"

 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' }"

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 if 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.

    [author:]

        Claus Gittinger

"

!

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:'accessing'!

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 - 1.

    collection size == lastIndex ifFalse:[

        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: / 19.2.1997 / 08:57:28 / stefan"

    "Modified: / 30.10.1997 / 16:21:23 / cg"

!

last

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

    ^ collection at:(position - 1).

    "

     |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) to:(position - 1).

    "

     |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.        

    "

!

reset

    "reset the stream; write anew.

     See the comment in WriteStream>>contents"

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

    super reset

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

! !

!WriteStream methodsFor:'positioning'!

position:index

    "redefined to allow positioning past the readLimit"

    ((index > (collection size + 1)) or:[index < ZeroPosition]) ifTrue: [^ self positionError].

    position := index

! !

!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 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'!

isReadable 

    "return true if the receiver supports reading - thats not true"

    ^ false

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

!

isWritable

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

     Always return true here"

    ^ true

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

!

size

    "return the current size"

    ^ position - 1.

    "Created: 14.10.1997 / 20:43:49 / cg"

! !

!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"

    ^ position == 1

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

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

	^ super next:count put:anObject

    ].

    final := position + count - 1.

    (final > collection size) ifTrue:[

	self growCollection:final

    ].

    position to:final do:[:index |

	collection at:index put:anObject.

    ].

    position := position + count.

    (position > readLimit) ifTrue:[readLimit := position - 1].

    ^ anObject

!

next:n putAll:aCollection startingAt:pos1

    "append some elements of the argument, aCollection to the stream."

    ^ self nextPutAll:aCollection startingAt:pos1 to:pos1+n-1

    "

     |s|

     s := '' writeStream.

     s nextPutAll:'hello '.

     s next:5 putAll:'1234world012345' startingAt:5.

     s contents   

    "

    "Modified: 12.7.1996 / 10:31:36 / cg"

!

nextPut:anObject

    "append the argument, anObject to the stream.

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

%{  /* NOCONTEXT */

    REGISTER int pos;

    unsigned ch;

    OBJ coll;

    OBJ p, wL, rL;

    int __readLimit = -1;

    coll = __INST(collection);

    p = __INST(position);

#ifndef NO_PRIM_STREAM

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

        pos = __intVal(p);

        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;

                    __INST(position) = __MKSMALLINT(pos + 1);

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

                        __INST(readLimit) = __MKSMALLINT(pos);

                    }

                    RETURN ( anObject );

                }

            } else if (cls == @global(ByteArray)) {

                if (__isSmallInteger(anObject) 

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

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

                    __ByteArrayInstPtr(coll)->ba_element[pos-1] = ch;

                    __INST(position) = __MKSMALLINT(pos + 1);

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

                        __INST(readLimit) = __MKSMALLINT(pos);

                    }

                    RETURN ( anObject );

                }

            } else if (cls == @global(Array)) {

                if (pos <= __arraySize(coll)) {

                     __ArrayInstPtr(coll)->a_element[pos-1] = anObject;

                    __STORE(coll, anObject);

                    __INST(position) = __MKSMALLINT(pos + 1);

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

                        __INST(readLimit) = __MKSMALLINT(pos);

                    }

                    RETURN ( anObject );

                }

            }

        }

    }

#endif

%}.

    (writeLimit isNil

    or:[position <= writeLimit]) ifTrue:[

        (position > collection size) ifTrue:[self growCollection].

        collection at:position put:anObject.

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

        position := position + 1.

    ] ifFalse:[

        WriteErrorSignal raiseErrorString:'write beyond writeLimit'

    ].

    ^anObject

!

nextPutAll:aCollection

    "append all elements of the argument, aCollection to the stream.

     Redefined to avoid count grows of the underlying collection -

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

    |nMore final|

    collection isNil ifTrue:[

	^ super nextPutAll:aCollection

    ].

    nMore := aCollection size.

    final := position + nMore - 1.

    (writeLimit notNil

    and:[final > writeLimit]) ifTrue:[

	final := writeLimit.

	nMore := final - position + 1

    ].

    (final > collection size) ifTrue:[

	self growCollection:final

    ].

    collection replaceFrom:position

			to:final

		      with:aCollection 

		startingAt:1.

    position := position + nMore.

    (position > readLimit) ifTrue:[readLimit := position - 1].

    ^ aCollection

!

nextPutAll:aCollection startingAt:pos1 to:pos2

    "append some elements of the argument, aCollection to the stream.

     Redefined to avoid count grows of the underlying collection -

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

    |nMore final|

    collection isNil ifTrue:[

        ^ super nextPutAll:aCollection startingAt:pos1 to:pos2

    ].

    nMore := pos2 - pos1 + 1.

    final := position + nMore - 1.

    (writeLimit notNil

    and:[final > writeLimit]) ifTrue:[

        final := writeLimit.

        nMore := final - position + 1

    ].

    (final > collection size) ifTrue:[

        self growCollection:final

    ].

    collection replaceFrom:position

                        to:final

                      with:aCollection 

                startingAt:pos1.

    position := position + nMore.

    (position > readLimit) ifTrue:[readLimit := position - 1].

    ^ aCollection

    "

     |s|

     s := '' writeStream.

     s nextPutAll:'hello '.

     s nextPutAll:'1234world012345' startingAt:5 to:9.

     s contents

    "

    "Modified: 12.7.1996 / 10:31:36 / cg"

! !

!WriteStream class methodsFor:'documentation'!

version

    ^ '$Header: /cvs/stx/stx/libbasic/WriteStream.st,v 1.45 2001-07-10 10:06:56 cg Exp $'

! !