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git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@524 51baf565-9d33-0410-a72c-fc3788e3496d
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Tom Copeland
2002-07-26 16:19:43 +00:00
parent 7666f355b9
commit 9af343b2a3
1 changed files with 28 additions and 5 deletions
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33
pmd/xdocs/howtowritearule.xml
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@ -9,15 +9,20 @@
<p>
Writing PMD rules is cool because you don't have to wait for us to get around to implementing feature requests.
</p>
<subsection name="Get a development environment set up first">
<p>
In order to do rules, it'll help if you can modify the PMD source.
So download the latest source release (i.e., pmd-src-0.7.zip or something) and unzip it somewhere on your computer.
</p>
</subsection>
<subsection name="Figure out what you want to look for">
<p>
First, figure out what you're looking for. Let's use "While loops must use braces" as an example.
Now lets's figure out what problem you want to spot. Let's use "While loops must use braces" as an example.
You've seen this before a thousand times so you know what it looks like:
</p>
<source>
<![CDATA[
public class Foo {
public class Example {
public void bar() {
while (baz)
buz.doSomething();
@ -25,12 +30,15 @@ Writing PMD rules is cool because you don't have to wait for us to get around to
}
]]>
</source>
<p>
So we know what an example in source code looks like, which is half the battle.
</p>
</subsection>
<subsection name="Write a test-data example and look at the AST">
<p>
PMD uses a JJTree/JavaCC generated parser to parse the source code and produce an AST (Abstract Syntax Tree).
This means that the code above looks like this:
PMD doesn't use the source code directly; it uses a JJTree/JavaCC generated parser to parse the source code and
produce an AST (Abstract Syntax Tree). The AST for the code above looks like this:
</p>
<source>
<![CDATA[
@ -76,6 +84,21 @@ CompilationUnit
Arguments
]]>
</source>
<p>
You can generate this yourself by:
<ul>
<li>Put the example file in the pmd/test-data directory in a file called "Example.java"</li>
<li>Edit the class <code>net.sourceforge.pmd.PMD</code> and uncomment the line that says <code>c.dump();</code></li>
<li>Open a command prompt and cd into the pmd/etc directory</li>
<li>Recompile the project using the Ant task; i.e., <code>ant compile</ant></li>
<li>Run the <code>go</code> batch file to run PMD on one file, like this: <code>go Example xml rulesets/basic.xml</code>. The go.bat file
will fill in the directories and main class and whatnot.
You'll probably have to edit this batch file to match where you unzipped PMD.</li>
<li>If you get a ClassNotFoundException, make sure the pmd-?.?.jar file is on your classpath.</li>
<li>The rulesets need to be on there too - so make sure the pmd directory is on your classpath too.</li>
<li>If you get a FileNotFoundException, make sure that go.bat is pointing to the test-data directory where you put Example.java</li>
</ul>
</p>
</subsection>