Function: viper-ring-insert

viper-ring-insert is a byte-compiled function defined in viper-util.el.gz.

Signature

(viper-ring-insert RING ITEM)

Source Code

;; Defined in /usr/src/emacs/lisp/emulation/viper-util.el.gz
(defun viper-ring-insert (ring item)
  (let* ((ln (ring-length ring))
	 (vec (cdr (cdr ring)))
	 (veclen (length vec))
	 (hd (car ring))
	 (vecpos-after-hd (if (= hd 0) ln hd))
	 (idx ln))

    (if (= ln veclen)
	(progn
	  (aset vec hd item) ; hd is always 1+ the actual head index in vec
	  (setcar ring (ring-plus1 hd ln)))
      (setcar (cdr ring) (1+ ln))
      (setcar ring (ring-plus1 vecpos-after-hd (1+ ln)))
      (while (and (>= idx vecpos-after-hd) (> ln 0))
	(aset vec idx (aref vec (1- idx)))
	(setq idx (1- idx)))
      (aset vec vecpos-after-hd item))
    item))