Merge #9728 from justinmk/autocmd-once

8 files changed, 79 insertions, 51 deletions

diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index b0b36271e9..4372342c02 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -40,7 +40,7 @@ effects.  Be careful not to destroy your text.
 2. Defining autocommands				*autocmd-define*
 
 							*:au* *:autocmd*
-:au[tocmd] [group] {event} {pat} [-once] [-nested] {cmd}
+:au[tocmd] [group] {event} {pat} [++once] [++nested] {cmd}
 			Add {cmd} to the list of commands that Vim will
 			execute automatically on {event} for a file matching
 			{pat} |autocmd-patterns|.
@@ -48,9 +48,9 @@ effects.  Be careful not to destroy your text.
 			:autocmd and won't start a comment.
 			Nvim always adds {cmd} after existing autocommands so
 			they execute in the order in which they were defined.
-			See |autocmd-nested| for [-nested].
+			See |autocmd-nested| for [++nested].
 							*autocmd-once*
-			If [-once] is supplied the command is executed once,
+			If [++once] is supplied the command is executed once,
 			then removed ("one shot").
 
 The special pattern <buffer> or <buffer=N> defines a buffer-local autocommand.
@@ -119,11 +119,11 @@ prompt.  When one command outputs two messages this can happen anyway.
 ==============================================================================
 3. Removing autocommands				*autocmd-remove*
 
-:au[tocmd]! [group] {event} {pat} [-once] [-nested] {cmd}
+:au[tocmd]! [group] {event} {pat} [++once] [++nested] {cmd}
 			Remove all autocommands associated with {event} and
 			{pat}, and add the command {cmd}.
-			See |autocmd-once| for [-once].
-			See |autocmd-nested| for [-nested].
+			See |autocmd-once| for [++once].
+			See |autocmd-nested| for [++nested].
 
 :au[tocmd]! [group] {event} {pat}
 			Remove all autocommands associated with {event} and
@@ -1446,9 +1446,9 @@ instead of ":q!".
 							*autocmd-nested* *E218*
 By default, autocommands do not nest.  If you use ":e" or ":w" in an
 autocommand, Vim does not execute the BufRead and BufWrite autocommands for
-those commands.  If you do want this, use the "-nested" flag for those
+those commands.  If you do want this, use the "++nested" flag for those
 commands in which you want nesting.  For example: >
-  :autocmd FileChangedShell *.c -nested e!
+  :autocmd FileChangedShell *.c ++nested e!
 The nesting is limited to 10 levels to get out of recursive loops.
 
 It's possible to use the ":au" command in an autocommand.  This can be a
diff --git a/runtime/doc/nvim_terminal_emulator.txt b/runtime/doc/nvim_terminal_emulator.txt
index 2eaaf82934..af94c60629 100644
--- a/runtime/doc/nvim_terminal_emulator.txt
+++ b/runtime/doc/nvim_terminal_emulator.txt
@@ -35,7 +35,7 @@ There are 3 ways to create a terminal buffer:
 <
     Note: The "term://" pattern is handled by a BufReadCmd handler, so the
     |autocmd-nested| modifier is required to use it in an autocmd. >
-        autocmd VimEnter * -nested split term://sh
+        autocmd VimEnter * ++nested split term://sh
 <    This is only mentioned for reference; use |:terminal| instead.
 
 When the terminal starts, the buffer contents are updated and the buffer is
diff --git a/runtime/doc/usr_40.txt b/runtime/doc/usr_40.txt
index abb4a1dbfa..9a1fe50f31 100644
--- a/runtime/doc/usr_40.txt
+++ b/runtime/doc/usr_40.txt
@@ -453,14 +453,14 @@ matching BufWritePre autocommands and executes them, and then it
 performs the ":write".
    The general form of the :autocmd command is as follows: >
 
-	:autocmd [group] {events} {file_pattern} [-nested] {command}
+	:autocmd [group] {events} {file_pattern} [++nested] {command}
 
 The [group] name is optional.  It is used in managing and calling the commands
 (more on this later).  The {events} parameter is a list of events (comma
 separated) that trigger the command.
    {file_pattern} is a filename, usually with wildcards.  For example, using
 "*.txt" makes the autocommand be used for all files whose name end in ".txt".
-The optional [-nested] flag allows for nesting of autocommands (see below),
+The optional [++nested] flag allows for nesting of autocommands (see below),
 and finally, {command} is the command to be executed.
 
 
@@ -576,9 +576,9 @@ NESTING
 Generally, commands executed as the result of an autocommand event will not
 trigger any new events.  If you read a file in response to a FileChangedShell
 event, it will not trigger the autocommands that would set the syntax, for
-example.  To make the events triggered, add the "-nested" flag: >
+example.  To make the events triggered, add the "++nested" flag: >
 
-	:autocmd FileChangedShell * -nested  edit
+	:autocmd FileChangedShell * ++nested  edit
 
 
 EXECUTING AUTOCOMMANDS
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 3b5a5cded2..55c3be9a57 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -133,7 +133,7 @@ Command-line highlighting:
   removed in the future).
 
 Commands:
-  |:autocmd| accepts the `once` flag
+  |:autocmd| accepts the `++once` flag
   |:checkhealth|
   |:cquit| can use [count] to set the exit code
   |:drop| is always available
diff --git a/runtime/doc/windows.txt b/runtime/doc/windows.txt
index 65ce72d62c..63ffd91bfc 100644
--- a/runtime/doc/windows.txt
+++ b/runtime/doc/windows.txt
@@ -880,15 +880,15 @@ CTRL-W g }						*CTRL-W_g}*
 		cursor.  This is less clever than using |:ptag|, but you don't
 		need a tags file and it will also find matches in system
 		include files.  Example: >
-  :au! CursorHold *.[ch] -nested exe "silent! psearch " . expand("<cword>")
+  :au! CursorHold *.[ch] ++nested exe "silent! psearch " . expand("<cword>")
 <		Warning: This can be slow.
 
 Example						*CursorHold-example*  >
 
-  :au! CursorHold *.[ch] -nested exe "silent! ptag " . expand("<cword>")
+  :au! CursorHold *.[ch] ++nested exe "silent! ptag " . expand("<cword>")
 
 This will cause a ":ptag" to be executed for the keyword under the cursor,
-when the cursor hasn't moved for the time set with 'updatetime'.  "-nested"
+when the cursor hasn't moved for the time set with 'updatetime'.  "++nested"
 makes other autocommands be executed, so that syntax highlighting works in the
 preview window.  The "silent!" avoids an error message when the tag could not
 be found.  Also see |CursorHold|.  To disable this again: >
@@ -898,7 +898,7 @@ be found.  Also see |CursorHold|.  To disable this again: >
 A nice addition is to highlight the found tag, avoid the ":ptag" when there
 is no word under the cursor, and a few other things: >
 
-  :au! CursorHold *.[ch] -nested call PreviewWord()
+  :au! CursorHold *.[ch] ++nested call PreviewWord()
   :func PreviewWord()
   :  if &previewwindow			" don't do this in the preview window
   :    return
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 51180c4939..7be4107c94 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -5591,39 +5591,48 @@ static void au_del_cmd(AutoCmd *ac)
   au_need_clean = true;
 }
 
-/*
- * Cleanup autocommands and patterns that have been deleted.
- * This is only done when not executing autocommands.
- */
+/// Cleanup autocommands and patterns that have been deleted.
+/// This is only done when not executing autocommands.
 static void au_cleanup(void)
 {
   AutoPat     *ap, **prev_ap;
   AutoCmd     *ac, **prev_ac;
   event_T event;
 
-  if (autocmd_busy || !au_need_clean)
+  if (autocmd_busy || !au_need_clean) {
     return;
+  }
 
-  /* loop over all events */
+  // Loop over all events.
   for (event = (event_T)0; (int)event < (int)NUM_EVENTS;
        event = (event_T)((int)event + 1)) {
-    /* loop over all autocommand patterns */
+    // Loop over all autocommand patterns.
     prev_ap = &(first_autopat[(int)event]);
     for (ap = *prev_ap; ap != NULL; ap = *prev_ap) {
-      /* loop over all commands for this pattern */
+      // Loop over all commands for this pattern.
       prev_ac = &(ap->cmds);
+      bool has_cmd = false;
+
       for (ac = *prev_ac; ac != NULL; ac = *prev_ac) {
-        /* remove the command if the pattern is to be deleted or when
-         * the command has been marked for deletion */
+        // Remove the command if the pattern is to be deleted or when
+        // the command has been marked for deletion.
         if (ap->pat == NULL || ac->cmd == NULL) {
           *prev_ac = ac->next;
           xfree(ac->cmd);
           xfree(ac);
-        } else
+        } else {
+          has_cmd = true;
           prev_ac = &(ac->next);
+        }
       }
 
-      /* remove the pattern if it has been marked for deletion */
+      if (ap->pat != NULL && !has_cmd) {
+        // Pattern was not marked for deletion, but all of its commands were.
+        // So mark the pattern for deletion.
+        au_remove_pat(ap);
+      }
+
+      // Remove the pattern if it has been marked for deletion.
       if (ap->pat == NULL) {
         if (ap->next == NULL) {
           if (prev_ap == &(first_autopat[(int)event])) {
@@ -5637,12 +5646,13 @@ static void au_cleanup(void)
         *prev_ap = ap->next;
         vim_regfree(ap->reg_prog);
         xfree(ap);
-      } else
+      } else {
         prev_ap = &(ap->next);
+      }
     }
   }
 
-  au_need_clean = FALSE;
+  au_need_clean = false;
 }
 
 /*
@@ -6050,18 +6060,18 @@ void do_autocmd(char_u *arg_in, int forceit)
     cmd = skipwhite(cmd);
     for (size_t i = 0; i < 2; i++) {
       if (*cmd != NUL) {
-        // Check for "-once" flag.
-        if (!once && STRNCMP(cmd, "-once", 5) == 0 && ascii_iswhite(cmd[5])) {
+        // Check for "++once" flag.
+        if (!once && STRNCMP(cmd, "++once", 6) == 0 && ascii_iswhite(cmd[6])) {
           once = true;
-          cmd = skipwhite(cmd + 5);
+          cmd = skipwhite(cmd + 6);
         }
-        // Check for "-nested" flag.
+        // Check for "++nested" flag.
         if (!nested
-            && ((STRNCMP(cmd, "-nested", 7) == 0 && ascii_iswhite(cmd[7]))
-                // Deprecated form (without "-").
+            && ((STRNCMP(cmd, "++nested", 8) == 0 && ascii_iswhite(cmd[8]))
+                // Deprecated form (without "++").
                 || (STRNCMP(cmd, "nested", 6) == 0 && ascii_iswhite(cmd[6])))) {
           nested = true;
-          cmd = skipwhite(cmd + ('-' == cmd[0] ? 7 : 6));
+          cmd = skipwhite(cmd + ('+' == cmd[0] ? 8 : 6));
         }
       }
     }
diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index 703feac305..0bdda17299 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -363,8 +363,8 @@ static void set_bg_deferred(void **argv)
     if (starting) {
       // Wait until after startup, so OptionSet is triggered.
       do_cmdline_cmd((bgvalue[0] == 'l')
-                     ? "autocmd VimEnter * once nested set background=light"
-                     : "autocmd VimEnter * once nested set background=dark");
+                     ? "autocmd VimEnter * ++once ++nested set bg=light"
+                     : "autocmd VimEnter * ++once ++nested set bg=dark");
     } else {
       set_option_value("bg", 0L, bgvalue, 0);
       reset_option_was_set("bg");
diff --git a/test/functional/autocmd/autocmd_spec.lua b/test/functional/autocmd/autocmd_spec.lua
index 4efabd37fb..814624d8e2 100644
--- a/test/functional/autocmd/autocmd_spec.lua
+++ b/test/functional/autocmd/autocmd_spec.lua
@@ -59,9 +59,9 @@ describe('autocmd', function()
     end)
   end)
 
-  it('-once', function()  -- :help autocmd-once
+  it('++once', function()  -- :help autocmd-once
     --
-    -- ":autocmd ... -once" executes its handler once, then removes the handler.
+    -- ":autocmd ... ++once" executes its handler once, then removes the handler.
     --
     local expected = {
       'Many1',
@@ -76,10 +76,10 @@ describe('autocmd', function()
     }
     command('let g:foo = []')
     command('autocmd TabNew * :call add(g:foo, "Many1")')
-    command('autocmd TabNew * -once :call add(g:foo, "Once1")')
-    command('autocmd TabNew * -once :call add(g:foo, "Once2")')
+    command('autocmd TabNew * ++once :call add(g:foo, "Once1")')
+    command('autocmd TabNew * ++once :call add(g:foo, "Once2")')
     command('autocmd TabNew * :call add(g:foo, "Many2")')
-    command('autocmd TabNew * -once :call add(g:foo, "Once3")')
+    command('autocmd TabNew * ++once :call add(g:foo, "Once3")')
     eq(dedent([[
 
        --- Autocommands ---
@@ -103,27 +103,45 @@ describe('autocmd', function()
        funcs.execute('autocmd Tabnew'))
 
     --
-    -- ":autocmd ... -once" handlers can be deleted.
+    -- ":autocmd ... ++once" handlers can be deleted.
     --
     expected = {}
     command('let g:foo = []')
-    command('autocmd TabNew * -once :call add(g:foo, "Once1")')
+    command('autocmd TabNew * ++once :call add(g:foo, "Once1")')
     command('autocmd! TabNew')
     command('tabnew')
     eq(expected, eval('g:foo'))
 
     --
-    -- ":autocmd ... <buffer> -once -nested"
+    -- ":autocmd ... <buffer> ++once ++nested"
     --
     expected = {
       'OptionSet-Once',
       'CursorMoved-Once',
     }
     command('let g:foo = []')
-    command('autocmd OptionSet binary -nested -once :call add(g:foo, "OptionSet-Once")')
-    command('autocmd CursorMoved <buffer> -once -nested setlocal binary|:call add(g:foo, "CursorMoved-Once")')
+    command('autocmd OptionSet binary ++nested ++once :call add(g:foo, "OptionSet-Once")')
+    command('autocmd CursorMoved <buffer> ++once ++nested setlocal binary|:call add(g:foo, "CursorMoved-Once")')
     command("put ='foo bar baz'")
     feed('0llhlh')
     eq(expected, eval('g:foo'))
+
+    --
+    -- :autocmd should not show empty section after ++once handlers expire.
+    --
+    expected = {
+      'Once1',
+      'Once2',
+    }
+    command('let g:foo = []')
+    command('autocmd! TabNew')  -- Clear all TabNew handlers.
+    command('autocmd TabNew * ++once :call add(g:foo, "Once1")')
+    command('autocmd TabNew * ++once :call add(g:foo, "Once2")')
+    command('tabnew')
+    eq(expected, eval('g:foo'))
+    eq(dedent([[
+
+       --- Autocommands ---]]),
+       funcs.execute('autocmd Tabnew'))
   end)
 end)