org.apache.lucene.index

Class BaseTermsEnum

java.lang.Object

org.apache.lucene.index.TermsEnum

org.apache.lucene.index.BaseTermsEnum

All Implemented Interfaces:

BytesRefIterator

Direct Known Subclasses:

MultiTermsEnum

public abstract class BaseTermsEnum
extends TermsEnum

A base TermsEnum that adds default implementations for

• attributes()
• termState()
• seekExact(BytesRef)
• seekExact(BytesRef, TermState)

In some cases, the default implementation may be slow and consume huge memory, so subclass SHOULD have its own implementation if possible.

Nested Class Summary

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

Constructors

Modifier	Constructor and Description
protected	BaseTermsEnum() Sole constructor.

Method Summary

Modifier and Type	Method and Description
AttributeSource	attributes() Returns the related attributes.
boolean	seekExact(BytesRef text) Attempts to seek to the exact term, returning true if the term is found.
void	seekExact(BytesRef term, TermState state) Expert: Seeks a specific position by TermState previously obtained from TermsEnum.termState().
TermState	termState() Expert: Returns the TermsEnums internal state to position the TermsEnum without re-seeking the term dictionary.

Methods inherited from class org.apache.lucene.index.TermsEnum

docFreq, impacts, ord, postings, postings, seekCeil, seekExact, term, totalTermFreq

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.lucene.util.BytesRefIterator

next

Constructor Detail

BaseTermsEnum

protected BaseTermsEnum()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Detail

termState

public TermState termState()
                    throws IOException

Description copied from class: TermsEnum

Expert: Returns the TermsEnums internal state to position the TermsEnum without re-seeking the term dictionary.

NOTE: A seek by TermState might not capture the AttributeSource's state. Callers must maintain the AttributeSource states separately

Specified by:

termState in class TermsEnum

Throws:

IOException

See Also:

TermState, TermsEnum.seekExact(BytesRef, TermState)

seekExact

public boolean seekExact(BytesRef text)
                  throws IOException

Description copied from class: TermsEnum

Attempts to seek to the exact term, returning true if the term is found. If this returns false, the enum is unpositioned. For some codecs, seekExact may be substantially faster than TermsEnum.seekCeil(org.apache.lucene.util.BytesRef).

Specified by:

seekExact in class TermsEnum

Returns:

true if the term is found; return false if the enum is unpositioned.

Throws:

IOException

seekExact

public void seekExact(BytesRef term,
                      TermState state)
               throws IOException

Description copied from class: TermsEnum

Expert: Seeks a specific position by TermState previously obtained from TermsEnum.termState(). Callers should maintain the TermState to use this method. Low-level implementations may position the TermsEnum without re-seeking the term dictionary.

Seeking by TermState should only be used iff the state was obtained from the same TermsEnum instance.

NOTE: Using this method with an incompatible TermState might leave this TermsEnum in undefined state. On a segment level TermState instances are compatible only iff the source and the target TermsEnum operate on the same field. If operating on segment level, TermState instances must not be used across segments.

NOTE: A seek by TermState might not restore the AttributeSource's state. AttributeSource states must be maintained separately if this method is used.

Specified by:

seekExact in class TermsEnum

Parameters:

term - the term the TermState corresponds to

state - the TermState

Throws:

IOException

attributes

public AttributeSource attributes()

Description copied from class: TermsEnum

Returns the related attributes.

Specified by:

attributes in class TermsEnum