Cs-doclet

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Contents

Abstract

Cs-doclet is a JAVADOC doclet that generates the metadata files for CheckStyle and eclipse-cs from annotations and 'doc tags' in the source code of your checks and filters.

Intended audience

This tool is useful for the development of CheckStyle checks and filters, and for their integration in eclipse-cs and MediaWiki.

Extending CheckStyle

CheckStyle comes with an API to extend it with custom checks and filters. Here is a completely useless, yet typical example of a custom check:

File "src/com/pany/cs/checks/ColorCheck.java":

package com.pany.cs.checks;

import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

public
class ColorCheck extends Check {

    public void
    setColor(String value) { this.color = value; }
    private String color = "Yellow";

    @Override public int[]
    getDefaultTokens() { return new int[] { TokenTypes.ANNOTATION }; }

    @Override public void
    visitToken(DetailAST ast) { this.log(ast, "theColorIs", this.color); }
}

The CheckStyle extension API supports internationalization be means of "messages.properties" files:

File "src/com/pany/cs/checks/messages.properties":

theColorIs = The color is {0}

File "src/com/pany/cs/checks/messages_de.properties":

theColorIs = Die Farbe ist {0}

To make use of this check, you'd write a "CheckStyle configuration file"

File "checkstyle-config.xml":

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN" "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<module name="Checker">
  <property name="severity" value="warning" />
  <module name="TreeWalker">
    <module name="com.pany: ColorCheck">
      <property name="color" value="blue" />
    </module>
  </module>
</module>

, and execute CheckStyle on a target project, e.g. on the example project itself:

$ javac -d bin src/com/pany/cs/checks/ColorCheck.java
$ java -classpath 'bin;path/to/checkstyle-6.1-all.jar' \
> com.puppycrawl.tools.checkstyle.Main \
> -c checkstyle-config.xml \
> -r src
Starting audit...
C:\dev\EclipseWS\de.unkrig.cs-contrib\foo\src\com\pany\cs\checks\ColorCheck.java:14:5: warning: The color is 'blue'
C:\dev\EclipseWS\de.unkrig.cs-contrib\foo\src\com\pany\cs\checks\ColorCheck.java:17:5: warning: The color is 'blue'
Audit done.
$

(We get the two warnings because there are two "@Override" annotations in the code.)

Obviously, the Java code and the "messages.properties" files must be kept in sync with the Java code at all times, which is naturally very error-prone.

Cs-doclet facilitates the task by generating the "messages.properties" file from annotations in the source code:

File "src/com/pany/cs/checks/MyCheck.java":

package com.pany.cs.checks;

import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

public
class ColorCheck extends Check {

    @Message("The color is {0}")
    private static final String MESSAGE_KEY_THE_COLOR_IS = "theColorIs";

    public void
    setColor(String value) { this.color = value; }
    private String color = "Yellow";

    @Override public int[]
    getDefaultTokens() { return new int[] { TokenTypes.ANNOTATION }; }

    @Override public void
    visitToken(DetailAST ast) { this.log(ast, MESSAGE_KEY_THE_COLOR_IS, this.color); }
}

To generate the "messages.properties" file, you'd run JAVADOC with the cs-doclet and the "-messages.properties-dir" command line option:

$ javadoc \
> -doclet de.unkrig.doclet.cs.CsDoclet \
> -docletpath "path/to/cs-doclet.jar;bin;path/to/checkstyle-6.1-all.jar;path/to/net.sf.eclipsecs.core-6.1.jar" \
> -messages.properties-dir src \
> -sourcepath src \
> -classpath ../net.sf.checkstyle-6.1/checkstyle-6.1/checkstyle-6.1-all.jar \
> com.pany.cs.checks
Loading source files for package com.pany.cs.checks...
Constructing Javadoc information...
$

Notice that both "checkstyle.jar" and "net.sf.eclipsecs-core.jar" must be on the "-docletpath".

The generated "src/com/pany/cs/checks/messages.properties" file looks like this:

# This file was generated by the CS doclet; see http://cs-contrib.unkrig.de

# Custom check messages, in alphabetical order.

# --------------- com.pany: ColorCheck ---------------
theColorIs = The color is {0}

And voilĂ ! All the messages are where they belong: In the source code.

Integrating with eclipse-cs

When you integrate your checks with eclipse-cs, then you learn that you have to write two more metadata files:

File "checkstyle-metadata.xml":

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE checkstyle-metadata PUBLIC
"-//eclipse-cs//DTD Check Metadata 1.1//EN"
"http://eclipse-cs.sourceforge.net/dtds/checkstyle-metadata_1_1.dtd">
<checkstyle-metadata>

    <rule-group-metadata name="%Whitespace.group" priority="999">
        <rule-metadata
            internal-name="com.pany.cs.checks.ColorCheck"
            parent="TreeWalker"
            name="%ColorCheck.name"
        >
            <alternative-name internal-name="com.pany.cs.checks.ColorCheck" />
            <description>%ColorCheck.desc</description>

            <property-metadata
                name="color"
                datatype="String"
                default-value="Yellow"
            >
                <description>%ColorCheck.color</description>
            </property-metadata>
            <message-key key="theColorIs" />
        </rule-metadata>
    </rule-group-metadata>
</checkstyle-metadata>

File "checkstyle-metadata.properties":

Whitespace.group = Whitespace
ColorCheck.name = com.pany: ColorCheck
ColorCheck.desc =\
    A completely useless check which merely prints a (localizable) message each \
    time it encounters an annotation.
ColorCheck.color = A completely useless check parameter.

Tedious, isn't it? Well, you can tell cs-doclet to also generate these files from annotations (and doc comments):

File "src/com/pany/cs/checks/MyCheck.java":

// File "src/com/pany/cs/ColorCheck.java".

package com.pany.cs.checks;

import com.puppycrawl.tools.checkstyle.api.Check;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;

import de.unkrig.csdoclet.StringRuleProperty;
import de.unkrig.csdoclet.Rule;

/**
 * A completely useless check which merely prints a
 * (localizable) message each time it encounters an annotation.
 */
@Rule(
    group      = "%Whitespace.group",
    groupName  = "Whitespace",
    name       = "com.pany: ColorCheck",
    parent     = "TreeWalker"
)
public
class ColorCheck extends Check {

    @Message("The color is {0}")
    private static final String MESSAGE_KEY_THE_COLOR_IS = "theColorIs";

    /**
     * A completely useless check parameter.
     */
    @StringRuleProperty(defaultValue = DEFAULT_COLOR)
    public void
    setColor(String value) { this.color = value; }

    private String color = DEFAULT_COLOR;

    private static final String DEFAULT_COLOR = "Yellow";

    @Override public int[]
    getDefaultTokens() { return new int[] { TokenTypes.ANNOTATION }; }

    @Override public void
    visitToken(DetailAST ast) { this.log(ast, MESSAGE_KEY_THE_COLOR_IS, this.color); }
}
$ javadoc \
> -doclet de.unkrig.doclet.cs.CsDoclet \
> -docletpath "path/to/cs-doclet.jar;bin;path/to/checkstyle-6.1-all.jar;path/to/net.sf.eclipsecs.core-6.1.jar" \
> -checkstyle-metadata.properties-dir src \
> -checkstyle-metadata.xml-dir src \
> -messages.properties-dir src \
> -sourcepath src \
> -classpath ../net.sf.checkstyle-6.1/checkstyle-6.1/checkstyle-6.1-all.jar \
> com.pany.cs.checks
Loading source files for package com.pany.cs.checks...
Constructing Javadoc information...
$

And you'll get:

File "src/com/pany/cs/checks/checkstyle-metadata.properties":

# This file was generated by the CS doclet; see http://cs-contrib.unkrig.de.

# Rule groups:
Whitespace.group = Whitespace

# Custom checks, in alphabetical order.

# --------------- com.pany: ColorCheck ---------------

ColorCheck.name = com.pany: ColorCheck
ColorCheck.desc =\
    A completely useless check which merely prints a (localizable) message each time it encounters an annotation.
ColorCheck.color                                  = A completely useless check parameter.

File "src/com/pany/cs/checks/checkstyle-metadata.xml":

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE checkstyle-metadata PUBLIC
"-//eclipse-cs//DTD Check Metadata 1.1//EN"
"http://eclipse-cs.sourceforge.net/dtds/checkstyle-metadata_1_1.dtd">
<checkstyle-metadata>

    <!-- This file was generated by the CS doclet; see http://cs-contrib.unkrig.de -->

    <!-- ColorCheck -->

    <rule-group-metadata name="%Whitespace.group" priority="999">
        <rule-metadata
            internal-name="com.pany.cs.checks.ColorCheck"
            parent="TreeWalker"
            name="%ColorCheck.name"
        >
            <alternative-name internal-name="com.pany.cs.checks.ColorCheck" />
            <description>%ColorCheck.desc</description>

            <property-metadata
                name="color"
                datatype="String"
                default-value="Yellow"
            >
                <description>%ColorCheck.color</description>
            </property-metadata>
            <message-key key="theColorIs" />
        </rule-metadata>
    </rule-group-metadata>
</checkstyle-metadata>

MediaWiki markup documentation

Typically, you will also want to publish human-readable documentation for your checks and filters, which is more or less identical with the text in the eclipse-cs metadata files. This is also possible with the "-mediawiki-dir" command line option:

$ javadoc \
> -doclet de.unkrig.doclet.cs.CsDoclet \
> -docletpath "path/to/cs-doclet.jar;bin;path/to/checkstyle-6.1-all.jar;path/to/net.sf.eclipsecs.core-6.1.jar" \
> -checkstyle-metadata.properties-dir src \
> -checkstyle-metadata.xml-dir src \
> -messages.properties-dir src \
> -mediawiki-dir mediawiki \
> -sourcepath src \
> -classpath ../net.sf.checkstyle-6.1/checkstyle-6.1/checkstyle-6.1-all.jar \
> com.pany.cs.checks
Loading source files for package com.pany.cs.checks...
Constructing Javadoc information...
$

This will generate:

File "mediawiki/com.pany ColorCheck.mw":

A completely useless check which merely prints a (localizable) message each time it encounters an annotation.

== Properties ==

Default values appear <u>underlined</u>.

<dl>
<dt>color = "<i>String</i>" (optional; default value is "Yellow")
<dd>A completely useless check parameter.
</dl>

Upload this text to a MediaWiki repository, and you'll see:

Screenshot mediawiki.jpg

And you're done!

Summary

Before, you had to write one Java file and four more or less redundant metadata files per check; now you merely have to throw in a few annotations and doc comments and generate all four metadata files from the source code

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