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

10 files changed, 256 insertions, 5 deletions

diff --git a/runtime/doc/autocmd.txt b/runtime/doc/autocmd.txt
index 6cffbf4cb6..740f44414a 100644
--- a/runtime/doc/autocmd.txt
+++ b/runtime/doc/autocmd.txt
@@ -310,6 +310,8 @@ Name			triggered by ~
 |TabNew|		when creating a new tab page
 |TabNewEntered|		after entering a new tab page
 |TabClosed|		after closing a tab page
+|CmdlineEnter|		after entering cmdline mode
+|CmdlineLeave|		before leaving cmdline mode
 |CmdwinEnter|		after entering the command-line window
 |CmdwinLeave|		before leaving the command-line window
 
@@ -492,6 +494,28 @@ CmdUndefined			When a user command is used but it isn't
 				command is defined.  An alternative is to
 				always define the user command and have it
 				invoke an autoloaded function.  See |autoload|.
+							*CmdlineEnter*
+CmdlineEnter			After moving the cursor to the command line,
+				where the user can type a command or search
+				string.
+				<afile> is set to a single character,
+				indicating the type of command-line.
+				|cmdline-char|
+				Sets these |v:event| keys:
+				    cmdlevel
+				    cmdtype
+							*CmdlineLeave*
+CmdlineLeave			Before leaving the command line.
+				<afile> is set to a single character,
+				indicating the type of command-line.
+				|cmdline-char|
+				Sets these |v:event| keys:
+				    abort (mutable)
+				    cmdlevel
+				    cmdtype
+				Note: `abort` can only be changed from false
+				to true. An autocmd cannot execute an already
+				aborted cmdline by changing it to false.
 							*CmdwinEnter*
 CmdwinEnter			After entering the command-line window.
 				Useful for setting options specifically for
diff --git a/runtime/doc/cmdline.txt b/runtime/doc/cmdline.txt
index 4956b9e6fe..00e654841c 100644
--- a/runtime/doc/cmdline.txt
+++ b/runtime/doc/cmdline.txt
@@ -1088,7 +1088,7 @@ Another example: >
 	:au CmdwinEnter [/?]  startinsert
 This will make Vim start in Insert mode in the command-line window.
 
-						*cmdwin-char*
+					*cmdline-char* *cmdwin-char*
 The character used for the pattern indicates the type of command-line:
 	:	normal Ex command
 	>	debug mode command |debug-mode|
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index b752667d9a..ea4393bc6f 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1527,16 +1527,21 @@ v:event		Dictionary of event data for the current |autocommand|.  Valid
 <		Keys vary by event; see the documentation for the specific
 		event, e.g. |DirChanged| or |TextYankPost|.
 			KEY		DESCRIPTION ~
-			cwd		Current working directory
+			abort		Whether the event triggered during
+					an aborting condition, i e |c_Esc| or
+					|c_CTRL-c|for |CmdlineLeave|.
+			cmdlevel	Level of cmdline.
+			cmdtype		Type of cmdline, |cmdline-char|.
+			cwd		Current working directory.
 			scope		Event-specific scope name.
 			operator	Current |operator|.  Also set for Ex
 					commands (unlike |v:operator|). For
 					example if |TextYankPost| is triggered
 					by the |:yank| Ex command then
-					`v:event['operator']` is "y".
+					`v:event.operator` is "y".
 			regcontents	Text stored in the register as a
 					|readfile()|-style list of lines.
-			regname 	Requested register (e.g "x" for "xyy)
+			regname		Requested register (e.g "x" for "xyy)
 					or the empty string for an unnamed
 					operation.
 			regtype		Type of register as returned by
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,
diff --git a/test/functional/autocmd/cmdline_spec.lua b/test/functional/autocmd/cmdline_spec.lua
new file mode 100644
index 0000000000..b0ce03b141
--- /dev/null
+++ b/test/functional/autocmd/cmdline_spec.lua
@@ -0,0 +1,117 @@
+local helpers = require('test.functional.helpers')(after_each)
+local Screen = require('test.functional.ui.screen')
+
+local clear = helpers.clear
+local command = helpers.command
+local eq = helpers.eq
+local expect = helpers.expect
+local next_msg = helpers.next_message
+local feed = helpers.feed
+local meths = helpers.meths
+
+describe('cmdline autocommands', function()
+  local channel
+  before_each(function()
+    clear()
+    channel = meths.get_api_info()[1]
+    meths.set_var("channel",channel)
+    command("autocmd CmdlineEnter * call rpcnotify(g:channel, 'CmdlineEnter', v:event)")
+    command("autocmd CmdlineLeave * call rpcnotify(g:channel, 'CmdlineLeave', v:event)")
+    command("autocmd CmdWinEnter * call rpcnotify(g:channel, 'CmdWinEnter', v:event)")
+    command("autocmd CmdWinLeave * call rpcnotify(g:channel, 'CmdWinLeave', v:event)")
+  end)
+
+  it('works', function()
+    feed(':')
+    eq({'notification', 'CmdlineEnter', {{cmdtype=':', cmdlevel=1}}}, next_msg())
+    feed('redraw<cr>')
+    eq({'notification', 'CmdlineLeave',
+        {{cmdtype=':', cmdlevel=1, abort=false}}}, next_msg())
+
+    feed(':')
+    eq({'notification', 'CmdlineEnter', {{cmdtype=':', cmdlevel=1}}}, next_msg())
+
+    -- note: feed('bork<c-c>') might not consume 'bork'
+    -- due to out-of-band interupt handling
+    feed('bork<esc>')
+    eq({'notification', 'CmdlineLeave',
+        {{cmdtype=':', cmdlevel=1, abort=true}}}, next_msg())
+  end)
+
+  it('can abort cmdline', function()
+    command("autocmd CmdlineLeave * let v:event.abort= len(getcmdline())>15")
+    feed(":put! ='ok'<cr>")
+    expect([[
+      ok
+      ]])
+
+    feed(":put! ='blah blah'<cr>")
+    expect([[
+      ok
+      ]])
+  end)
+
+  it('handles errors correctly', function()
+    clear()
+    local screen = Screen.new(72, 8)
+    screen:attach()
+    screen:set_default_attr_ids({
+      [1] = {bold = true, foreground = Screen.colors.Blue1},
+      [2] = {foreground = Screen.colors.Grey100, background = Screen.colors.Red},
+      [3] = {bold = true, foreground = Screen.colors.SeaGreen4},
+    })
+    command("autocmd CmdlineEnter * echoerr 'FAIL'")
+    command("autocmd CmdlineLeave * echoerr 'very error'")
+    feed(':')
+    screen:expect([[
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      :                                                                       |
+      {2:E920: autocmd has thrown an exception: Vim(echoerr):FAIL}                |
+      :^                                                                       |
+    ]])
+    feed("put ='lorem ipsum'<cr>")
+    screen:expect([[
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      :                                                                       |
+      {2:E920: autocmd has thrown an exception: Vim(echoerr):FAIL}                |
+      :put ='lorem ipsum'                                                     |
+      {2:E920: autocmd has thrown an exception: Vim(echoerr):very error}          |
+                                                                              |
+      {3:Press ENTER or type command to continue}^                                 |
+    ]])
+
+    feed('<cr>')
+    screen:expect([[
+                                                                              |
+      ^lorem ipsum                                                             |
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+      {1:~                                                                       }|
+                                                                              |
+    ]])
+  end)
+
+  it('works with nested cmdline', function()
+    feed(':')
+    eq({'notification', 'CmdlineEnter', {{cmdtype=':', cmdlevel=1}}}, next_msg())
+    feed('<c-r>=')
+    eq({'notification', 'CmdlineEnter', {{cmdtype='=', cmdlevel=2}}}, next_msg())
+    feed('<c-f>')
+    eq({'notification', 'CmdWinEnter', {{}}}, next_msg())
+    feed(':')
+    eq({'notification', 'CmdlineEnter', {{cmdtype=':', cmdlevel=3}}}, next_msg())
+    feed('<c-c>')
+    eq({'notification', 'CmdlineLeave', {{cmdtype=':', cmdlevel=3, abort=true}}}, next_msg())
+    feed('<c-c>')
+    eq({'notification', 'CmdWinLeave', {{}}}, next_msg())
+    feed('1+2<cr>')
+    eq({'notification', 'CmdlineLeave', {{cmdtype='=', cmdlevel=2, abort=false}}}, next_msg())
+  end)
+end)