(in-package :com.superadditive.incf-cl)
;;; Copyright (c) 2008 Juan M. Bello Rivas <jmbr@superadditive.com>
;;;
;;; Permission is hereby granted, free of charge, to any person
;;; obtaining a copy of this software and associated documentation
;;; files (the "Software"), to deal in the Software without
;;; restriction, including without limitation the rights to use, copy,
;;; modify, merge, publish, distribute, sublicense, and/or sell copies
;;; of the Software, and to permit persons to whom the Software is
;;; furnished to do so, subject to the following conditions:
;;;
;;; The above copyright notice and this permission notice shall be
;;; included in all copies or substantial portions of the Software.
;;;
;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
;;; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
;;; DEALINGS IN THE SOFTWARE.
(defun ensure-and-copy-list (x)
(if (listp x)
(copy-list x)
(list x)))
(defun nest-list (function initial-values &key test test-not n (m 1) max)
"Returns a list of the results of applying FUNCTION successively to
INITIAL-VALUES and continuing until applying TEST (respectively
TEST-NOT) to the result is non NIL.
If M is specified, then NEST-LIST supplies the M most recent results
as arguments for TEST (respectivelly TEST-NOT) at each step.
If MAX is specified then FUNCTION is applied at most MAX times."
(check-type function function)
(when max
(assert (not (minusp max))))
(let* ((initial-values (ensure-and-copy-list initial-values))
(l (length initial-values))
(n (or n l))
(test (if (or test test-not)
(canonicalize-test test test-not)
nil))
(max (or max -1)))
(%nest-list function
(if (> m l)
(%nest-list function initial-values nil n 0 (- m l))
initial-values)
test
n
m
max)))
(defun %nest-list (function initial-values test n m max)
(assert (and (plusp n) (>= m 0)))
(do ((max max (1- max))
(splice
(last initial-values)
(setf (rest splice) (cons (apply function (last initial-values n))
nil))))
((or (= max 0)
(if test
(not (apply test (last initial-values m)))
nil))
initial-values)))
(defun nest (function initial-values &key test test-not n (m 1) max)
;; XXX - This is good enough for the moment.
(first (last (nest-list function
initial-values
:test test :test-not test-not
:n n :m m :max max))))
