Make it possible to undo prefix transforms

[ellatrix]

Description

Fixes #11358.

This PR adjusts the prefix transforms so that they only execute when they match text right at the caret, so that they are undoable, and makes the check faster checking if the previous character is a space and not using any regular expressions otherwise on the whole text. Also adds e2e tests for all prefix and enter transforms, and adds some documentation.

How has this been tested?

Extra e2e tests have been added, but ensure e.g. list shortcuts like 1.  still work and it's possible to undo them and have it so that the prefix can be at the start without it being transformed.

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[youknowriad]

Seems like a good enhancement but I'd appreciate a second opinion as I'm not very familiar with this code.

[youknowriad]

Going to punt this for 4.4 as well. Tests are failing and this is just a way to divide work an ship.

[ellatrix]

Yes, let’s merge the other undo PR first :)

…

On Fri, 9 Nov 2018 at 13:06, Riad Benguella ***@***.***> wrote: Going to punt this for 4.4 as well. Tests are failing and this is just a way to divide work an ship. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#11497 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEfg60JtWO87z9-iQNHX7MJ0lwGUMRfFks5utWG-gaJpZM4YOqvO> .

[youknowriad]

Should we schim the old API?

[ellatrix]

I don't know. It was never official/documented.

[youknowriad]

have it so that the prefix can be at the start without it being transformed.

This is still very hard to do as if you add a space it's still transformed, I wonder if the undo should reset to the value with a space in it.

[gziolo]

It needs to be rebased with the master branch.

With the latest refactoring, we are able to reuse logic from @wordpress/keycodes package and express this using primary modifier:

await pressWithModifier( 'primary', 'z' );

[youknowriad]

I'm not certain I understand what's different between this PR and master in terms of behavior.

[youknowriad]

I noticed that this fixes some issues with focus jumps.

[ellatrix]

This is still very hard to do as if you add a space it's still transformed, I wonder if the undo should reset to the value with a space in it.

Haven't looked deeper, but probably some browsers, like Chrome, fail to visualise the trailing space. We might have to pad it with a non breaking space.