Class FilteredTermsEnum

Abstract class for enumerating a subset of all terms.

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

Please note: Consumers of this enumeration cannot call Seek(), it is forward only; it throws NotSupportedException when a seeking method is called.
Inheritance
object
TermsEnum
FilteredTermsEnum
SingleTermsEnum
PrefixTermsEnum
TermRangeTermsEnum
Implements
Inherited Members
Namespace: Lucene.Net.Index
Assembly: Lucene.Net.dll
Syntax
public abstract class FilteredTermsEnum : TermsEnum, IBytesRefEnumerator

Constructors

FilteredTermsEnum(TermsEnum)

Creates a filtered TermsEnum on a terms enum.

Declaration
protected FilteredTermsEnum(TermsEnum tenum)
Parameters
Type Name Description
TermsEnum tenum

the terms enumeration to filter.

FilteredTermsEnum(TermsEnum, bool)

Creates a filtered TermsEnum on a terms enum.

Declaration
protected FilteredTermsEnum(TermsEnum tenum, bool startWithSeek)
Parameters
Type Name Description
TermsEnum tenum

the terms enumeration to filter.
bool startWithSeek

start with seek

Properties

Attributes

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

Declaration
public override AttributeSource Attributes { get; }
Property Value
Type Description
AttributeSource
Overrides

Comparer

Return the BytesRef Comparer 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.

Declaration
public override IComparer<BytesRef> Comparer { get; }
Property Value
Type Description
IComparer<BytesRef>
Overrides

DocFreq

Returns the number of documents containing the current term. Do not call this when the enum is unpositioned.

Declaration
public override int DocFreq { get; }
Property Value
Type Description
int
Overrides
See Also

Ord

Returns ordinal position for current term. This is an optional property (the codec may throw NotSupportedException. Do not call this when the enum is unpositioned.

Declaration
public override long Ord { get; }
Property Value
Type Description
long
Overrides

Term

Returns current term. Do not call this when the enum is unpositioned.

Declaration
public override BytesRef Term { get; }
Property Value
Type Description
BytesRef
Overrides

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). 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.

Declaration
public override long TotalTermFreq { get; }
Property Value
Type Description
long
Overrides

Methods

Accept(BytesRef)

Return if term is accepted, not accepted or the iteration should ended (and possibly seek).

Declaration
protected abstract FilteredTermsEnum.AcceptStatus Accept(BytesRef term)
Parameters
Type Name Description
BytesRef term
Returns
Type Description
FilteredTermsEnum.AcceptStatus

Docs(IBits, DocsEnum, DocsFlags)

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.

Declaration
public override DocsEnum Docs(IBits bits, DocsEnum reuse, DocsFlags flags)
Parameters
Type Name Description
IBits bits
DocsEnum reuse

Pass a prior DocsEnum for possible reuse
DocsFlags flags

Specifies which optional per-document values you require; DocsFlags
Returns
Type Description
DocsEnum
Overrides
See Also

DocsAndPositions(IBits, DocsAndPositionsEnum, DocsAndPositionsFlags)

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.

Declaration
public override DocsAndPositionsEnum DocsAndPositions(IBits bits, DocsAndPositionsEnum reuse, DocsAndPositionsFlags flags)
Parameters
Type Name Description
IBits bits
DocsAndPositionsEnum reuse

Pass a prior DocsAndPositionsEnum for possible reuse
DocsAndPositionsFlags flags

Specifies which optional per-position values you require; see DocsAndPositionsFlags.
Returns
Type Description
DocsAndPositionsEnum
Overrides

GetTermState()

Returns the filtered enums term state

Declaration
public override TermState GetTermState()
Returns
Type Description
TermState
Overrides

MoveNext()

Moves to the next item in the TermsEnum.

The default implementation can and should be overridden with a more optimized version.
Declaration
public override bool MoveNext()
Returns
Type Description
bool

true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.
Overrides

NextSeekTerm(BytesRef)

On the first call to MoveNext() or if Accept(BytesRef) returns YES_AND_SEEK or 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 behavior of this enum violates the contract for TermsEnums.
Declaration
protected virtual BytesRef NextSeekTerm(BytesRef currentTerm)
Parameters
Type Name Description
BytesRef currentTerm
Returns
Type Description
BytesRef

SeekCeil(BytesRef)

this enum does not support seeking!

Declaration
public override TermsEnum.SeekStatus SeekCeil(BytesRef term)
Parameters
Type Name Description
BytesRef term
Returns
Type Description
TermsEnum.SeekStatus
Overrides
Exceptions
Type Condition
NotSupportedException

In general, subclasses do not support seeking.

SeekExact(BytesRef)

this enum does not support seeking!

Declaration
public override bool SeekExact(BytesRef term)
Parameters
Type Name Description
BytesRef term
Returns
Type Description
bool
Overrides
Exceptions
Type Condition
NotSupportedException

In general, subclasses do not support seeking.

SeekExact(BytesRef, TermState)

this enum does not support seeking!

Declaration
public override void SeekExact(BytesRef term, TermState state)
Parameters
Type Name Description
BytesRef term
TermState state
Overrides
Exceptions
Type Condition
NotSupportedException

In general, subclasses do not support seeking.

SeekExact(long)

this enum does not support seeking!

Declaration
public override void SeekExact(long ord)
Parameters
Type Name Description
long ord
Overrides
Exceptions
Type Condition
NotSupportedException

In general, subclasses do not support seeking.

SetInitialSeekTerm(BytesRef)

Use this method to set the initial BytesRef to seek before iterating. This is a convenience method for subclasses that do not override NextSeekTerm(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(BytesRef).
Declaration
protected void SetInitialSeekTerm(BytesRef term)
Parameters
Type Name Description
BytesRef term

Implements