org.apache.lucene.facet.search
Interface CategoryListIterator

All Known Implementing Classes:

MultiCategoryListIterator, PayloadIntDecodingIterator

public interface CategoryListIterator

An interface for iterating over a "category list", i.e., the list of categories per document.

NOTE:

• This class operates as a key to a Map. Appropriate implementation of hashCode() and equals() must be provided.
• init() must be called before you consume any categories, or call skipTo(int).
• skipTo(int) must be called before any calls to nextCategory().
• nextCategory() returns values < Integer.MAX_VALUE, so you can use it as a stop condition.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Method Summary

boolean	init() Initializes the iterator.
long	nextCategory() Returns the next category for the current document that is set through skipTo(int), or a number higher than Integer.MAX_VALUE.
boolean	skipTo(int docId) Skips forward to document docId.

Method Detail

init

boolean init()
             throws IOException

Initializes the iterator. This method must be called before any calls to skipTo(int), and its return value indicates whether there are any relevant documents for this iterator. If it returns false, any call to skipTo(int) will return false as well.
NOTE: calling this method twice may result in skipping over documents for some implementations. Also, calling it again after all documents were consumed may yield unexpected behavior.

Throws:

IOException

skipTo

boolean skipTo(int docId)
               throws IOException

Skips forward to document docId. Returns true iff this document exists and has any categories. This method must be called before calling nextCategory() for a particular document.
NOTE: Users should call this method with increasing docIds, and implementations can assume that this is the case.

Throws:

IOException

nextCategory

long nextCategory()
                  throws IOException

Returns the next category for the current document that is set through skipTo(int), or a number higher than Integer.MAX_VALUE. No assumptions can be made on the order of the categories.

Throws:

IOException