[folding] language-aware folding

[aeschli]

The current implementation of folding uses an indentation based folding strategy that is unaware of the language it works on. Knowledge on the underlying language allows us to solve the following requests:

• [folding] Cannot code fold empty functions [folding] Cannot code fold empty functions #3349
• [folding] Collapse ending brace to the same line [folding] Collapse ending brace to the same line #3352
• [folding] Folded block comments should show */ [folding] Folded block comments should show */ #3350
• [folding] should not fold whitespace after function [folding] should not fold whitespace after function #3353
• [folding] Add code folding for markdown based on heading level [folding] Add code folding for markdown based on heading level #3347
• [folding] [lua] Weird code folding with Lua [folding] [lua] Weird code folding with Lua #3602
• [folding] Collapse code block ignore comments inside this block [folding] Collapse code block ignore comments inside this block #3957
• [folding] Code Folding: support golang multiline strings [folding] support golang multiline strings #5994
• [folding] Optionally fold chained method calls [folding] Optionally fold chained method calls #6991

[rkeithhill]

Another issue I don't see in that list is user-configured folding like this example from C#:

#region Public methods
...
#endregion

In the PowerShell extension we would like to provide this same sort of feature the same syntax as what C# uses which, in PowerShell, looks like a "special" comment.

[fromthewoods]

PowerShell block comment folding is weird in the Insider build 0.10.10.
<#
Comments here
and here
#>
Broken: http://i.imgur.com/M6Ay1vl.gif
It should fold around the <# + #>
Like this: http://i.imgur.com/HFRHJJL.gif
https://blogs.msdn.microsoft.com/powershell/2008/06/14/block-comments-in-v2/

[fromthewoods]

Now I understand. It's the indentation level. Language-aware folding ftw!

[bgelens]

PowerShell here-string breaks folding logic.
Here-string end marker must be placed on first column of new line.

As you can see, the function isn't folded correctly anymore although folding was done on the function keyword. Code after the here-string stays visible as well.

[rkeithhill]

Yeah, I think for VSCode to give the best experience for code-folding they're definitely going to need help from the various language extensions/services.

[daviwil]

Either that or we're going to have to tweak the PowerShell syntax definition to jive with their folding model a little better. May need some pointers from Martin about what we can do to improve folding if the tmLanguage definition is a factor.

[aeschli]

@rkeithhill For the moment there's nothing you can tweek on your side until we allow languages to control code folding.