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, 2 deletions

diff --git a/hash.c b/hash.c
index cc4c36ca..cc1b161f 100644
--- a/hash.c
+++ b/hash.c
@@ -408,7 +408,7 @@ static cnum hash_hash_op(val obj, int *count)
 static void hash_print_op(val hash, val out, val pretty, struct strm_ctx *ctx)
 {
   struct hash *h = coerce(struct hash *, hash->co.handle);
-  int need_space = 0;
+  int need_space = 0, force_br = 0;
   val save_mode = test_set_indent_mode(out, num_fast(indent_off),
                                        num_fast(indent_data));
   val save_indent;
@@ -461,7 +461,8 @@ static void hash_print_op(val hash, val out, val pretty, struct strm_ctx *ctx)
     while ((cell = hash_next(iter))) {
       val key = car(cell);
       val value = cdr(cell);
-      width_check(out, chr(' '));
+      if (width_check(out, chr(' ')))
+        force_br = 1;
 
       put_string(lit("("), out);
       obj_print_impl(key, out, pretty, ctx);
@@ -476,6 +477,9 @@ static void hash_print_op(val hash, val out, val pretty, struct strm_ctx *ctx)
   }
   put_string(lit(")"), out);
 
+  if (force_br)
+    force_break(out);
+
   set_indent_mode(out, save_mode);
   set_indent(out, save_indent);
 }