Moving by word (w/b) and staying within the line

Question

Background

I'm attempting to remap the arrow keys to move by word while staying within the current line. I.e. I'm looking for a behavior similar to w and b, but that acts like h and l in the sense that it doesn't move to a line above or below. For moving right, I have the current solution:

nnoremap <expr> <Right> getline('.')[col('.')-1:] =~# '\s\S' ? 'w' : '$'

It gets most of the way there, but since \s\S is only looking to see if there are more whitespaces, the behavior breaks down at the end of a line. For instance, it misses instrs in the following example line:`

'>'::xs -> parse_chars xs ((Next 1)::instrs)

Question

How do I get the behavior I'm looking for? Is there any way to regex match a "vim word" to get the desired behavior?

Edit

I'm aware that this is technically possible by a short script using norm, like below:

function! CustomRight()
    let last = line('.')
    norm w
    if line('.') != last
        norm b$
    endif
endfunction

But this isn't ideal, since norm brings you into normal mode. So it wouldn't work in visual mode.

Answer 1

This is what I came up with:

:nnoremap <expr> <Right> col('.') == (col('$') - 1) \|\| getline('.')[col('.')-1:] =~# '^[^[:keyword:]]\+$' ? '$' : 'w'

Unfortunately it still doesn't work quite right, so I came up with this:

:nnoremap <expr> <Right> col('.') == (col('$') - 1) \|\| getline('.')[col('.')-1:] =~# '^[^[:keyword:]]\+\s*$\\|^\k\+\s*$' ? '$' : 'w'