Expert: a FieldComparator compares hits so as to determine their sort order when collecting the top results with TopFieldCollector . The concrete public FieldComparator classes here correspond to the SortField types. More...

Classes
class	ByteComparator
	Parses field's values as byte (using FieldCache.GetBytes(Lucene.Net.Index.IndexReader,string) and sorts by ascending value More...

class	DocComparator
	Sorts by ascending docID More...

class	DoubleComparator
	Parses field's values as double (using FieldCache.GetDoubles(Lucene.Net.Index.IndexReader,string) and sorts by ascending value More...

class	FloatComparator
	Parses field's values as float (using FieldCache.GetFloats(Lucene.Net.Index.IndexReader,string) and sorts by ascending value More...

class	IntComparator
	Parses field's values as int (using FieldCache.GetInts(Lucene.Net.Index.IndexReader,string) and sorts by ascending value More...

class	LongComparator
	Parses field's values as long (using FieldCache.GetLongs(Lucene.Net.Index.IndexReader,string) and sorts by ascending value More...

class	RelevanceComparator
	Sorts by descending relevance. NOTE: if you are sorting only by descending relevance and then secondarily by ascending docID, peformance is faster using TopScoreDocCollector directly (which Searcher.Search(Query, int) uses when no Sort is specified). More...

class	ShortComparator
	Parses field's values as short (using FieldCache.GetShorts(IndexReader, string)) and sorts by ascending value More...

class	StringComparatorLocale
	Sorts by a field's value using the Collator for a given Locale. More...

class	StringOrdValComparator
	Sorts by field's natural String sort order, using ordinals. This is functionally equivalent to FieldComparator.StringValComparator , but it first resolves the string to their relative ordinal positions (using the index returned by FieldCache.GetStringIndex), and does most comparisons using the ordinals. For medium to large results, this comparator will be much faster than FieldComparator.StringValComparator. For very small result sets it may be slower. More...

class	StringValComparator
	Sorts by field's natural String sort order. All comparisons are done using String.compareTo, which is slow for medium to large result sets but possibly very fast for very small results sets. More...

Public Member Functions
abstract int	Compare (int slot1, int slot2)
	Compare hit at slot1 with hit at slot2.

abstract void	SetBottom (int slot)
	Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When CompareBottom is called, you should compare against this slot. This will always be called before CompareBottom.

abstract int	CompareBottom (int doc)
	Compare the bottom of the queue with doc. This will only invoked after setBottom has been called. This should return the same result as Compare(int,int) } as if bottom were slot1 and the new document were slot 2.

abstract void	Copy (int slot, int doc)
	This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.

abstract void	SetNextReader (IndexReader reader, int docBase)
	Set a new Reader. All doc correspond to the current Reader.

virtual void	SetScorer (Scorer scorer)
	Sets the Scorer to use in case a document's score is needed.

Properties
abstract IComparable	this[int slot] `[get]`
	Return the actual value in the slot.

Detailed Description

Expert: a FieldComparator compares hits so as to determine their sort order when collecting the top results with TopFieldCollector . The concrete public FieldComparator classes here correspond to the SortField types.

This API is designed to achieve high performance sorting, by exposing a tight interaction with FieldValueHitQueue as it visits hits. Whenever a hit is competitive, it's enrolled into a virtual slot, which is an int ranging from 0 to numHits-1. The FieldComparator is made aware of segment transitions during searching in case any internal state it's tracking needs to be recomputed during these transitions.

A comparator must define these functions:

Compare Compare a hit at 'slot a' with hit 'slot b'.
SetBottom This method is called by FieldValueHitQueue to notify the FieldComparator of the current weakest ("bottom") slot. Note that this slot may not hold the weakest value according to your comparator, in cases where your comparator is not the primary one (ie, is only used to break ties from the comparators before it).
CompareBottom Compare a new hit (docID) against the "weakest" (bottom) entry in the queue.
Copy Installs a new hit into the priority queue. The FieldValueHitQueue calls this method when a new hit is competitive.
SetNextReader Invoked when the search is switching to the next segment. You may need to update internal state of the comparator, for example retrieving new values from the FieldCache.
P:Lucene.Net.Search.FieldComparator.Item(System.Int32) Return the sort value stored in the specified slot. This is only called at the end of the search, in order to populate FieldDoc.fields when returning the top results.

NOTE: This API is experimental and might change in incompatible ways in the next release.

Definition at line 83 of file FieldComparator.cs.

Member Function Documentation

abstract int Lucene.Net.Search.FieldComparator.Compare	(	int	slot1,
		int	slot2
	)

pure virtual

Compare hit at slot1 with hit at slot2.

Parameters

slot1	first slot to compare
slot2	second slot to compare

Returns: any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

abstract int Lucene.Net.Search.FieldComparator.CompareBottom ( int doc )

pure virtual

Compare the bottom of the queue with doc. This will only invoked after setBottom has been called. This should return the same result as Compare(int,int) } as if bottom were slot1 and the new document were slot 2.

For a search that hits many results, this method will be the hotspot (invoked by far the most frequently).

Parameters

doc	that was hit

Returns: any N < 0 if the doc's value is sorted after the bottom entry (not competitive), any N > 0 if the doc's value is sorted before the bottom entry and 0 if they are equal.

abstract void Lucene.Net.Search.FieldComparator.Copy	(	int	slot,
		int	doc
	)

pure virtual

This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.

Parameters

slot	which slot to copy the hit to
doc	docID relative to current reader

abstract void Lucene.Net.Search.FieldComparator.SetBottom ( int slot )

pure virtual

Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When CompareBottom is called, you should compare against this slot. This will always be called before CompareBottom.

Parameters

slot	the currently weakest (sorted last) slot in the queue

abstract void Lucene.Net.Search.FieldComparator.SetNextReader	(	IndexReader	reader,
		int	docBase
	)

pure virtual

Set a new Reader. All doc correspond to the current Reader.

Parameters

reader	current reader
docBase	docBase of this reader

<throws> IOException </throws> <throws> IOException </throws>

virtual void Lucene.Net.Search.FieldComparator.SetScorer ( Scorer scorer )

virtual

Sets the Scorer to use in case a document's score is needed.

Parameters

scorer Scorer instance that you should use to obtain the current hit's score, if necessary.

Reimplemented in Lucene.Net.Search.FieldComparator.RelevanceComparator.

Definition at line 158 of file FieldComparator.cs.

Property Documentation

abstract IComparable Lucene.Net.Search.FieldComparator.this[int slot]

get

Return the actual value in the slot.

Parameters

slot the value

Returns: value in this slot upgraded to Comparable

Definition at line 171 of file FieldComparator.cs.

The documentation for this class was generated from the following file:

core/Search/FieldComparator.cs

Classes

Public Member Functions

Properties

Detailed Description

Member Function Documentation

Property Documentation