List/navigate specific syntax elements in a file?

Question

I would like to jump through specific syntax elements in a file. For example, quickly navigate to the next string element. In a .vim file strings are defined as vimString syntax elements. For clarification, the syntax element under the cursor can be found with the following command:

synIDattr(synID(line('.'), col('.'), 1), "name")

If I wanted to jump through all the strings or comments in a file, it would be useful to be able to get a list of line,col arrays of all syntax elements of a certain type. Or at least a list of line,col arrays of syntax elements of the file or current line.

Answer 1

In recent versions of vim (around patch 8.2.0915), search takes a skip argument which can be used to create a move forward/backward to syntax group motion. Here is a rudimentary implementation:

function! SynMatches(syn) abort
  return synIDattr(synID(line('.'), col('.'), 1), "name") =~# a:syn
endfunction

function! SynMove(syn, dir) abort
  let l:flags = a:dir ? 'W' : 'Wb'
  if SynMatches(a:syn)
    call search('.', l:flags, 0, 0, 'SynMatches(a:syn)')
  endif
  call search('.', l:flags, 0, 0, '!SynMatches(a:syn)')
endfunction

nnoremap <left> <cmd>call SynMove('vimString', 0)<cr>
nnoremap <right> <cmd>call SynMove('vimString', 1)<cr>

Answer 2

Here is a quick starter implementation which simply moves forward until the syntax is matched. synID is generally quite slow, but fortunately, vim accelerates it in the forward direction using caching.

nnoremap <plug>(forward) <space>

function! s:forward_to(syn) abort
  let l:save_view = winsaveview()
  let [l:ol, l:oc] = [line('.'), col('.')]
  while 1
    execute "normal \<plug>(forward)"
    if line('.') == l:ol && col('.') == l:oc
      break
    endif
    let l:syn = synIDattr(synID(line('.'), col('.'), 1), "name")
    if l:syn ==# a:syn
      return
    endif
    let [l:ol, l:oc] = [line('.'), col('.')]
  endwhile
  call winrestview(l:save_view)
endfunction

nnoremap <space> <cmd>call <sid>forward_to('vimString')<cr>

Answer 3

With Neovim, you can use nvim-treesitter for parsing the syntax together with nvim-treesitter-textobjects to achieve this. Treesitter provides a parser rather than using regular expressions to find the objects, and can be used to replace Vim's native highlighting as well.