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Regex:  Replace and parse code within custom tags

Posted on 2007-11-16
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Last Modified: 2013-11-07
I have a number of long strings in a database that are interspersed with custom tags example:
texttexttexttext[%im 111023%]... text text text[%im 111010%]text text text.

i need some code that will give me the ability to build a string that looks like:
texttexttext <img src="EVALUATEDCODE(111023)" /> text text <img src="EVALUATEDCODE(111010)" />text text text
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Question by:DidiahProd
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LVL 47

Expert Comment

by:Wayne Taylor (webtubbs)
ID: 20297455
Hi DidiahProd,

Try this...

        Dim InputString As String = "texttexttexttext[%im 111023%]... text text text[%im 111010%]text text text."
        Dim rx As New System.Text.RegularExpressions.Regex("(\[%im)(.*?)(%\])")
        MsgBox(rx.Replace(InputString, "<img src=""EVALUATEDCODE$2"" />"))

Regards,

Wayne
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LVL 47

Expert Comment

by:Wayne Taylor (webtubbs)
ID: 20297464
Actually, this is probably more like it....
        Dim InputString As String = "texttexttexttext[%im 111023%]... text text text[%im 111010%]text text text."
        Dim rx As New System.Text.RegularExpressions.Regex("(\[%im )(.*?)(%\])")
        MsgBox(rx.Replace(InputString, "<img src=""EVALUATEDCODE($2)"" />"))

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LVL 27

Expert Comment

by:ddrudik
ID: 20297998
webtubbs has it, but if you want an alternate pattern:
match on:
\[%im\x20(\d+)%\]
replace with:
<img src="EVALUATEDCODE($1)" />
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Expert Comment

by:ventaur
ID: 20298586
If you actually want to call some function to generate an image path for the custom tag matches, check out the code below. You would call ParseText and send it your string from the database.

Let me know if you need it in VB instead of C#.
using System.Text.RegularExpressions;
...
 
public string ParseText(string inputText) {
	return Regex.Replace(inputText, @"\[%im (\d+)%\]", new MatchEvaluator(EvaluateTagMatch), RegexOptions.IgnoreCase | RegexOptions.Multiline);
}
 
private string EvaluateTagMatch(Match match) {
	// Get the number (maybe it's an image ID) from the match.
	int ImageId = int.Parse(match.Groups[1].Value);
	
	// Evaluate some code with the number as the parameter to get an image source path.
	string ImagePath = GetImagePath(ImageId);
	
	// Return the custom tag replacement in full.
	return string.Format(@"<img src=""{0}"" />", ImagePath);
}

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Author Comment

by:DidiahProd
ID: 20299817
i got webtubbs to work as follows-   is there a benefit to ventaur's solution?  (I do need vb insead of C#).
Thanks!
    Private Function CREval(ByVal strToEval)
 
        Return "HI" & strToEval & "Bye"
    End Function
    Public Function GetMainContent(ByVal mstr As String) As String
 
        Dim rx As New System.Text.RegularExpressions.Regex("(\[%im)(.*?)(%\])")
        Return (rx.Replace(mstr, CREval("$2")))
 
    End Function

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Expert Comment

by:ddrudik
ID: 20299836
The one benefit to the pattern that ventaur used (essentially identical to mine) is that is only utilizes one capture group while webtubbs used a pattern that contained three capture groups, two more than required.  Other than that, effectively it will work the same.
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Author Comment

by:DidiahProd
ID: 20300513
ventaur, could you post a vb version of that?
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Expert Comment

by:ventaur
ID: 20300519
I must have misunderstood your use with "EVALUATEDCODE"; thus, the implementation using a match evaluator. But, yes the pattern is the same as ddrudik's and he should get credit if the rest of your code works.

Otherwise, here's the VB of mine using the match evaluator.
Imports System.Text.RegularExpressions
...
 
Public ParseText(inputText As String) As String
    Return Regex.Replace(inputText, "\[%im (\d+)%\]", new MatchEvaluator(EvaluateTagMatch), RegexOptions.IgnoreCase Or RegexOptions.Multiline)
End Function
 
Private EvaluateTagMatch(match As Match) As String
    ' Get the number (maybe it's an image ID) from the match.
    Dim ImageId As Integer = Integer.Parse(match.Groups[1].Value)
 
    ' Evaluate some code with the number as the parameter to get an image source path.
    Dim ImagePath As String = GetImagePath(ImageId)
 
    ' Return the custom tag replacement in full.
    Return String.Format("<img src=""{0}"" />", ImagePath)
End Function

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Author Comment

by:DidiahProd
ID: 20300755
Thanks! Looks like we're on the right track.

This code doesn't seem to work, however. I get the error "Error      37      'System.Text.RegularExpressions.MatchEvaluator' is a delegate type and requires a single 'addressof' expression as the only argument to the constructor.      D:\inetpub\vhosts\jhcr\dev\SitePage.aspx.vb      10      78      D:\...\dev\
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Expert Comment

by:ventaur
ID: 20300792
Sorry about that. I converted without the IDE.
Public ParseText(inputText As String) As String
    Return Regex.Replace(inputText, "\[%im (\d+)%\]", new MatchEvaluator(AddressOf(EvaluateTagMatch)), RegexOptions.IgnoreCase Or RegexOptions.Multiline)
End Function

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Author Comment

by:DidiahProd
ID: 20300935
hmmm- we're close!

now i get this error
Compiler Error Message: BC30455: Argument not specified for parameter 'match' of 'Private Function EvaluateTagMatch(match As System.Text.RegularExpressions.Match) As String'.

    Private Function EvaluateTagMatch(ByVal match As Match) As String
        ' Get the number (maybe it's an image ID) from the match.
        Dim ImageId As Integer = Integer.Parse(match.Groups(1).Value)
 
        ' Evaluate some code with the number as the parameter to get an image source path.
        Dim ImagePath As String = ImageId.ToString
 
        ' Return the custom tag replacement in full.
        Return String.Format("<img src=""{0}"" />", ImagePath)
    End Function
 
 
    Public Function GetMainContent(ByVal inputText As String) As String
 
        Return Regex.Replace(inputText, "\[%show (\d+)%\]", New MatchEvaluator(AddressOf (EvaluateTagMatch())), RegexOptions.IgnoreCase Or RegexOptions.Multiline)
end function

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Expert Comment

by:ventaur
ID: 20301057
Make sure you do not use parentheses after "EvaluateTagMatch" or you'll end up actually calling that function instead of passing the address of it to the match evaluator.
Return Regex.Replace(inputText, "\[%show (\d+)%\]", New MatchEvaluator(AddressOf (EvaluateTagMatch)), RegexOptions.IgnoreCase Or RegexOptions.Multiline)

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Author Comment

by:DidiahProd
ID: 20301498
I'm sorry i'm not following-  EvaluateTagMatch requires a match as a parameter- this function doesn't include one.
i get that as anerror as well

Thanks
JEd
0
 
LVL 6

Accepted Solution

by:
ventaur earned 325 total points
ID: 20301615
No, I'm sorry. I'm just not with it today. I finally got to a location that had Visual Studio so I can refresh my memory on VB syntax. The AddressOf statement is not a function, so please use the code below to avoid all errors this time.
Return Regex.Replace(inputText, "\[%show (\d+)%\]", New MatchEvaluator(AddressOf EvaluateTagMatch), RegexOptions.IgnoreCase Or RegexOptions.Multiline)

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Author Closing Comment

by:DidiahProd
ID: 31409517
Thanks! vb/csharp can be headache
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