Update :emacs sheet

Sync with v1.5 of cheat-sh.el

share/emacs.txt

@@ -2,7 +2,7 @@
 ;; Copyright 2017 by Dave Pearson <davep@davep.org>
 
 ;; Author: Dave Pearson <davep@davep.org>
-;; Version: 1.3
+;; Version: 1.5
 ;; Keywords: docs, help
 ;; URL: https://github.com/davep/cheat-sh.el
 ;; Package-Requires: ((emacs "24"))
@@ -18,6 +18,20 @@
 
 ;;; Code:
 
+(defgroup cheat-sh nil
+  "Interact with cheat.sh."
+  :group 'docs)
+
+(defface cheat-sh-caption
+  '((t :inherit (bold font-lock-function-name-face)))
+  "Face used on captions in the cheat-sh output window."
+  :group 'cheat-sh)
+
+(defcustom cheat-sh-list-timeout (* 60 60 4)
+  "Seconds to wait before deciding the cached sheet list is \"stale\"."
+  :type 'integer
+  :group 'cheat-sh)
+
 (defconst cheat-sh-url "http://cheat.sh/%s?T"
   "URL for cheat.sh.")
 
@@ -44,15 +58,37 @@ text.")
 (defvar cheat-sh-sheet-list nil
   "List of all available sheets.")
 
+(defvar cheat-sh-sheet-list-acquired nil
+  "The time when variable `cheat-sh-sheet-list' was populated.")
+
+(defun cheat-sh-sheet-list-cache ()
+  "Return the list of sheets.
+
+The list is cached in memory, and is considered \"stale\" and is
+refreshed after `cheat-sh-list-timeout' seconds."
+  (when (and cheat-sh-sheet-list-acquired
+             (> (- (time-to-seconds) cheat-sh-sheet-list-acquired) cheat-sh-list-timeout))
+    (setq cheat-sh-sheet-list nil))
+  (or cheat-sh-sheet-list
+      (progn
+        (setq cheat-sh-sheet-list-acquired (time-to-seconds))
+        (setq cheat-sh-sheet-list (split-string (cheat-sh-get ":list") "\n")))))
+
 (defun cheat-sh-read (prompt)
   "Read input from the user, showing PROMPT to prompt them.
 
 This function is used by some `interactive' functions in
 cheat-sh.el to get the item to look up. It provides completion
 based of the sheets that are available on cheat.sh."
-  (completing-read prompt
-                   (or cheat-sh-sheet-list
-                       (setq cheat-sh-sheet-list (split-string (cheat-sh-get ":list") "\n")))))
+  (completing-read prompt (cheat-sh-sheet-list-cache)))
+
+(defun cheat-sh-decorate-results (buffer)
+  "Decorate BUFFER with properties to highlight results."
+  (with-current-buffer buffer
+    (save-excursion
+      (setf (point) (point-min))
+      (while (search-forward-regexp "^\\(#.*\\)$" nil t)
+        (replace-match (propertize (match-string 1) 'font-lock-face 'cheat-sh-caption) nil t)))))
 
 ;;;###autoload
 (defun cheat-sh (thing)
@@ -61,7 +97,8 @@ based of the sheets that are available on cheat.sh."
   (let ((result (cheat-sh-get thing)))
     (if result
         (with-help-window "*cheat.sh*"
-          (princ result))
+          (princ result)
+          (cheat-sh-decorate-results standard-output))
       (error "Can't find anything for %s on cheat.sh" thing))))
 
 ;;;###autoload