[Use Case]: Visitors

[gavinking]

As a ...

• Application user/user of the configuration itself
• API user (application developer)
• SPI user (container or runtime developer)
• Specification implementer

I need to be able to ...

Visit the tree.

Which enables me to ...

More easily transform Restrictions and Expressions.

Additional information

Our expressions/restrictions API is getting quite complex and powerful (which is how these things tend to go).

This has me, as an implementor of the specification now turning my thoughts to how to actually translate all this stuff to SQL/JPQL/Criteria objects.

On thing that I guess might make this easier would be an SPI Visitor interface which spec implementors can implement to do the transformation, instead of having to do lots of type switching.