"

 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.

"

PeekableStream subclass:#PositionableStream

	instanceVariableNames:'collection position readLimit writeLimit'

	classVariableNames:'ZeroPosition InvalidPositionErrorSignal ErrorDuringFileInSignal

	poolDictionaries:''

	category:'Streams'

!

!PositionableStream 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

"

    Instances of PositionableStream allow positioning the read pointer.

    The PositionableStream class also adds methods for source-chunk reading

    and writing, and for filing-in/out of source code.

    This is an abstract class.

    Compatibility Notice:

       For historical reasons, ST/X starts with a 1-position (i.e. as in collections),

       while ST-80 uses 0-based postions for streams and 1-based positions for collections.

    THIS CERTAINLY IS BAD.

    To allow for portable code, this method can be asked to return the initial position.

    (for code, which ought to execute under other systems, use:

       posZero := (PositionableStream class respondsTo:#zeroPosition) 

                       ifTrue:[PositionableStream zeroPosition]

                       ifFalse:[0] 

    [author:]

        Claus Gittinger

"

! !

!PositionableStream class methodsFor:'initialization'!

initialize

    "setup the signal used to handle errors during fileIn"

    ErrorDuringFileInSignal isNil ifTrue:[

        ErrorDuringFileInSignal := ErrorSignal newSignalMayProceed:true.

        ErrorDuringFileInSignal nameClass:self message:#errorDuringFileInSignal.

        ErrorDuringFileInSignal notifierString:'error during fileIn'.

        InvalidPositionErrorSignal := PositionErrorSignal newSignalMayProceed:true.

        InvalidPositionErrorSignal nameClass:self message:#invalidPositionErrorSignal.

        InvalidPositionErrorSignal notifierString:'invalid position'.

        ChunkSeparator := $!!.

        ZeroPosition := 1.

    ]

! !

!PositionableStream class methodsFor:'instance creation'!

on:aCollection

    "return a new PositionableStream streaming on aCollection"

    ^ (self basicNew) on:aCollection

!

on:aCollection from:first to:last

    "return a new PositionableStream streaming on aCollection

     from first to last"

    ^ (self basicNew) on:aCollection from:first to:last

!

with:aCollection

    "return a new PositionableStream streaming on aCollection,

     the stream is positioned to the end of the collection."

    ^ (self basicNew) with:aCollection

! !

!PositionableStream class methodsFor:'Signal constants'!

invalidPositionErrorSignal

    "return the signal raised if positioning is attempted to an

     invalid position (i.e. before the begin of the stream or after

     the end)"

    ^ InvalidPositionErrorSignal

! !

!PositionableStream class methodsFor:'constants'!

chunkSeparator

    "return the chunk-separation character"

    ^ ChunkSeparator

!

zeroPosition

    "return the number, which marks the initial position.

     Compatibility Notice:

        For historical reasons, ST/X starts with a 1-position (i.e. as in collections),

        while ST-80 uses 0-based postions for streams and 1-based positions for collections.

     THIS CERTAINLY IS BAD.

     To allow for portable code, this method can be asked to return the initial position.

     (for code, which ought to execute under other systems, use:

        posZero := (PositionableStream class respondsTo:#zeroPosition) 

                        ifTrue:[PositionableStream zeroPosition]

                        ifFalse:[0] 

     Be prepared for this to be changed to return 0 as other ST's do.

        "

    ^ ZeroPosition

! !

!PositionableStream methodsFor:'accessing'!

contents

    "return the entire contents of the stream"

    ^ collection

!

peek

    "look ahead for and return the next element"

    |peekObject|

    peekObject := self next.

    self backStep.

    ^ peekObject

!

peekFor:something

    "return true and move past if next == something; 

     otherwise stay and let position unchanged"

    self next == something ifTrue:[

	^ true

    ].

    self backStep.

    ^ false

!

peekForAll:aCollection

    "return true and advance if the next elements are the same

     as aCollection. 

     otherwise stay and let the position unchanged"

    |oldPos|

    oldPos := self position.

    (self next:(aCollection size)) = aCollection ifTrue:[

        ^ true

    ].

    self position:oldPos.

    ^ false

    "Created: 1.3.1997 / 15:11:25 / cg"

!

readLimit

    "return the read-limit; thats the position at which EOF is returned"

    ^ readLimit

    "Created: / 30.10.1998 / 16:47:04 / cg"

!

readLimit:aNumber

    "set the read-limit; thats the position at which EOF is returned"

    readLimit := aNumber

!

writeLimit:aNumber

    "set the writeLimit; thats the position after which writing is prohibited"

    writeLimit := aNumber

! !

!PositionableStream methodsFor:'chunk input/output'!

nextChunk

    "return the next chunk, i.e. all characters up to the next

     exclamation mark. Within the chunk, exclamation marks have to be doubled,

     they are undoubled here.

     Except for primitive code, in which doubling is not needed (allowed).

     This exception was added to make it easier to edit primitive code with 

     external editors. However, this means, that other Smalltalks cannot always 

     read chunks containing primitive code 

     - but that doesnt really matter, since C-primitives are an ST/X feature anyway."

    |theString sep newString done thisChar nextChar inPrimitive

     index    "{ Class:SmallInteger }"

     currSize "{ Class:SmallInteger }" |

    sep := ChunkSeparator.

    theString := String new:500.

    currSize := 500.

    thisChar := self skipSeparators.

    thisChar := self next.

    index := 0.

    done := false.

    inPrimitive := false.

    [done] whileFalse:[

	((index + 2) <= currSize) ifFalse:[

	    newString := String new:(currSize * 2).

	    newString replaceFrom:1 to:currSize with:theString.

	    currSize := currSize * 2.

	    theString := newString

	].

	thisChar isNil ifTrue:[

	    done := true

	] ifFalse:[

	    (thisChar == $% ) ifTrue:[

		nextChar := self peek.

		(nextChar == ${ ) ifTrue:[

		    inPrimitive := true.

		    index := index + 1.

		    theString at:index put:thisChar.

		    thisChar := self next

		] ifFalse:[

		    (nextChar == $} ) ifTrue:[

			inPrimitive := false.

			index := index + 1.

			theString at:index put:thisChar.

			thisChar := self next

		    ]

		]

	    ] ifFalse:[

		inPrimitive ifFalse:[

		    (thisChar == sep) ifTrue:[

			(self peek == sep) ifFalse:[

			    done := true

			] ifTrue:[

			    self next

			]

		    ]

		]

	    ]

	].

	done ifFalse:[

	    index := index + 1.

	    theString at:index put:thisChar.

	    thisChar := self next

	]

    ].

    (index == 0) ifTrue:[^ ''].

    ^ theString copyTo:index

!

nextChunkPut:aString

    "put aString as a chunk onto the receiver;

     double all exclamation marks except within primitives and append a 

     single delimiting exclamation mark at the end.

     This modification of the chunk format (not doubling exclas in primitive code)

     was done to have primitive code more readable and easier be edited in the fileBrowser

     or other editors.

     Its no incompatibility, since inline primitives are an ST/X special

     and code containing ST/X primitives cannot be loaded into other smalltalks anyway."

    self nextPutAllAsChunk:aString.

    self nextPut:ChunkSeparator

    "Modified: 9.12.1995 / 15:56:54 / cg"

!

nextPutAllAsChunk:aString

    "put aString as a chunk onto the receiver;

     double all exclamation marks except within primitives.

     This modification of the chunk format (not doubling exclas in primitive code)

     was done to have primitive code more readable and easier be edited in the fileBrowser

     or other editors.

     Its no incompatibility, since inline primitives are an ST/X special

     and code containing ST/X primitives cannot be loaded into other smalltalks anyway."

    |sep stopChars inPrimitive character

     index    "{ Class:SmallInteger }"

     endIndex "{ Class:SmallInteger }"

     stop     "{ Class:SmallInteger }"

     next     "{ Class:SmallInteger }"|

    endIndex := aString size.

    endIndex == 0 ifTrue:[^ self].

    sep := ChunkSeparator.

    stopChars := '{}' copyWith:sep.

    inPrimitive := false.

    index := 1.

    stop := endIndex + 1.

    [index <= endIndex] whileTrue:[

        "

         find position of next interesting character; 

         output stuff up to that one in one piece

        "

        next := aString indexOfAny:stopChars startingAt:index ifAbsent:stop.

        ((index == 1) and:[next == stop]) ifTrue:[

            self nextPutAll:aString

        ] ifFalse:[

            self nextPutAll:aString startingAt:index to:(next - 1)

        ].

        index := next.

        (index <= endIndex) ifTrue:[

            character := aString at:index.

            (character == ${ ) ifTrue:[

                "/ starts a primitive

                ((index > 1) and:[(aString at:index-1) == $%]) ifTrue:[

                    inPrimitive := true

                ]

            ] ifFalse:[

                "/ ends a primitive

                (character == $} ) ifTrue:[

                    ((index > 1) and:[(aString at:index-1) == $%]) ifTrue:[

                        inPrimitive := false

                    ]

                ] ifFalse:[

                    "/

                    "/ exclas have to be doubled - except if within a primitive

                    "/

                    inPrimitive ifFalse:[

                        (character == sep) ifTrue:[

                            self nextPut:sep

                        ]

                    ]

                ]

            ].

            self nextPut:character.

            index := index + 1

        ]

    ].

    "Modified: / 21.4.1998 / 17:22:47 / cg"

!

nextPutChunkSeparator

    "append a chunk separator character"

    self nextPut:ChunkSeparator

    "Created: 13.9.1995 / 17:39:26 / claus"

! !

!PositionableStream methodsFor:'fileIn'!

askForDebug:message

    "launch a box asking if a debugger is wanted - used when an error

     occurs while filing in"

    ^ self askForDebug:message canContinueForAll:false

!

askForDebug:message canContinueForAll:canContinueForAll

    "launch a box asking if a debugger is wanted - used when an error

     occurs while filing in"

    |labels values|

    Smalltalk isInitialized ifFalse:[

        'PositionableStream [warning]: fileIn error during startup: ' errorPrint. message errorPrintCR.

        ^ #debug

    ].

    "/

    "/ are we in the startup sequence of an image restart ?

    "/

    Processor activeProcessIsSystemProcess ifTrue:[

        'PositionableStream [warning]: fileIn error during startup: ' errorPrint. message errorPrintCR.

        ^ #continue

    ].

    canContinueForAll ifTrue:[

          labels := #('cancel' 'skip' 'debug' 'dont ask again' 'continue').

          values := #(#abort #skip #debug #continueForAll #continue).

    ] ifFalse:[

          labels := #('cancel' 'skip' 'debug' 'continue').

          values := #(#abort #skip #debug #continue).

    ].

    ^ OptionBox 

          request:message 

          label:'Error in fileIn'

          form:(WarningBox iconBitmap)

          buttonLabels:labels

          values:values

          default:#continue.

    "Modified: 10.1.1997 / 18:00:56 / cg"

!

fileIn

    "file in from the receiver, i.e. read chunks and evaluate them -

     return the value of the last chunk."

    |oldPath val|

    self isFileStream ifFalse:[

        ^ self fileInNotifying:(SourceFileLoader on:self) passChunk:true.

    ].

        oldPath := Smalltalk systemPath.

    ] valueNowOrOnUnwindDo:[

        Smalltalk systemPath:oldPath.

    ].

    ^ val

    "Modified: / 16.10.1999 / 12:25:27 / cg"

!

fileInNextChunkNotifying:someone

    "read next chunk, evaluate it and return the result;

     someone (which is usually some codeView) is notified of errors.

     Filein is done as follows:

	read a chunk

	if it started with an excla, evaluate it, and let the resulting object

	fileIn more chunks.

	This is a nice trick, since the methodsFor: expression evaluates to

	a ClassCategoryReader which reads and compiles chunks for its class.

	However, other than methodsFor expressions are possible - you can

	(in theory) create readers for any syntax.

    "

    ^ self fileInNextChunkNotifying:someone passChunk:false

!

fileInNextChunkNotifying:someone passChunk:passChunk

    "read next chunk, evaluate it and return the result;

     someone (which is usually some codeView) is notified of errors.

     Filein is done as follows:

        read a chunk

        if it started with an excla, evaluate it, and let the resulting object

        fileIn more chunks.

        This is a nice trick, since the methodsFor: expression evaluates to

        a ClassCategoryReader which reads and compiles chunks for its class.

        However, other than methodsFor expressions are possible - you can

        (in theory) create readers for any syntax.

    "

    |aString sawExcla rslt done|

    self skipSeparators.

    self atEnd ifFalse:[

        sawExcla := self peekFor:ChunkSeparator.