Tips to show similarities in files

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+3 Q:

Tips to show similarities in files

In a project, I found some css files that "smell" like there are copy-pasted rules in them.

I wonder what are your strategies for detecting copy-paste stuff in files.

Just of curiosity i'd like to hear your tips and tricks for showing file similarities!

+1 A:

There is a Copy-Paste Detection (CPD) project on sourceforge; http://pmd.sourceforge.net/cpd.html

But even in large projects I find my own knowledge of the code to be a reliable (although not foolproof) detection mechanism.

Also see this question for other suggestions.

Ed Guiness 2009-10-08 09:25:54

The CPD tool seems very limited in languages. And does not have javascript or CSS

Jesper Rønn-Jensen 2009-10-08 09:34:33

Thanks for pointing to "this question". Very similar to this, btw :)

Jesper Rønn-Jensen 2009-10-08 10:19:06

+1 A:

Try Simian.

It is used for copy-paste-detection in source code (Java, C#, C, C++, COBOL, Ruby, JSP, ASP, HTML, XML, Visual Basic, Groovy), but you can run this on plain text files too.

The Chairman 2009-10-08 09:32:49

is there a way to make simian show the actual similarities? On my test-run, it only shows a summary that "lines a to b in file X are similar to lines c to d in file Y"???Showing the actual lines will help clarify a lot

Jesper Rønn-Jensen 2009-10-08 12:02:06

Or better yet: is there a way to make it show diffs for the lines that are similar?

Jesper Rønn-Jensen 2009-10-08 12:02:37

I'm afraid you'll have to check the results manually or write a tool that evaluates Simian results and attaches them to a file viewer. Maybe you could utilize a free diff tool (e.g. WinMerge, http://winmerge.org/) for that purpose. If you decide for the latter: I would be interested in such a solution too...

The Chairman 2009-10-11 10:08:41

See my answer on CloneDR for a tool that explicitly shows similarities and differences.

Ira Baxter 2010-02-01 18:45:01

The Semantic Designs CloneDR is a tool that detects copy-paste-edit blocks of code, for many languages: C, C++, Java, C++, COBOL, ECMAScript, PHP, ...

It generates a report that shows exactly how the blocks of code are similar, and precisely how they vary. You can see sample reports at the link.

Ira Baxter 2010-02-01 18:44:21

Your link is not working? Could you please update your response?

Jesper Rønn-Jensen 2010-02-01 19:37:01

...oops... fixed.

Ira Baxter 2010-02-01 20:19:18

ansaurus

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Tips to show similarities in files

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