Module org.apache.lucene.expressions

Package org.apache.lucene.expressions

Class ExpressionValueSource

java.lang.Object

org.apache.lucene.search.DoubleValuesSource

org.apache.lucene.expressions.ExpressionValueSource

All Implemented Interfaces:

SegmentCacheable

Direct Known Subclasses:

CachingExpressionValueSource

class ExpressionValueSource
extends DoubleValuesSource

A DoubleValuesSource which evaluates a Expression given the context of an Bindings.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final Expression	expression
(package private) final boolean	needsScores
(package private) final DoubleValuesSource[]	variables

Fields inherited from class org.apache.lucene.search.DoubleValuesSource

SCORES

Constructor Summary

Constructors

Constructor	Description
ExpressionValueSource(Bindings bindings, Expression expression)
ExpressionValueSource(DoubleValuesSource[] variables, Expression expression, boolean needsScores)

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)
Explanation	explain(LeafReaderContext ctx, int docId, Explanation scoreExplanation)	An explanation of the value for the named document.
DoubleValues	getValues(LeafReaderContext readerContext, DoubleValues scores)	Returns a DoubleValues instance for the passed-in LeafReaderContext and scores
int	hashCode()
boolean	isCacheable(LeafReaderContext ctx)
boolean	needsScores()	Return true if document scores are needed to calculate values
DoubleValuesSource	rewrite(IndexSearcher searcher)	Return a DoubleValuesSource specialised for the given IndexSearcher
String	toString()
(package private) static DoubleValues	zeroWhenUnpositioned(DoubleValues in)	Create a wrapper around all the expression arguments to do two things: Default to 0 for any argument that doesn't have a value for a given doc (i.e., #advanceExact returns false) Be as lazy as possible about actually advancing to the given doc until the argument value is actually needed by the expression.

Methods inherited from class org.apache.lucene.search.DoubleValuesSource

constant, fromDoubleField, fromField, fromFloatField, fromIntField, fromLongField, fromQuery, fromScorer, getSortField, similarityToQueryVector, similarityToQueryVector, toLongValuesSource

Methods inherited from class java.lang.Object

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

Field Details

variables

final DoubleValuesSource[] variables

expression

final Expression expression

needsScores

final boolean needsScores

Constructor Details

ExpressionValueSource

ExpressionValueSource(Bindings bindings,
 Expression expression)

ExpressionValueSource

ExpressionValueSource(DoubleValuesSource[] variables,
 Expression expression,
 boolean needsScores)

Method Details

getValues

public DoubleValues getValues(LeafReaderContext readerContext,
 DoubleValues scores)
                       throws IOException

Description copied from class: DoubleValuesSource

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.

Specified by:

getValues in class DoubleValuesSource

Throws:

IOException

zeroWhenUnpositioned

static DoubleValues zeroWhenUnpositioned(DoubleValues in)

Create a wrapper around all the expression arguments to do two things:

1. Default to 0 for any argument that doesn't have a value for a given doc (i.e., #advanceExact returns false)
2. Be as lazy as possible about actually advancing to the given doc until the argument value is actually needed by the expression. For a given doc, some arguments may not actually be needed, e.g., because of condition short-circuiting ((true || X) doesn't need to evaluate X) or ternary branching (true ? X : Y doesn't need to evaluate Y).

toString

public String toString()

Specified by:

toString in class DoubleValuesSource

hashCode

public int hashCode()

Specified by:

hashCode in class DoubleValuesSource

equals

public boolean equals(Object obj)

Specified by:

equals in class DoubleValuesSource

needsScores

public boolean needsScores()

Description copied from class: DoubleValuesSource

Return true if document scores are needed to calculate values

Specified by:

needsScores in class DoubleValuesSource

isCacheable

public boolean isCacheable(LeafReaderContext ctx)

Returns:

true if the object can be cached against a given leaf

explain

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

Description copied from class: DoubleValuesSource

An explanation of the value for the named document.

Overrides:

explain in class DoubleValuesSource

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

rewrite

public DoubleValuesSource rewrite(IndexSearcher searcher)
                           throws IOException

Description copied from class: DoubleValuesSource

Return a DoubleValuesSource specialised for the given IndexSearcher

Implementations should assume that this will only be called once. IndexReader-independent implementations can just return this

Queries that use DoubleValuesSource objects should call rewrite() during Query.createWeight(IndexSearcher, ScoreMode, float) rather than during Query.rewrite(IndexSearcher) to avoid IndexReader reference leakage.

For the same reason, implementations that cache references to the IndexSearcher should return a new object from this method.

Specified by:

rewrite in class DoubleValuesSource

Throws:

IOException