org.apache.lucene.index
Class FilteredTermsEnum

java.lang.Object
  extended by org.apache.lucene.index.TermsEnum
      extended by org.apache.lucene.index.FilteredTermsEnum
All Implemented Interfaces:
BytesRefIterator
Direct Known Subclasses:
PrefixTermsEnum, SingleTermsEnum, TermRangeTermsEnum

public abstract class FilteredTermsEnum
extends TermsEnum

Abstract class for enumerating a subset of all terms.

Term enumerations are always ordered by getComparator(). Each term in the enumeration is greater than all that precede it.

Please note: Consumers of this enum cannot call seek(), it is forward only; it throws UnsupportedOperationException when a seeking method is called.


Nested Class Summary
protected static class FilteredTermsEnum.AcceptStatus
          Return value, if term should be accepted or the iteration should END.
 
Nested classes/interfaces inherited from class org.apache.lucene.index.TermsEnum
TermsEnum.SeekStatus
 
Field Summary
 
Fields inherited from class org.apache.lucene.index.TermsEnum
EMPTY
 
Constructor Summary
FilteredTermsEnum(TermsEnum tenum)
          Creates a filtered TermsEnum on a terms enum.
FilteredTermsEnum(TermsEnum tenum, boolean startWithSeek)
          Creates a filtered TermsEnum on a terms enum.
 
Method Summary
protected abstract  FilteredTermsEnum.AcceptStatus accept(BytesRef term)
          Return if term is accepted, not accepted or the iteration should ended (and possibly seek).
 AttributeSource attributes()
          Returns the related attributes, the returned AttributeSource is shared with the delegate TermsEnum.
 int docFreq()
          Returns the number of documents containing the current term.
 DocsEnum docs(Bits bits, DocsEnum reuse, int flags)
          Get DocsEnum for the current term, with control over whether freqs are required.
 DocsAndPositionsEnum docsAndPositions(Bits bits, DocsAndPositionsEnum reuse, int flags)
          Get DocsAndPositionsEnum for the current term, with control over whether offsets and payloads are required.
 Comparator<BytesRef> getComparator()
          Return the BytesRef Comparator used to sort terms provided by the iterator.
 BytesRef next()
          Increments the iteration to the next BytesRef in the iterator.
protected  BytesRef nextSeekTerm(BytesRef currentTerm)
          On the first call to next() or if accept(org.apache.lucene.util.BytesRef) returns FilteredTermsEnum.AcceptStatus.YES_AND_SEEK or FilteredTermsEnum.AcceptStatus.NO_AND_SEEK, this method will be called to eventually seek the underlying TermsEnum to a new position.
 long ord()
          Returns ordinal position for current term.
 TermsEnum.SeekStatus seekCeil(BytesRef term)
          This enum does not support seeking!
 boolean seekExact(BytesRef term)
          This enum does not support seeking!
 void seekExact(BytesRef term, TermState state)
          This enum does not support seeking!
 void seekExact(long ord)
          This enum does not support seeking!
protected  void setInitialSeekTerm(BytesRef term)
          Use this method to set the initial BytesRef to seek before iterating.
 BytesRef term()
          Returns current term.
 TermState termState()
          Returns the filtered enums term state
 long totalTermFreq()
          Returns the total number of occurrences of this term across all documents (the sum of the freq() for each doc that has this term).
 
Methods inherited from class org.apache.lucene.index.TermsEnum
docs, docsAndPositions
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FilteredTermsEnum

public FilteredTermsEnum(TermsEnum tenum)
Creates a filtered TermsEnum on a terms enum.

Parameters:
tenum - the terms enumeration to filter.

FilteredTermsEnum

public FilteredTermsEnum(TermsEnum tenum,
                         boolean startWithSeek)
Creates a filtered TermsEnum on a terms enum.

Parameters:
tenum - the terms enumeration to filter.
Method Detail

accept

protected abstract FilteredTermsEnum.AcceptStatus accept(BytesRef term)
                                                  throws IOException
Return if term is accepted, not accepted or the iteration should ended (and possibly seek).

Throws:
IOException

setInitialSeekTerm

protected final void setInitialSeekTerm(BytesRef term)
Use this method to set the initial BytesRef to seek before iterating. This is a convenience method for subclasses that do not override nextSeekTerm(org.apache.lucene.util.BytesRef). If the initial seek term is null (default), the enum is empty.

You can only use this method, if you keep the default implementation of nextSeekTerm(org.apache.lucene.util.BytesRef).


nextSeekTerm

protected BytesRef nextSeekTerm(BytesRef currentTerm)
                         throws IOException
On the first call to next() or if accept(org.apache.lucene.util.BytesRef) returns FilteredTermsEnum.AcceptStatus.YES_AND_SEEK or FilteredTermsEnum.AcceptStatus.NO_AND_SEEK, this method will be called to eventually seek the underlying TermsEnum to a new position. On the first call, currentTerm will be null, later calls will provide the term the underlying enum is positioned at. This method returns per default only one time the initial seek term and then null, so no repositioning is ever done.

Override this method, if you want a more sophisticated TermsEnum, that repositions the iterator during enumeration. If this method always returns null the enum is empty.

Please note: This method should always provide a greater term than the last enumerated term, else the behaviour of this enum violates the contract for TermsEnums.

Throws:
IOException

attributes

public AttributeSource attributes()
Returns the related attributes, the returned AttributeSource is shared with the delegate TermsEnum.

Overrides:
attributes in class TermsEnum

term

public BytesRef term()
              throws IOException
Description copied from class: TermsEnum
Returns current term. Do not call this when the enum is unpositioned.

Specified by:
term in class TermsEnum
Throws:
IOException

getComparator

public Comparator<BytesRef> getComparator()
Description copied from interface: BytesRefIterator
Return the BytesRef Comparator used to sort terms provided by the iterator. This may return null if there are no items or the iterator is not sorted. Callers may invoke this method many times, so it's best to cache a single instance & reuse it.


docFreq

public int docFreq()
            throws IOException
Description copied from class: TermsEnum
Returns the number of documents containing the current term. Do not call this when the enum is unpositioned. TermsEnum.SeekStatus.END.

Specified by:
docFreq in class TermsEnum
Throws:
IOException

totalTermFreq

public long totalTermFreq()
                   throws IOException
Description copied from class: TermsEnum
Returns the total number of occurrences of this term across all documents (the sum of the freq() for each doc that has this term). This will be -1 if the codec doesn't support this measure. Note that, like other term measures, this measure does not take deleted documents into account.

Specified by:
totalTermFreq in class TermsEnum
Throws:
IOException

seekExact

public boolean seekExact(BytesRef term)
                  throws IOException
This enum does not support seeking!

Overrides:
seekExact in class TermsEnum
Throws:
UnsupportedOperationException - In general, subclasses do not support seeking.
IOException

seekCeil

public TermsEnum.SeekStatus seekCeil(BytesRef term)
                              throws IOException
This enum does not support seeking!

Specified by:
seekCeil in class TermsEnum
Throws:
UnsupportedOperationException - In general, subclasses do not support seeking.
IOException

seekExact

public void seekExact(long ord)
               throws IOException
This enum does not support seeking!

Specified by:
seekExact in class TermsEnum
Throws:
UnsupportedOperationException - In general, subclasses do not support seeking.
IOException

ord

public long ord()
         throws IOException
Description copied from class: TermsEnum
Returns ordinal position for current term. This is an optional method (the codec may throw UnsupportedOperationException). Do not call this when the enum is unpositioned.

Specified by:
ord in class TermsEnum
Throws:
IOException

docs

public DocsEnum docs(Bits bits,
                     DocsEnum reuse,
                     int flags)
              throws IOException
Description copied from class: TermsEnum
Get DocsEnum for the current term, with control over whether freqs are required. Do not call this when the enum is unpositioned. This method will not return null.

Specified by:
docs in class TermsEnum
Parameters:
bits - unset bits are documents that should not be returned
reuse - pass a prior DocsEnum for possible reuse
flags - specifies which optional per-document values you require; see DocsEnum.FLAG_FREQS
Throws:
IOException
See Also:
TermsEnum.docs(Bits, DocsEnum, int)

docsAndPositions

public DocsAndPositionsEnum docsAndPositions(Bits bits,
                                             DocsAndPositionsEnum reuse,
                                             int flags)
                                      throws IOException
Description copied from class: TermsEnum
Get DocsAndPositionsEnum for the current term, with control over whether offsets and payloads are required. Some codecs may be able to optimize their implementation when offsets and/or payloads are not required. Do not call this when the enum is unpositioned. This will return null if positions were not indexed.

Specified by:
docsAndPositions in class TermsEnum
Parameters:
bits - unset bits are documents that should not be returned
reuse - pass a prior DocsAndPositionsEnum for possible reuse
flags - specifies which optional per-position values you require; see DocsAndPositionsEnum.FLAG_OFFSETS and DocsAndPositionsEnum.FLAG_PAYLOADS.
Throws:
IOException

seekExact

public void seekExact(BytesRef term,
                      TermState state)
               throws IOException
This enum does not support seeking!

Overrides:
seekExact in class TermsEnum
Parameters:
term - the term the TermState corresponds to
state - the TermState
Throws:
UnsupportedOperationException - In general, subclasses do not support seeking.
IOException

termState

public TermState termState()
                    throws IOException
Returns the filtered enums term state

Overrides:
termState in class TermsEnum
Throws:
IOException
See Also:
TermState, TermsEnum.seekExact(BytesRef, TermState)

next

public BytesRef next()
              throws IOException
Description copied from interface: BytesRefIterator
Increments the iteration to the next BytesRef in the iterator. Returns the resulting BytesRef or null if the end of the iterator is reached. The returned BytesRef may be re-used across calls to next. After this method returns null, do not call it again: the results are undefined.

Returns:
the next BytesRef in the iterator or null if the end of the iterator is reached.
Throws:
IOException - If there is a low-level I/O error.


Copyright © 2000-2013 Apache Software Foundation. All Rights Reserved.