Binding a function which contains the movement command 'b' to 'nmap b'

Question

I am trying to write a function that will only let me call nmap b when the cursor is not on the first column in the current window. This is to make b only work on the current line and encourage more efficient navigation bindings.

I wrote a function which does what I want:

function CurrentLineB() 
  let column = getcurpos()[2]
 echo column
 if column != 1
   normal b%
 endif
endfunction

When I call it with :call CurrentLineB() without binding it to b, it works as expected. When I map the function with nnoremap b :call CurrentLineB() the function keeps recurring without exiting.

How can I avoid this recursion, and make the function work as it did when it was not bound to b?

Answer 1

The issue with your function is that you're using plain normal, when you need normal! to make it non-recursive, which you need to ignore the b mapping you created. That should be enough to fix the problem.

But a simpler way to implement what you're trying to accomplish is to use an <expr> mapping and the ternary operator, to expand to b when on a column after 1, or to an empty string otherwise.

nnoremap <expr> b col('.') > 1 ? 'b' : ''

I also used col(), which is a more direct way to get the column.

Note that this mapping still doesn't work if you have a line with indentation, in which case it will move to the preceding line when sitting on the first character of the first indented word, or on an indentation character other than the first... You can use indent() to check for the indentation of the current line and compare it to virtcol() (to properly account for tabs):

nnoremap <expr> b virtcol('.') > indent('.') + 1 ? 'b' : ''