Add usage of and spec for io:printable_range/0

This makes both io:format("~tp", ...) and
the shell honor the +pc setting and also reverts the shell to
the old behaviour of only interpreting latin1 strings as "strings"
by default. +pc unicode turns on the R16A behaviour. Doing
io:format("~tp~n", [[1024,1025]]).
will show you the difference when starting with +pc unicode.

2 files changed, 40 insertions, 15 deletions

diff --git a/lib/stdlib/src/io.erl b/lib/stdlib/src/io.erl
index 3dddb0d6e7..c92e9e3ade 100644
--- a/lib/stdlib/src/io.erl
+++ b/lib/stdlib/src/io.erl
@@ -32,6 +32,8 @@
          parse_erl_exprs/4,parse_erl_form/1,parse_erl_form/2,
          parse_erl_form/3,parse_erl_form/4]).
 -export([request/1,request/2,requests/1,requests/2]).
+%% Implemented in native code
+-export([printable_range/0]).
 
 -export_type([device/0, format/0, server_no_data/0]).
 
@@ -66,6 +68,11 @@ o_request(Io, Request, Func) ->
 	    Other
     end.
 
+%% Request what the user considers printable characters
+-spec printable_range() -> 'unicode' | 'latin1'.
+printable_range() ->
+    erlang:nif_error(undefined).
+
 %% Put chars takes mixed *unicode* list from R13 onwards.
 -spec put_chars(CharData) -> 'ok' when
       CharData :: unicode:chardata().
diff --git a/lib/stdlib/src/io_lib.erl b/lib/stdlib/src/io_lib.erl
index b7ec848e1e..ff389cbe22 100644
--- a/lib/stdlib/src/io_lib.erl
+++ b/lib/stdlib/src/io_lib.erl
@@ -72,7 +72,7 @@
 
 -export([quote_atom/2, char_list/1, latin1_char_list/1,
 	 deep_char_list/1, deep_latin1_char_list/1,
-	 printable_list/1, printable_latin1_list/1]).
+	 printable_list/1, printable_latin1_list/1, printable_unicode_list/1]).
 
 %% Utilities for collecting characters.
 -export([collect_chars/3, collect_chars/4,
@@ -533,27 +533,45 @@ printable_latin1_list(_) -> false.			%Everything else is false
 %%  Return true if CharList is a list of printable characters, else
 %%  false. The notion of printable in Unicode terms is somewhat floating.
 %%  Everything that is not a control character and not invalid unicode
-%%  will be considered printable.
+%%  will be considered printable. 
+%%  What the user has noted as printable characters is what actually 
+%%  specifies when this function will return true. If the VM is started
+%%  with +pc latin1, only the latin1 range will be deemed as printable
+%%  if on the other hand +pc unicode is given, all characters in the Unicode
+%%  character set are deemed printable. latin1 is default.
 
 -spec printable_list(Term) -> boolean() when
       Term :: term().
 
-printable_list([C|Cs]) when is_integer(C), C >= $\040, C =< $\176 ->
-    printable_list(Cs);
-printable_list([C|Cs])
+printable_list(L) ->
+    %% There will be more alternatives returns from io:printable range 
+    %% in the future. To not have a catch-all caluse is deliberate.
+    case io:printable_range() of
+	latin1 ->
+	    printable_latin1_list(L);
+	unicode ->
+	    printable_unicode_list(L)
+    end.
+
+-spec printable_unicode_list(Term) -> boolean() when
+      Term :: term().
+
+printable_unicode_list([C|Cs]) when is_integer(C), C >= $\040, C =< $\176 ->
+    printable_unicode_list(Cs);
+printable_unicode_list([C|Cs])
   when is_integer(C), C >= 16#A0, C < 16#D800;
        is_integer(C), C > 16#DFFF, C < 16#FFFE;
        is_integer(C), C > 16#FFFF, C =< 16#10FFFF ->
-    printable_list(Cs);
-printable_list([$\n|Cs]) -> printable_list(Cs);
-printable_list([$\r|Cs]) -> printable_list(Cs);
-printable_list([$\t|Cs]) -> printable_list(Cs);
-printable_list([$\v|Cs]) -> printable_list(Cs);
-printable_list([$\b|Cs]) -> printable_list(Cs);
-printable_list([$\f|Cs]) -> printable_list(Cs);
-printable_list([$\e|Cs]) -> printable_list(Cs);
-printable_list([]) -> true;
-printable_list(_) -> false.		%Everything else is false
+    printable_unicode_list(Cs);
+printable_unicode_list([$\n|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\r|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\t|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\v|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\b|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\f|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([$\e|Cs]) -> printable_unicode_list(Cs);
+printable_unicode_list([]) -> true;
+printable_unicode_list(_) -> false.		%Everything else is false
 
 %% List = nl()
 %%  Return a list of characters to generate a newline.