From 264720be8ea9bde2ac8c8f40aa1708fecd9051d0 Mon Sep 17 00:00:00 2001
From: Howard Abrams <howard.abrams@workday.com>
Date: Wed, 5 Jul 2023 10:18:18 -0700
Subject: [PATCH] Wrote functions to change from camelCase to snake_case.

Need to also do something for dashed case (Lisp case?).
---
 ha-config.org      |  2 +-
 ha-programming.org | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/ha-config.org b/ha-config.org
index 4408a96..468aa47 100644
--- a/ha-config.org
+++ b/ha-config.org
@@ -562,7 +562,7 @@ Can’t remember all the shortcuts on the ~g~ key, and =which-key= displays the
              ;; These go into operator mode, so the key sequence, g U i o
              ;; upper cases the symbol at point:
              "g u" '("downcase" . evil-downcase)
-             "g U" '("upcase" . evil-case)
+             "g U" '("upcase" . evil-upcase)
              "g ~" '("invert case" . evil-invert-case)
 
              ;; Use this ALL the time:
diff --git a/ha-programming.org b/ha-programming.org
index 6f1daca..6b5718b 100644
--- a/ha-programming.org
+++ b/ha-programming.org
@@ -557,6 +557,63 @@ While there are language-specific ways to rename variables and functions, [[http
     :config
     (ha-leader "s e" '("iedit" . iedit-mode)))
 #+end_src
+** Case Conversion
+Sure we can upper– and lower–case stuff, but can we change from Camel to Snake case and back? For instance, =fooBarBaz=, would with ~z s~ keybinding, change to =foo_bar_baz= (and repeating that sequence would return it to =fooBarBaz=).
+
+#+begin_src emacs-lisp
+  (defun get-bounds-of-symbol ()
+    "Return a list of the start and end of the current symbol at point.
+  Return the start and end of region, if the region is active."
+   (if (region-active-p)
+        (cons (region-beginning) (region-end))
+     (bounds-of-thing-at-point 'symbol)))
+
+  (defun camel-to-snake-case ()
+    "Convert the active region or current symbol to snake case.
+  For instance, fooBarBaz will be foo_bar_baz."
+    (interactive)
+    (cl-destructuring-bind (start . end) (get-bounds-of-symbol)
+      (save-excursion
+        (goto-char start)
+        (narrow-to-region start end)
+        (let ((case-fold-search nil))
+          (while (re-search-forward (rx (group (one-or-more upper))) nil t)
+            (replace-match (concat "_" (downcase (match-string 1))) t nil)))
+        (widen))))
+
+  (defun snake-to-camel-case ()
+    "Convert the active region or current symbol to camel case.
+  For instance, foo_bar_baz will be fooBarBaz."
+    (interactive)
+    (cl-destructuring-bind (start . end) (get-bounds-of-symbol)
+      (save-excursion
+        (goto-char start)
+        (narrow-to-region start end)
+        (let ((case-fold-search nil))
+          (while (re-search-forward (rx "_" (group  alpha)) nil t)
+            (replace-match (upcase (match-string 1)) t nil)))
+        (widen))))
+
+  (defun toggle-snake-to-camel-case ()
+    "Toggle current symbol from snake to camel, and visa-versa."
+    (interactive)
+    (cl-destructuring-bind (start . end) (get-bounds-of-symbol)
+      (save-excursion
+        (goto-char start)
+        (if (looking-at (rx (zero-or-more alphanumeric) "_"))
+            (snake-to-camel-case)
+          (camel-to-snake-case)))))
+#+end_src
+And we can put this on the ~z~ keybinding:
+#+begin_src emacs-lisp
+  (use-package evil
+    :general
+    (:states '(normal visual motion operator)
+             "z s" '("toggle snake/camel" . toggle-snake-to-camel-case)
+             "z S" '("to snake case" . camel-to-snake-case)
+             "z C" '("to camel case" . snake-to-camel-case)))
+#+end_src
+I would like to have this bound on the ~g~ sequence, but that is crowded.
 ** Commenting
 I like =comment-dwim= (~M-;~), and I like =comment-box=, but I have an odd personal style that I like to codify: