Add org_clean_folds option

TODO

@@ -1,7 +1,6 @@
 MAYBE:
   - Better link syntax highlighting (more similar to links in vim-markdown)
   - Syntax highlight bullets and checkboxes
-  - Option to enable/disable folding (similar to g:markdown_folding)
   - Different syntax group for heading delimiters
   - Change log in Vim doc
 

autoload/org.vim

@@ -4,9 +4,23 @@
 " License:      Vim (see `:help license`)
 " Location:     autoload/org.vim
 " Website:      https://github.com/axvr/org.vim
-" Last Change:  2019-09-22
+" Last Change:  2020-01-04
 
 " Fallback chain for options. Buffer local --> Global --> default.
-function org#option(name, default)
+function org#option(name, default) abort
     return get(b:, a:name, get(g:, a:name, a:default))
 endfunction
+
+" Emacs-like fold text.
+function org#fold_text() abort
+    return getline(v:foldstart) . '...'
+endfunction
+
+" Check fold depth of a line.
+function org#fold_expr()
+    let l:depth = match(getline(v:lnum), '\(^\*\+\)\@<=\( .*$\)\@=')
+    if l:depth > 0 && synIDattr(synID(v:lnum, 1, 1), 'name') =~# '\m^o\(rg\|utline\)Heading'
+        return ">" . l:depth
+    endif
+    return "="
+endfunction

doc/org.txt

@@ -106,6 +106,23 @@ following command.
 ==============================================================================
  4. CONFIGURATION                                           *org-configuration*
 
+                                                                  *org-folding*
+
+To control how Org.vim handles folding, just use the standard Vim |folding|
+options and commands.
+
+For example if you want to enable or disable folding, use 'foldenable'.
+>
+    autocmd FileType org,outline setlocal nofoldenable
+<
+Or if you want folding enabled and all folds opened by default, use
+'foldlevelstart'.
+>
+    autocmd FileType org,outline setlocal foldenable foldlevelstart=99
+<
+For more information on folding in Vim, refer to |fold.txt|.
+
+------------------------------------------------------------------------------
                                *'b:org_state_keywords'*  *'g:org_state_keywords'*
 Value: list of strings~
 Default: ['TODO', 'NEXT', 'DONE']~
@@ -149,6 +166,26 @@ an |autocmd| like so.
 >
     autocmd FileType org setlocal conceallevel=2 concealcursor=nc
 <
+------------------------------------------------------------------------------
+                                     *'b:org_clean_folds'*  *'g:org_clean_folds'*
+Value: numeric~
+Default: 0~
+
+Vim's default styling for folds is quite ugly.  Enabling this option will
+remove much of the visual noise and suffix the folded heading text with an
+ellipsis (`...`) making folds look the same as they do in Emacs' Org mode (and
+Outline mode).
+>
+    * Heading 1...
+<
+This option can be enabled for all buffers like so:
+>
+    let g:org_clean_folds = 1
+<
+Alternatively it can be enabled for specific buffers:
+>
+    let b:org_clean_folds = 1
+<
 ------------------------------------------------------------------------------
                                      *'b:org_use_italics'*  *'g:org_use_italics'*
 Value: numeric~
@@ -180,7 +217,7 @@ works are:
 
 Org.vim is distributed under the same terms as Vim itself.
 
-Copyright (c) 2018-2019, Alex Vear.
+Copyright (c) 2018-2020, Alex Vear.
 
 A copy of the full licence text should have been provided with this extension
 in the `LICENCE` file.  The license can also be viewed on the web [3] or by

ftplugin/org.vim

@@ -4,7 +4,7 @@
 " License:      Vim (see `:help license`)
 " Location:     ftplugin/org.vim
 " Website:      https://github.com/axvr/org.vim
-" Last Change:  2019-09-22
+" Last Change:  2020-01-04
 "
 " Reference Specification: Org mode manual
 "   GNU Info: `$ info Org`
@@ -12,17 +12,15 @@
 
 setlocal commentstring=#%s
 
-function! OrgFold()
+setlocal foldexpr=org#fold_expr()
-    let l:depth = match(getline(v:lnum), '\(^\*\+\)\@<=\( .*$\)\@=')
-    if l:depth > 0 && synIDattr(synID(v:lnum, 1, 1), 'name') =~# 'orgHeading'
-        return ">" . l:depth
-    endif
-    return "="
-endfunction
-
-setlocal foldexpr=OrgFold()
 setlocal foldmethod=expr
 
+if org#option('org_clean_folds', 0)
+    setlocal foldtext=org#fold_text()
+    setlocal fillchars-=fold:-
+    setlocal fillchars-=fold:\
+endif
+
 " Conceal Org mode link syntax
 if org#option('org_conceal_links', 1)
     setlocal conceallevel=2

ftplugin/outline.vim

@@ -4,19 +4,17 @@
 " License:      Vim (see `:help license`)
 " Location:     ftplugin/outline.vim
 " Website:      https://github.com/axvr/org.vim
-" Last Change:  2019-09-22
+" Last Change:  2020-01-04
 "
 " Reference Specification: GNU Emacs Manual, section 'Outline Mode'
 "   GNU Info: `$ info Emacs Outline Mode`
 "   Web: <https://www.gnu.org/software/emacs/manual/html_node/emacs/Outline-Mode.html>
 
-function! OutlineFold()
+setlocal foldexpr=org#fold_expr()
-    let l:depth = match(getline(v:lnum), '\(^\*\+\)\@<=\( .*$\)\@=')
-    if l:depth > 0 && synIDattr(synID(v:lnum, 1, 1), 'name') =~# 'outlineHeading'
-        return ">" . l:depth
-    endif
-    return "="
-endfunction
-
-setlocal foldexpr=OutlineFold()
 setlocal foldmethod=expr
+
+if org#option('org_clean_folds', 0)
+    setlocal foldtext=org#fold_text()
+    setlocal fillchars-=fold:-
+    setlocal fillchars-=fold:\
+endif