New #J syntax for JSON objects in TXR Lisp.

(needs buffer literal error message cleanup)

* parser.c (json_s): New symbol variable.
(is_balanced_line): Follow braces out of initial state.
This concession allows the listener to accept input
like #J{"a":"b"}.
(me_json): New static function (macro expander). The #J X
syntax produces a (json Y) form, with the JSON syntax X
translated to a Lisp object Y. If that is evaluated,
this macro translates it to (quote Y).
(parse_init): initialize json_s variable with interned symbol,
and register the json macro.

* parser.h (json_s): Declared.
(end_of_json): Declared.

* parser.l (num_esc): Treat u escape sequences in the same way
as x. This function can then be used for handling the \u
escapes in JSON string literals.
(DIG19, JNUM, JPUNC, NJPUNC): New lex named patterns.
(JSON, JLIT): New lex start conditions.
(grammar): Recognize #J syntax, mapping to HASH_J token,
which transitions into JSON start state.
In JSON start state, handle all the elements: numbers,
keywords, arrays and objects. Transition into JLIT state.
In JLIT start state, handle all the elements of JSON string
literals, including surrogate pair escapes.
JSON literals share the fallback {UANY} fallback patter with
other literals.
(end_of_jason): New function.

* parser.y (HASH_J, JSKW): New token symbols.
(json, json_val, json_vals, json_pairs): New nonterminal
symbols, and rules.
(i_expr, n_expr): Generate json nonterminal, to hook the
stuff into the grammar.
(yybadtoken): Handle JKSW and HASH_J tokens.

* lex.yy.c.shipped, y.tab.c.shipped, y.tab.h.shipped:
Updated.

1 files changed, 15 insertions, 0 deletions

diff --git a/parser.c b/parser.c
index c6a291fa..1037cc27 100644
--- a/parser.c
+++ b/parser.c
@@ -73,6 +73,7 @@ val parser_s, unique_s, circref_s;
 val listener_hist_len_s, listener_multi_line_p_s, listener_sel_inclusive_p_s;
 val listener_pprint_s, listener_greedy_eval_s;
 val rec_source_loc_s;
+val json_s;
 val intr_s;
 static lino_t *lino_ctx;
 static int repl_level = 0;
@@ -1251,6 +1252,12 @@ static int is_balanced_line(const wchar_t *line, void *ctx)
         else
           state[++sp] = ST_BKT;
         break;
+      case '{':
+        if (state[sp] == ST_BRC)
+          count[sp]++;
+        else
+          state[++sp] = ST_BRC;
+        break;
       case ')': case ']': case '}':
         {
           enum state match = ST_START;
@@ -1824,6 +1831,12 @@ static_def(lino_os_t linenoise_txr_binding =
                         lino_open, lino_open8, lino_fdopen, lino_close,
                         wide_display_char_p));
 
+static val me_json(val form, val menv)
+{
+  (void) menv;
+  return cons(quote_s, cdr(form));
+}
+
 void parse_init(void)
 {
   parser_s = intern(lit("parser"), user_package);
@@ -1835,6 +1848,7 @@ void parse_init(void)
   listener_pprint_s = intern(lit("*listener-pprint-p*"), user_package);
   listener_greedy_eval_s = intern(lit("*listener-greedy-eval-p*"), user_package);
   rec_source_loc_s = intern(lit("*rec-source-loc*"), user_package);
+  json_s = intern(lit("json"), user_package);
   unique_s = gensym(nil);
   protect(&stream_parser_hash, &unique_s, &catch_all, convert(val *, 0));
   stream_parser_hash = make_hash(t, nil, nil);
@@ -1852,4 +1866,5 @@ void parse_init(void)
   reg_fun(intern(lit("parser-errors"), system_package), func_n1(parser_errors));
   reg_fun(intern(lit("parser-eof"), system_package), func_n1(parser_eof));
   reg_fun(intern(lit("repl"), system_package), func_n4(repl));
+  reg_mac(json_s, func_n2(me_json));
 }