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Added notes on Steve's rewrite, general restructuring

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git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@2571 51baf565-9d33-0410-a72c-fc3788e3496d
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Tom Copeland
2004-03-15 20:28:14 +00:00
parent 117af84e8e
commit ec21c86d34
1 changed files with 13 additions and 4 deletions
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pmd/xdocs/cpd.xml
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@ -9,9 +9,17 @@
<body>
<section name="Copied and pasted code is usually bad">
<p>But it can be hard to find, especially in a large project. So we wrote a utility - CPD - to find it for us.
First we wrote it using a variant of Michael Wise's Greedy String Tiling algorithm (our variant is described
<a href="http://www.onjava.com/pub/a/onjava/2003/03/12/pmd_cpd.html">here</a>). Then it was completely
rewritten by Brian Ewins using the <a href="http://dogma.net/markn/articles/bwt/bwt.htm">Burrows-Wheeler transform</a> - or, at least, the first part of it.</p>
It's been through three major incarnations:</p>
<ul>
<li>First we wrote it using a variant of Michael Wise's Greedy String Tiling algorithm (our variant is described
<a href="http://www.onjava.com/pub/a/onjava/2003/03/12/pmd_cpd.html">here</a>)</li>
<li>Then it was completely
rewritten by Brian Ewins using the
<a href="http://dogma.net/markn/articles/bwt/bwt.htm">Burrows-Wheeler transform</a></li>
<li>Finally, it was rewritten by Steve Hawkins to use the
<a href="http://www.nist.gov/dads/HTML/karpRabin.html">Karp-Rabin</a> string matching algorithm.</li>
</ul>
<p>Each rewrite made it much faster, and now it can process the JDK java.* packages in about 4 seconds (on my Linux workstation, at least).</p>
<p>Here's a <a href="images/screenshot_cpd.png">screenshot</a> of CPD after running on the JDK java.lang package.</p>
<p>Note that CPD works with Java, C, C++, and PHP code.</p>
<p>If you have <a href="http://java.sun.com/products/javawebstart/">Java Web Start</a>, you can <a href="cpd.jnlp">run CPD by clicking here</a>.</p>
@ -33,7 +41,8 @@
</source>
<p>Also, you can get verbose output from this task by running ant with the <code>-v</code> flag; i.e., <code>ant -v -f mybuildfile.xml cpd</code>.</p>
<p>There's also a JavaSpaces version available for splitting the CPD effort across a farm of machines.
I usually post news on that <a href="http://cpd.jini.org/">here</a> and the releases are <a href="http://sf.net/projects/pmd/">here</a>. This project is pretty much dead, though, since Brian's rewrite is fast enough to just run it on one machine.</p>
I usually post news on that <a href="http://cpd.jini.org/">here</a> and the releases are <a href="http://sf.net/projects/pmd/">here</a>.
This project is pretty much dead, though, since the current code is fast enough to just run it on one machine.</p>
<p>Suggestions? Comments? Post them <a href="http://sourceforge.net/forum/forum.php?forum_id=188192">here</a>. Thanks!</p>
</section>
</body>