Package org.apache.lucene.queries.function

# Class FunctionQuery

java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.queries.function.FunctionQuery

public class FunctionQuery extends Query
Returns a score for each document based on a ValueSource, often some function of the value of a field.

See Also:
  - `ValueSourceScorer`
WARNING: This API is experimental and might change in incompatible ways in the next release.

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `protected class`
  `FunctionQuery.AllScorer`
  Scores all documents, applying the function to each document
  `protected class`
  `FunctionQuery.FunctionWeight`
  Creates FunctionQuery scorer instances

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `FunctionQuery(ValueSource func)`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Weight`
  `createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)`
  `boolean`
  `equals(Object other)`
  Returns true if `o` is equal to this.
  `ValueSource`
  `getValueSource()`
  `int`
  `hashCode()`
  `String`
  `toString(String field)`
  Prints a user-readable version of this query.
  `void`
  `visit(QueryVisitor visitor)`

  ### Methods inherited from class org.apache.lucene.search.Query

  `classHash, rewrite, sameClassAs, toString`

  ### Methods inherited from class java.lang.Object

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

- ## Constructor Details

  - ### FunctionQuery

    public FunctionQuery(ValueSource func)
    Parameters:
      `func` - defines the function to be used for scoring

- ## Method Details

  - ### getValueSource

    public ValueSource getValueSource()
    Returns:
      The associated ValueSource

  - ### visit

    public void visit(QueryVisitor visitor)
    Specified by:
      `visit` in class `Query`

  - ### createWeight

    public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException
    Overrides:
      `createWeight` in class `Query`
    Throws:
      `IOException`

  - ### toString

    public String toString(String field)
    Prints a user-readable version of this query.
    Specified by:
      `toString` in class `Query`

  - ### equals

    public boolean equals(Object other)
    Returns true if `o` is equal to this.
    Specified by:
      `equals` in class `Query`

  - ### hashCode

    public int hashCode()
    Specified by:
      `hashCode` in class `Query`