json: new special var *print-json-type*.

This variable controls whether we emit the "__type" key
for structures.

* lib.c (out_json_rec): React to the new variable, via
the flag in the json_opts structure: include the "__type" key
only if it is requested.
(out_json, put_json): Initialize the type flag in the josn_opts
according to the *print-json-type* dynamic variable.

* stream.c (print_json_type_s): New symbol variable.
(stream_init): print_json_type_s initialized, and
corresponding special variable registered, with intial value t.

* stream.h (struct json_opts): New bitfield member, type.
(print_json_type_s): Declared.

* txr.1: Documented.

1 files changed, 2 insertions, 1 deletions

diff --git a/stream.h b/stream.h
index a334a8ff..06cf5cec 100644
--- a/stream.h
+++ b/stream.h
@@ -142,6 +142,7 @@ enum json_fmt {
 struct json_opts {
   enum json_fmt fmt : 4;
   unsigned flat : 1;
+  unsigned type : 1;
 };
 
 loc lookup_var_l(val env, val sym);
@@ -162,7 +163,7 @@ extern val get_error_s, get_error_str_s, clear_error_s, get_fd_s;
 
 extern val print_flo_precision_s, print_flo_digits_s, print_flo_format_s;
 extern val pprint_flo_format_s, print_base_s, print_circle_s;
-extern val print_json_format_s;
+extern val print_json_format_s, print_json_type_s;
 
 #if HAVE_SOCKETS
 extern val socket_error_s;