org.apache.lucene.search
Class CachingWrapperFilter

java.lang.Object
  extended by org.apache.lucene.search.Filter
      extended by org.apache.lucene.search.CachingWrapperFilter
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
QueryFilter

public class CachingWrapperFilter
extends Filter

Wraps another filter's result and caches it. The purpose is to allow filters to simply filter, and then wrap with this class to add caching.

See Also:
Serialized Form

Field Summary
protected  Map cache
          A transient Filter cache.
protected  Filter filter
           
 
Constructor Summary
CachingWrapperFilter(Filter filter)
           
 
Method Summary
 BitSet bits(IndexReader reader)
          Deprecated. Use getDocIdSet(IndexReader) instead.
protected  DocIdSet docIdSetToCache(DocIdSet docIdSet, IndexReader reader)
          Provide the DocIdSet to be cached, using the DocIdSet provided by the wrapped Filter.
 boolean equals(Object o)
           
 DocIdSet getDocIdSet(IndexReader reader)
          Creates a DocIdSet enumerating the documents that should be permitted in search results.
 int hashCode()
           
 String toString()
           
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

filter

protected Filter filter

cache

protected transient Map cache
A transient Filter cache.

Constructor Detail

CachingWrapperFilter

public CachingWrapperFilter(Filter filter)
Parameters:
filter - Filter to cache results of
Method Detail

bits

public BitSet bits(IndexReader reader)
            throws IOException
Deprecated. Use getDocIdSet(IndexReader) instead.

Overrides:
bits in class Filter
Returns:
A BitSet with true for documents which should be permitted in search results, and false for those that should not.

NOTE: See Filter.getDocIdSet(IndexReader) for handling of multi-segment indexes (which applies to this method as well).

Throws:
IOException

docIdSetToCache

protected DocIdSet docIdSetToCache(DocIdSet docIdSet,
                                   IndexReader reader)
                            throws IOException
Provide the DocIdSet to be cached, using the DocIdSet provided by the wrapped Filter.

This implementation returns the given DocIdSet, if DocIdSet.isCacheable() returns true, else it copies the DocIdSetIterator into an OpenBitSetDISI.

Throws:
IOException

getDocIdSet

public DocIdSet getDocIdSet(IndexReader reader)
                     throws IOException
Description copied from class: Filter
Creates a DocIdSet enumerating the documents that should be permitted in search results. NOTE: null can be returned if no documents are accepted by this Filter.

Note: This method will be called once per segment in the index during searching. The returned DocIdSet must refer to document IDs for that segment, not for the top-level reader.

Overrides:
getDocIdSet in class Filter
Parameters:
reader - a IndexReader instance opened on the index currently searched on. Note, it is likely that the provided reader does not represent the whole underlying index i.e. if the index has more than one segment the given reader only represents a single segment.
Returns:
a DocIdSet that provides the documents which should be permitted or prohibited in search results. NOTE: null can be returned if no documents will be accepted by this Filter.
Throws:
IOException
See Also:
DocIdBitSet

toString

public String toString()
Overrides:
toString in class Object

equals

public boolean equals(Object o)
Overrides:
equals in class Object

hashCode

public int hashCode()
Overrides:
hashCode in class Object


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