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ASP.NET/VB/REGEX: First expression messed up by additional expressions

Posted on 2013-02-01
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Last Modified: 2013-02-05
The first regular expression works however the ones after it mess it up.  How can I prevent proceeding regular expressions from messing up the first one?

' BB Links
' {[link=url]}text{[/link]}
input = RegularExpressions.Regex.Replace(input, "\{\[link=([^\]]+)\]\}([^\]]+)\{\[\/link\]\}", "<a href=""$1"">$2</a>")

' Links
input = RegularExpressions.Regex.Replace(input, "(https?://\S+[^\s@,.""']+)", "<a href=""$1"">$1</a>")
input = RegularExpressions.Regex.Replace(input, "(?<!\S)(\www\.\S+[^\s@,.""']+)", "<a href=""http://$1"">$1</a>")

' Email Addresses
input = RegularExpressions.Regex.Replace(input, "\w[\w\.]*\w?@[\w\.]+\w", "<a href=""mailto:$0"">$0</a>")

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Question by:hankknight
  • 2
4 Comments
 
LVL 12

Assisted Solution

by:tel2
tel2 earned 200 total points
ID: 38846149
Hi hankknight,

Please explain the way in which the 1st expression is getting messed up, exactly.  An example may help, too.

Thanks.
tel2
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LVL 16

Author Comment

by:hankknight
ID: 38848833
The problem is that this:
{[link=http://www.example.com/]}Link Text{[/link]}

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becomes this:
<a href="<a href="http://www.example.com/">Link">http://www.example.com/">Link</a> Text</a>

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The regex should not apply to the links that already are inside <a> tags.
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LVL 35

Accepted Solution

by:
Terry Woods earned 1800 total points
ID: 38849246
I believe .NET allows flexible length look behinds, so this change to the 2nd replacement may work:

input = RegularExpressions.Regex.Replace(input, "(?<!href\s*=\s['"])(https?://\S+[^\s@,.""']+)", "<a href=""$1"">$1</a>")

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You'll probably want to turn on the ignore case option, since href can be in caps.
0
 
LVL 16

Author Comment

by:hankknight
ID: 38856391
Thanks!


' BB Links
' {[link=url]}text{[/link]}
input = RegularExpressions.Regex.Replace(input, "\{\[link=([^\]]+)\]\}([^\]]+)\{\[\/link\]\}", "<a href=""$1"">$2</a>")

' Links
input = RegularExpressions.Regex.Replace(input, "(?<!\S)(https?://\S+[^\s@,.""']+)", "<a href=""$1"">$1</a>")
input = RegularExpressions.Regex.Replace(input, "(?<!\S)(\www\.\S+[^\s@,.""']+)", "<a href=""http://$1"">$1</a>")

' Email Addresses
input = RegularExpressions.Regex.Replace(input, "(?<!\S)\w[\w\.]*\w?@[\w\.]+\w", "<a href=""mailto:$0"">$0</a>")

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0

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