"{ Package: 'stx:goodies/smaCC' }"

"{ NameSpace: SmaCC }"

Object subclass:#SmaCCScanner

	instanceVariableNames:'stream start matchActions matchEnd currentCharacter outputStream

		lastOutputStreamMatchPosition lastMatchWasEmpty returnMatchBlock'

	classVariableNames:''

	poolDictionaries:''

	category:'SmaCC-Runtime'

!

SmaCCScanner class instanceVariableNames:'keywordMap'

"

 No other class instance variables are inherited by this class.

"

!

SmaCCScanner comment:'SmaCCScanner is an abstract class that represents a scanner for the parser. The scanner converts its string input into SmaCCToken objects that the parser then uses for its parsing.

Subclasses must implement the following messages:

	accessing

		scanForToken

Instance Variables:

	currentCharacter	<Character>	the current character we are scanning

	lastMatchWasEmpty	<Boolean>	was our last scanning match an empty string -- don''t allow two empty matches in a row

	lastOutputStreamMatchPosition	<Integer>	the position in the outputStream of the last match

	matchActions	<Array | Symbol>	the actions for the last match (a symbol means that the action should be performed on the scanner)

	matchEnd	<Integer>	the position of the last match in the stream (our input stream)

	outputStream	<PositionableStream>	the matched characters go in this stream. After a match is made, we take this stream''s contents and create a token object.

	returnMatchBlock	<BlockClosure>	when we match a token evaluate this block with the token (hack to return from multiple levels)

	start	<Integer>	the starting position of a match in the stream

	stream	<Stream>	our input

'

!

!SmaCCScanner class methodsFor:'instance creation'!

new

	^(super new)

		initialize;

		yourself

!

on: aStream 

	^(self new)

		on: (self needsLineNumbers 

					ifTrue: [SmaCCLineNumberStream on: aStream]

					ifFalse: [aStream]);

		yourself

! !

!SmaCCScanner class methodsFor:'accessing'!

frequencyTable

	^#(1)

!

keywordMap

	keywordMap isNil ifTrue: [self initializeKeywordMap].

	^keywordMap

! !

!SmaCCScanner class methodsFor:'class initialization'!

initialize

	self initializeKeywordMap

!

initializeKeywordMap

	keywordMap := Dictionary new

! !

!SmaCCScanner class methodsFor:'public'!

needsLineNumbers

	"Redefine to return true, if you need line number information"

	^false

! !

!SmaCCScanner methodsFor:'accessing'!

contents

	| writeStream token |

	writeStream := WriteStream on: Array new.

	[self atEnd] whileFalse: 

			[token := self next.

			token notNil ifTrue: [writeStream nextPut: token]].

	^writeStream contents

!

emptySymbolTokenId

	^self subclassResponsibility

!

errorTokenId

	^self subclassResponsibility

!

lineNumber

	"This requires the stream to be a line number stream (see the #needsLineNumbers class method)."

	^stream lineNumber

!

next

	self resetScanner.

	returnMatchBlock := [:match | ^match].

	self scanForToken

!

position

	^stream position

!

position: anInteger

	^stream position: anInteger

!

scanForToken

	^self subclassResponsibility

!

stream

    ^stream

    "Created: / 06-06-2008 / 20:51:09 / Jan Vrany <vranyj1@fel.cvut.cz>"

! !

!SmaCCScanner methodsFor:'default token handling'!

comment

	"In case someone wants to record the comments"

	self whitespace

!

whitespace

        "By default, eat the whitespace"

        self resetScanner.

        self scanForToken

! !

!SmaCCScanner methodsFor:'initialize-release'!

initialize

	outputStream := WriteStream on: (String new: self initialBufferSize).

	lastMatchWasEmpty := true

!

on: aStream 

	stream := aStream.

	start := stream position

! !

!SmaCCScanner methodsFor:'private'!

checkForKeyword: aString 

	| stateMap action |

	action := matchActions isSymbol 

				ifTrue: [matchActions]

				ifFalse: [matchActions first].

	stateMap := self class keywordMap at: action ifAbsent: [nil].

	stateMap isNil ifTrue: [^self].

	matchActions := stateMap at: (self keywordFor: aString)

				ifAbsent: [matchActions].

	matchActions isInteger 

		ifTrue: [matchActions := Array with: matchActions with: action]

!

checkForValidMatch

	matchActions isNil ifTrue: [self scannerError]

!

createTokenFor: string 

	| token |

	token := SmaCCToken 

				value: string

				start: start

				id: matchActions.

	outputStream reset.

	matchActions := nil.

	returnMatchBlock value: token

!

initialBufferSize

	^128

!

recordAndReportMatch: aCollection 

	self

		recordMatch: aCollection;

		reportLastMatch

!

recordMatch: aCollection 

	matchActions := aCollection.

	matchEnd := stream position.

	lastOutputStreamMatchPosition := outputStream position

!

reportLastMatch

        "The scanner has found the end of a token and must report it"

        | string |

        self checkForValidMatch.

        self resetOutputToLastMatch.

        stream position: matchEnd.

        string := outputStream contents.

        Smalltalk isSmalltalkX ifTrue:[

            outputStream reset.

        ].

        self checkForKeyword: string.

        matchActions isSymbol 

                ifTrue: [self perform: matchActions]

                ifFalse: [self createTokenFor: string]

!

resetOutputToLastMatch

        |streamStartPosition|

        outputStream position: lastOutputStreamMatchPosition.

        Smalltalk isSmalltalkX ifTrue:[

            streamStartPosition := outputStream class zeroPosition.

        ] ifFalse:[

            streamStartPosition := 0.

        ].

        lastOutputStreamMatchPosition == streamStartPosition 

                ifTrue: 

                        [lastMatchWasEmpty ifTrue: [self scannerError].

                        lastMatchWasEmpty := true]

                ifFalse: [lastMatchWasEmpty := false]

!

resetScanner

        start := stream position.

        outputStream reset.

        Smalltalk isSmalltalkX ifTrue:[

            lastOutputStreamMatchPosition := outputStream class zeroPosition .

        ] ifFalse:[

            lastOutputStreamMatchPosition := 0 .

        ].

!

scannerError

	(stream atEnd and: [start == stream position]) 

		ifTrue: 

			[returnMatchBlock value: (SmaCCToken 

						value: ''

						start: stream position

						id: (Array with: self emptySymbolTokenId))].

	stream position: start.

	returnMatchBlock value: (SmaCCToken 

				value: (String with: stream next)

				start: start

				id: #(0))

!

step

	stream atEnd ifTrue: [^self reportLastMatch].

	currentCharacter := stream next.

	outputStream nextPut: currentCharacter

! !

!SmaCCScanner methodsFor:'private-utility'!

keywordFor: aString 

	"Subclasses can override this to ignore case"

	^aString

! !

!SmaCCScanner methodsFor:'public'!

atEnd

	^stream atEnd

! !

!SmaCCScanner class methodsFor:'documentation'!

version

    ^ '$Header: /opt/data/cvs/stx/goodies/smaCC/SmaCC__SmaCCScanner.st,v 1.1 2006-02-09 21:15:31 vranyj1 Exp $'

!

version_SVN

    ^ '$Id$'

! !

SmaCCScanner initialize!