printer: improve object formatting.

There is an issue with the printer in that it produces
output whereby objects continue on the same line after
a multi-line object, e.g:

   (foo (foobly bar
         xyzzy quux) (oops same
                      line))

rather than:

   (foo (foobly bar
         xyzzy quux)
        (oops same line))

There is a simple fix for this: set a flag to force
a line break on the next width-check operation whenever
an object has been broken into multiple lines.

width-check can return a Boolean indication whether
it generated a line break, and so aggregate object
printing routines can tell whether their object
has been broken into lines, and set the flag.

* stream.h (struct strm_base): New member, force_break.
(force_break): Declared.

* stream.c (strm_base_init): Extent initializer to cover
force_break flag.
(put_string, put_char): Clear the force_break flag whenever
we hit column zero.
(width_check): If indent mode is on, and force_break is
true, generate a break. Clear force_break.
(force_break): New function.
(stream_init): Register force-break intrinsic.

* buf.c (buf_print): Set the force break flag if the buffer
was broken into multiple lines.

* hash.c (hash_print_op): Set the force break flag if the
hash was broken into multiple lines.

* lib.c (obj_print_impl): Same logic for lists.

* struct.c (struct_inst_print): Same logic for structs.

* tests/009/json.expected, tests/011/macros-2.expected,
tests/012/struct.tl, tests/017/glob-zarray.expected:
Update expected textual output to reflect new formatting.

1 files changed, 6 insertions, 1 deletions

diff --git a/buf.c b/buf.c
index 3e1ed76a..efd2e4a6 100644
--- a/buf.c
+++ b/buf.c
@@ -622,6 +622,7 @@ val buf_print(val buf, val stream_in)
   val save_mode = test_set_indent_mode(stream, num_fast(indent_off),
                                        num_fast(indent_data));
   val save_indent;
+  int fb = 0;
 
   put_string(lit("#b'"), stream);
 
@@ -630,12 +631,16 @@ val buf_print(val buf, val stream_in)
   while (len-- > 0) {
     format(stream, lit("~,02x"), num_fast(*data++), nao);
     if ((++count & 7) == 0 && len)
-      width_check(stream, chr(' '));
+      if (width_check(stream, chr(' ')))
+        fb = 1;
   }
 
   set_indent(stream, save_indent);
   set_indent_mode(stream, save_mode);
 
+  if (fb)
+    force_break(stream);
+
   return put_char(chr('\''), stream);
 }