Separate NormalizedUnitSpec from CompositeUnitSpec

[kanitw]

and introduce ExtendedUnitSpec = NormalizedUnitSpec | CompositeUnitSpec

This makes the typing clearer between what's normalized (supported internally) vs what's composite unit spec only.

cc: @jakevdp

Merge #4493 First

[jakevdp]

sounds good

[kanitw]

@domoritz It looks like the schema generator does not generate the right output for TopLevelFacetedUnitSpec in this branch. ("mark" and "encoding" are missing, for example.)

[domoritz]

Hmm, that's bad but I don't have time to look into it until next month. Can you try to create a small test case in the schema generator repo?

[kanitw]

I don't have time to look into it until next month.

FYI, this is extremely high priority as it's blocking several PRs downstream.
So within your limited time, better cut down time for other less important efforts.

[domoritz]

Okay, I will try to make some time. Can you describe what exactly is wrong (besides "mark" and "encoding" missing?)

[kanitw]

export type TopLevelFacetedUnitSpec = TopLevel<FacetedExtendedUnitSpec> & DataMixins;`

export type FacetedExtendedUnitSpec = ExtendedUnitSpec<FacetMapping<Field>>;

export type ExtendedUnitSpec<
  /** Extra Encoding */
  EE = EmptyObject
> = NormalizedUnitSpec<EE> | CompositeUnitSpec<EE>;

It seems like TopLevelFacetedUnitSpec currently only gets things from TopLevel, but nothing from FacetedExtendedUnitSpec.

Perhaps, the NormalizedUnitSpec<EE> | CompositeUnitSpec<EE> part is something the schema isn't smart about.

[kanitw]

@domoritz I found a workaround, so you don't have to rush to fix this.

[domoritz]

Great. I should still look into it to make sure it’s not a problem elsewhere.

[kanitw]

<FacetMapping> => WithFacet

[kanitw]

This is still incorrect due to the same problem...

export type CompositeMarkUnitSpec<
  EE = {} // extra encoding parameter (for faceted composite unit spec)
> = ErrorBarUnitSpec<EE> | ErrorBandUnitSpec<EE> | BoxPlotUnitSpec<EE>;

[kanitw]

Closing in favor of #4528, which simplify this PR and avoids splitting unit specs into multiple pieces (for now).