Add folding markers to syntax configuration

[KevinGliewe]

This PR adds the region markers //#region and //#endregion to add custom folding regions in the Haxe Code.
The snipped for the marker definition comes from the TypeScript configuration file in the VSCode repo:

https://github.com/Microsoft/vscode/blob/master/extensions/typescript/language-configuration.json#L28

I hope you guys like this feature.

[KevinGliewe]

Well, this is a strange build error... 🤔

[Gama11]

There was a discussion about this here: #179

[KevinGliewe]

Oh, sorry for the useless PR then.

[RealyUniqueName]

This feature is going to be implemented in IDEA too: HaxeFoundation/intellij-haxe#744
Maybe it should be treated as a convention.

[EricBishton]

IDEA is going to have two flavors available, at first:

• An FD style: // { region MyRegionTitle and // } endregion (with spaces optional between the comment signifier and the bracket, between the brackets and the region marker -- because they aren't actually required for FD -- and and between "end" and "region").
• An AS3 style: // region MyRegionTitle and // end region (again, the spaces are optional).

Eventually, the user will be allowed to specify starting and ending markers by providing regexes via a dialog.

Edit: Oh, yeah. It works with any comment type (single line, block, documentation), if the marker is on the top line of the block, and the two types don't styles don't match each other.

[KevinGliewe]

Maybe we could use a regex as default which matches all the styles at once?

The start:
^\s*\/[\/\*]\s*[#{]?\s*region\b
https://regex101.com/r/3vWgnm/1

The end:
^\s*\/[\/\*]\s*[#}]?\s*end ?region\b
https://regex101.com/r/MPOk8s/1

Afterwards the pattern could be swapped out by a command or something along this line to use a specific style.
The method vscode.setLanguageConfiguration(language: string, configuration: LanguageConfiguration): Disposable should hopefully provide a way to accomplish it without reloading vscode.

Note:
It looks like the documentation here is not up to date:
https://code.visualstudio.com/docs/extensionAPI/vscode-api#_a-namelanguageconfigurationaspan-classcodeitem-id962languageconfigurationspan

There is no folding property in the documentation, but there is one in the sourcecode:
https://github.com/Microsoft/vscode/blob/777fddd4f7c65b4b1b040328b045c30c3c08f7bc/src/vs/editor/common/modes/languageConfiguration.ts#L68

Edit:
It looks like the LanguageConfiguration definition from the vscode-extern library isn't up do date as well.

https://github.com/vshaxe/vscode-extern/blob/7073e5eee91ca8c2389e7a5c6b899aac36af4562/src/vscode/LanguageConfiguration.hx

It lacks the folding property to.

[EricBishton]

Is the #region marker common in other languages/IDEs? It seems that some folks like/expect it for JS.

EDIT: C#, it would appear. Except that it doesn't appear in comments.

[KevinGliewe]

I think the #region swapped over from C# to vscode. It looks like it is sort of convention now for vscode to fold using this marke. They even included it in Java.

https://github.com/Microsoft/vscode/blob/master/extensions/java/language-configuration.json#L27

[Gama11]

@nadako Any thoughts on this?

[nadako]

Not really, but this won't hurt I guess

[Gama11]

Since there's not really a convention, it would be strange to pick out one specific style to support. I'm going to use the @KevinGliewe's "match-all" regexes with support for:

• // #region name - // #endregion
• // region name - // end region
• // { region name - // } endregion