Fix double backslash issue

jsonian-tests.el

@@ -858,5 +858,24 @@ If START and END are provided, they are set as point and mark."
       (should (eq major-mode 'jsonian-mode))
       (remove-hook 'jsonian-edit-string-hook hook-fn))))
 
+(ert-deftest jsonian-special-chars ()
+  "Test `jsonian--intern-special-chars' and `jsonian--unintern-special-chars' translate properly"
+  (with-temp-buffer
+    (mapc (lambda (testcase)
+            (let ((raw (car testcase))
+                  (escaped (cdr testcase)))
+              (insert escaped)
+              (jsonian--unintern-special-chars (current-buffer))
+              (should (equal (buffer-string) raw))
+              (jsonian--intern-special-chars (current-buffer))
+              (should (equal (buffer-string) escaped))
+              (delete-region (point-min) (point-max))))
+          '(("\t" . "\\t")
+            ("\n" . "\\n")
+            ("\"" . "\\\"")
+            ("\\" . "\\\\")
+            ("\\\n" . "\\\\\\n"))))
+  nil)
+
 (provide 'jsonian-tests)
 ;;; jsonian-tests.el ends here

jsonian.el

@@ -1136,10 +1136,13 @@ BUFFER defaults to the current buffer."
 
 (defun jsonian--intern-special-chars (buffer)
   "Translates whitespace operators to their ansi equivalents in BUFFER.
-This means replacing '\n' with '\\n', '\t' with '\\t'."
+This means replacing '\n' with '\\n', '\t' with '\\t', and escaping quotes and backslashes"
   (with-current-buffer buffer
     (save-excursion
       (goto-char (point-min))
+      (while (search-forward "\\" nil t)
+        (replace-match "\\\\\\\\"))
+      (goto-char (point-min))
       (while (search-forward "\n" nil t)
         (replace-match "\\\\n"))
       (goto-char (point-min))
@@ -1151,18 +1154,18 @@ This means replacing '\n' with '\\n', '\t' with '\\t'."
 
 (defun jsonian--unintern-special-chars (buffer)
   "Translate special characters to their unescaped equivalents in BUFFER.
-This means replacing '\\n' with '\n' and '\\t' with '\t'."
+This means replacing '\\n' with '\n' and '\\t' with '\t' and unescaping escaped characters."
   (with-current-buffer buffer
     (save-excursion
       (goto-char (point-min))
-      (while (search-forward "\\n" nil t)
-        (replace-match "\n"))
-      (goto-char (point-min))
-      (while (search-forward "\\t" nil t)
-        (replace-match "\t"))
-      (goto-char (point-min))
-      (while (search-forward "\\\"" nil t)
-        (replace-match "\"")))))
+      (while (search-forward "\\" nil t)
+        (let ((c (char-after)))
+          (delete-region (1- (point)) (1+ (point)))
+          (insert
+           (cond
+            ((eql c ?t) ?\t)
+            ((eql c ?n) ?\n)
+            (t c))))))))
 
 (defun jsonian-edit-mode-return ()
   "Jump back from `json-edit-string', actualizing the change made."