From 92c79e394041f76d8f676cafe9b6af44522497bd Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Wed, 22 Mar 2017 09:41:57 +0100
Subject: stdlib: Add function to io_lib to handle Unicode atoms

---
 lib/stdlib/src/io_lib.erl        | 24 +++++++++++++++++++-----
 lib/stdlib/src/io_lib_pretty.erl | 14 ++++++++++++--
 2 files changed, 31 insertions(+), 7 deletions(-)

(limited to 'lib/stdlib/src')

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) ->
-- 
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