ValueSource (Lucene 3.6.2 API)

java.lang.Object
- org.apache.lucene.search.function.ValueSource

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

FieldCacheSource, OrdFieldSource, ReverseOrdFieldSource
```
public abstract class ValueSource
extends Object
implements Serializable
```
Expert: source of values for basic function queries.
At its default/simplest form, values - one per doc - are used as the score of that doc.
Values are instantiated as DocValues for a particular reader.
ValueSource implementations differ in RAM requirements: it would always be a factor of the number of documents, but for each document the number of bytes can be 1, 2, 4, or 8.

See Also:

Serialized Form

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors
Constructor Description

ValueSource()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract String`	`description()`	description of field, used in explain()
`abstract boolean`	`equals(Object o)`	Needed for possible caching of query results - used by `ValueSourceQuery.equals(Object)`.
`abstract DocValues`	`getValues(IndexReader reader)`	Return the DocValues used by the function query.
`abstract int`	`hashCode()`	Needed for possible caching of query results - used by `ValueSourceQuery.hashCode()`.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - ValueSource
```
public ValueSource()
```
- Method Detail
  - getValues
```
public abstract DocValues getValues(IndexReader reader)
                             throws IOException
```
    Return the DocValues used by the function query.
    
    Parameters:
    
    reader - the IndexReader used to read these values. If any caching is involved, that caching would also be IndexReader based.
    
    Throws:
    
    IOException - for any error.
  - description
```
public abstract String description()
```
    description of field, used in explain()
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - equals
```
public abstract boolean equals(Object o)
```
    Needed for possible caching of query results - used by ValueSourceQuery.equals(Object).
    
    Overrides:
    
    equals in class Object
    
    See Also:
    
    Object.equals(Object)
  - hashCode
```
public abstract int hashCode()
```
    Needed for possible caching of query results - used by ValueSourceQuery.hashCode().
    
    Overrides:
    
    hashCode in class Object
    
    See Also:
    
    Object.hashCode()