stdlib: Add function to io_lib to handle Unicode atoms

4 files changed, 70 insertions, 11 deletions

diff --git a/lib/stdlib/doc/src/io_lib.xml b/lib/stdlib/doc/src/io_lib.xml
index 931e50f6f2..5ae400da62 100644
--- a/lib/stdlib/doc/src/io_lib.xml
+++ b/lib/stdlib/doc/src/io_lib.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>1996</year><year>2016</year>
+      <year>1996</year><year>2017</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -147,7 +147,7 @@
           format string (that is, <c>~ts</c> or <c>~tc</c>), the resulting list
           can contain characters beyond the ISO Latin-1 character range
           (that is, numbers &gt; 255). If so, the
-          result is not an ordinary Erlang <c>string()</c>, but can well be
+          result is still an ordinary Erlang <c>string()</c>, and can well be
           used in any context where Unicode data is allowed.</p>
       </desc>
     </func>
@@ -384,6 +384,16 @@
     </func>
 
     <func>
+      <name name="write_atom_as_latin1" arity="1"/>
+      <fsummary>Write an atom.</fsummary>
+      <desc>
+        <p>Returns the list of characters needed to print atom
+          <c><anno>Atom</anno></c>. Non-Latin-1 characters
+          are escaped.</p>
+      </desc>
+    </func>
+
+    <func>
       <name name="write_char" arity="1"/>
       <fsummary>Write a character.</fsummary>
       <desc>
diff --git a/lib/stdlib/src/io_lib.erl b/lib/stdlib/src/io_lib.erl
index a91143a764..28e5007e5a 100644
--- a/lib/stdlib/src/io_lib.erl
+++ b/lib/stdlib/src/io_lib.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2016. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2017. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -68,8 +68,8 @@
 -export([write_atom/1,write_string/1,write_string/2,write_latin1_string/1,
          write_latin1_string/2, write_char/1, write_latin1_char/1]).
 
--export([write_string_as_latin1/1, write_string_as_latin1/2,
-         write_char_as_latin1/1]).
+-export([write_atom_as_latin1/1, write_string_as_latin1/1,
+         write_string_as_latin1/2, write_char_as_latin1/1]).
 
 -export([quote_atom/2, char_list/1, latin1_char_list/1,
 	 deep_char_list/1, deep_latin1_char_list/1,
@@ -344,6 +344,11 @@ write_binary_body(B, _D) ->
     <<X:L>> = B,
     [integer_to_list(X),$:,integer_to_list(L)].
 
+%%% There are two functions to write Unicode atoms:
+%%% - they both escape control characters < 160;
+%%% - write_atom() never escapes characters >= 160;
+%%% - write_atom_as_latin1() also escapes characters >= 255.
+
 %% write_atom(Atom) -> [Char]
 %%  Generate the list of characters needed to print an atom.
 
@@ -351,17 +356,26 @@ write_binary_body(B, _D) ->
       Atom :: atom().
 
 write_atom(Atom) ->
+    write_possibly_quoted_atom(Atom, fun write_string/2).
+
+-spec write_atom_as_latin1(Atom) -> latin1_string() when
+      Atom :: atom().
+
+write_atom_as_latin1(Atom) ->
+    write_possibly_quoted_atom(Atom, fun write_string_as_latin1/2).
+
+write_possibly_quoted_atom(Atom, PFun) ->
     Chars = atom_to_list(Atom),
     case quote_atom(Atom, Chars) of
 	true ->
-	    write_string(Chars, $');   %'
+            PFun(Chars, $');   %'
 	false ->
 	    Chars
     end.
 
 %% quote_atom(Atom, CharList)
 %%  Return 'true' if atom with chars in CharList needs to be quoted, else
-%%  return 'false'.
+%%  return 'false'. Notice that characters >= 160 are always quoted.
 
 -spec quote_atom(atom(), chars()) -> boolean().
 
diff --git a/lib/stdlib/src/io_lib_pretty.erl b/lib/stdlib/src/io_lib_pretty.erl
index aabccfc5d9..ff368d02da 100644
--- a/lib/stdlib/src/io_lib_pretty.erl
+++ b/lib/stdlib/src/io_lib_pretty.erl
@@ -105,6 +105,8 @@ print(_, _, _, 0, _M, _RF, _Enc, _Str) -> "...";
 print(Term, Col, Ll, D, M, RecDefFun, Enc, Str) when Col =< 0 ->
     %% ensure Col is at least 1
     print(Term, 1, Ll, D, M, RecDefFun, Enc, Str);
+print(Atom, _Col, _Ll, _D, _M, _RF, Enc, _Str) when is_atom(Atom) ->
+    write_atom(Atom, Enc);
 print(Term, Col, Ll, D, M0, RecDefFun, Enc, Str) when is_tuple(Term);
                                                       is_list(Term);
                                                       is_map(Term);
@@ -407,6 +409,9 @@ print_length({}, _D, _RF, _Enc, _Str) ->
     {"{}", 2};
 print_length(#{}=M, _D, _RF, _Enc, _Str) when map_size(M) =:= 0 ->
     {"#{}", 3};
+print_length(Atom, _D, _RF, Enc, _Str) when is_atom(Atom) ->
+    S = write_atom(Atom, Enc),
+    {S, lists:flatlength(S)};
 print_length(List, D, RF, Enc, Str) when is_list(List) ->
     %% only flat lists are "printable"
     case Str andalso printable_list(List, D, Enc) of
@@ -500,7 +505,7 @@ print_length_tuple(Tuple, D, RF, Enc, Str) ->
 print_length_record(_Tuple, 1, _RF, _RDefs, _Enc, _Str) ->
     {"{...}", 5};
 print_length_record(Tuple, D, RF, RDefs, Enc, Str) ->
-    Name = [$# | io_lib:write_atom(element(1, Tuple))],
+    Name = [$# | write_atom(element(1, Tuple), Enc)],
     NameL = length(Name),
     Elements = tl(tuple_to_list(Tuple)),
     L = print_length_fields(RDefs, D - 1, Elements, RF, Enc, Str),
@@ -515,7 +520,7 @@ print_length_fields([Def | Defs], D, [E | Es], RF, Enc, Str) ->
      print_length_fields(Defs, D - 1, Es, RF, Enc, Str)].
 
 print_length_field(Def, D, E, RF, Enc, Str) ->
-    Name = io_lib:write_atom(Def),
+    Name = write_atom(Def, Enc),
     {S, L} = print_length(E, D, RF, Enc, Str),
     NameL = length(Name) + 3,
     {{field, Name, NameL, {S, L}}, NameL + L}.
@@ -664,6 +669,11 @@ printable_char(C,unicode) ->
     C > 16#DFFF andalso C < 16#FFFE orelse
     C > 16#FFFF andalso C =< 16#10FFFF.
 
+write_atom(A, latin1) ->
+    io_lib:write_atom_as_latin1(A);
+write_atom(A, _Uni) ->
+    io_lib:write_atom(A).
+
 write_string(S, latin1) ->
     io_lib:write_latin1_string(S, $"); %"
 write_string(S, _Uni) ->
diff --git a/lib/stdlib/test/io_SUITE.erl b/lib/stdlib/test/io_SUITE.erl
index d546e8fad2..b2754e47ba 100644
--- a/lib/stdlib/test/io_SUITE.erl
+++ b/lib/stdlib/test/io_SUITE.erl
@@ -30,7 +30,8 @@
 	 io_lib_print_binary_depth_one/1, otp_10302/1, otp_10755/1,
          otp_10836/1, io_lib_width_too_small/1,
          io_with_huge_message_queue/1, format_string/1,
-	 maps/1, coverage/1, otp_14178_unicode_atoms/1, otp_14175/1]).
+	 maps/1, coverage/1, otp_14178_unicode_atoms/1, otp_14175/1,
+         otp_14285/1]).
 
 -export([pretty/2]).
 
@@ -61,7 +62,8 @@ all() ->
      printable_range, bad_printable_range,
      io_lib_print_binary_depth_one, otp_10302, otp_10755, otp_10836,
      io_lib_width_too_small, io_with_huge_message_queue,
-     format_string, maps, coverage, otp_14178_unicode_atoms, otp_14175].
+     format_string, maps, coverage, otp_14178_unicode_atoms, otp_14175,
+     otp_14285].
 
 %% Error cases for output.
 error_1(Config) when is_list(Config) ->
@@ -755,6 +757,8 @@ rfd(rrrrr, 3) ->
     [f1, f2, f3];
 rfd(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, 0) ->
     [];
+rfd('\x{400}', 1) ->
+    ['\x{400}'];
 rfd(_, _) ->
     no.
 
@@ -1881,6 +1885,7 @@ otp_10302(Suite) when is_list(Suite) ->
 pretty(Term, Depth) when is_integer(Depth) ->
     Opts = [{column, 1}, {line_length, 20},
             {depth, Depth}, {max_chars, 60},
+            {record_print_fun, fun rfd/2},
             {encoding, unicode}],
     pretty(Term, Opts);
 pretty(Term, Opts) when is_list(Opts) ->
@@ -2324,3 +2329,23 @@ text1([T|Ts]) ->
     [erl_anno:text(Anno) | text1(Ts)].
 
 -endif. % EXACT
+
+otp_14285(_Config) ->
+    UOpts = [{record_print_fun, fun rfd/2},
+             {encoding, unicode}],
+    LOpts = [{record_print_fun, fun rfd/2},
+             {encoding, latin1}],
+
+    RT = {'\x{400}','\x{400}'},
+    "#'\x{400}'{'\x{400}' = '\x{400}'}" = pretty(RT, UOpts),
+    "#'\\x{400}'{'\\x{400}' = '\\x{400}'}" = pretty(RT, LOpts),
+
+    Chars = lists:seq(0, 512),
+    [] = [C ||
+             C <- Chars,
+             S <- io_lib:write_atom_as_latin1(list_to_atom([C])),
+             not is_latin1(S)],
+    L1 = [S || C <- Chars, S <- io_lib:write_atom(list_to_atom([C])),
+               not is_latin1(S)],
+    L1 = lists:seq(256, 512),
+    ok.