[exBegin]

     |s|

     s := WriteStream on:''.

     s nextPutAll:'hello';

       space;

       nextPutAll:'world'.

     s contents inspect

								[exEnd]

								[exBegin]

     |s|

     s := WriteStream on:''.

     s nextPutAll:'hello';

       space;

       nextPutAll:'world'.

     Transcript nextPutLine:(s contents)

								[exEnd]

								[exBegin]

     |s|

     s := '' writeStream.

     s nextPutAll:'hello';

       space;

       nextPutAll:'world'.

     Transcript nextPutLine:(s contents)

								[exEnd]

"

! !

!WriteStream methodsFor:'Compatibility-Squeak'!

resetContents

    "Squeak compatibility"

    self reset

! !

!WriteStream methodsFor:'accessing'!

clear

    "for compatibility with Transcript"

    self reset

!

contents

    "return the current contents (a collection) of the stream.

     Currently, this returns the actual collection if possible

     (and reset is implemented to create a new one) in contrast to

     ST80, where contents returns a copy and reset only sets the writePointer.

     The ST/X behavior creates less temporary garbage in the normal case

     (where things are written for the contents only) but may be incompatible

     with some applications. Time will show, if this is to be changed."

    |lastIndex|

    lastIndex := position.

    collection size ~~ lastIndex ifTrue:[

        collection isFixedSize ifTrue:[

            "

             grow is expensive - return a copy.

             (is this what users of writeStream expect ?)

            "

            collection := collection copyFrom:1 to:lastIndex

        ] ifFalse:[

            collection grow:lastIndex

        ]

    ].

    ^ collection

    "Modified: / 30-10-1997 / 16:21:23 / cg"

    "Modified: / 20-03-2018 / 16:34:29 / stefan"

!

last

    "return the last element - report an error if the stream is empty"

    ^ collection at:position.

    "

     |s|

     s := '' writeStream.

     s nextPut:$a.

     s last.

     s nextPut:$b.

     s last.

     s nextPut:$c.

     s last.

    "

!

last:n

    "return the last n elements as species of the underlying collection;

     Report an error if the stream is empty"

    ^ collection copyFrom:(position - n + 1) to:position.

    "

     |s|

     s := '' writeStream.

     s nextPut:$a.

     s last:1.

     s nextPut:$b.

     s last:1.

     s last:2.

     s nextPut:$c.

     s last:1.

     s last:2.

     s last:3.

    "

!

readStream

    "return a readstream on the current contents;

     that is: if more is written to the stream in the meantime,

     the readStream will NOT show it.

     To avoid copying the contents, a readStream with a readLimit

     is created. In the hope, that noone repositions and rewrites the

     underlying writeStream.

     If that leads to problems, you should use contents readStream."

    ^ ReadStream on:collection from:1 to:self position.

    "

     |w r|

     w := WriteStream on:(String new).

     w nextPutAll:'12345'.

     r := w readStream.

     w nextPutAll:'abc'.

     w nextPutAll:(r upToEnd).

     w nextPutAll:'def'.

     w contents.

    "

!

reset

    "reset the stream; write anew.

     See the comment in WriteStream>>contents"

    collection := collection species new:(collection size).

    position := 0.

    "Modified: 19.2.1997 / 08:57:00 / stefan"

! !

!WriteStream methodsFor:'positioning'!

position:index0Based

    "redefined to allow positioning past the readLimit"

    ((index0Based > collection size) or:[index0Based < 0]) ifTrue: [^ self positionError].

    position := index0Based

!

skip:count

    "redefined to allow positioning back over already written characters"

    self position:(self position + count).

!

truncateTo:givenMax

    "if the streamed contents is larger than maxSize,

     reset the write position back to this size.

     Otherwise do nothing."

    self size > givenMax ifTrue:[

        self position:givenMax.

    ].    

    "

     |s|

     s := '' writeStream.

     s nextPutAll:'123456'.

     s truncateTo:4.

     s nextPutAll:'abc'.

     s contents

    "

    "

     |s|

     s := '' writeStream.

     s nextPutAll:'1234'.

     s truncateTo:4.

     s nextPutAll:'abc'.

     s contents

    "

    "

     |s|

     s := '' writeStream.

     s nextPutAll:'123'.

     s truncateTo:4.

     s nextPutAll:'abc'.

     s contents

    "

    "

     |s|

     s := 'testFile' asFilename writeStream.

     s nextPutAll:'123456'.

     s truncateTo:4.

     s nextPutAll:'abc'.

     s close.

     'testFile' asFilename contents

    "

    "Created: / 02-08-2017 / 09:24:58 / cg"

! !

!WriteStream methodsFor:'private'!

growCollection

    "grow the streamed collection to at least 10 elements"

    self growCollection:10

    "Modified: 19.8.1997 / 17:53:28 / cg"

!

growCollection:minNewSize

    "grow the streamed collection to at least minNewSize"

    |oldSize newSize newColl|

    oldSize := collection size.

    (oldSize == 0) ifTrue:[

	newSize := minNewSize

    ] ifFalse:[

	newSize := oldSize * 2.

	(newSize < minNewSize) ifTrue:[newSize := minNewSize].

    ].

    collection isFixedSize ifTrue:[

	newColl := collection species new:newSize.

	newColl replaceFrom:1 to:oldSize with:collection startingAt:1.

	collection := newColl

    ] ifFalse:[

	collection grow:newSize

    ].

    "Modified: 19.8.1997 / 17:53:11 / cg"

! !

!WriteStream methodsFor:'private-accessing'!

on:aCollection

    super on:aCollection.

    readLimit := 0.

!

on:aCollection from:start to:last

    "create and return a new stream for writing onto aCollection, where

     writing is limited to the elements in the range start to last."

    super on:aCollection from:start to:last.

    writeLimit := last.

! !

!WriteStream methodsFor:'queries'!

endsWith:aCollection

    "Answer true, if the contents of the stream ends with aCollection.

     Speedup for upToAll:, throughAll etc."

    |sz start "{ Class: SmallInteger }"|

    collection isNil ifTrue:[

        "only supported for internal streams"

        self shouldNotImplement.

    ].

    sz := aCollection size.

    start := position + 1 - sz.

    ^ start > 0 and:[(collection copyFrom:position+1-sz to:position) endsWith:aCollection].

    "

        (WriteStream with:'abcdef') endsWith:'def'

        (WriteStream with:'def') endsWith:'def'

        (WriteStream with:'abc') endsWith:'def'

        (WriteStream with:'ef') endsWith:'def'

false    "

!

size

    "return the current size"

    ^ position

! !

!WriteStream methodsFor:'reading'!

next

    "catch read access to write stream - report an error"

    self shouldNotImplement

!

peek

    "catch read access to write stream - report an error"

    self shouldNotImplement

! !

!WriteStream methodsFor:'testing'!

isEmpty

    "return true, if the contents of the stream is empty"

    ^ self position == 0

    "Created: 14.10.1997 / 20:44:37 / cg"

!

isReadable

    "return true if the receiver supports reading - that's not true"

    ^ false

    "Created: / 8.11.1997 / 14:06:07 / cg"

!

isWritable

    "return true, if writing is supported by the receiver.

     Always return true here"

    ^ true

    "Modified: 16.5.1996 / 14:44:49 / cg"

! !

!WriteStream methodsFor:'writing'!

next:count put:anObject

    "append anObject count times to the receiver.

     Redefined to avoid count grows of the underlying collection -

     instead a single grow on the final size is performed."

    |final|

    count == 0 ifTrue:[^ self].

    (collection isNil or:[writeLimit notNil]) ifTrue:[

        super next:count put:anObject.

        ^ self.

    ].

    final := position + count.

    (final > collection size) ifTrue:[

        self growCollection:final

    ].

    collection from:position + 1 to:final put:anObject.

    position := position + count.

    (position > readLimit) ifTrue:[readLimit := position].

    "/ ^ anObject -- return self

    "

     '' writeStream next:10 put:$*

    "

!

nextPut:anObject

    "append the argument, anObject to the stream.

     Specially tuned for appending to String, ByteArray and Array streams."

%{  /* NOCONTEXT */

#ifndef NO_PRIM_STREAM

    REGISTER int pos;

    unsigned ch;

    OBJ coll;

    OBJ p, wL, rL;

    int __readLimit = -1;

    coll = __INST(collection);

    p = __INST(position);

    if (__isNonNilObject(coll) && __isSmallInteger(p)) {

        pos = __intVal(p);

        /* make 1-based */

        pos = pos + 1;

        wL = __INST(writeLimit);

        if ((wL == nil)

         || (__isSmallInteger(wL) && (pos <= __intVal(wL)))) {

            OBJ cls;

            cls = __qClass(coll);

            rL = __INST(readLimit);

            if (__isSmallInteger(rL)) {

                __readLimit = __intVal(rL);

            }

            if (cls == @global(String)) {

                if (__isCharacter(anObject)

                 && ((ch = __intVal(__characterVal(anObject))) <= 255) /* ch is unsigned */

                 && (pos <= __stringSize(coll))) {

                    __StringInstPtr(coll)->s_element[pos-1] = ch;

advancePositionAndReturn: ;

                    if ((__readLimit >= 0) && (pos > __readLimit)) {

                        __INST(readLimit) = __mkSmallInteger(pos);

                    }