Question

I’ve been working on this RegEx for the past day or so and I think I have it worked out so that it returns the data I want. First a little background.

I have a content editor that users will be able to edit web pages. They can format text, add links, etc.. standard content editor stuff. When they click save, the editor provides the ability to get the content (editor.Content) and put it into a string. What I want to do is get any links (<a> tags) and find out if they are internal or external links and if they are PDF files.

Here is the Expression I’ve come up with:

<a\b[^<>]*href\s*=\s*[\''\'](?<domain>https?:\/\/[^\/\s\'\'']*)*\/?(?<path>\/?[^\s\'']+?)?[[>\''\'] 

With this, I am able to separate the domain (if it has one) and the path out. Then, I loop through the matches…

dim matchColl as MatchCollection = Regex.Matches(editorContent, regExString) For Each m as Match in matchColl    If m.Groups('domain').value <> myInternalDomain and m.Groups('domain').value <> '' then        'this is an external domain... do some stuff    End If    If m.Groups('path').value.EndsWith('.pdf') then          'it is a pdf, do some other stuff...    End if Next 

My question is this… the parts where I ‘do some stuff’ to the values, what would be the best way to get that back into my ‘editorContent’ string? I could probably put the editorContent into a StringBuilder and do a whole bunch of replaces on it, but is that very efficient?

So, for example, with the PDF, I want to specify that it open in a new window (target=’_blank’) and for the external URL, add some javascript code into the onclick attribute.

Any ideas would be great!

Thanks!

Answer 1

I think you want do a Regex.Replace and pass in a MatchEvaluator. Basically the MatchEvaluator is a delegate to a function that returns a replacement string.