How can I get the value of iskeyword as characters?

Question

I am trying to get the value of iskeyword as character. When I run set iskeyword?, I get iskeyword=@,48-57,_,192-255. Using 48-57 as an example, how can I turn them back to characters? Is there any helper function in vim or lua that can help me do that?

Answer 1

You can use the nr2char() function:

echo nr2char(48)

This will display the character for the number zero, '0'.

To print that first range using Vimscript you could, for example, do something like:

for i in range(48, 57)
   echo nr2char(i)
endfor

That will print out characters representing numbers 0-9, one per line.

Alternatively, to put the associated characters in a list:

let chlist = map(range(48, 57), {_, val -> nr2char(val)})

Another function that does the same number-to-char conversions but can handle multiple numbers at once is list2str()

echo list2str(range(48, 57))

...or the equivalent "method call"...

echo range(48, 57)->list2str()

Both will display the string 0123456789.

Answer 2

You can retrieve a string containing all (ASCII + 127-255) iskeyword characters via the following:

echo substitute(join(map(range(256), 'nr2char(v:val)'), ''), '[^[:keyword:]]', '', 'g')

In patterns \k refers to characters in iskeyword (it is dynamic with this option), however this cannot be easily negated. Instead we can use the class expression [:keyword:] which can easily be negated in a character class via [^[:keyword:]]. We create a length 255 string containing all of the characters of interest, and substitute out all non-keyword chars.