configure switch-to-prev-buffer-skip

when cycling through buffers, skip over a bunch of built-in emacs
buffers. as well, skip over dired-sidebar-mode buffers, as these get
super annoyingly mixed in all over the place at times

emacs.d/functions.el

@@ -0,0 +1,6 @@
+(defun buffer-mode (&optional buffer-or-name)
+  "Returns the major mode associated with a buffer. If buffer-name is ni, return
+current buffer's mode."
+  (buffer-local-value
+   'major-mode
+   (if buffer-or-name (get-buffer buffer-or-name) (current-buffer))))

emacs.d/init.el

@@ -1,4 +1,5 @@
 (dolist (f '("packages.el"
+             "functions.el"
              "later-init.el"
              "ui.el"
              "dired.el"

emacs.d/ui.el

@@ -161,3 +161,29 @@
           compilation-mode))
   (popper-mode t)
   (popper-echo-mode t))
+
+(defcustom gered/buffer-name-skip-regexp
+  (rx bos
+      (or "*Backtrace*"
+          "*Compile-Log*"
+          "*Completions*"
+          "*Messages*"
+          "*package*"
+          "*Warnings*"
+          "*Async-native-compile-log*")
+      eos)
+  "Regular expression matching buffer names to be ignored by `next-buffer' and `previous-buffer'"
+  :type 'regexp)
+
+(defcustom gered/buffer-mode-skip-regexp
+  (rx bos
+      (or "dired-sidebar-mode")
+      eos)
+  "Regular expression matching buffer major modes to be ignored by `next-buffer' and `previous-buffer'"
+  :type 'regexp)
+
+(defun gered/buffer-skip-p (window buffer bury-or-kill)
+  (or (string-match-p gered/buffer-name-skip-regexp (buffer-name buffer))
+      (string-match-p gered/buffer-mode-skip-regexp (symbol-name (buffer-mode buffer)))))
+
+(setq switch-to-prev-buffer-skip 'gered/buffer-skip-p)