emacs: Create the increment package

1 files changed, 84 insertions, 0 deletions

diff --git a/.config/emacs/increment.el b/.config/emacs/increment.el
new file mode 100644
index 0000000..ade0246
--- /dev/null
+++ b/.config/emacs/increment.el
@@ -0,0 +1,84 @@
+;;; increment.el -- Increment numbers at point  -*- lexical-binding: t; -*-
+
+(defun increment--number-to-binary-string (number)
+  (let (s)
+    (while (not (= number 0))
+      (setq s (concat (if (= 1 (logand number 1)) "1" "0") s)
+            number (lsh number -1)))
+    (when (string= s "")
+      (setq s "0"))
+    s))
+
+(defun increment--format-number-with-base
+    (number base leading-zeros buffer-substr hex-style)
+  (let* ((neg (> 0 number))
+         (number (abs number))
+         (number-string
+          (cond ((= base  2) (increment--number-to-binary-string number))
+                ((= base  8) (format "%o" number))
+                ((= base 10) (number-to-string number))
+                ((= base 16) (format (if (eq hex-style 'lower)
+                                         "%x"
+                                       "%X")
+                                     number))
+                ((t (error (format "Invalid base %d") base)))))
+         (length-diff (- (length buffer-substr)
+                         (length number-string)))
+         (leading-zeros (if (> leading-zeros 0)
+                            (+ leading-zeros length-diff)
+                          0)))
+    (concat
+     (when neg
+       "-")
+     (cond ((= base  2) "0b")
+           ((= base  8) "0o")
+           ((= base 16) "0x"))
+     (when (> leading-zeros 0)
+       (make-string leading-zeros ?0))
+     number-string)))
+
+;;;###autoload
+(defun increment-number-at-point (&optional arg)
+  "Increment the number at point by ARG or 1 if ARG is nil.  If called
+interactively, the universal argument can be used to specify ARG.  If
+the number at point has leading zeros then the width of the number is
+preserved."
+  (interactive "*p")
+  (save-match-data
+    (let* (hex-style
+           (case-fold-search nil)
+           (base (cond
+                  ((thing-at-point-looking-at
+                    "\\(-\\|\\b\\)0x\\(0*\\)\\([0-9a-f]+\\)\\b")
+                   (setq hex-style 'lower)
+                   16)
+                  ((thing-at-point-looking-at
+                    "\\(-\\|\\b\\)0x\\(0*\\)\\([0-9A-Fa-f]+\\)\\b")
+                   16)
+                  ((thing-at-point-looking-at
+                    "\\(-?\\)\\(0*\\)\\([0-9]+\\)")
+                   10)
+                  ((thing-at-point-looking-at
+                    "\\(-\\|\\b\\)0o\\(0*\\)\\([0-7]+\\)\\b")
+                   8)
+                  ((thing-at-point-looking-at
+                    "\\(-\\|\\b\\)0b\\(0*\\)\\([01]+\\)\\b")
+                   2)))
+           (substr (buffer-substring-no-properties (match-beginning 3)
+                                                   (match-end 3)))
+           (sign (if (= (match-beginning 1) (match-end 1)) +1 -1))
+           (result (+ (* (string-to-number substr base) sign)
+                      (or arg 1))))
+      (replace-match (increment--format-number-with-base
+                      result base
+                      (- (match-end 2)
+                         (match-beginning 2))
+                      substr hex-style)))))
+
+;;;###autoload
+(defun decrement-number-at-point (&optional arg)
+  "The same as `increment-number-at-point', but ARG is negated."
+  (interactive "*p")
+  (increment-number-at-point (- (or arg 1))))
+
+(provide 'increment)