updated for version 7.3.196

Problem:    Can't intercept a character that is going to be inserted.
Solution:   Add the InsertCharPre autocommand event. (Jakson A. Aquino)

runtime/doc/autocmd.txt

@@ -299,6 +299,8 @@ Name			triggered by ~
 |InsertEnter|		starting Insert mode
 |InsertChange|		when typing <Insert> while in Insert or Replace mode
 |InsertLeave|		when leaving Insert mode
+|InsertCharPre|		when a character was typed in Insert mode, before
+			inserting it
 
 |ColorScheme|		after loading a color scheme
 
@@ -657,6 +659,17 @@ InsertChange			When typing <Insert> while in Insert or
 				indicates the new mode.
 				Be careful not to move the cursor or do
 				anything else that the user does not expect.
+							*InsertCharPre*
+InsertCharPre			When a character is typed in Insert mode,
+				before inserting the char.
+				The |v:char| variable indicates the char typed
+				and can be changed during the event to insert
+				a different character.  When |v:char| is set
+				to more than one character this text is
+				inserted literally.
+				It is not allowed to change the text |textlock|.
+				The event is not triggered when 'paste' is
+				set.
 							*InsertEnter*
 InsertEnter			Just before starting Insert mode.  Also for
 				Replace mode and Virtual Replace mode.  The

runtime/doc/eval.txt

@@ -1293,6 +1293,7 @@ v:beval_winnr	The number of the window, over which the mouse pointer is. Only
 					*v:char* *char-variable*
 v:char		Argument for evaluating 'formatexpr' and used for the typed
 		character when using <expr> in an abbreviation |:map-<expr>|.
+		It is also used by the |InsertPreChar| event.
 
 			*v:charconvert_from* *charconvert_from-variable*
 v:charconvert_from

runtime/doc/map.txt

@@ -226,7 +226,7 @@ text before the cursor and start omni completion when some condition is met.
 
 For abbreviations |v:char| is set to the character that was typed to trigger
 the abbreviation.  You can use this to decide how to expand the {lhs}.  You
-can't change v:char and you should not insert it.
+you should not either insert or change the v:char.
 
 Be very careful about side effects!  The expression is evaluated while
 obtaining characters, you may very well make the command dysfunctional.