Regex in Vi: How does one use character classes inside groups? (e.g. [\s\w])

Question

In Vim, the character class \s matches any whitespace character. When I'm using those special characters in groups e.g. [\s\w] it does not match any single whitespace or word character, it does match s or w.

How does one use character classes inside groups?

Answer 1

That's not a group, it's a range, and in Vim you can't use character classes (although it's possible in other regex implementations, e.g. in python). You'll have to use an alternation instead:

/\(\w\|\s\)

or:

/\v(\s|\w)

(or, the solution proposed by Peter Lewerin).

Answer 2

Unlike some implementations of regular expression engines, Vim's doesn't seem to support that notation ([\s\w]) in collections. One can use POSIX character class expressions, though.

• [:blank:] is the same as \s.
• [:space:] matches a greater number of whitespace characters than \s does, and seems to be equivalent to \_s.
• [:alnum:] approximates \w, but does not match the underscore (_).

So the collection you wanted could be written as [[:blank:][:alnum:]_] or [[:space:][:alnum:]_].

I haven't verified this by testing, but it is documented in :h regexp, :h /character-classes, and :h /collection.

Portability note: In other regex engines, \s is typically the same as [:space:] (or \_s) is in Vim.