Fix #590: Add support for fold markers

autoload/vimtex/fold.vim

@@ -29,6 +29,7 @@ function! vimtex#fold#init_options() " {{{1
   call vimtex#util#set_default('g:vimtex_fold_documentclass', 0)
   call vimtex#util#set_default('g:vimtex_fold_usepackage', 1)
   call vimtex#util#set_default('g:vimtex_fold_newcommands', 1)
+  call vimtex#util#set_default('g:vimtex_fold_markers', 1)
 
   " Disable manual mode in vimdiff
   let g:vimtex_fold_manual = &diff ? 0 : g:vimtex_fold_manual
@@ -44,8 +45,11 @@ function! vimtex#fold#init_script() " {{{1
   "
   " List of identifiers for improving efficiency
   "
-  let s:folded  = '\v^\s*\%|^\s*\]\{'
+  let s:folded  = '\v'
+  let s:folded .= ' ^\s*\%'
+  let s:folded .= '|^\s*\]\{'
   let s:folded .= '|^\s*}\s*$'
+  let s:folded .= '|\%\s*%(\{\{\{|}}})'
   let s:folded .= '|\\%(' . join([
         \   'begin',
         \   'end',
@@ -208,6 +212,13 @@ function! vimtex#fold#level(lnum) " {{{1
     endif
   endif
 
+  " Fold markers
+  if line =~# '%\s*{{{'
+    return 'a1'
+  elseif line =~# '%\s*}}}'
+    return 's1'
+  endif
+
   " Never fold \end{document}
   if line =~# '^\s*\\end{document}'
     return 0

doc/vimtex.txt

@@ -510,6 +510,12 @@ Options~
 
   Default value: 0
 
+*g:vimtex_fold_markers*
+  Use this option to disable/enable vim-style markers for folding, i.e. pairs
+  of `{{{` and `}}}`.
+
+  Default value: 1
+
 *g:vimtex_imaps_enabled*
   Use this option to disable/enable the insert mode mappings.