Merge pull request #9005 from frazze-jobb/frazze/kernel/handle_compos…

…ing_unicode_on_empty_prompt/OTP-19297

kernel: fix bug with composing unicode character
OTP-19297

lib/kernel/src/prim_tty.erl

@@ -865,13 +865,18 @@ handle_request(State = #state{ unicode = U, cols = W }, {delete, N}) when N < 0
     BBCols = cols(State#state.buffer_before, U),
     BACols = cols(State#state.buffer_after, U),
     NewBBCols = cols(NewBB, U),
-    Output = [move_cursor(State, NewBBCols + DelCols, NewBBCols),
-              encode(State#state.buffer_after,U),
-              lists:duplicate(DelCols, $\s),
-              xnfix(State, NewBBCols + BACols + DelCols),
-              move_cursor(State, NewBBCols + BACols + DelCols, NewBBCols)],
+    %% DelCols is 0 only when we are removing a ZWJ or a ZWNJ that is the first character of
+    %% the user buffer. We remove the character from the buffer, but we don't output anything
+    Output = if
+        DelCols =:= 0 -> "";
+        true -> [move_cursor(State, NewBBCols + DelCols, NewBBCols),
+            encode(State#state.buffer_after,U),
+            lists:duplicate(DelCols, $\s),
+            xnfix(State, NewBBCols + BACols + DelCols),
+            move_cursor(State, NewBBCols + BACols + DelCols, NewBBCols)]
+    end,
     NewState0 = State#state{ buffer_before = NewBB },
-    if State#state.lines_after =/= [], (BBCols+BACols+N) rem W =:= 0 ->
+    if DelCols =/= 0, State#state.lines_after =/= [], (BBCols+BACols+N) rem W =:= 0 ->
             {Delete, _} = handle_request(State, delete_line),
             {Redraw, NewState1} = handle_request(NewState0, redraw_prompt_pre_deleted),
             {[Delete, Redraw], NewState1};
@@ -1023,9 +1028,15 @@ split_cols(_N, [], Acc, Chars, Cols, _Unicode) ->
     {Chars, Cols, Acc, []};
 split_cols(N, [Char | T], Acc, Cnt, Cols, Unicode) when is_integer(Char) ->
     split_cols(N - npwcwidth(Char), T, [Char | Acc], Cnt + 1, Cols + npwcwidth(Char, Unicode), Unicode);
-split_cols(N, [Chars | T], Acc, Cnt, Cols, Unicode) when is_list(Chars) ->
-    split_cols(N - length(Chars), T, [Chars | Acc],
-               Cnt + length(Chars), Cols + cols(Chars, Unicode), Unicode).
+split_cols(N, [GC|T], Acc, Cnt, Cols, Unicode) when is_list(GC) ->
+    %% We have to remove parts of the grapheme cluster
+    CGC = cols(GC, Unicode),
+    if CGC > N ->
+            {CntList2, ColsList2, List2, List1} = split_cols(N, GC, Unicode),
+            split_cols(N-ColsList2, [List1|T], List2 ++ Acc, Cnt+CntList2, Cols+ColsList2, Unicode);
+       true ->
+            split_cols(N-CGC, T, GC ++ Acc, Cnt+length(GC), Cols+CGC, Unicode)
+    end.
 
 %% Split the buffer after N logical characters returning
 %% the number of real characters deleted and the column length
@@ -1042,6 +1053,9 @@ split(_N, [], Acc, Chars, Cols, _Unicode) ->
     {Chars, Cols, Acc, []};
 split(N, [Char | T], Acc, Cnt, Cols, Unicode) when is_integer(Char) ->
     split(N - 1, T, [Char | Acc], Cnt + 1, Cols + npwcwidth(Char, Unicode), Unicode);
+split(N, [GC|T], Acc, Cnt, Cols, Unicode) when is_list(GC), N < length(GC) ->
+    {NumL2, ColsL2, List2, List1} = split(N, GC, Unicode),
+    split(N-NumL2, List1 ++ T, List2 ++ Acc, Cnt+NumL2, Cols+ColsL2, Unicode);
 split(N, [Chars | T], Acc, Cnt, Cols, Unicode) when is_list(Chars) ->
     split(N - length(Chars), T, [Chars | Acc],
           Cnt + length(Chars), Cols + cols(Chars, Unicode), Unicode);

lib/kernel/test/interactive_shell_SUITE.erl

@@ -52,6 +52,7 @@
          shell_navigation/1, shell_multiline_navigation/1, shell_multiline_prompt/1, shell_multiline_prompt_ssh/1,
          shell_xnfix/1, shell_delete/1,
          shell_transpose/1, shell_search/1, shell_insert/1,
+         shell_combining_unicode/1,
          shell_update_window/1, shell_small_window_multiline_navigation/1, shell_huge_input/1,
          shell_invalid_unicode/1, shell_support_ansi_input/1,
          shell_invalid_ansi/1, shell_suspend/1, shell_full_queue/1,
@@ -163,6 +164,7 @@ groups() ->
      {tty_tests, [parallel],
       [shell_navigation, shell_multiline_navigation, shell_multiline_prompt,
        shell_xnfix, shell_delete, shell_format,
+       shell_combining_unicode,
        shell_transpose, shell_search, shell_insert,
        shell_update_window, shell_small_window_multiline_navigation, shell_huge_input,
        shell_support_ansi_input,
@@ -972,6 +974,40 @@ shell_search(C) ->
         ok
     end.
 
+shell_combining_unicode(Config) ->
+    %% Tests that its possible to delete a combining unicode character as
+    %% the first character of the input line.
+    Term = start_tty(Config),
+    X = 0,
+    check_location(Term, {X,0}),
+    %% COMBINING DIAERESIS, ZWNJ, ZWJ
+    CombiningUnicode = [776, 8204, 8205],
+    try
+        [
+            begin
+                send_tty(Term,[J]),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,[J,$a]),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,[$a,J]),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,"BSpace"),
+                check_location(Term, {X,0}),
+                send_tty(Term,[$",$a,J,$b,$",$.,10]),
+                check_location(Term, {X,0})
+            end || J <- CombiningUnicode],
+        ok
+    after
+        stop_tty(Term)
+    end.
+
 shell_insert(Config) ->
     Term = start_tty(Config),