Update src

Author: jcs090218

fextern.el

@@ -32,7 +32,62 @@
 
 ;;; Code:
 
+(require 'cl-lib)
+(require 'subr-x)
 
+(defvar-local fextern-buffer-save-string-md5 nil
+  "Buffer string when buffer is saved; this value encrypted with md5 algorithm.
+This variable is used to check if file are edited externally.")
+
+;;;###autoload
+(defun fextern--update-buffer-save-string (&rest _)
+  "Update variable `fextern-buffer-save-string-md5' once."
+  (setq fextern-buffer-save-string-md5 (md5 (buffer-string))))
+
+;;;###autoload
+(advice-add 'save-buffer :after #'fextern--update-buffer-save-string)
+
+;;;###autoload
+(add-hook 'find-file-hook #'fextern--update-buffer-save-string)
+
+;;
+;; (@* "Util" )
+;;
+
+(defun fextern--file-content (path)
+  "Return PATH file content."
+  (if (file-exists-p path)
+      (with-temp-buffer (insert-file-contents path) (buffer-string))
+    ""))
+
+(defun fextern--valid-buffer-p (buffer)
+  "Return non-nil if BUFFER does exist on disk."
+  (when-let ((bfn (buffer-file-name buffer))) (file-exists-p bfn)))
+
+(defun fextern--valid-buffer-list ()
+  "Return a list of valid buffers."
+  (cl-remove-if-not #'fextern--valid-buffer-p (buffer-list)))
+
+;;
+;; (@* "Core" )
+;;
+
+;;;###autoload
+(defun fextern-buffer-edit-externally-p (&optional buf)
+  "Return non-nil if BUF is edited externally."
+  (let* ((buf (or buf (current-buffer)))
+         (path (buffer-file-name buf))
+         (buffer-saved-md5 (with-current-buffer buf fextern-buffer-save-string-md5))
+         (file-content (fextern--file-content path))
+         (file-content-md5 (md5 file-content)))
+    (not (equal file-content-md5 buffer-saved-md5))))
+
+;;;###autoload
+(defun fextern-buffers-edit-externally ()
+  "Return a list of buffers edit externally."
+  (cl-remove-if-not
+   (lambda (buf) (fextern-buffer-edit-externally-p (get-buffer buf)))
+   (fextern--valid-buffer-list)))
 
 (provide 'fextern)
 ;;; fextern.el ends here