"

 COPYRIGHT (c) 1994 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 }"

Stream subclass:#PeekableStream

	instanceVariableNames:''

	classVariableNames:'ErrorDuringFileInSignal CurrentFileInDirectoryQuerySignal

		CurrentSourceContainerQuery'

	poolDictionaries:''

	category:'Streams'

!

!PeekableStream class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1994 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

"

    abstract superclass for all Stream which support read-ahead

    (i.e. peeking) of one element.

    Concrete subclasses must implement a peek method.

    [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

"

! !

!PeekableStream class methodsFor:'initialization'!

initialize

    "setup the signal used to handle errors during fileIn"

    ErrorDuringFileInSignal isNil ifTrue:[

        ErrorDuringFileInSignal := Error newSignalMayProceed:true.

        ErrorDuringFileInSignal nameClass:self message:#errorDuringFileInSignal.

        ErrorDuringFileInSignal notifierString:'error during fileIn'.

    ]

    "

     self initialize

    "

    "Modified: / 23-10-2006 / 16:34:41 / cg"

! !

!PeekableStream class methodsFor:'Signal constants'!

currentFileInDirectoryQuerySignal

    "return the querySignal, which can be used to ask for the current directory

     during a fileIn (that is the directory where the filed-in file resides),

     and in a fileBrowsers doIt.

     Using this, allows for the loaded code or doIts to ask for the fileBrowsers

     current directory, by asking this querySignal (which is nice sometimes)."

    CurrentFileInDirectoryQuerySignal isNil ifTrue:[

        CurrentFileInDirectoryQuerySignal := QuerySignal new.

        CurrentFileInDirectoryQuerySignal nameClass:self message:#currentFileInDirectoryQuerySignal.

        CurrentFileInDirectoryQuerySignal notifierString:'query for current directory when filing in'.

        CurrentFileInDirectoryQuerySignal handlerBlock:[:ex | ex proceedWith:Filename currentDirectory].

    ].

    ^ CurrentFileInDirectoryQuerySignal

    "Modified: / 23-10-2006 / 16:34:37 / cg"

!

currentSourceContainerQuery

    "return the querySignal, which can be used to ask for the current source container filename

     during a fileIn 

     Using this, allows for the loaded code to remember the classes file name."

    CurrentSourceContainerQuery isNil ifTrue:[

        CurrentSourceContainerQuery := QuerySignal new.

        CurrentSourceContainerQuery nameClass:self message:#currentClassFilenameQuery.

        CurrentSourceContainerQuery notifierString:'query for current sorce container name when filing in'.

        CurrentSourceContainerQuery handlerBlock:[:ex | ex proceedWith:nil].

    ].

    ^ CurrentSourceContainerQuery

    "Modified: / 23-10-2006 / 16:32:49 / cg"

! !

!PeekableStream class methodsFor:'queries'!

currentFileInDirectory

    "during a fileIn (if a script), the script can ask for the current directory"

    ^ self currentFileInDirectoryQuerySignal query

    "Modified: / 23-10-2006 / 16:34:47 / cg"

!

currentSourceContainer

    "during a fileIn (if a script), the script can ask for the current filename"

    ^ self currentSourceContainerQuery query

    "Modified: / 23-10-2006 / 16:33:40 / cg"

! !

!PeekableStream 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 doesn't really matter, since C-primitives are an ST/X feature anyway."

    |buffer theString chunkSeparator newString done thisChar nextChar 

     atBeginOfLine inPrimitive  hasCR hasLF

     index    "{ Class:SmallInteger }"

     currSize "{ Class:SmallInteger }" |

    chunkSeparator := ChunkSeparator.

    buffer := CharacterWriteStream on:(String new:100).

    self skipSeparators.

    thisChar := self nextOrNil.

    done := false.

    atBeginOfLine := true.

    inPrimitive := false.

    hasCR := hasLF := false.

    [done not and:[thisChar notNil]] whileTrue:[

        "match primitive only at beginning of line 

         (ExternalStream>>#nextChunk did this, although stc allows primitive to start anywhere)"

        (atBeginOfLine and:[thisChar == $%]) ifTrue:[

            nextChar := self peekOrNil.

            (nextChar == ${ ) ifTrue:[

                inPrimitive := true.

                buffer nextPut:thisChar.

                thisChar := self next

            ] ifFalse:[

                (nextChar == $} ) ifTrue:[

                    inPrimitive := false.

                    buffer nextPut:thisChar.

                    thisChar := self next

                ]

            ]

        ] ifFalse:[

            "chunk can not end in primitive code"

            (inPrimitive not and:[thisChar == chunkSeparator]) ifTrue:[

                (self peekOrNil == chunkSeparator) ifTrue:[

                    "double chunkSeparator, make single"

                    self next.

                ] ifFalse:[

                    "single chunkSeparator: end of chunk"

                    done := true.

                ].

            ].

        ].

        done ifFalse:[

            "now map CR LF to LF (ExternalStream>>#nextChunk did this)"

            atBeginOfLine := false.

            thisChar == Character return ifTrue:[

                self peekOrNil == Character lf ifTrue:[

                    self next.

                    thisChar := Character lf.

                    hasLF := true.

                ] ifFalse:[

                    "CR without LF"

                    hasCR := true.

                ].

                atBeginOfLine := true.

            ] ifFalse:[thisChar == Character lf ifTrue:[

                hasLF := true.

                atBeginOfLine := true.

            ]].

            buffer nextPut:thisChar.

            thisChar := self nextOrNil.

        ].

    ].

    theString := buffer contents.

    (hasCR and:[hasLF not]) ifTrue:[

        "map all CR in a CR only file to NL (ExternalStream>>#nextChunk did this)"

    ].

    ^ theString

! !

!PeekableStream methodsFor:'fileIn'!

fileIn

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

     return the value of the last chunk."

    |notifiedLoader lastValue|

    SourceFileLoader notNil ifTrue:[

        notifiedLoader := SourceFileLoader on:self.

    ].

    Class nameSpaceQuerySignal handle:[:ex |

        ex proceedWith:Smalltalk

    ] do:[

        lastValue := self fileInNotifying:notifiedLoader passChunk:true.

    ].

    ^ lastValue.

!

fileInBinary

    "file in from the receiver, i.e. read binary stored classes and/or objects.

     Return the last object."

    |bos obj|

    bos := BinaryObjectStorage onOld:self.

    Class nameSpaceQuerySignal 

	answer:Smalltalk

	do:[

	    [self atEnd] whileFalse:[

		obj := bos next.

	    ]

	].

    bos close.

    ^ obj

    "Created: / 13.11.2001 / 10:12:30 / cg"

    "Modified: / 13.11.2001 / 10:14:04 / cg"

! !

!PeekableStream methodsFor:'positioning'!

skipAny:skipCollection

    "skip all characters included in the argument-set.

     returns the next peeked element or nil, if the end-of-stream was reached."

    |nextOne|

    nextOne := self peekOrNil.

    [nextOne notNil and:[skipCollection includes:nextOne]] whileTrue:[

        self next.

        nextOne := self peekOrNil

    ].

    ^ nextOne

    "

     |s skipChars|

     s := ReadStream on:'some numbers1234with\in other99 stuff' withCRs.

     skipChars := 'abcdefghijklmnopqrstuvwxyz\ ' withCRs.

     s skipAny:skipChars.

     Transcript showCR:(Integer readFrom:s).

     s skipAny:skipChars.

     Transcript showCR:(Integer readFrom:s).

    "

!

skipSeparators

    "skip all whitespace; 

     return the next peeked element or nil, if the end-of-stream was reached.

     The stream's elements should be characters.

     Notice: compare this method to skipSpaces"

    |nextOne|

    nextOne := self peekOrNil.

    [nextOne notNil and:[nextOne isSeparator]] whileTrue:[

        self next.

        nextOne := self peekOrNil

    ].

    ^ nextOne

    "

     |s|

     s := ReadStream on:'one      two\three' withCRs.

     s skipSeparators.

     Transcript showCR:(s nextWord).

     s skipSeparators.

     Transcript showCR:(s nextWord).

     s skipSeparators.

     Transcript showCR:(s next displayString).

    "

!

skipSeparatorsExceptCR

    "skip all whitespace except carriage return; returns the 

     next peeked element or nil, if the end-of-stream was reached.

     The streams elements should be characters.

     Notice: compare this method to skipSpaces and skipSeparators"

    |nextOne|

    nextOne := self peekOrNil.

    [nextOne notNil 

     and:[nextOne isSeparator

     and:[nextOne ~~ Character cr]]] whileTrue:[

        self next.

        nextOne := self peekOrNil

    ].

    ^ nextOne

!

skipSpaces

    "skip all spaces; returns the next peeked element or

     nil, if the end-of-stream was reached.

     The streams elements should be characters.

     Notice: this one skips only spaces (i.e. no cr, tabs etc)

             usually, skipSeparators is what you want."

    |nextOne|

    nextOne := self peekOrNil.

    [nextOne notNil and:[nextOne == Character space]] whileTrue:[

        self next.

        nextOne := self peekOrNil

    ].

    ^ nextOne

    "

     |s|

     s := ReadStream on:'one      two\three' withCRs.

     s skipSpaces.

     Transcript showCR:(s nextWord).

     s skipSpaces.

     Transcript showCR:(s nextWord).

     s skipSpaces.

     Transcript showCR:(s next displayString).

    "

! !

!PeekableStream methodsFor:'private fileIn'!

basicFileInNotifying:someone passChunk:passChunk

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

     return the value of the last chunk.

     Someone (which is usually some codeView) is notified of errors."

     ^(EncodedStream decodedStreamFor:self) basicFileInNotifying:someone passChunk:passChunk

    "Modified: / 10-09-1999 / 16:54:01 / stefan"

    "Modified: / 16-11-2001 / 16:21:28 / cg"

    "Modified: / 25-03-2013 / 22:57:55 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

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.

    "

    ^ self fileInNextChunkNotifying:someone passChunk:passChunk silent:nil

!

fileInNextChunkNotifying:someone passChunk:passChunk silent:beSilent

    "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 compiler lastClass|

    self skipSeparators.

    self atEnd ifFalse:[

        sawExcla := self peekFor:(self class chunkSeparator).

        aString := self nextChunk.

        "/

        "/ handle empty chunks;

        "/ this allows for Squeak code to be filedIn

        "/

        [aString size == 0 and:[self atEnd not]] whileTrue:[

            aString := self nextChunk.

        ].

        aString size ~~ 0 ifTrue:[

            passChunk ifTrue:[

                someone notNil ifTrue:[someone source:aString]

            ].

            someone perform:#reader: with:(SourceFileLoader::SourceFileReader new) ifNotUnderstood:[].

            compiler := (Smalltalk at:#Compiler) new.

            compiler allowUndeclaredVariables:false.

            sawExcla ifFalse:[

                "/ class definition chunks, etc., which are simply evaluated

                rslt := compiler evaluate:aString receiver:someone notifying:someone compile:false.

                rslt isBehavior ifTrue:[ 

                    lastClass := rslt 

                ] ifFalse:[

                    lastClass := nil 

                ].

            ] ifTrue:[

                "/ methodsFor chunks, etc., which generate a reader

                (Smalltalk at:#Compiler) emptySourceNotificationSignal handle:[:ex |

                    ^ nil

                ] do:[

                    rslt := compiler 

                                evaluate:aString 

                                notifying:someone 

                                compile:false.

                ].

                "

                 usually, the above chunk consists of some methodsFor:-expression

                 in this case, the returned value is a ClassCategoryReader,

                 which is used to load & compile the methods ...

                "

                (rslt isNil or:[rslt == #Error]) ifTrue:[

                    "

                     however, if that was nil (i.e. some error), we skip chunks

                     up to the next empty chunk.

                    "

                    Transcript showCR:'skipping chunks ...'.

                    done := false.

                    [done] whileFalse:[

                        aString := self nextChunk.

                        done := (aString size == 0).

                    ]

                ] ifFalse:[

                    Class packageQuerySignal handle:[:ex |

                        lastClass notNil ifTrue:[

                            ex proceedWith:lastClass package

                        ] ifFalse:[

                            ex reject

                        ].    

                    ] do:[    

                        rslt := rslt 

                                fileInFrom:self 

                                notifying:someone 

                                passChunk:passChunk

                                single:false

                                silent:beSilent

                    ].            

                ]