Cs-doclet

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<meta name="keywords" content="java, doclet, javadoc, checkstyle"></meta> <meta name="description" content="A doclet that generates the metadata files for CHECKSTYLE and ECLIPSE-CS from annotations and DOC tags in the source code of the checks and filters"></meta>

Abstract[edit]

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.

This doclet is useful only for authors of CheckStyle extensions, like cs-contrib.

Intended audience[edit]

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

Extending CheckStyle[edit]

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-doclet.unkrig.de/

# Custom check messages, in alphabetical order.

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

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

Integrating with eclipse-cs[edit]

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-doclet.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-doclet.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>

Javadoc-like documentation[edit]

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 "-d" 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" \
> -d ./csdoc \
> -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 a Javadoc-like HTML documentation for all checks and filters that are declared in the given Java packages.

And you're done!

Summary[edit]

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

Source code[edit]

The source code for the plug-in is here:

   https://github.com/aunkrig/doclet-cs
   https://github.com/aunkrig/doclet-cs-annotation