Regex For Finding Ctypes with Int32 - regex

Question

(Hey all,
I am looking for a little regex help...
I am trying to find all CType(expression,Int32) s and replace them with CInt(expression)
This, however, is proving quite difficult, considering there could be a nested Ctype(expression, Int32) within the regex match. Does anyone have any ideas for how to best go about doing this?
Here is what I have now:
Dim str As String = "CType((original.Width * CType((targetSize / CType(original.Height, Single)), Single)), Int32)"
Dim exp As New Regex("CType\((.+), Int32\)")
str = exp.Replace(str, "CInt($1)")
But this will match the entire string and replace it.
I was thinking of doing a recursive function to find the outer most match, and then work inwards, but that still presents a problem with things like
CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32)
Any tips would be appreciated.
Input
returnString.Replace(Chr(CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32)))
Output:
returnString.Replace(Chr(CInt(replaceChars(I))),Chr(CInt(replacementChars(I))))
Edit:
Been working on it a little more and have a recursive function that I'm still working out the kinks in. Recursion + regex. it kinda hurts.
Private Function FindReplaceCInts(ByVal strAs As String) As String
System.Console.WriteLine(String.Format("Testing : {0}", strAs))
Dim exp As New Regex("CType\((.+), Int32\)")
If exp.Match(strAs).Success Then
For Each match As Match In exp.Matches(strAs)
If exp.Match(match.Value.Substring(2)).Success Then
Dim replaceT As String = match.Value.Substring(2)
Dim Witht As String = FindReplaceCInts(match.Value.Substring(2))
System.Console.WriteLine(strAs.IndexOf(replaceT))
strAs.Replace(replaceT, Witht)
End If
Next
strAs = exp.Replace(strAs, "CInt($1)")
End If
Return strAs
End Function
Cheers,

Answer 1

What do you guys think of this?
I think it does it quite nicely for a variety of cases that I have tested so far...
Private Function FindReplaceCInts(ByVal strAs As String) As String
Dim exp As New Regex("CType\((.+), Int32\)")
If exp.Match(strAs).Success Then
For Each match As Match In exp.Matches(strAs)
If exp.Match(match.Value.Substring(2)).Success Then
Dim replaceT As String = match.Value.Substring(2)
Dim Witht As String = FindReplaceCInts(match.Value.Substring(2))
strAs = strAs.Replace(replaceT, Witht)
End If
Next
strAs = exp.Replace(strAs, "CInt($1)")
End If
Return strAs
End Function

Answer 2

try to use this (?!CType\(.+, )Int32 regex instead of yours
You need to use negative look ahead to accomplish your task.
Check regex at this site

Answer 3

I've tried this in VS 2008 (no copy of VS 2010 to try it out), using the Find & Replace dialog:
Regular Expression: CType\({.+}, Int32\)
Replace With: CInt(\1)
It won't fix the nested situations in one pass, but you should be able to continue searching with that pattern and replacing until no other matches are found.
BTW: That dialog also provides a link to this help page explaining characters used the VS flavor of regex http://msdn.microsoft.com/en-us/library/aa293063(VS.71).aspx