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

3 files changed, 33 insertions, 4 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