In UIMA, we support a Java-friendly style for accessing Feature Structures,
typically via the JCas which supplies a Java Class for each UIMA type.
A typical use pattern for indexes is to get a named index from the index
repository for a CAS view, and then use that index to get an iterator over
instances of that (or use the index as an "Iterable" in a for loop).
For iterators returning JCas instances, it would be nice to have those take
advantage of generics. So, for example, it would be nice to be able to write
without casts, etc.:
AnnotationIndex<SourceDocumentInformation>
anIndexOverSourceDocumentInformationType =
cas.getAnnotationIndex(the_UIMA_type_for_SourceDocumentInformation);
or
AnnotationIndex<SourceDocumentInformation>
anIndexOverSourceDocumentInformationType =
cas.getAnnotationIndex(SourceDocumentInformation.class); // << NEW!
and then
Iterator<SourceDocumentInformation> iter =
anIndexOverSourceDocumentInformationType.iterator();
or using Iterable:
for (SourceDocumentInformation sdi :
anIndexOverSourceDocumentInformationType) {
... // use as an iterable
}
It would be nice to be able to combine these two things (getting the index, then
getting the iterator over the index) by chaining these, like this:
Iterator<SourceDocumentInformation> iter =
cas.getAnnotationIndex(SourceDocumentInformation.class).iterator();
I've found a way to update the way generics are used to have the Index and
FSIterator APIs work like this. One thing I couldn't discover how to do was to
have this form work:
Iterator<SourceDocumentInformation> iter =
cas.getAnnotationIndex(the_UIMA_type_for_SourceDocumentInformation).iterator();
This variant (which inserts a Java Class) works, though (I didn't realize Java
even supported this syntax until recently:
Iterator<SourceDocumentInformation> iter = cas. <SourceDocumentInformation>
getAnnotationIndex(the_UIMA_type_for_SourceDocumentInformation).iterator();
I plan to add the support for making generics useful in this way, plus the
alternative which allows passing the class instance of a UIMA type (e.g.,
SourceDocumentInformation.class), and welcome suggestions for improvements :-)
; I hope the support for "iterables" (like the "for" loop example above) will
be especially useful.
-Marshall
