Improve 'json-insert' so it doesn't cons a string from JSON

* src/json.c (struct json_buffer_and_size): New member
inserted_bytes.
(json_insert): Instead of creating a string and inserting it
into the current buffer, copy the unibyte text into the gap.
(struct json_insert_data): New member inserted_bytes.
(json_insert_callback): Update commentary.  Pass the
inserted_bytes value to json_insert and on its return copy the
updated value back into DATA.
(Fjson_insert): Decode the unibyte text inserted into the gap.
Call before-change-functions and after-change-functions only
once, before and after processing the insertion of the entire
JSON representation.

* test/src/json-tests.el (json-insert/throw): Adapt to the
modified implementation of json-insert: it no longer calls the
modification hooks once for each inserted chunk of JSON
representation.

1 files changed, 5 insertions, 4 deletions

diff --git a/test/src/json-tests.el b/test/src/json-tests.el
index 911bc49730d..bffee8f39d3 100644
--- a/test/src/json-tests.el
+++ b/test/src/json-tests.el
@@ -272,10 +272,11 @@ Test with both unibyte and multibyte strings."
                   (cl-incf calls)
                   (throw 'test-tag 'throw-value))
                 :local)
-      (should-error
-       (catch 'test-tag
-         (json-insert '((a . "b") (c . 123) (d . [1 2 t :false]))))
-       :type 'no-catch)
+      (should
+       (equal
+        (catch 'test-tag
+          (json-insert '((a . "b") (c . 123) (d . [1 2 t :false]))))
+        'throw-value))
       (should (equal calls 1)))))
 
 (ert-deftest json-serialize/bignum ()