How do you :tag: every word of a line using substitution?

Question

How do you substitute every word of a line, so that it becomes a useful vimwiki tag?

Provided the following line:

Word Compund_Word

I want:

:Word: :Compund_Word:

I guess it involves some use of regex, but I haven't been able to figure out which string.

Answer 1

While on the line in question:

:s/\w\+/:&:/g

Breakdown

• \w\+ will match 1 or more word characters ([0-9A-Za-z_]).
• & has a special meaning in a replacement, depending on the value of 'magic' (default: on). It is replaced with the matched pattern.
• the g flag will perform this substitution for every occurrence on the line, not just the first.

Non-ASCII use

• To use any non-whitespace character as a word character use \S:

  :s/\S\+/:&:/g
  

• To use any character except specific delimiters, use [^{delimiters}] (substituting {delimiters} with any number of delimiters):

  :s/[^;,|]\+/:&:/g
  

See:

:h /\w
:h /\+
:h sub-replace-special
:h 'magic'
:h :s_flags
:h :s_g

Answer 2

Vimwiki also allows you to list all the tags together, with a single : separating multiple tags, such as in:

:Word:Compund_Word:Other_Tag:

To accomplish this replacement, you can use a :s command that will replace a sequence of whitespace with a single :, and additionally match the beginning and end of the line to insert an extra : on each end.

You can perform that substitution on a specific line with:

:s/^\s*\zs\|\s\+\|\ze\s*$/:/g

See :help /\zs and :help /\ze to understand how the matches for the start and end of the line work... The match for whitespace between words should be easy to grasp.