Add User event "SignifyHunk"

By hooking into that event, you can show "Hunk [3/15]" (third hunk from a total
of 15) in the command-line, when jumping between hunks with [c, ]c and
friends.

See `:h signify-mappings`.

Closes #363

Author: mhinz

autoload/sy/jump.vim

@@ -13,6 +13,10 @@ function! sy#jump#next_hunk(count)
   if !empty(hunk)
     execute 'sign jump '. hunk.ids[0] .' buffer='. b:sy.buffer
   endif
+
+  if exists('#User#SignifyHunk')
+    doautocmd <nomodeline> User SignifyHunk
+  endif
 endfunction
 
 " #prev_hunk {{{1
@@ -26,4 +30,8 @@ function! sy#jump#prev_hunk(count)
   if !empty(hunk)
     execute 'sign jump '. hunk.ids[0] .' buffer='. b:sy.buffer
   endif
+
+  if exists('#User#SignifyHunk')
+    doautocmd <nomodeline> User SignifyHunk
+  endif
 endfunction

autoload/sy/util.vim

@@ -115,6 +115,22 @@ endfunction
 
 let s:popup_window = 0
 
+" #get_hunk_stats {{{1
+function! sy#util#get_hunk_stats() abort
+  execute sy#util#return_if_no_changes()
+
+  let curline = line('.')
+  let total_hunks = len(b:sy.hunks)
+
+  for i in range(total_hunks)
+    if b:sy.hunks[i].start <= curline && b:sy.hunks[i].end >= curline
+      return { 'total_hunks': total_hunks, 'current_hunk': i + 1 }
+    endif
+  endfor
+
+  return {}
+endfunction
+
 " #popup_close {{{1
 function! sy#util#popup_close() abort
   if s:popup_window

doc/signify.txt

@@ -520,6 +520,17 @@ Mapping other keys:
     nmap <leader>gJ 9999<leader>gj
     nmap <leader>gK 9999<leader>gk
 <
+When you jump to a hunk, show "[Hunk 2/15]" by putting this in your vimrc:
+>
+    autocmd User SignifyHunk call s:show_current_hunk()
+
+    function! s:show_current_hunk() abort
+      let h = sy#util#get_hunk_stats()
+      if !empty(h)
+        echo printf('[Hunk %d/%d]', h.current_hunk, h.total_hunks)
+      endif
+    endfunction
+<
 ------------------------------------------------------------------------------
 Hunk text object:~
 >