What is the syntax to use character classes inside Vim regex bracket expression?

Question

I did the following tests:

code	output	notes
:echo substitute("s s", '\v[^s]', "<&>", "g")	s< >s	space replaced. All fine
:echo substitute("s s", '\v[^\s]', "<&>", "g")	s< >s	[^\s] is the same as [^s]! ??
:echo substitute("s s", '\v[^ \t]', "<&>", "g")	<s> <s>	both s replaced

It looks like \s does not work inside [ ] brackets in Vim regular expression.

Is this expected?

Is there any way I can use \s \S inside bracket expressions in Vim?

Answer 1

You are right the character atom (e.g.: \s, \S, \d, ...) cannot be part of a collection ([])

To get the reference in the doc you can look for the NOTE in the section: :help collection:

NOTE: The other backslash codes mentioned above do not work inside []!

The following answer gives you more details about what is allowed and not allowed in a collection.