Package org.apache.lucene.expressions

Class SimpleBindings

java.lang.Object

org.apache.lucene.expressions.Bindings

org.apache.lucene.expressions.SimpleBindings

public final class SimpleBindings
extends Bindings

Simple class that binds expression variable names to SortFields or other Expressions.

Example usage:

   SimpleBindings bindings = new SimpleBindings();
   // document's text relevance score
   bindings.add(new SortField("_score", SortField.Type.SCORE));
   // integer NumericDocValues field
   bindings.add(new SortField("popularity", SortField.Type.INT));
   // another expression
   bindings.add("recency", myRecencyExpression);
   
   // create a sort field in reverse order
   Sort sort = new Sort(expr.getSortField(bindings, true));
 

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

Constructor Summary

Constructors

Constructor	Description
SimpleBindings()	Creates a new empty Bindings

Method Summary

Modifier and Type	Method	Description
void	add(String name, Expression expression)	Adds an Expression to the bindings.
void	add(String name, DoubleValuesSource source)	Bind a DoubleValuesSource directly to the given name.
void	add(SortField sortField)	Adds a SortField to the bindings.
DoubleValuesSource	getDoubleValuesSource(String name)	Returns a DoubleValuesSource bound to the variable name
void	validate()	Traverses the graph of bindings, checking there are no cycles or missing references

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimpleBindings

public SimpleBindings()

Creates a new empty Bindings

Method Detail

add

public void add(SortField sortField)

Adds a SortField to the bindings.

This can be used to reference a DocValuesField, a field from FieldCache, the document's score, etc.

add

public void add(String name,
                DoubleValuesSource source)

Bind a DoubleValuesSource directly to the given name.

add

public void add(String name,
                Expression expression)

Adds an Expression to the bindings.

This can be used to reference expressions from other expressions.

getDoubleValuesSource

public DoubleValuesSource getDoubleValuesSource(String name)

Description copied from class: Bindings

Returns a DoubleValuesSource bound to the variable name

Specified by:

getDoubleValuesSource in class Bindings

validate

public void validate()

Traverses the graph of bindings, checking there are no cycles or missing references

Throws:

IllegalArgumentException - if the bindings is inconsistent