New JSON encoder (bug#70007)

It is in general at least 2x faster than the old encoder and does not
depend on any external library.  Using our own code also gives us
control over translation details: for example, we now have full
bignum support and tighter float formatting.

* src/json.c (json_delete, json_initialized, init_json_functions)
(json_malloc, json_free, init_json, json_out_of_memory)
(json_releae_object, check_string_without_embedded_nulls, json_check)
(json_check_utf8, lisp_to_json_nonscalar_1, lisp_to_json_nonscalar)
(lisp_to_json, json_available_p, ensure_json_available, json_insert)
(json_handle_nonlocal_exit, json_insert_callback):
Remove.  Remaining uses updated.
* src/json.c (json_out_t, symset_t, struct symset_tbl)
(symset_size, make_symset_table, push_symset, pop_symset)
(cleanup_symset_tables, symset_hash, symset_expand, symset_add)
(json_out_grow_buf, cleanup_json_out, json_make_room, JSON_OUT_STR)
(json_out_str, json_out_byte, json_out_fixnum, string_not_unicode)
(json_plain_char, json_out_string, json_out_nest, json_out_unnest)
(json_out_object_cons, json_out_object_hash), json_out_array)
(json_out_float, json_out_bignum, json_out_something)
(json_out_to_string, json_serialize): New.
(Fjson_serialize, Fjson_insert):
New JSON encoder implementation.
* test/src/json-tests.el (json-serialize/object-with-duplicate-keys)
(json-serialize/string): Update tests.

src/emacs.c

@@ -2013,10 +2013,6 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
   init_random ();
   init_xfaces ();
 
-#if defined HAVE_JSON && !defined WINDOWSNT
-  init_json ();
-#endif
-
   if (!initialized)
     syms_of_comp ();
 

src/lisp.h

@@ -4327,7 +4327,6 @@ extern void syms_of_image (void);
 
 #ifdef HAVE_JSON
 /* Defined in json.c.  */
-extern void init_json (void);
 extern void syms_of_json (void);
 #endif
 

src/print.c

@@ -2859,6 +2859,7 @@ decimal point.  0 is not allowed with `e' or `g'.
 A value of nil means to use the shortest notation
 that represents the number without losing information.  */);
   Vfloat_output_format = Qnil;
+  DEFSYM (Qfloat_output_format, "float-output-format");
 
   DEFVAR_BOOL ("print-integers-as-characters", print_integers_as_characters,
 	       doc: /* Non-nil means integers are printed using characters syntax.

test/src/json-tests.el

@@ -126,11 +126,38 @@
 
 (ert-deftest json-serialize/object-with-duplicate-keys ()
   (skip-unless (fboundp 'json-serialize))
-  (let ((table (make-hash-table :test #'eq)))
-    (puthash (copy-sequence "abc") [1 2 t] table)
-    (puthash (copy-sequence "abc") :null table)
-    (should (equal (hash-table-count table) 2))
-    (should-error (json-serialize table) :type 'wrong-type-argument)))
+
+  (dolist (n '(1 5 20 100))
+    (let ((symbols (mapcar (lambda (i) (make-symbol (format "s%d" i)))
+                           (number-sequence 1 n)))
+          (expected (concat "{"
+                            (mapconcat (lambda (i) (format "\"s%d\":%d" i i))
+                                       (number-sequence 1 n) ",")
+                            "}")))
+      ;; alist
+      (should (equal (json-serialize
+                      (append
+                       (cl-mapcar #'cons
+                                  symbols (number-sequence 1 n))
+                       (cl-mapcar #'cons
+                                  symbols (number-sequence 1001 (+ 1000 n)))))
+                     expected))
+      ;; plist
+      (should (equal (json-serialize
+                      (append
+                       (cl-mapcan #'list
+                                  symbols (number-sequence 1 n))
+                       (cl-mapcan #'list
+                                  symbols (number-sequence 1001 (+ 1000 n)))))
+                     expected))))
+
+  ;; We don't check for duplicated keys in hash tables.
+  ;; (let ((table (make-hash-table :test #'eq)))
+  ;;   (puthash (copy-sequence "abc") [1 2 t] table)
+  ;;   (puthash (copy-sequence "abc") :null table)
+  ;;   (should (equal (hash-table-count table) 2))
+  ;;   (should-error (json-serialize table) :type 'wrong-type-argument))
+  )
 
 (ert-deftest json-parse-string/object ()
   (skip-unless (fboundp 'json-parse-string))
@@ -173,8 +200,8 @@
   (should (equal (json-serialize ["\nasdфыв\u001f\u007ffgh\t"])
                  "[\"\\nasdфыв\\u001F\u007ffgh\\t\"]"))
   (should (equal (json-serialize ["a\0b"]) "[\"a\\u0000b\"]"))
-  ;; FIXME: Is this the right behavior?
-  (should (equal (json-serialize ["\u00C4\xC3\x84"]) "[\"\u00C4\u00C4\"]")))
+  (should-error (json-serialize ["\xC3\x84"]))
+  (should-error (json-serialize ["\u00C4\xC3\x84"])))
 
 (ert-deftest json-serialize/invalid-unicode ()
   (skip-unless (fboundp 'json-serialize))