How to use `syn` in regex match?

Question

I'm trying to follow a link using <CR> in a markdown file.

I was giving a look into the native markdown syntax file vim ships with and found a few that use the syn command syntax

syn region markdownUrlTitle matchgroup=markdownUrlTitleDelimiter start=+(+ end=+)+ keepend contained

Is there any way to use a similar matching syntax and maybe pipe the match to a variable?

Thanks in advance

Answer 1

Here is a function that return the text of the highlighting text if it match the argument:

function! GetSynWord(syname)
  let l:line = line('.')
  let l:col = col('.')

  let l:stack = synstack(l:line, l:col)
  if len(l:stack) == 0
    return ''
  endif

  let l:syname = map(synstack(line('.'), col('.')), 'synIDattr(v:val, "name")')[0]
  " echo l:syname
  if l:syname != a:syname
    return ''
  endif

  let l:id = l:stack[0]

  let l:start = l:col
  while l:start >= 0 
    let l:nstack = synstack(l:line, l:start)
    if len(l:nstack) == 0
      break
    endif

    let l:nid = l:nstack[0]
    if l:nid != l:id
      break
    endif

    let l:start = l:start - 1
  endwhile

  let l:end = l:col
  let l:sline = getbufline(bufnr(), l:line)[0]
  while l:end < (len(l:sline) + 1)
    let l:nstack = synstack(l:line, l:end)
    if len(l:nstack) == 0
      break
    endif

    let l:nid = l:nstack[0]
    if l:nid != l:id
      break
    endif

    let l:end = l:end + 1
  endwhile


  return l:sline[l:start: l:end - 2]
endfunction

The GetSynWord('markdownLink')[1:] will give you the markdown url if your cursor is on a markdown link.