First commit.

lisp/ux/undo.el

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+;;; undo.el --- Configure Emacs undo -*- lexical-binding: t; -*-
+;;; Commentary:
+;;; Code:
+
+(defconst *user-undo-tree-cache-directory*
+  (path-join *user-cache-directory* "undo-tree")
+  "Path to user's undo-tree cache store.")
+
+
+;;; (Bindings) ;;;
+(user/bind-key-global :basic :undo 'undo)
+
+(use-package undo-tree
+  :bind-wrap
+  (([remap undo] . undo-tree-undo)
+   ([remap redo] . undo-tree-redo)
+   ((:key :basic :undo) . undo-tree-undo)
+   ((:key :basic :redo) . undo-tree-redo)
+   ((:key :util :undo-tree) . undo-tree-visualize))
+  :config
+  ;; Ensure that cache store exists.
+  (make-directory *user-undo-tree-cache-directory* t)
+
+  (validate-setq
+   ;; Set up undo history cache store.
+   undo-tree-history-directory-alist
+   `((".*" . ,*user-undo-tree-cache-directory*))
+   ;; Persistent undo history.
+   undo-tree-auto-save-history t
+   ;; Don't display in mode-line.
+   undo-tree-mode-lighter ""
+   ;; Display time stamps in visualizer by default.
+   undo-tree-visualizer-timestamps t
+   ;; Display diffs in visualizer by default.
+   undo-tree-visualizer-diff t)
+
+  ;; Compress undo history.
+  (defadvice undo-tree-make-history-save-file-name
+      (after undo-tree activate)
+    (validate-setq ad-return-value (concat ad-return-value ".gz")))
+
+  (global-undo-tree-mode t))
+
+
+(provide 'ux/undo)
+;;; undo.el ends here