feat: split up hide_cursor option (#491)

This revision introduces changes to the 'g:fern#hide_cursor' option.

Before these changes, this option forcibly disables 'cursorline' when
focus is not on the fern window and unsets 't_ve' to hide the cursor for
the fern window.

In some configurations, it's desirable to hide the cursor but not change
the cursorline configuration. For instance, the user may want to see
what item is selected in the fern window when working in other buffers.

Although it's relatively trivial to skip 'hide_cursor' altogether and
manually update 't_ve', I believe there's value in supporting this in
Fern.

This revision introduces a new option, 'g:fern#hide_cursorline', which
enables/disables the 'cursorline' option on WinEnter/WinLeave, similar
to what 'hide_cursor' did before.

Documentation has been updated to reflect this change.

autoload/fern.vim

@@ -18,6 +18,7 @@ call s:Config.config(expand('<sfile>:p'), {
       \ 'loglevel': g:fern#INFO,
       \ 'opener': 'edit',
       \ 'hide_cursor': 0,
+      \ 'hide_cursorline': 0,
       \ 'keepalt_on_edit': 0,
       \ 'keepjumps_on_edit': 0,
       \ 'disable_auto_buffer_delete': 0,

autoload/fern/internal/viewer.vim

@@ -61,6 +61,7 @@ function! s:init() abort
   augroup END
   call fern#internal#viewer#auto_duplication#init()
   call fern#internal#viewer#hide_cursor#init()
+  call fern#internal#viewer#hide_cursorline#init()
 
   " Add unique fragment to make each buffer uniq
   let bufname = bufname('%')

autoload/fern/internal/viewer/hide_cursor.vim

@@ -1,24 +1,14 @@
 function! fern#internal#viewer#hide_cursor#init() abort
-  if !g:fern#hide_cursor
-    return
+  if g:fern#hide_cursor
+    call s:hide_cursor_init()
   endif
-  call s:hide_cursor_init()
 endfunction
 
 function! s:hide_cursor_init() abort
   augroup fern_internal_viewer_smart_cursor_init
     autocmd! * <buffer>
-    autocmd BufEnter,WinEnter,TabLeave,CmdwinLeave,CmdlineLeave <buffer> setlocal cursorline
-    autocmd BufLeave,WinLeave,TabLeave,CmdwinEnter,CmdlineEnter <buffer> setlocal nocursorline
     autocmd BufEnter,WinEnter,TabLeave,CmdwinLeave,CmdlineLeave <buffer> call fern#internal#cursor#hide()
     autocmd BufLeave,WinLeave,TabLeave,CmdwinEnter,CmdlineEnter <buffer> call fern#internal#cursor#restore()
     autocmd VimLeave <buffer> call fern#internal#cursor#restore()
   augroup END
-
-  " Do NOT allow cursorlineopt=number while the cursor is hidden (Fix #182)
-  if exists('+cursorlineopt')
-    " NOTE:
-    " Default value is `number,line` (or `both` prior to patch-8.1.2029)
-    setlocal cursorlineopt&
-  endif
 endfunction

autoload/fern/internal/viewer/hide_cursorline.vim

@@ -0,0 +1,20 @@
+function! fern#internal#viewer#hide_cursorline#init() abort
+  if g:fern#hide_cursorline
+    call s:hide_cursorline_init()
+  endif
+endfunction
+
+function! s:hide_cursorline_init() abort
+  augroup fern_internal_viewer_smart_cursor_line_init
+    autocmd! * <buffer>
+    autocmd BufEnter,WinEnter,TabLeave,CmdwinLeave,CmdlineLeave <buffer> setlocal cursorline
+    autocmd BufLeave,WinLeave,TabLeave,CmdwinEnter,CmdlineEnter <buffer> setlocal nocursorline
+  augroup END
+
+  " Do NOT allow cursorlineopt=number while the cursor is hidden (Fix #182)
+  if exists('+cursorlineopt')
+    " NOTE:
+    " Default value is `number,line` (or `both` prior to patch-8.1.2029)
+    setlocal cursorlineopt&
+  endif
+endfunction

doc/fern.txt

@@ -327,13 +327,15 @@ VARIABLE						*fern-variable*
 	Default: 'edit'
 
 *g:fern#hide_cursor*
-	Set 1 to hide cursor and forcedly enable |cursorline| to visualize the
-	cursor node. The |cursorline| is automatically enabled when the focus
-	is on the buffer and automatically disabled when the cursor is out of
-	the buffer.
+	Set 1 to forcibly hide the cursor for the fern window (see |t_ve|).
+
 	Note that Neovim prior to 0.5.0 cannot hide the cursor thus faint
 	vertical bar is used instead.
 
+*g:fern#hide_cursorline*
+	Set 1 to forcibly disable |cursorline| for the fern window
+	when focus is not on the fern window.
+
 *g:fern#keepalt_on_edit*
 	Set 1 to apply |keepalt| on the "open:edit" action to keep an
 	|alternate-file| in a split windows style like: