From bb2d155ef7ae73a00eba53ed7e0d1acee6c0902e Mon Sep 17 00:00:00 2001
From: Artur Malabarba <bruce.connor.am@gmail.com>
Date: Tue, 18 Nov 2014 16:35:19 +0000
Subject: Define sorted insertion macro.

---
 sx.el | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'sx.el')

diff --git a/sx.el b/sx.el
index 64c555c..387c6bb 100644
--- a/sx.el
+++ b/sx.el
@@ -27,6 +27,21 @@
 
 ;;; Utility Functions
 
+(defmacro sx-sorted-insert-skip-first (newelt list &optional predicate)
+  "Inserted NEWELT into LIST sorted by PREDICATE.
+This is designed for the (site id id ...) lists. So the first car
+is intentionally skipped."
+  `(let ((tail ,list)
+         (x ,newelt))
+     ;; The first element is never less-than.
+     (while (and 
+             ;; We're at the end.
+             (cdr-safe tail)
+             ;; We're at the right place.
+             (,(or predicate #'<) x (cadr tail)))
+       (setq tail (cdr tail)))
+     (setcdr tail (cons x (cdr tail)))))
+
 (defun sx-message (format-string &rest args)
   "Display a message"
   (message "[stack] %s" (apply #'format format-string args)))
-- 
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