;General-purpose C-like directive processor
;==========================================
;Not very useful by itself, but you can plug it in to a code processor or script compiler easily
;Commands:
; #define NAME CONSTANT - replace all occurences of NAME with CONSTANT. Cannot refer to other #defines
; #undef NAME - remove a #defined constant so it isn't replaced any more
; #if EXPRESSION - either compare a constant to another constant (literal or #defined) or assert that it's nonzero
; #ifdef NAME - include the following block of code only if NAME has been #defined
; #ifndef NAME - include the following block of code only if NAME has not been #defined
; #elif EXPRESSION - short for ElseIf
; #else - if the last check evaluated false, do this instead
; #endif - mark the end of a conditional inclusion block. These are allowed to nest
; #include FILE - copy the entire contents of the specified filename (quotemarks optional)
; #option OPTION - does nothing: add language-relevant options here
; #error ERR - issues error ERR via error handler. Best used with a condition check...!
;Notes:
; - #define does not create macros, only simple substitution constants
; - commands must be the first text on their line
; - any text after a command will potentially be considered part of it, or at best ignored
;Replace these with tokens that match your language
Const PP_LINECOMMENT$ = "//" ;Single-line comment
Const PP_BLOCKCOMMENTSTART$ = "/*" ;Start of block-comment
Const PP_BLOCKCOMMENTEND$ = "*/" ;End of block-comment
Const PP_ESCAPECHR$ = "" ;Escape character (to allow " to appear in strings)
Type PP_Macro ;As defined with #define. No regular expressions, just cut and paste
Field tok$ ;Constant token to use in source
Field def$ ;Definition
End Type
Function PP_Preprocess(inputFilename$,outputFilename$) ;Loads the source from file and applies preprocessor commands
Local m.PP_Macro,n.PP_Macro,pos,ptr,i
Local com,sep,skip,debugout,srcline$,remain$
Local inquote,incomment,cfile,filelist=CreateBank(4)
Local sourceBank=CreateBank(4),iStack=CreateBank(0)
cfile=ReadFile(inputFilename)
PokeInt(filelist,0,cfile)
Repeat
srcline=ReadLine(cfile)
If Left(Trim(srcline),1)="#"
srcline=Replace(srcline,Chr(9)," ")
com=Instr(srcline,PP_BLOCKCOMMENTSTART)
If com>0
remain=Right(srcline,Len(srcline)-(com-1)) ;Rescue comments with /* as otherwise there will be parse errors later
ResizeBank sourceBank,BankSize(sourceBank)+Len(remain)+2
For ptr=0 To Len(remain)-1
PokeByte sourceBank,pos+ptr,Asc(Mid(remain,ptr+1,1))
Next
PokeShort sourceBank,pos+ptr,$A0D ;CR+LF - end of line
pos=pos+ptr+2
srcline=Left(srcline,com-1)
EndIf
com=Instr(srcline,PP_LINECOMMENT)
If com>0 Then srcline=Left(srcline,com-1)
srcline=Trim(srcline)+" " ;Force control line to end in a space
Select True
Case Lower(Left(srcline,8))="#define " ;Add a macro
If skip=0
m=New PP_Macro
srcline=Trim(Mid(srcline,8))
sep=Instr(srcline," ")
If sep
m ok=Trim(Left(srcline,sep))
mdef=Trim(Mid(srcline,sep+1))
Else
m ok=srcline
mdef=""
EndIf
For n=Each PP_Macro
If n<>m And m ok=n ok Then PP_Error("Token "+m ok+" is already defined")
Next
EndIf
Case Lower(Left(srcline,7))="#undef " ;Remove a macro
If skip=0
srcline=Trim(Mid(srcline,7))
For m=Each PP_Macro
If m ok=srcline Then Delete m:Exit
Next
If m=Null Then PP_Error("token "+Chr(34)+srcline+Chr(34)+" does not exist")
EndIf
Case Lower(Left(srcline,4))="#if " ;Conditional compilation by value
srcline=Trim(Mid(srcline,4))
If skip=0
ResizeBank iStack,BankSize(iStack)+1
skip=skip+(Not(PP_EvalDirective(srcline)))
PokeByte iStack,BankSize(iStack)-1,Not(skip)
Else
skip=skip+1
EndIf
Case Lower(Left(srcline,7))="#ifdef " ;Conditional compilation by definition
srcline=Trim(Mid(srcline,7))
If skip=0
ResizeBank iStack,BankSize(iStack)+1
skip=skip+1
For m=Each PP_Macro
If m ok=srcline Then skip=skip-1:Exit
Next
PokeByte iStack,BankSize(iStack)-1,Not(skip)
Else
skip=skip+1
EndIf
Case Lower(Left(srcline,8))="#ifndef " ;Conditional lack of compilation by definition
srcline=Trim(Mid(srcline,8))
If skip=0
ResizeBank iStack,BankSize(iStack)+1
For m=Each PP_Macro
If m ok=srcline Then skip=skip+1:Exit
Next
PokeByte iStack,BankSize(iStack)-1,Not(skip)
Else
skip=skip+1
EndIf
Case Lower(Left(srcline,6))="#elif " ;Alternate condition check
If skip=1
srcline=Trim(Mid(srcline,6))
If PeekByte(iStack,BankSize(iStack)-1)=0 ;Only try if this #if level hasn't done anything yet
If PP_EvalDirective(srcline)
PokeByte iStack,BankSize(iStack)-1,1
skip=0
EndIf
Else
skip=1
EndIf
EndIf
Case Lower(Left(srcline,6))="#else " ;Default condition
If skip=1
If PeekByte(iStack,BankSize(iStack)-1)=0 Then skip=0
ElseIf skip=0
skip=1
EndIf
Case Lower(Left(srcline,7))="#endif " ;End of conditional compilation block
If skip>0 Then skip=skip-1
If skip=0
If BankSize(iStack) Then ResizeBank iStack,BankSize(iStack)-1
EndIf
Case Lower(Left(srcline,9))="#include " ;Include files
If skip=0
srcline=Trim(Mid(srcline,9))
If Left(srcline,1)=Chr(34) And Right(srcline,1)=Chr(34) Then srcline=Mid(srcline,2,Len(srcline)-2) ;Cut off quote marks
cfile=ReadFile(srcline)
If cfile=0 Then PP_Error "file "+Chr(34)+srcline+Chr(34)+" does not exist"
ResizeBank(filelist,BankSize(filelist)+4)
PokeInt filelist,BankSize(filelist)-4,cfile
EndIf
Case Lower(Left(srcline,8))="#option " ;Set compilation options
If skip=0
srcline=Trim(Mid(srcline,8))
Select srcline
;Left empty for future expansion
Default:PP_Error("unrecognised compiler option")
End Select
EndIf
Case Lower(Left(srcline,7))="#error "
If skip=0
srcline=Trim(Mid(srcline,7))
PP_Error(srcline)
EndIf
Default
PP_Error("unrecognised preprocessor command: "+Chr(34)+srcline+Chr(34))
End Select
Else
If skip=0
If First PP_Macro<>Null ;Replace #defined tokens
inquote=0
For ptr=1 To Len(srcline)
If Mid(srcline,ptr,2)=PP_LINECOMMENT Then Exit
If Mid(srcline,ptr,1)=Chr(34)
If inquote=0
inquote=True
Else
If Mid(srcline,ptr-1,1)<>PP_ESCAPECHR Then inquote=False
EndIf
EndIf
If Mid(srcline,ptr,2)=PP_BLOCKCOMMENTSTART Then incomment=True:ElseIf Mid(srcline,ptr,2)=PP_BLOCKCOMMENTEND Then incomment=False
If inquote=False And incomment=False
For m=Each PP_Macro
If ptr>1 Then i=Asc(Mid(srcline,ptr-1,1)):Else i=0
If Not((i>47 And i<58) Or (i>64 And i<91) Or i=95 Or (i>96 And i<123))
i=Asc(Mid(srcline,ptr+Len(m ok),1))
If Not((i>47 And i<58) Or (i>64 And i<91) Or i=95 Or (i>96 And i<123))
If Mid(srcline,ptr,Len(m ok))=m ok
srcline=Left(srcline,ptr-1)+mdef+Right(srcline,Len(srcline)-(ptr-1)-Len(m ok))
EndIf
EndIf
EndIf
Next
EndIf
Next
EndIf
ResizeBank sourceBank,BankSize(sourceBank)+Len(srcline)+2
For ptr=0 To Len(srcline)-1
PokeByte sourceBank,pos+ptr,Asc(Mid(srcline,ptr+1,1))
Next
PokeShort sourceBank,pos+ptr,$A0D ;CR+LF - end of line
pos=pos+ptr+2
EndIf
EndIf
If Eof(cfile)
CloseFile cfile
ResizeBank filelist,BankSize(filelist)-4
If BankSize(filelist)=0 Then Exit:Else cfile=PeekInt(filelist,BankSize(filelist)-4)
EndIf
Forever
;Dump out a copy of the source to be read by the tokeniser
debugout=WriteFile(outputFilename)
WriteBytes(sourceBank,debugout,0,BankSize(sourceBank))
CloseFile debugout
FreeBank filelist ;Tidy up
FreeBank sourceBank
FreeBank iStack
Delete Each PP_Macro
End Function
Function PP_EvalDirective(directive$) ;Evaluate an #if directive
Local lArg$,op$,rArg$,i,m.PP_Macro
i=Instr(directive," ")
lArg=Trim(Left(directive,i))
directive=Trim(Mid(directive,i))
i=Instr(directive," ")
op=Trim(Left(directive,i))
rArg=Trim(Mid(directive,i))
For m=Each PP_Macro
If m ok=lArg Then lArg=mdef
If m ok=rArg Then rArg=mdef
Next
Select op
Case "=","==" ;On tests for equality, strings will be compared directly so "6.0" != "6" - must be converted if floats are involved
If Instr(lArg,".") Or Instr(rArg,".")
Return (Float(lArg) = Float(rArg))
Else
Return lArg=rArg
EndIf
Case "<>","!="
If Instr(lArg,".") Or Instr(rArg,".")
Return (Float(lArg) <> Float(rArg))
Else
Return lArg <> rArg
EndIf
Case "<" ;On tests that imply numerical value, strings will be automagically converted!
Return lArg < rArg
Case ">"
Return lArg > rArg
Case "<="
Return lArg <= rArg
Case ">="
Return lArg >= rArg
Case ""
Return lArg<>0
End Select
End Function
Function PP_Error(errorMessage$) ;Replace calls to this with your compiler's main error handler function
Print "ERROR: "+errorMessage
WaitKey:End
End Function
