Commit 6fb45b7b authored by Stefan Monnier's avatar Stefan Monnier
Browse files

* lisp/emacs-lisp/cl-extra.el (cl--random-state): New defstruct

(cl--random-state, cl--random-time): Move from cl-lib.el.
(cl-random): Use struct accessors.
(cl-random-state-p): Remove, provided by the defstruct.
(cl-make-random-state): Rewrite to struct constructor.
parent 7618d29d
......@@ -437,22 +437,38 @@ as an integer unless JUNK-ALLOWED is non-nil."
;; Random numbers.
(defun cl--random-time ()
(let* ((time (copy-sequence (current-time-string))) (i (length time)) (v 0))
(while (>= (cl-decf i) 0) (setq v (+ (* v 3) (aref time i))))
;;;###autoload (autoload 'cl-random-state-p "cl-extra")
(cl-defstruct (cl--random-state
(:copier nil)
(:predicate cl-random-state-p)
(:constructor nil)
(:constructor cl--make-random-state (vec)))
(i -1) (j 30) vec)
(defvar cl--random-state (cl--make-random-state (cl--random-time)))
(defun cl-random (lim &optional state)
"Return a random nonnegative number less than LIM, an integer or float.
Optional second arg STATE is a random-state object."
(or state (setq state cl--random-state))
;; Inspired by "ran3" from Numerical Recipes. Additive congruential method.
(let ((vec (aref state 3)))
(let ((vec (cl--random-state-vec state)))
(if (integerp vec)
(let ((i 0) (j (- 1357335 (abs (% vec 1357333)))) (k 1))
(aset state 3 (setq vec (make-vector 55 nil)))
(setf (cl--random-state-vec state)
(setq vec (make-vector 55 nil)))
(aset vec 0 j)
(while (> (setq i (% (+ i 21) 55)) 0)
(aset vec i (setq j (prog1 k (setq k (- j k))))))
(while (< (setq i (1+ i)) 200) (cl-random 2 state))))
(let* ((i (aset state 1 (% (1+ (aref state 1)) 55)))
(j (aset state 2 (% (1+ (aref state 2)) 55)))
(let* ((i (cl-callf (lambda (x) (% (1+ x) 55)) (cl--random-state-i state)))
(j (cl-callf (lambda (x) (% (1+ x) 55)) (cl--random-state-j state)))
(n (logand 8388607 (aset vec i (- (aref vec i) (aref vec j))))))
(if (integerp lim)
(if (<= lim 512) (% n lim)
......@@ -466,17 +482,10 @@ Optional second arg STATE is a random-state object."
(defun cl-make-random-state (&optional state)
"Return a copy of random-state STATE, or of the internal state if omitted.
If STATE is t, return a new state object seeded from the time of day."
(cond ((null state) (cl-make-random-state cl--random-state))
((vectorp state) (copy-tree state t))
((integerp state) (vector 'cl--random-state-tag -1 30 state))
(t (cl-make-random-state (cl--random-time)))))
(defun cl-random-state-p (object)
"Return t if OBJECT is a random-state object."
(and (vectorp object) (= (length object) 4)
(eq (aref object 0) 'cl--random-state-tag)))
(unless state (setq state cl--random-state))
(if (cl-random-state-p state)
(copy-tree state t)
(cl--make-random-state (if (integerp state) state (cl--random-time)))))
;; Implementation limits.
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