Break the Patterns up in short steps and test as you go. Regular Expression patterns tend to be long and complex.
Some Regular Expression pattern are fifty lines long or more, break up the complicated pattern into chunks that
are easier to handle. 

'---Script created on 08-29-2023 20:39:59 by 
uses "VBREGEXP"
Uses "Console" 
uses "File"


dim text2 as String,mask as string 
Dim variables as string,quotes as string, typeOfVar as String
Dim parameter as string,MultipleParameters as String
Dim func as string ,frontPar as string,backPar as String
dim  funcName as string 


frontPar = "[ ]*\([ ]*"  'front parenthesis (
backPar  = "[ ]*\)[ ]*"  'back parenthesis  )
funcName = "[ ]*function[ ]*"


'note: [ ]* is zero of more spaces 


'variables start with letter next is letter or numbers or underscore ex... a_12 van3 va33n not 1van
Variables = "([ ]*[a-zA-Z][a-zA-Z0-9_]*[ ]*)*"  
quotes = "[ ]*[\x34](.*)[\x34][ ]*"
typeOfVar = "([ ]*(as)[ ]*(long|string)[ ]*)*"  ' as string or as long
Parameter = Variables + typeOfVar   'the parameter either long or string 
MultipleParameters = "([ ]*,[ ]*"+Parameter+")*"  'Multiple parameters




'regular expression patterns tend to be long and complex so break them up and test as you go
func=funcName + variables + FrontPar + Parameter + MultipleParameters + backPar + typeofvar


text2 =  "function " & $crlf        'data errors no function Name or no parenthesis
text2 += "function bbb " & $crlf   'data errors no parenthesis
text2 += "function bbb (" & $crlf  'data error Miss parenthesis
text2 += "function bbb ( )" & $crlf
text2 += "function bbb (aa as string , bb as long , cc as string) as string" & $crlf
text2 += "function aaa()" & $crlf        
text2 += "function bbb (aa as string)" & $crlf  
text2 += "function bbb (aa as string , bb as long , cc as string) as long" & $crlf
text2 += "function bbb (aa as string , bb as long )" & $crlf
text2 += "function bbb (aa as string , bb as long , cc as string) as string" & $crlf


 print vbregex(func , text2 ) + $CRLF




print "========================================" +$crlf 


 Console_WaitKey






'returns one value that pattern matched and replaced 
function vbregReplace(pattern as string,txt as string,replaceTxt as string ) as string  'returns the Value that was match and replaced
'pattern is a Visual Basic regular expression pattern
'replaceTxt is the text that is used in replacement            $1           $2
'$1$2$3 is the patterns that are surrounded by parenthesis ([A-Za-z]+)[ ]*([0-9]+)  
'[classes]  (sub-patterns)
'[a-z] all lower case [A-Z] all upper case  [0-9] any 0123456789 number
'  using $1$2$3 you can separate the part of the pattern you want returned and in which order
'VBREGEXP_SetPattern lpRegExp, "(\S+)(\s+)(\S+)"
  'strRetVal = VbRegExp_Replace(lpRegExp, txt, "$3$2$1")
  'third pattern found would come first second pattern then first pattern
dim lpRegExp  as dword
  'dim txt   as string value "The quick brown fox jumped over the lazy dog."
  dim strRetVal as string


  '---Allocate a new regular expression instance
  lpRegExp = VBREGEXP_New


  '---Check if it was possible to allocate and if not stop the script
  if isfalse lpRegExp then
    print "Unable to create an instance of the RegExp object." & $crlf & "Script terminated"
    stop
  end if


  '---Set case insensitivity
  VBREGEXP_SetIgnoreCase lpRegExp, -1
  '---Set global applicability
  VBREGEXP_SetGlobal lpRegExp, -1


  
  '---Replace example 1
  '---Replace 'fox' with 'cat'.
  VBREGEXP_SetPattern lpRegExp, pattern
  strRetVal = VbRegExp_Replace(lpRegExp, txt, replaceTxt )
  
 


  
  '---Replace example 2
  '---In addition, the Replace method can replace subexpressions in the pattern.
  '---The following swaps the first pair of words in the original string:
  'VBREGEXP_SetPattern lpRegExp, "(\S+)(\s+)(\S+)"
  'strRetVal = VbRegExp_Replace(lpRegExp, txt, "$3$2$1")
  
  'print strRetVal+$crlf


  '---Deallocate regular expression resource
  IF istrue lpRegExp   THEN VBREGEXP_Release(lpRegExp)
   
   'returns the Value that was match and replaced
   function = strRetVal 


end function






Function File2Text(sfn As String) As String


    Dim st  As String
    Dim n   As Long
     Dim FileHandle As DWORD,s as string
    FileHandle= FILE_OPEN(sfn, "INPUT")  
    while not FILE_EOF(FileHandle)
       s=FILE_LineInput(FileHandle)
       st=st+s+$crlf 
    wend
    
    s = FILE_Close(FileHandle)
    Function=st
End Function




'Makes a Comma Separated Value list of the patterns found 
function vbregex(pattern as string, txt as string ) as string   'returns patterns found
'pattern is VisualBasic regular expression pattern
'txt is the text to be evaluated with the vbregex regular expression


  dim I as long ,allStr as string
  dim lpRegExp  as dword
  dim lpMatches as dword
  dim lpMatch   as dword
  dim strValue  as string




  '---Allocate a new regular expression instance
  lpRegExp = VBREGEXP_New


  '---Check if it was possible to allocate and if not stop the script
  if isfalse lpRegExp then
    Print "Unable to create an instance of the RegExp object." & $crlf & "Script terminated" + $crlf
    stop
  end if
  
  '---Set pattern
  VBREGEXP_SetPattern lpRegExp, pattern  '"[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}"
  
  '---Set case insensitivity
  VBREGEXP_SetIgnoreCase lpRegExp, -1
  '---Set global applicability
  VBREGEXP_SetGlobal lpRegExp, -1


  '---Execute search '"Please send a mail to eros.olmi@thinbasic.com or to <support@thinbasic.com>. Thanks!"
  lpMatches = VBREGEXP_Execute(lpRegExp, txt)
  IF ISFALSE lpMatches THEN
    Print "1. No match found"
  else
    
    dim nCount as long value VBMatchCollection_GetCount(lpMatches)
    IF nCount = 0 THEN
      Print "2. No match found" + $crlf
    else


      '---Iterate the Matches collection
      
      
      'strValue += "match number,position,getLength,patternMatched" & $crlf 
      FOR i = 1 TO nCount


        lpMatch = VBMatchCollection_GetItem(lpMatches, i)


        IF ISFALSE lpMatch THEN EXIT FOR
        
        'strValue +=  i & "," & VBMatch_GetFirstIndex(lpMatch) & "," & VBMatch_Getlength(lpMatch) & "," & VBMatch_GetValue(lpMatch) & $CRLF
        strValue =  VBMatch_GetValue(lpMatch) ' & $CRLF
        allStr = allStr + StrValue + $crlf 
        VBREGEXP_Release lpMatch
        
      NEXT
      
      'Print strValue  + $crlf


    END IF
    
  END IF
  
  
  IF istrue lpMatches  THEN VBREGEXP_Release(lpMatches)
  IF istrue lpRegExp   THEN VBREGEXP_Release(lpRegExp)
  
  
  
  'matches of pattern
  function = allstr


end function