RFR: 8323706: Move SimpleSelector and CompoundSelector to internal packages [v3]

[Kevin Rushforth]

On Tue, 9 Jul 2024 12:25:07 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> Moves `SimpleSelector` and `CompoundSelector` to internal packages.
>> 
>> This can be done with only a minor API break, as `SimpleSelector` and `CompoundSelector` were public before.  However, these classes could not be constructed by 3rd parties.  The only way to access them was by doing a cast (generally they're accessed via `Selector` not by their sub types).  The reason they were public at all was because the CSS engine needs to be able to access them from internal packages.
>> 
>> This change fixes a mistake (or possibly something that couldn't be modelled at the time) when the CSS API was first made public. The intention was always to have a `Selector` interface/abstract class, with private implementations (`SimpleSelector` and `CompoundSelector`).
>> 
>> This PR as said has a small API break.  The other changes are (AFAICS) source and binary compatible:
>> 
>> - Made `Selector` `sealed` only permitting `SimpleSelector` and `CompoundSelector` -- as `Selector` had a package private constructor, there are no concerns with pre-existing subclasses
>> - `Selector` has a few more methods that are now `protected` -- given that the class is now sealed, these modified methods are not accessible (they may still require rudimentary documentation I suppose)
>> - `Selector` now has a `public` default constructor -- as the class is sealed, it is inaccessible
>> - `SimpleSelector` and `CompoundSelector` have a few more `public` methods, but they're internal now, so it is irrelevant
>> - `createMatch` was implemented directly in `Selector` to avoid having to expose package private fields in `Match` for use by `CompoundSelector`
>> - No need anymore for the `SimpleSelectorShim`
>
> John Hendrikx has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:
> 
>  - Merge branch 'master' of https://git.openjdk.org/jfx into feature/selectors-to-private-api-standalone
>  - Add since tags
>  - Move SimpleSelector and CompoundSelector to private classes

I left a couple quick comments on the API changes. I'll review the rest after the fork.

modules/javafx.graphics/src/main/java/javafx/css/Selector.java line 51:

> 49:      * Explicit constructor for subtype use.
> 50:      *
> 51:      * @since 23

The pattern we use elsewhere is:

"Constructor for subclasses to call."

Also, that should be `@since 24`.

modules/javafx.graphics/src/main/java/javafx/css/Selector.java line 197:

> 195:      * @return a selector, never {@code null}
> 196:      * @throws IOException if reading from {@code DataInputStream} fails
> 197:      * @since 23

That should be `@since 24`.

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PR Review: https://git.openjdk.org/jfx/pull/1333#pullrequestreview-2166691276
PR Review Comment: https://git.openjdk.org/jfx/pull/1333#discussion_r1670750269
PR Review Comment: https://git.openjdk.org/jfx/pull/1333#discussion_r1670751417