# expressions

{@link org.apache.lucene.expressions.Expression} - result of compiling an expression, which can evaluate it for a given document. Each expression can have external variables are resolved by {@code Bindings}.

{@link org.apache.lucene.expressions.Bindings} - abstraction for binding external variables to a way to get a value for those variables for a particular document (ValueSource).

{@link org.apache.lucene.expressions.SimpleBindings} - default implementation of bindings which provide easy ways to bind sort fields and other expressions to external variables