Sublime Forum

Configure auto-indent with multiple scopes per line


Sublime modes configure their automatic indentation via certain plist files, documented here. The problem is that the way in which this is done is by denoting lines which signal indent/dedent/ignore with the option of indenting just the next line or all subsequent lines. There is no way to denote a line which signals multiple indents/dedents, and this is a serious limitation for several languages. A quick and obvious example:



Imagine a C-like language. While this is poor style, and you can argue about the correct indentation of the third line, the fourth line is clearly correctly indented. More generally:



Ditto again.

Here’s an example from Scala (you can recreate this example pretty easily in C++ or Java as well, using the switch/case construct):

x match {
  case Foo =>

  case Bar =>
    more things

This is the correct indentation. The trick is on the final line. The } denotes the closing of two scopes: the pattern match block, and the second match itself. Thus, it should be dedented twice. As far as I can find, there is no way to indicate this in the mode metadata. All I can do is have it dedent a single time.

There’s more tricky things going on here with the second case line, which must both dedent and indent while the first case must only indent, but that can be resolved through clever meta scoping.

Anyway, is there anything I’m missing here? As far as I can tell, Sublime just can’t handle this kind of auto-indentation.

My proposal to fix this (again, assuming I’m not missing anything) would be to leverage meta scoping and give a special meta scope (say, meta.indent.increase.1, where the final sub-scope indicates the number of increases/decreases to apply) to the relevant tokens in the syntax mode. We have more than enough context to do this with extreme precision, and it would allow for very robust auto-indentation. This alternate auto indent/dedent encoding would need to be opted into by modes in their metadata, so that we don’t break old modes which might not correctly apply the scoping.


Everything you (n)ever wanted to know about indentation in ST3
Bash case indentation

yes, same thing with case statements in ASP (maybe this example will be easier for some others to follow, if they are more familiar with Basic than Scala :slight_smile: ):

Select Case abc
    Case 123
    Case Else
End Select

currently it has to settle for not automatically indenting the code after the Case 123 and Case Else.

so a :+1: from me for better auto indentation support for these scenarios



I mentioned this somewhere else, but I believe that with the power of syntax lexing, auto indentation should be based on scope names (as determined by the syntax) and not by individual regular expressions.

This would also allow an easier implementation of multiple dedents or proper detection of opened-then-closed braces in the same line.



I mentioned this in the “API Suggestion” thread : API Suggestions

Hope it will be implemented !