Support custom null and false objects when parsing JSON

* doc/lispref/text.texi (Parsing JSON): Describe new :null-object
and :false-object kwargs to json-parse-string and
json-parse-buffer.

* src/json.c
(struct json_configuration): New type.
(json_to_lisp): Accept a struct json_configuration* param.
(json_parse_args): Rename from json_parse_object_type.
(Fjson_parse_string): Rework docstring.
(Fjson_parse_string, Fjson_parse_buffer): Update call to
json_to_lisp.
(syms_of_json): Two new syms, QCnull_object and QCfalse_object.

* test/src/json-tests.el
(json-parse-with-custom-null-and-false-objects): New test.

1 files changed, 29 insertions, 0 deletions

diff --git a/test/src/json-tests.el b/test/src/json-tests.el
index 7a193545b1a..918b2336d0f 100644
--- a/test/src/json-tests.el
+++ b/test/src/json-tests.el
@@ -209,6 +209,35 @@ Test with both unibyte and multibyte strings."
     (should-not (bobp))
     (should (looking-at-p (rx " [456]" eos)))))
 
+(ert-deftest json-parse-with-custom-null-and-false-objects ()
+  (let ((input
+         "{ \"abc\" : [1, 2, true], \"def\" : null, \"abc\" : [9, false] }\n"))
+    (should (equal (json-parse-string input
+                                      :object-type 'plist
+                                      :null-object :json-null
+                                      :false-object :json-false)
+                   '(:abc [9 :json-false] :def :json-null)))
+    (should (equal (json-parse-string input
+                                      :object-type 'plist
+                                      :false-object :json-false)
+                   '(:abc [9 :json-false] :def :null)))
+    (should (equal (json-parse-string input
+                                      :object-type 'alist
+                                      :null-object :zilch)
+                   '((abc . [9 :false]) (def . :zilch))))
+    (should (equal (json-parse-string input
+                                      :object-type 'alist
+                                      :false-object nil
+                                      :null-object nil)
+                   '((abc . [9 nil]) (def))))
+    (let* ((thingy '(1 2 3))
+           (retval (json-parse-string input
+                                      :object-type 'alist
+                                      :false-object thingy
+                                      :null-object nil)))
+      (should (equal retval `((abc . [9 ,thingy]) (def))))
+      (should (eq (elt (cdr (car retval)) 1) thingy)))))
+
 (ert-deftest json-insert/signal ()
   (skip-unless (fboundp 'json-insert))
   (with-temp-buffer