This extension provides the ability for checkstyle to check on XML files. Build the jar, add it to the classpath and run checkstyle over XML!

Types are translated from Java to reuse available checks. Here is the current mapping:

• DOCUMENT corresponds to Java CLASS_DEF
• ELEMENT corresponds to Java METHOD_DEF
• ATTRIBUTES corresponds to Java PARAMETERS
• ATTRIBUTE corresponds to Java PARAMETER_DEF
• IDENT corresponds to Java IDENT
• STRING_LITERAL corresponds to Java STRING_LITERAL
• PCDATA corresponds to Java VARIABLE_DEF
• PROCESSING_INSTRUCTION corresponds to Java PACKAGE_DEF
• PROCESSING_TARGET corresponds to Java ANNOTATION
• PROCESSING_DATA corresponds to Java ANNOTATION_DEF
• SKIPPED_ENTITY corresponds to Java SL_COMMENT
• WHITE_SPACE corresponds to Java WILDCARD_TYPE
• PREFIX_MAPPING corresponds to Java IMPORT

The following existing checks are supported:

• TypeName -- Checks the XML file name format
• PackageName -- Checks the path to the file format
• MethodName -- Checks an element name format
• ParameterName -- Checks an attribute name format
• ParameterNumber -- Checks the number of attributes
• MethodLength -- Checks the length of an element body
• MethodCount -- Checks the number of child in an element
• FileLength
• LineLength

• XPathCheck -- Checks the number of occurencies of a XPath expression
• XQueryCheck -- Checks the number of occurencies of a XQuery expression

Want to contribute? Great! There are two ways to add checks.

The original guide remains available to the XML extension. Just keep in mind that the AST tree for XML is not the same as the Java one.

You can use the a GUI that displays the structure of a Java source file. To run it type

java -classpath "checkstyle-5.4-all.jar;" \
    com.puppycrawl.tools.checkstyle.gui.XmlMain

on the command line. Click the button at the bottom of the frame and select a syntactically correct XML file. The frame will be populated with a tree that corresponds to the structure of the XML document.

You can extends existing Checks such as XPathCheck or XQueryChek. More to come!

Build the extension jar with maven :

mvn install

Put this jar and the dependencies in the checkstyle classpath and use checkstyle as usual.

The configuration XML file of checkstyle have to specify the XmlTreeWalker to activate the XML extension:

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
    "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
<module name="Checker">
  <module name="XmlTreeWalker">
    <module name="XPathCheck">
      <property name="expression" value="//patient"/>
      <property name="min" value="1"/>
      <property name="max" value="5"/>
    </module>
  </module>
</module>

To run the tests:

mvn test

1. Fork it.
2. Create a branch (git checkout -b my-xml-ext)
3. Commit your changes (git commit -am "Added new XML based Ext")
4. Push to the branch (git push origin my-xml-ext)
5. Create an Issue with a link to your branch
6. Enjoy a refreshing beer and wait