Regex to match C# code

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I am writing a small tool to give me some code stats. Most of what I need is written, but I still need to identify commented-out lines of code. Identifying comments is not hard, but I specifically want to separate genuine comments from old commented out code.

I'm thinking along the lines of

Regex ccRegex = new Regex(C#pattern, RegexOptions.Ignorecase);
IEnumerable<string> commentedCode = linesInFile.Where(l => ccregex.IsMatch(l);

linesInFile is a string array of the lines of text read from the source file.

The question is: what should the string 'C#pattern' be?

Can this be done with a single Regex?

TIA

Posted 18-Aug-10 0:00am

Neil Haughton

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OriginalGriff 18-Aug-10 13:55pm

"something that was mostly right would suffice."
It's not a case of "mostly right" - it's how much can you afford to be "mostly wrong"?

Neil Haughton 19-Aug-10 3:53am

In this case, probably quite a lot. I'm identifying all the comment lines, and within those I want to identify as closely as practical which are the commented-out code and which are genuine comments. This will tell me(broadly) how extensively the code is commented, and how progress is being made cleaning up unwanted (dead) code, two metrics I need to report. It's a big application so simply reading the code to achieve this is not practical. So if I can apply some process to a commented line to see if it is very probably old code, that will suffice. It doesn't have to be precisely definitive, and I can see from your explanation why that would be very difficult to achieve - although the C# compiler clearly does exactly what I am suggesting in order to compile the code in the first place. If I can apply the same process to commented lines I will be home and dry.

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OriginalGriff · Accepted Answer · 2010-08-18T01:01:00

"Can this be done with a single Regex?"

No.

To expand a little, in theory it could be done. But in practice the regex would be so complex that it would take more time to develop and debug than it is worth. Think about it:

// Console.WriteLine

Is that a comment? Or commented out code?
If we look at the following line

// Console.WriteLine
//      ("TestString");

Then yes, it is commented out code.
If we look at a different following line:

// Console.WriteLine
//      Prints a message on the console

Then it isn't.
Now, write a regex that works for those two. Now replace "Console" with "MyClass" and write one that handles that as well...