public abstract class TermsEnum extends Object implements BytesRefIterator
seekCeil(BytesRef)
, seekExact(BytesRef)
) or step through (BytesRefIterator.next()
terms to obtain frequency information (docFreq()
), PostingsEnum
or PostingsEnum
for the current term (postings(org.apache.lucene.index.PostingsEnum)
.
Term enumerations are always ordered by BytesRef.compareTo, which is Unicode sort order if the terms are UTF-8 bytes. Each term in the enumeration is greater than the one before it.
The TermsEnum is unpositioned when you first obtain it
and you must first successfully call BytesRefIterator.next()
or one
of the seek
methods.
Modifier and Type | Class and Description |
---|---|
static class |
TermsEnum.SeekStatus
Represents returned result from
seekCeil(org.apache.lucene.util.BytesRef) . |
Modifier and Type | Field and Description |
---|---|
static TermsEnum |
EMPTY
An empty TermsEnum for quickly returning an empty instance e.g.
|
Modifier | Constructor and Description |
---|---|
protected |
TermsEnum()
Sole constructor.
|
Modifier and Type | Method and Description |
---|---|
AttributeSource |
attributes()
Returns the related attributes.
|
abstract int |
docFreq()
Returns the number of documents containing the current
term.
|
abstract long |
ord()
Returns ordinal position for current term.
|
PostingsEnum |
postings(PostingsEnum reuse)
Get
PostingsEnum for the current term. |
abstract PostingsEnum |
postings(PostingsEnum reuse,
int flags)
Get
PostingsEnum for the current term, with
control over whether freqs, positions, offsets or payloads
are required. |
abstract TermsEnum.SeekStatus |
seekCeil(BytesRef text)
Seeks to the specified term, if it exists, or to the
next (ceiling) term.
|
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 termState() . |
abstract void |
seekExact(long ord)
Seeks to the specified term by ordinal (position) as
previously returned by
ord() . |
abstract BytesRef |
term()
Returns current term.
|
TermState |
termState()
Expert: Returns the TermsEnums internal state to position the TermsEnum
without re-seeking the term dictionary.
|
abstract 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).
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
next
public static final TermsEnum EMPTY
MultiTermQuery
Please note: This enum should be unmodifiable, but it is currently possible to add Attributes to it. This should not be a problem, as the enum is always empty and the existence of unused Attributes does not matter.
protected TermsEnum()
public AttributeSource attributes()
public boolean seekExact(BytesRef text) throws IOException
seekCeil(org.apache.lucene.util.BytesRef)
.IOException
public abstract TermsEnum.SeekStatus seekCeil(BytesRef text) throws IOException
IOException
public abstract void seekExact(long ord) throws IOException
ord()
. The target ord
may be before or after the current ord, and must be
within bounds.IOException
public void seekExact(BytesRef term, TermState state) throws IOException
TermState
previously obtained
from 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.
term
- the term the TermState corresponds tostate
- the TermState
IOException
public abstract BytesRef term() throws IOException
IOException
public abstract long ord() throws IOException
UnsupportedOperationException
). Do not call this
when the enum is unpositioned.IOException
public abstract int docFreq() throws IOException
TermsEnum.SeekStatus.END
.IOException
public abstract long totalTermFreq() throws IOException
IOException
public final PostingsEnum postings(PostingsEnum reuse) throws IOException
PostingsEnum
for the current term. Do not
call this when the enum is unpositioned. This method
will not return null.
NOTE: the returned iterator may return deleted documents, so
deleted documents have to be checked on top of the PostingsEnum
.
Use this method if you only require documents and frequencies,
and do not need any proximity data.
This method is equivalent to
postings(reuse, PostingsEnum.FREQS)
reuse
- pass a prior PostingsEnum for possible reuseIOException
postings(PostingsEnum, int)
public abstract PostingsEnum postings(PostingsEnum reuse, int flags) throws IOException
PostingsEnum
for the current term, with
control over whether freqs, positions, offsets or payloads
are required. Do not call this when the enum is
unpositioned. This method may return null if the postings
information required is not available from the index
NOTE: the returned iterator may return deleted documents, so
deleted documents have to be checked on top of the PostingsEnum
.
reuse
- pass a prior PostingsEnum for possible reuseflags
- specifies which optional per-document values
you require; see PostingsEnum.FREQS
IOException
public TermState termState() throws IOException
NOTE: A seek by TermState
might not capture the
AttributeSource
's state. Callers must maintain the
AttributeSource
states separately
IOException
TermState
,
seekExact(BytesRef, TermState)
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