Refactoring: move UTF-8 decoding functions into coding.h.

json_make_string and json_build_string are generally useful and not
JSON-specific.  Move them to coding.[ch].

* src/coding.h (build_utf8_string): Move from json.c.

* src/coding.c (make_utf8_string): Move from json.c.

* src/json.c (json_make_string, json_build_string): Move to
coding.[ch].  Split out JSON-specific comment.
(json_parse_error, Fjson_serialize, json_to_lisp): Fix callers.

* src/emacs-module.c (module_make_function, module_make_string): Use
new functions.
(module_decode, module_decode_copy): Remove.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/coding.c b/src/coding.c
index 2c6b2c4d051..71f687a14e3 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -6353,6 +6353,25 @@ utf8_string_p (Lisp_Object string)
   return check_utf_8 (&coding) != -1;
 }
 
+Lisp_Object
+make_utf8_string (const char *data, ptrdiff_t size)
+{
+  ptrdiff_t chars, bytes;
+  parse_str_as_multibyte ((const unsigned char *) data, size, &chars, &bytes);
+  /* If DATA is a valid UTF-8 string, we can convert it to a Lisp
+     string directly.  Otherwise, we need to decode it.  */
+  if (chars == size || bytes == size)
+    return make_specified_string (data, chars, size, true);
+  else
+    {
+      struct coding_system coding;
+      setup_coding_system (Qutf_8_unix, &coding);
+      coding.mode |= CODING_MODE_LAST_BLOCK;
+      coding.source = (const unsigned char *) data;
+      decode_coding_object (&coding, Qnil, 0, 0, size, size, Qt);
+      return coding.dst_object;
+    }
+}
 
 /* Detect how end-of-line of a text of length SRC_BYTES pointed by
    SOURCE is encoded.  If CATEGORY is one of