Do nothing if the current symbol is not space

Question

I'm trying to configure line splitting which I want to make available only if the current symbol is space. I currently configured it as so:

r<ENTER>k$

But this does the following:

line1 line2
     ^
   cursor

to

line1
line2

and

line1line2
    ^
  cursor

to

line          <---------- 1 is missing
line2

which is not desirable. So I want to allow to split the line only if the current symbol is space. Is it possible to do?

Answer 1

You can use an expression mapping:

nnoremap <expr> <Leader>s getline('.')[col('.')-1] =~ "\\s" ? "r<Enter>k$" : ""

The <expr> will make Vim evaluate a Vimscript expression, instead of just a "static" list of keys.

Here, we use getline('.')[col('.')-1] to get the character under the cursor, we check if this is whitespace with =~ "\\s" (this will also match tabs etc.) and run r<Enter>k$ if it is.

If it doesn't match, we do nothing.

---

Perhaps a more useful mapping is:

nnoremap <expr> <Leader>q getline('.')[col('.')-1] =~ "\\s" ? "r<Enter>k$" : "i<Enter><Esc>k$"

Which will split the line without deleting whitespace.