* lib.c (obj_print): Render character DC00 as "pnul".

Clean up code which chooses rendering for characters.
Print C0 and C1 control characters, as well as D800-DFFF,
FFFE and FFFF and characters above FFFF using hex;
others are printed using the #\<char> notation.

* parser.y (char_from_name): map "pnul" to DC00.

* txr.1: Documented pnul, clarified character
printing rules, and added a cautionary note about
possible ambiguity in printing.

1 files changed, 8 insertions, 3 deletions

diff --git a/lib.c b/lib.c
index e2b42506..52c7fa5d 100644
--- a/lib.c
+++ b/lib.c
@@ -5754,11 +5754,16 @@ finish:
       case '\r': put_string(lit("return"), out); break;
       case 27: put_string(lit("esc"), out); break;
       case ' ': put_string(lit("space"), out); break;
+      case 0xDC00: put_string(lit("pnul"), out); break;
       default:
-        if (ch >= ' ')
-          put_char(chr(ch), out);
-        else
+        if ((ch < 0x20) || (ch >= 0x80 && ch < 0xA0))
           format(out, lit("x~,02x"), num(ch), nao);
+        else if ((ch >= 0xD800 && ch < 0xE000) || ch == 0xFFFE || ch == 0xFFFF)
+          format(out, lit("x~,04x"), num(ch), nao);
+        else if (ch >= 0xFFFF)
+          format(out, lit("x~,06x"), num(ch), nao);
+        else
+          put_char(chr(ch), out);
       }
     }
     return obj;