Problem finding pattern matching and parsing it.

Posted on 2000-03-28
Last Modified: 2010-05-02
I have a string "EXEC (@SQL1 + @SQL2 + @SQL3)". My task is to find all substrings starting with '@'. Having to find such a string, I need to write that string to the database. For example, write '@SQL1', '@SQL2', and '@SQL3' to the database. The writing part to the database is not a problem. The hard part is finding the matching pattern.

Hope someone could help me with that.
Question by:ervinloh
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Expert Comment

ID: 2666071
Private Sub Command1_Click()
Dim nStart As Integer, nEnd As Integer, i As Integer
Dim s As String, sqlArr() As String
s = "EXEC (@SQL1 + @SQL2 + @SQL3)"
nEnd = 1
  i = i + 1
  nStart = InStr(nEnd, s, "@") + 1
  If nStart = 1 Then Exit Do
  nEnd = InStr(nStart, s, "+") - 1
  If nEnd < 0 Then nEnd = Len(s)
  ReDim Preserve sqlArr(i)
  sqlArr(i) = Mid$(s, nStart, nEnd - nStart)
End Sub

Expert Comment

ID: 2667249
Private Sub Command1_Click()
Dim s As String
Dim outstr As String
Dim nextpos As Long

s = "EXEC (@SQL1 + @SQL2 + @SQL3)"
' Remove everything up til first @
s = Mid$(s, InStr(1, s, "@"))
' Remove last ')' and append a ' +'
s = Mid$(s, 1, InStr(1, s, ")") - 1) & " +"

nextpos = InStr(nextpos + 1, s, "@")
Do Until nextpos = 0
    outstr = Mid$(s, nextpos, InStr(nextpos + 1, s, " +") - nextpos)
    'insert outstr into table
    nextpos = InStr(nextpos + 1, s, "@")
End Sub

Accepted Solution

cymbolic earned 100 total points
ID: 2670564
Here's a little token parser I've developed and used for years:

Public Function Toke$(Inst$, Sep$)
'takes off first substring in inst$, shortening inst$ each time. Destructive to Inst$.
Dim i As Integer
i = InStr(Inst$, Sep$)
If i = 0 Then
  Toke$ = Inst$
  Inst$ = ""
  Toke$ = Left$(Inst$, i - 1)
  Inst$ = Mid$(Inst$, i + Len(Sep$))
End If
End Function

Using this function you would parse your sample data like this:

ParseWrite "EXEC (@SQL1 + @SQL2 + @SQL3)"

sub ParseWrite(istr$)
dim x$,y$
y$=istr$  'because toke$ is destructive
x$=toke$(y$,"(") 'istr gets "EXEC (" peeled off
y$=toke$(y$,")") 'now we have just @SQL1+@SQL2+@SQL3 in y$
while len(y$)>0
 'write x$ value to database

end sub

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