# Package org.apache.lucene.queries.function

package org.apache.lucene.queries.function
Queries that compute score based upon a function.

- Related Packages
  Package
  Description
  org.apache.lucene.queries
  Filters and Queries that add to core Lucene.
  org.apache.lucene.queries.function.docvalues
  FunctionValues for different data types.
  org.apache.lucene.queries.function.valuesource
  A variety of functions to use with FunctionQuery.
  org.apache.lucene.queries.intervals
  Intervals queries
  org.apache.lucene.queries.mlt
  Document similarity query generators.
  org.apache.lucene.queries.payloads
  The payloads package provides Query mechanisms for finding and using payloads.
  org.apache.lucene.queries.spans
  The calculus of spans.
- Classes
  Class
  Description
  FunctionMatchQuery
  A query that retrieves all documents with a `DoubleValues` value matching a predicate
  FunctionQuery
  Returns a score for each document based on a ValueSource, often some function of the value of a field.
  FunctionRangeQuery
  A Query wrapping a `ValueSource` that matches docs in which the values in the value source match a configured range.
  FunctionScoreQuery
  A query that wraps another query, and uses a DoubleValuesSource to replace or modify the wrapped query's score
  FunctionValues
  Represents field values as different types.
  FunctionValues.ValueFiller
  Abstraction of the logic required to fill the value of a specified doc into a reusable `MutableValue`.
  IndexReaderFunctions
  Class exposing static helper methods for generating DoubleValuesSource instances over some IndexReader statistics
  ValueSource
  Instantiates `FunctionValues` for a particular reader.
  ValueSourceScorer
  `Scorer` which returns the result of `FunctionValues.floatVal(int)` as the score for a document, and which filters out documents that don't match `ValueSourceScorer.matches(int)`.