runtime(lua): add optional lua function folding
closes: #16151
Signed-off-by: Konfekt <Konfekt@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/ftplugin/lua.vim b/runtime/ftplugin/lua.vim
index 80cbba7..22b9986 100644
--- a/runtime/ftplugin/lua.vim
+++ b/runtime/ftplugin/lua.vim
@@ -5,7 +5,7 @@
" Contributor: Dorai Sitaram <ds26@gte.com>
" C.D. MacEachern <craig.daniel.maceachern@gmail.com>
" Tyler Miller <tmillr@proton.me>
-" Last Change: 2024 Jan 14
+" Last Change: 2024 Dec 03
if exists("b:did_ftplugin")
finish
@@ -48,6 +48,64 @@
let b:undo_ftplugin ..= " | unlet! b:browsefilter"
endif
+if has("folding") && get(g:, "lua_folding", 0)
+ setlocal foldmethod=expr
+ setlocal foldexpr=LuaFold(v:lnum)
+ let b:lua_lasttick = -1
+ let b:undo_ftplugin ..= "|setl foldexpr< foldmethod< | unlet! b:lua_lasttick b:lua_foldlists"
+endif
+
+
+" The rest of the file needs to be :sourced only once per Vim session
+if exists('s:loaded_lua') || &cp
+ let &cpo = s:cpo_save
+ unlet s:cpo_save
+ finish
+endif
+let s:loaded_lua = 1
+
+let s:patterns = [
+ \ ['do', 'end'],
+ \ ['if\s+.+\s+then', 'end'],
+ \ ['repeat', 'until\s+.+'],
+ \ ['for\s+.+\s+do', 'end'],
+ \ ['while\s+.+\s+do', 'end'],
+ \ ['function.+', 'end'],
+ \ ['return\s+function.+', 'end'],
+ \ ['local\s+function\s+.+', 'end'],
+ \ ]
+
+function! LuaFold(lnum) abort
+ if b:lua_lasttick == b:changedtick
+ return b:lua_foldlists[a:lnum-1]
+ endif
+ let b:lua_lasttick = b:changedtick
+
+ let b:lua_foldlists = []
+ let foldlist = []
+ let buf = getline(1, '$')
+ for line in buf
+ for t in s:patterns
+ let tagopen = '\v^\s*'..t[0]..'\s*$'
+ let tagclose = '\v^\s*'..t[1]..'\s*$'
+ if line =~# tagopen
+ call add(foldlist, t)
+ break
+ elseif line =~# tagclose
+ if len(foldlist) > 0 && line =~# foldlist[-1][1]
+ call remove(foldlist, -1)
+ else
+ let foldlist = []
+ endif
+ break
+ endif
+ endfor
+ call add(b:lua_foldlists, len(foldlist))
+ endfor
+
+ return lua_foldlists[a:lnum-1]
+endfunction
+
let &cpo = s:cpo_save
unlet s:cpo_save