man.vim: rewrite

- Smart autocomplete. It's automatically sorted, filtered for duplicates
  and even formats the candidates based on what is needed. For example,
  `:Man 1 printf<TAB>` will show the pages that are in section 1m as
  'page(sect)' to let you know they are in a more specific section.
- Instead of trying to unset $MANPAGER we use the -P flag to set the
  pager to cat
- Always use the section arg '-s', it makes the code much simpler
  (see comment in s:man-args).
- A manpage name starting with '-' is invalid. It's fine for sections
  because of the use of '-s'.

- The tagstack is an actual stack now, makes it much simpler.
- By using v:count and v:count1, the plugin can explicitly check whether
  the user set a count, instead of relying on a default value (0) that
  is actually a real manpage section.
- Extraction of a manpage reference is much more simple. No giant long
  complicated regexes. Now, the plugin lets `man` handle the actual
  validation. We merely extract the section and page. Syntax regexes are
  a bit more specific though to prevent highlighting everything.
- Multilingual support in the syntax file. Removed the cruft that was only
  relevent to vim. Also simplified and improved many of the regexes.

- Using shellescape when sending the page and sect as arguments
- In general, the code flow is much more obvious.
- man#get_page has been split up into smaller functions with explicit
  responsibilties
- ':help' behavior in opening splits and manpages
- Comments explaining anything that needs explaining and isn't
  immediately obvious.
- If a manpage has already been loaded but if it were to reloaded at the
  current width which is the same as the width at which it was loaded at
  previously, it is not reloaded.

- Use substitute to remove the backspaced instead of `col -b`, as the
  latter doesn't work with other languages.
- Open paths to manpages
- It uses cWORD instead of cword to get the manpage under the cursor, this
  helps with files that do not have (,) in iskeyword. It also means the
  plugin does not set iskeyword locally anymore.
- <Plug>(Man) mapping for easy remapping
- Switched to single quotes wherever possible.
- Updated docs in $VIMRUNTIME/doc/filetype.txt (still need to update
  user-manual)

- Always call tolower on section name. See comment in
  s:extract_page_and_sect_fpage
- Formatting/consistency cleanup
- Automatically map q to ':q<CR>' when invoked as $MANPAGER
- It also fully supports being used as $MANPAGER. Setting the name and
  stuff automatically.
- Split up the setlocals into multiple lines for easier readability
- Better detection of errors by redirecting stderr to /dev/null. If an
  error occured, stdout will be empty.

- Functions return [sect, page] not [page, sect]. Makes more sense with
  how man takes the arguments as sect and then page.
- Pretty prints errors on a single line.
- If no section is given, automatically finds the correct section for
  the buffer name. It also gets the correct page. See the comment in
  s:get_page
- If $MANWIDTH is not set, do not assign directly to $MANWIDTH because
  then $MANWIDTH will always stay set to the same value as we only use
  winwidth(0) when the global $MANWIDTH is empty. Instead we set it
  locally for the command.
- Maintainer notes on all files.

1 files changed, 251 insertions, 97 deletions

diff --git a/runtime/autoload/man.vim b/runtime/autoload/man.vim
index 0dfcc424e2..6f50cce9dc 100644
--- a/runtime/autoload/man.vim
+++ b/runtime/autoload/man.vim
@@ -1,137 +1,291 @@
-let s:man_tag_depth = 0
-let s:man_sect_arg = ''
-let s:man_find_arg = '-w'
+" Maintainer: Anmol Sethi <anmol@aubble.com>
 
+" Ensure Vim is not recursively invoked (man-db does this)
+" by forcing man to use cat as the pager.
+" More info here http://comments.gmane.org/gmane.editors.vim.devel/29085
+if &shell =~# 'fish$'
+  let s:man_cmd = 'man -P cat ^/dev/null'
+else
+  let s:man_cmd = 'man -P cat 2>/dev/null'
+endif
+
+let s:man_find_arg = "-w"
+
+" TODO(nhooyr) I do not think completion will work on SunOS because I'm not sure if `man -l`
+" displays the list of directories that are searched by man for manpages.
+" I also do not think Solaris supports the '-P' flag used above and uses only $PAGER.
 try
-  if !has('win32') && $OSTYPE !~? 'cygwin\|linux' && system('uname -s') =~? 'SunOS' && system('uname -r') =~? '^5'
-    let s:man_sect_arg = '-s'
+  if !has('win32') && $OSTYPE !~? 'cygwin\|linux' && system('uname -s') =~? 'SunOS' && system('uname -r') =~# '^5'
     let s:man_find_arg = '-l'
   endif
 catch /E145:/
   " Ignore the error in restricted mode
 endtry
 
-" Load man page {page} from {section}
-"   call man#get_page([{section}, ]{page})
-function man#get_page(...) abort
-  let invoked_from_man = (&filetype ==# 'man')
-
-  if a:0 == 0
-    echoerr 'argument required'
+function! man#open_page_command(...) abort
+  if a:0 > 2
+    call s:error('too many arguments')
     return
-  elseif a:0 > 2
-    echoerr 'too many arguments'
+  elseif a:0 ==# 0
+    call s:error('what manual page do you want?')
     return
+  elseif a:0 ==# 1
+    let ref = a:000[0]
+  else
+    " We combine the name and sect into a manpage reference so that all
+    " verification/extraction can be kept in a single function.
+    " If a:000[1] is a reference as well, that is fine because it is the only
+    " reference that will match.
+    let ref = a:000[1].'('.a:000[0].')'
   endif
+  try
+    let [sect, name] = s:extract_sect_and_name_ref(ref)
+    let [sect, name] = s:verify_exists(sect, name)
+  catch
+    call s:error(v:exception)
+    return
+  endtry
+  call s:open_page(sect, name)
+endfunction
 
-  let sect = get(a:000, 0)
-  let page = get(a:000, 1, sect)
-
-  let [page, sect] = s:parse_page_and_section(sect, page)
-
-  if !empty(sect) && s:find_page(sect, page) == 0
-    let sect = ''
-  endif
-
-  if s:find_page(sect, page) == 0
-    echo 'No manual entry for '.page
+" We need count and count1 to ensure the section was explicitly set
+" by the user. count defaults to 0 which is a valid section and
+" count1 defaults to 1 which is also a valid section. Only when they
+" are equal was the count explicitly set.
+function! man#open_page_mapping(count, count1, ref) abort
+  if empty(a:ref)
+    call s:error('what manual page do you want?')
     return
   endif
+  try
+    let [sect, name] = s:extract_sect_and_name_ref(a:ref)
+    if a:count ==# a:count1
+      " user explicitly set a count
+      let sect = string(a:count)
+    endif
+    let [sect, name] = s:verify_exists(sect, name)
+  catch
+    call s:error(v:exception)
+    return
+  endtry
+  call s:open_page(sect, name)
+endfunction
 
-  exec 'let s:man_tag_buf_'.s:man_tag_depth.' = '.bufnr('%')
-  exec 'let s:man_tag_lin_'.s:man_tag_depth.' = '.line('.')
-  exec 'let s:man_tag_col_'.s:man_tag_depth.' = '.col('.')
-  let s:man_tag_depth = s:man_tag_depth + 1
-
-  let editcmd = 'edit'
-  " Use an existing 'man' window, else open a new one.
-  if &filetype !=# 'man'
-    let thiswin = winnr()
-    wincmd b
-    if winnr() > 1
-      exec thiswin . 'wincmd w'
-      while 1
-        if &filetype ==# 'man'
-          break
-        endif
-        wincmd w
-        if thiswin == winnr()
-          break
-        endif
-      endwhile
+" attempt to extract the name and sect out of 'name(sect)'
+" otherwise just return the largest string of valid characters in ref
+function! s:extract_sect_and_name_ref(ref) abort
+  if a:ref[0] ==# '-' " try ':Man -pandoc' with this disabled.
+    throw 'manpage name starts with ''-'''
+  endif
+  let ref = matchstr(a:ref, '[^()]\+([^()]\+)')
+  if empty(ref)
+    let name = matchstr(a:ref, '[^()]\+')
+    if empty(name)
+      throw 'manpage reference contains only parantheses'
     endif
+    return ['', name]
+  endif
+  let left = split(ref, '(')
+  " see ':Man 3X curses' on why tolower.
+  " TODO(nhooyr) Not sure if this is portable across OSs
+  " but I have not seen a single uppercase section.
+  return [tolower(split(left[1], ')')[0]), left[0]]
+endfunction
 
-    if &filetype !=# 'man'
-      let editcmd = 'tabnew'
+function! s:verify_exists(sect, name) abort
+  let path = system(s:man_cmd.' '.s:man_find_arg.' '.s:man_args(a:sect, a:name))
+  if path !~# '^\/'
+    if empty(a:sect)
+      throw 'no manual entry for '.a:name
     endif
+    let path = system(s:man_cmd.' '.s:man_find_arg.' '.shellescape(a:name))
+    if path !~# '^\/'
+      throw 'no manual entry for '.a:name.'('.a:sect.') or '.a:name
+    endif
+  endif
+  call s:push_tag()
+  if a:name =~# '\/'
+    " We do not need to extract the section/name from the path if the name is
+    " just a path.
+    return ['', a:name]
+  endif
+  " We need to extract the section from the path because sometimes
+  " the actual section of the manpage is more specific than the section
+  " we provided to `man`. Try ':Man 3 App::CLI'.
+  " Also on linux, it seems that the name is case insensitive. So if one does
+  " ':Man PRIntf', we still want the name of the buffer to be 'printf' or
+  " whatever the correct capitilization is.
+  return s:extract_sect_and_name_path(path[:len(path)-2])
+endfunction
+
+let s:tag_stack = []
+
+function! s:push_tag() abort
+  let s:tag_stack += [{
+        \ 'buf':  bufnr('%'),
+        \ 'lnum': line('.'),
+        \ 'col':  col('.'),
+        \ }]
+endfunction
+
+function! man#pop_tag() abort
+  if !empty(s:tag_stack)
+    let tag = remove(s:tag_stack, -1)
+    execute tag['buf'].'b'
+    call cursor(tag['lnum'], tag['col'])
   endif
+endfunction
 
-  silent exec editcmd.' man://'.page.(empty(sect)?'':'('.sect.')')
+" extracts the name and sect out of 'path/name.sect'
+function! s:extract_sect_and_name_path(path) abort
+  let tail = fnamemodify(a:path, ':t')
+  if a:path =~# '\.\%([glx]z\|bz2\|lzma\|Z\)$' " valid extensions
+    let tail = fnamemodify(tail, ':r')
+  endif
+  let sect = matchstr(tail, '\.\zs[^.]\+$')
+  let name = matchstr(tail, '^.\+\ze\.[^.]\+$')
+  return [sect, name]
+endfunction
 
-  setlocal modifiable
-  silent keepjumps norm! 1G"_dG
+function! s:open_page(sect, name)
+  let bufname = 'man://'.a:name.(empty(a:sect)?'':'('.a:sect.')')
+  let found_man = s:find_man()
+  " The reason for respecting $MANWIDTH even if it is wider/smaller than the
+  " current window is that the current window might only be temporarily
+  " narrow/wide. Since we don't reflow, we should just assume the
+  " user knows what they're doing and respect $MANWIDTH.
   if empty($MANWIDTH)
-    let $MANWIDTH = winwidth(0)
+    " If $MANWIDTH is not set, we do not assign directly to $MANWIDTH because
+    " then $MANWIDTH will always stay the same value as we only use
+    " winwidth(0) when $MANWIDTH is empty. Instead we set it locally for the command.
+    let manwidth = winwidth(0)
+  else
+    let manwidth = $MANWIDTH
+  endif
+  if getbufvar(bufname, 'manwidth') ==# manwidth
+    if found_man
+      silent execute 'buf '.bufnr(bufname)
+    else
+      execute 'split '.bufname
+    endif
+    keepjumps 1
+    return
+  endif
+  let already_opened = bufexists(bufname)
+  if found_man
+    execute 'edit '.bufname
+  else
+    execute 'split '.bufname
   endif
-  silent exec 'r!/usr/bin/man '.s:cmd(sect, page).' | col -b'
-  " Remove blank lines from top and bottom.
+  if already_opened
+    setlocal modifiable
+    setlocal noreadonly
+    keepjumps %delete _
+  endif
+  silent execute 'read!env MANWIDTH='.manwidth.' '.s:man_cmd.' '.s:man_args(a:sect, a:name)
+  let b:manwidth = manwidth
+  " remove all the backspaced text
+  silent keeppatterns keepjumps %substitute,.\b,,ge
   while getline(1) =~# '^\s*$'
     silent keepjumps 1delete _
   endwhile
-  while getline('$') =~# '^\s*$'
-    silent keepjumps $delete _
-  endwhile
-  setlocal nomodified
   setlocal filetype=man
-
-  if invoked_from_man || editcmd ==# 'tabnew'
-    call s:set_window_local_options()
-  endif
 endfunction
 
-function s:set_window_local_options() abort
-  setlocal colorcolumn=0 foldcolumn=0 nonumber
-  setlocal nolist norelativenumber nofoldenable
+function! s:find_man() abort
+  if &filetype ==# 'man'
+    return 1
+  endif
+  let thiswin = winnr()
+  while 1
+    wincmd w
+    if &filetype ==# 'man'
+      return 1
+    elseif thiswin ==# winnr()
+      return 0
+    endif
+  endwhile
 endfunction
 
-function man#pop_page() abort
-  if s:man_tag_depth > 0
-    let s:man_tag_depth = s:man_tag_depth - 1
-    exec "let s:man_tag_buf=s:man_tag_buf_".s:man_tag_depth
-    exec "let s:man_tag_lin=s:man_tag_lin_".s:man_tag_depth
-    exec "let s:man_tag_col=s:man_tag_col_".s:man_tag_depth
-    exec s:man_tag_buf."b"
-    exec s:man_tag_lin
-    exec "norm! ".s:man_tag_col."|"
-    exec "unlet s:man_tag_buf_".s:man_tag_depth
-    exec "unlet s:man_tag_lin_".s:man_tag_depth
-    exec "unlet s:man_tag_col_".s:man_tag_depth
-    unlet s:man_tag_buf s:man_tag_lin s:man_tag_col
+function! s:man_args(sect, name) abort
+  if empty(a:sect)
+    return shellescape(a:name)
   endif
+  " The '-s' flag is very useful.
+  " We do not need to worry about stuff like 'printf(echo)'
+  " (two manpages would be interpreted by man without -s)
+  " We do not need to check if the sect starts with '-'
+  " Lastly, the 3pcap section on macOS doesn't work without -s
+  return '-s '.shellescape(a:sect).' '.shellescape(a:name)
 endfunction
 
-" Expects a string like 'access' or 'access(2)'.
-function s:parse_page_and_section(sect, str) abort
-  try
-    let [page, sect] = matchlist(a:str, '\v\C([-.[:alnum:]_]+)%(\(([-.[:alnum:]_]+)\))?')[1:2]
-    if empty(sect)
-      let sect = a:sect
-    endif
-  catch
-    echoerr 'man.vim: failed to parse: "'.a:str.'"'
-  endtry
-
-  return [page, sect]
+function! s:error(msg) abort
+  redraw
+  echon 'man.vim: '
+  echohl ErrorMsg
+  echon a:msg
+  echohl None
 endfunction
 
-function s:cmd(sect, page) abort
-  if !empty(a:sect)
-    return s:man_sect_arg.' '.a:sect.' '.a:page
+let s:mandirs = join(split(system(s:man_cmd.' '.s:man_find_arg), ':\|\n'), ',')
+
+" see s:extract_sect_and_name_ref on why tolower(sect)
+function! man#complete(arg_lead, cmd_line, cursor_pos) abort
+  let args = split(a:cmd_line)
+  let l = len(args)
+  if l > 3
+    return
+  elseif l ==# 1
+    let name = ''
+    let sect = ''
+  elseif a:arg_lead =~# '^[^()]\+([^()]*$'
+    " cursor (|) is at ':Man printf(|' or ':Man 1 printf(|'
+    " The later is is allowed because of ':Man pri<TAB>'.
+    " It will offer 'priclass.d(1m)' even though section is specified as 1.
+    let tmp = split(a:arg_lead, '(')
+    let name = tmp[0]
+    let sect = tolower(get(tmp, 1, ''))
+  elseif args[1] !~# '^[^()]\+$'
+    " cursor (|) is at ':Man 3() |' or ':Man (3|' or ':Man 3() pri|'
+    " or ':Man 3() pri |'
+    return
+  elseif l ==# 2
+    if empty(a:arg_lead)
+      " cursor (|) is at ':Man 1 |'
+      let name = ''
+      let sect = tolower(args[1])
+    else
+      " cursor (|) is at ':Man pri|'
+      if a:arg_lead =~# '\/'
+        " if the name is a path, complete files
+        " TODO(nhooyr) why does this complete the last one automatically
+        return glob(a:arg_lead.'*', 0, 1)
+      endif
+      let name = a:arg_lead
+      let sect = ''
+    endif
+  elseif a:arg_lead !~# '^[^()]\+$'
+    " cursor (|) is at ':Man 3 printf |' or ':Man 3 (pr)i|'
+    return
+  else
+    " cursor (|) is at ':Man 3 pri|'
+    let name = a:arg_lead
+    let sect = tolower(args[1])
   endif
-  return a:page
+  " We remove duplicates incase the same manpage in different languages was found.
+  return uniq(sort(map(globpath(s:mandirs,'man?/'.name.'*.'.sect.'*', 0, 1), 's:format_candidate(v:val, sect)'), 'i'))
 endfunction
 
-function s:find_page(sect, page) abort
-  let where = system('/usr/bin/man '.s:man_find_arg.' '.s:cmd(a:sect, a:page))
-  return (where =~# '^ */')
+function! s:format_candidate(c, sect) abort
+  if a:c =~# '\.\%(pdf\|in\)$' " invalid extensions
+    return
+  endif
+  let [sect, name] = s:extract_sect_and_name_path(a:c)
+  if sect ==# a:sect
+    return name
+  elseif sect =~# a:sect.'[^.]\+$'
+    " We include the section if the user provided section is a prefix
+    " of the actual section.
+    return name.'('.sect.')'
+  endif
 endfunction