# Package org.apache.lucene.expressions

Expressions.

See: Description

Class Summary
Bindings: Binds variable names in expressions to actual data.
Expression: Base class that computes the value of an expression for a document.
SimpleBindings: Simple class that binds expression variable names to `DoubleValuesSource`s or other `Expression`s.

## Package org.apache.lucene.expressions Description

Expressions.

`Expression` - result of compiling an expression, which can evaluate it for a given document. Each expression can have external variables are resolved by `Bindings`.

`Bindings` - abstraction for binding external variables to a way to get a value for those variables for a particular document (DoubleValuesSource).

`SimpleBindings` - default implementation of bindings which provide easy ways to bind sort fields and other expressions to external variables