Feature Request: ability to add custom operators which are not automatically traversed for evaluation, v2

[josephdpurcell]

Fixes #116

This PR is a revision of #117. I have to admit I wasn't sure the best way to go about this PR -- let me know if I should instead make it against https://github.com/Sykander/json-logic-js/tree/feature/controlled-execution.

I included @Skyander's commits here. The "diff" from @Skyander's version is that I renamed the param from controlledExecution to traverse, and changed the state tracking object from runOperationAsControlled to opOptions which allows future options to be supported.

Here is a revision to the PR description as well:

Changes:

• Added traverse option on add_operation function
• Added unit tests traverse

Description

This PR adds functionality so that when registering a custom operator with the add_operator method, you can now pass in a third param options with the property traverse. This option allows you to specify how your operator should be treated during evaluation and also prevents all nested parameters to the operator from being pre-evaluated.

I believe this PR addresses one of the noted limitations described in https://jsonlogic.com/add_operation.html:

Every other operator including custom operators, performs depth-first recursion.

Once this PR is merged, that sentence could be revised to say:

Every other operator including custom operators, performs depth-first recursion. Unless, the implementation supports a flag to disable the depth-first traversal, such as the JavaScript implementation.

[josephdpurcell]

If this does get merged, a revision to the Types to include this flag would be useful. I saw DefinitelyTyped/DefinitelyTyped#49234.

[Sykander]

Looks good to me 👌

[josephdpurcell]

Thanks for giving it a review!

I was just talking this week to several engineers about this feature. It's a very powerful concept.

@jwadhams What do you think?

[josephdpurcell]

Is there any interest in merging this? @jwadhams is there openness to adding a maintainer to help review issues and merge PRs?

[jwadhams]

@josephdpurcell hey I made time in my sprint to review this today or tomorrow. What I've read so far I'm really excited about.