Emacs: Add next-register and prev-register.

init.d/text/common.el

@@ -1,6 +1,6 @@
 ;;; common.el --- Common settings for text files. -*- lexical-binding: t; -*-
 
-;; Time-stamp: <2020-02-18T19:27:15+0100>
+;; Time-stamp: <2020-02-19T01:15:14+0100>
 
 ;;; Commentary:
 
@@ -16,9 +16,54 @@
   (fill-column 80)                     ; Documents are 80 chars wide by default.
   (word-wrap t)                        ; Wrap at word for continuation lines.
 
+  :config
+  (defvar my/current-marker-register 0
+    "An index to the current marker register.")
+
+  (defun my/sort-marker-register-elements (a b)
+    "Returns `t' if the file name is the same and A < B."
+    (and (string= (buffer-file-name (marker-buffer (cdr a)))
+                  (buffer-file-name (marker-buffer (cdr b))))
+         (< (marker-position (cdr a))
+            (marker-position (cdr b)))))
+
+  (defun my/marker-registers ()
+    "Returns all registers which markers."
+    (let (result)
+      (dolist (item register-alist)
+        (when (markerp (cdr item))
+          (setq result (cons item result))))
+      (sort result 'my/sort-marker-register-elements)))
+
+  (defun my/next-register ()
+    "Jump to next register."
+    (interactive)
+    (setq my/current-marker-register (+ my/current-marker-register 1))
+    (when (>= my/current-marker-register (length (my/marker-registers)))
+      (setq my/current-marker-register 0))
+    (let (register-element register-name)
+      (setq register-element
+            (car (nthcdr my/current-marker-register (my/marker-registers))))
+      (setq register-name (car register-element))
+      (register-to-point register-name)))
+
+  (defun my/prev-register ()
+    "Jump to previous register."
+    (interactive)
+    (setq my/current-marker-register (- my/current-marker-register 1))
+    (when (< my/current-marker-register 0)
+      (setq my/current-marker-register (- (length (my/marker-registers)) 1)))
+    (let (register-element register-name)
+      (setq register-element
+            (car (nthcdr my/current-marker-register (my/marker-registers))))
+      (setq register-name (car register-element))
+      (register-to-point register-name)))
+
   :bind
   ("C-r" . jump-to-register)            ; Move point to location in register.
   ("C-S-r" . point-to-register)         ; Store location of point in register.
+  ("C-<f5>" . my/prev-register)         ; Jump to previous marker register.
+  ("C-<f6>" . my/next-register)         ; Jump to next marker register.
 
   :hook
   (text-mode . auto-fill-mode)          ; Enable word-wrapping at fill-column.