# Package org.apache.lucene.queries.function

Queries that compute score based upon a function.

See: Description

Class Summary
FunctionMatchQuery: A query that retrieves all documents with a `DoubleValues` value matching a predicate This query works by a linear scan of the index, and is best used in conjunction with other queries that can restrict the number of documents visited
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 If the DoubleValuesSource doesn't return a value for a particular document, then that document will be given a score of 0.
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)`.

## Package org.apache.lucene.queries.function Description

Queries that compute score based upon a function.