Merge pull request #259 from vermiculus/bind-answer-sorting-to-a-key

Bind answer sorting to a key

3 files changed, 34 insertions, 4 deletions

diff --git a/sx-question-mode.el b/sx-question-mode.el
index 6125416..846ad7f 100644
--- a/sx-question-mode.el
+++ b/sx-question-mode.el
@@ -214,6 +214,7 @@ Letters do not insert themselves; instead, they are commands.
    ("v" sx-visit-externally)
    ("u" sx-upvote)
    ("d" sx-downvote)
+   ("O" sx-question-mode-order-by)
    ("q" quit-window)
    (" " scroll-up-command)
    ("a" sx-answer)
@@ -256,6 +257,18 @@ query the api."
   (unless (derived-mode-p 'sx-question-mode)
     (error "Not in `sx-question-mode'")))
 
+(defun sx-question-mode-order-by (sort)
+  "Order answers in the current buffer by the method SORT.
+Sets `sx-question-list--order' and then calls
+`sx-question-list-refresh' with `redisplay'."
+  (interactive
+   (list (let ((order (sx-completing-read "Order answers by: "
+                       (mapcar #'car sx-question-mode--sort-methods))))
+           (cdr-safe (assoc-string order sx-question-mode--sort-methods)))))
+  (when (and sort (functionp sort))
+    (setq sx-question-mode-answer-sort-function sort)
+    (sx-question-mode-refresh 'no-update)))
+
 (provide 'sx-question-mode)
 ;;; sx-question-mode.el ends here
 
diff --git a/sx-question-print.el b/sx-question-print.el
index 6c85d5f..c350d8c 100644
--- a/sx-question-print.el
+++ b/sx-question-print.el
@@ -148,13 +148,24 @@ replaced with the comment."
   :type 'boolean
   :group 'sx-question-mode)
 
+(defconst sx-question-mode--sort-methods
+  (let ((methods
+         '(("Higher-scoring" . sx-answer-higher-score-p)
+           ("Newer"          . sx-answer-newer-p)
+           ("More active"    . sx-answer-more-active-p))))
+    (append (mapcar (lambda (x) (cons (concat (car x) " first") (cdr x)))
+              methods)
+            (mapcar (lambda (x) (cons (concat (car x) " last")
+                                 (sx--invert-predicate (cdr x))))
+              methods))))
+
 (defcustom sx-question-mode-answer-sort-function
   #'sx-answer-higher-score-p
   "Function used to sort answers in the question buffer."
-  :type '(choice
-          (const :tag "Higher-scoring first" sx-answer-higher-score-p)
-          (const :tag "Newer first"          sx-answer-newer-p)
-          (const :tag "More active first"    sx-answer-more-active-p))
+  :type
+  (cons 'choice
+        (mapcar (lambda (x) `(const :tag ,(car x) ,(cdr x)))
+          sx-question-mode--sort-methods))
   :group 'sx-question-mode)
 
 (defcustom sx-question-mode-use-images
diff --git a/sx.el b/sx.el
index ccad1b0..501f1e0 100644
--- a/sx.el
+++ b/sx.el
@@ -340,6 +340,12 @@ GET-FUNC and performs the actual comparison."
   "Return STRING with consecutive whitespace squashed together."
   (replace-regexp-in-string "[ 	\r\n]+" " " string))
 
+(defun sx--invert-predicate (predicate)
+  "Return PREDICATE function with arguments inverted.
+For instance (sx--invert-predicate #'<) is the same as #'>.
+Note this is not the same as negating PREDICATE."
+  (lambda (&rest args) (apply predicate (reverse args))))
+
 
 ;;; Printing request data
 (defvar sx--overlays nil