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, 12 insertions, 2 deletions

diff --git a/lib.c b/lib.c
index cf800c52..f2a62d11 100644
--- a/lib.c
+++ b/lib.c
@@ -11109,6 +11109,7 @@ val obj_print_impl(val obj, val out, val pretty, struct strm_ctx *ctx)
         val iter;
         val closepar = chr(')');
         val indent = zero;
+        int force_br = 0;
 
         if (sym == dwim_s && consp(cdr(obj))) {
           put_char(chr('['), out);
@@ -11181,7 +11182,8 @@ finish:
             iter = nil;
             goto dot;
           } else if (consp(d)) {
-            width_check(out, chr(' '));
+            if (width_check(out, chr(' ')))
+              force_br = 1;
           } else {
 dot:
             put_string(lit(" . "), out);
@@ -11189,6 +11191,9 @@ dot:
             put_char(closepar, out);
           }
         }
+
+        if (force_br)
+          force_break(out);
       }
 
       if (save_indent)
@@ -11299,6 +11304,7 @@ dot:
       val save_mode = test_set_indent_mode(out, num_fast(indent_off),
                                            num_fast(indent_data));
       val save_indent;
+      int force_br = 0;
 
       put_string(lit("#("), out);
 
@@ -11308,11 +11314,15 @@ dot:
         val elem = obj->v.vec[i];
         obj_print_impl(elem, out, pretty, ctx);
         if (i < length - 1)
-          width_check(out, chr(' '));
+          if (width_check(out, chr(' ')))
+            force_br = 1;
       }
 
       put_char(chr(')'), out);
 
+      if (force_br)
+        force_break(out);
+
       set_indent(out, save_indent);
       set_indent_mode(out, save_mode);
     }