Public API for programmatic registration of Taglet?

[Martin Desruisseaux]

Hello

I'm trying to write an extension of the standard doclet together with
custom taglets in the same JAR file. The custom taglets and doclet need
to share information. But I faced the following difficulties:

When the Taglet.init​(DocletEnvironment,Doclet) method is invoked, the
doclet argument given by the caller is the internal HtmlDoclet wrapped
by StandardDoclet, not my custom StandardDoclet subtype. So I can not
get my doclet and taglet in touch that way.

The lazy workaround - shared static fields - does not work because the
taglet is loaded in a different class loader than the doclet. So even if
I change a static field value from the taglet, the doclet never see that
change. This is not a multi-threading issue; I tested with volatile
static field. I also verified that the class loaders for the same class
were different depending on whether the class of my JAR file is accessed
from the doclet or from the taglet.

I tried to wrap DocletEnvironment in order to return a customised
ForwardingJavaFileManager, in an attempt to control which ClassLoader is
used for loading the taglet. But the standard doclet does not seem to
accept customized DocletEnvironment, as suggested by the error that I got:

    java.lang.ClassCastException: org.opengis.tools.doclet.ForwardingDocletEnvironment cannot be cast to jdk.javadoc/jdk.javadoc.internal.tool.DocEnvImpl
            at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.WorkArounds.<init>(WorkArounds.java:101)
            at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.run(AbstractDoclet.java:108)
            at jdk.javadoc/jdk.javadoc.doclet.StandardDoclet.run(StandardDoclet.java:72)
            (...snip...)

The jdk.javadoc.internal.doclets.toolkit.taglets.TagletManager class has
public void addCustomTag(Taglet) method which seems perfect for my need,
but I found no public API for accessing this functionality.

Is there a public way for a doclet to know its registered taglets, or
any other workaround that I may have missed? If not, would the following
evolution of Javadoc tools be possible?

  * When extending the StandardDoclet, the doclet given in
    Taglet.init(...) method should be the user StandardDoclet instance
    instead than the JDK internal HtmlDoclet.
  * Alternatively, a public API for addCustomTag(…) functionality would
    also work.

Regards,

    Martin


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