org.apache.lucene.search

Class DoubleValuesSource

java.lang.Object

org.apache.lucene.search.DoubleValuesSource

public abstract class DoubleValuesSource
extends Object

Base class for producing DoubleValues To obtain a DoubleValues object for a leaf reader, clients should call getValues(LeafReaderContext, DoubleValues). DoubleValuesSource objects for NumericDocValues fields can be obtained by calling fromDoubleField(String), fromFloatField(String), fromIntField(String) or fromLongField(String), or from fromField(String, LongToDoubleFunction) if special long-to-double encoding is required. Scores may be used as a source for value calculations by wrapping a Scorer using fromScorer(Scorer) and passing the resulting DoubleValues to getValues(LeafReaderContext, DoubleValues). The scores can then be accessed using the SCORES DoubleValuesSource.

Field Summary

Fields

Modifier and Type	Field and Description
static DoubleValuesSource	SCORES A DoubleValuesSource that exposes a document's score If this source is used as part of a values calculation, then callers must not pass null as the DoubleValues parameter on getValues(LeafReaderContext, DoubleValues)

Constructor Summary

Constructors

Constructor and Description
DoubleValuesSource()

Method Summary

Modifier and Type	Method and Description
static DoubleValuesSource	constant(double value) Creates a DoubleValuesSource that always returns a constant value
abstract boolean	equals(Object obj)
Explanation	explain(LeafReaderContext ctx, int docId, Explanation scoreExplanation) An explanation of the value for the named document.
static DoubleValuesSource	fromDoubleField(String field) Creates a DoubleValuesSource that wraps a double-valued field
static DoubleValuesSource	fromField(String field, LongToDoubleFunction decoder) Creates a DoubleValuesSource that wraps a generic NumericDocValues field
static DoubleValuesSource	fromFloatField(String field) Creates a DoubleValuesSource that wraps a float-valued field
static DoubleValuesSource	fromIntField(String field) Creates a DoubleValuesSource that wraps an int-valued field
static DoubleValuesSource	fromLongField(String field) Creates a DoubleValuesSource that wraps a long-valued field
static DoubleValues	fromScorer(Scorer scorer) Returns a DoubleValues instance that wraps scores returned by a Scorer
SortField	getSortField(boolean reverse) Create a sort field based on the value of this producer
abstract DoubleValues	getValues(LeafReaderContext ctx, DoubleValues scores) Returns a DoubleValues instance for the passed-in LeafReaderContext and scores If scores are not needed to calculate the values (ie returns false, callers may safely pass null for the scores parameter.
abstract int	hashCode()
abstract boolean	needsScores() Return true if document scores are needed to calculate values
LongValuesSource	toLongValuesSource() Convert to a LongValuesSource by casting the double values to longs
abstract String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

SCORES

public static final DoubleValuesSource SCORES

A DoubleValuesSource that exposes a document's score If this source is used as part of a values calculation, then callers must not pass null as the DoubleValues parameter on getValues(LeafReaderContext, DoubleValues)

Constructor Detail

DoubleValuesSource

public DoubleValuesSource()

Method Detail

getValues

public abstract DoubleValues getValues(LeafReaderContext ctx,
                                       DoubleValues scores)
                                throws IOException

Returns a DoubleValues instance for the passed-in LeafReaderContext and scores If scores are not needed to calculate the values (ie returns false, callers may safely pass null for the scores parameter.

Throws:

IOException

needsScores

public abstract boolean needsScores()

Return true if document scores are needed to calculate values

explain

public Explanation explain(LeafReaderContext ctx,
                           int docId,
                           Explanation scoreExplanation)
                    throws IOException

An explanation of the value for the named document.

Parameters:

ctx - the readers context to create the Explanation for.

docId - the document's id relative to the given context's reader

Returns:

an Explanation for the value

Throws:

IOException - if an IOException occurs

getSortField

public SortField getSortField(boolean reverse)

Create a sort field based on the value of this producer

Parameters:

reverse - true if the sort should be decreasing

hashCode

public abstract int hashCode()

Overrides:

hashCode in class Object

equals

public abstract boolean equals(Object obj)

Overrides:

equals in class Object

toString

public abstract String toString()

Overrides:

toString in class Object

toLongValuesSource

public final LongValuesSource toLongValuesSource()

Convert to a LongValuesSource by casting the double values to longs

fromField

public static DoubleValuesSource fromField(String field,
                                           LongToDoubleFunction decoder)

Creates a DoubleValuesSource that wraps a generic NumericDocValues field

Parameters:

field - the field to wrap, must have NumericDocValues

decoder - a function to convert the long-valued doc values to doubles

fromDoubleField

public static DoubleValuesSource fromDoubleField(String field)

Creates a DoubleValuesSource that wraps a double-valued field

fromFloatField

public static DoubleValuesSource fromFloatField(String field)

Creates a DoubleValuesSource that wraps a float-valued field

fromLongField

public static DoubleValuesSource fromLongField(String field)

Creates a DoubleValuesSource that wraps a long-valued field

fromIntField

public static DoubleValuesSource fromIntField(String field)

Creates a DoubleValuesSource that wraps an int-valued field

constant

public static DoubleValuesSource constant(double value)

Creates a DoubleValuesSource that always returns a constant value

fromScorer

public static DoubleValues fromScorer(Scorer scorer)

Returns a DoubleValues instance that wraps scores returned by a Scorer