cmdline: CmdlineEnter and CmdlineLeave autocommands (#7422)

vim-patch:fafcf0dd59fd

patch 8.0.1206: no autocmd for entering or leaving the command line

Problem:    No autocmd for entering or leaving the command line.
Solution:   Add CmdlineEnter and CmdlineLeave.

https://github.com/vim/vim/commit/fafcf0dd59fd9c4ef743bb333ae40d1d322b6079

6 files changed, 106 insertions, 1 deletions

diff --git a/src/nvim/auevents.lua b/src/nvim/auevents.lua
index 68a47c244f..7dfaf54ff0 100644
--- a/src/nvim/auevents.lua
+++ b/src/nvim/auevents.lua
@@ -19,6 +19,8 @@ return {
     'BufWriteCmd',            -- write buffer using command
     'BufWritePost',           -- after writing a buffer
     'BufWritePre',            -- before writing a buffer
+    'CmdLineEnter',           -- after entering cmdline mode
+    'CmdLineLeave',           -- before leaving cmdline mode
     'CmdUndefined',           -- command undefined
     'CmdWinEnter',            -- after entering the cmdline window
     'CmdWinLeave',            -- before leaving the cmdline window
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index c339a5cdd2..262ea922ef 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -1374,6 +1374,29 @@ int tv_dict_add_nr(dict_T *const d, const char *const key,
   return OK;
 }
 
+/// Add a special entry to dictionary
+///
+/// @param[out]  d  Dictionary to add entry to.
+/// @param[in]  key  Key to add.
+/// @param[in]  key_len  Key length.
+/// @param[in]  val SpecialVarValue to add.
+///
+/// @return OK in case of success, FAIL when key already exists.
+int tv_dict_add_special(dict_T *const d, const char *const key,
+                        const size_t key_len, SpecialVarValue val)
+{
+  dictitem_T *const item = tv_dict_item_alloc_len(key, key_len);
+
+  item->di_tv.v_lock = VAR_UNLOCKED;
+  item->di_tv.v_type = VAR_SPECIAL;
+  item->di_tv.vval.v_special = val;
+  if (tv_dict_add(d, item) == FAIL) {
+    tv_dict_item_free(item);
+    return FAIL;
+  }
+  return OK;
+}
+
 /// Add a string entry to dictionary
 ///
 /// @param[out]  d  Dictionary to add entry to.
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 9c9ccbca4d..c1500e3121 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -348,8 +348,57 @@ static uint8_t *command_line_enter(int firstc, long count, int indent)
   got_int = false;
   s->state.check = command_line_check;
   s->state.execute = command_line_execute;
+
+  TryState tstate;
+  Error err = ERROR_INIT;
+  bool tl_ret = true;
+  dict_T *dict = get_vim_var_dict(VV_EVENT);
+  char firstcbuf[2];
+  firstcbuf[0] = firstc > 0 ? firstc : '-';
+  firstcbuf[1] = 0;
+
+  if (has_event(EVENT_CMDLINEENTER)) {
+    // set v:event to a dictionary with information about the commandline
+    tv_dict_add_str(dict, S_LEN("cmdtype"), firstcbuf);
+    tv_dict_add_nr(dict, S_LEN("cmdlevel"), ccline.level);
+    tv_dict_set_keys_readonly(dict);
+    try_enter(&tstate);
+
+    apply_autocmds(EVENT_CMDLINEENTER, (char_u *)firstcbuf, (char_u *)firstcbuf,
+                   false, curbuf);
+    tv_dict_clear(dict);
+
+
+    tl_ret = try_leave(&tstate, &err);
+    if (!tl_ret && ERROR_SET(&err)) {
+      msg_putchar('\n');
+      msg_printf_attr(hl_attr(HLF_E)|MSG_HIST, (char *)e_autocmd_err, err.msg);
+      api_clear_error(&err);
+      redrawcmd();
+    }
+    tl_ret = true;
+  }
+
   state_enter(&s->state);
 
+  if (has_event(EVENT_CMDLINELEAVE)) {
+    tv_dict_add_str(dict, S_LEN("cmdtype"), firstcbuf);
+    tv_dict_add_nr(dict, S_LEN("cmdlevel"), ccline.level);
+    tv_dict_set_keys_readonly(dict);
+    // not readonly:
+    tv_dict_add_special(dict, S_LEN("abort"),
+                        s->gotesc ? kSpecialVarTrue : kSpecialVarFalse);
+    try_enter(&tstate);
+    apply_autocmds(EVENT_CMDLINELEAVE, (char_u *)firstcbuf, (char_u *)firstcbuf,
+                   false, curbuf);
+    // error printed below, to avoid redraw issues
+    tl_ret = try_leave(&tstate, &err);
+    if (tv_dict_get_number(dict, "abort") != 0) {
+      s->gotesc = 1;
+    }
+    tv_dict_clear(dict);
+  }
+
   cmdmsg_rl = false;
 
   cmd_fkmap = 0;
@@ -410,8 +459,14 @@ static uint8_t *command_line_enter(int firstc, long count, int indent)
   msg_scroll = s->save_msg_scroll;
   redir_off = false;
 
+  if (!tl_ret && ERROR_SET(&err)) {
+    msg_putchar('\n');
+    msg_printf_attr(hl_attr(HLF_E)|MSG_HIST, (char *)e_autocmd_err, err.msg);
+    api_clear_error(&err);
+  }
+
   // When the command line was typed, no need for a wait-return prompt.
-  if (s->some_key_typed) {
+  if (s->some_key_typed && tl_ret) {
     need_wait_return = false;
   }
 
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 8f804ff888..2b025c2c50 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1167,6 +1167,8 @@ EXTERN char_u e_dirnotf[] INIT(= N_(
 EXTERN char_u e_unsupportedoption[] INIT(= N_("E519: Option not supported"));
 EXTERN char_u e_fnametoolong[] INIT(= N_("E856: Filename too long"));
 EXTERN char_u e_float_as_string[] INIT(= N_("E806: using Float as a String"));
+EXTERN char_u e_autocmd_err[] INIT(=N_(
+    "E920: autocmd has thrown an exception: %s"));
 
 
 EXTERN char top_bot_msg[] INIT(= N_("search hit TOP, continuing at BOTTOM"));
diff --git a/src/nvim/testdir/test_autocmd.vim b/src/nvim/testdir/test_autocmd.vim
index 835df42a10..82c04abf5b 100644
--- a/src/nvim/testdir/test_autocmd.vim
+++ b/src/nvim/testdir/test_autocmd.vim
@@ -420,3 +420,25 @@ function Test_autocmd_bufwipe_in_SessLoadPost2()
     call delete(file)
   endfor
 endfunc
+
+func Test_Cmdline()
+  au! CmdlineEnter : let g:entered = expand('<afile>')
+  au! CmdlineLeave : let g:left = expand('<afile>')
+  let g:entered = 0
+  let g:left = 0
+  call feedkeys(":echo 'hello'\<CR>", 'xt')
+  call assert_equal(':', g:entered)
+  call assert_equal(':', g:left)
+  au! CmdlineEnter
+  au! CmdlineLeave
+
+  au! CmdlineEnter / let g:entered = expand('<afile>')
+  au! CmdlineLeave / let g:left = expand('<afile>')
+  let g:entered = 0
+  let g:left = 0
+  call feedkeys("/hello<CR>", 'xt')
+  call assert_equal('/', g:entered)
+  call assert_equal('/', g:left)
+  au! CmdlineEnter
+  au! CmdlineLeave
+endfunc
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 1ceda55cf1..205c25b6cd 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -78,6 +78,7 @@ static char *features[] = {
 
 // clang-format off
 static const int included_patches[] = {
+  1206,
   // 1026,
   1025,
   1024,