clsr/ch-util/src/lists.cl

   1 ;;;
   2 ;;; lists.cl -- various lisp list utilities that make my life easier
   3 ;;;
   4 ;;; Author: Cyrus Harmon <ch-lisp@bobobeach.com>
   5 ;;;
   6
   7 (in-package :ch-util)
   8
   9 ;;; Miscellaneous list utilities
  10
  11 (defun insert-before (new old list)
  12   (labels ((build-list (old c &optional newlist)
  13              (if c
  14                  (if (eq old (car c))
  15                      (append (reverse (cdr c)) (cons (car c) (cons new newlist)))
  16                      (build-list old (cdr c) (cons (car c) newlist)))
  17                  (cons new newlist))))
  18     (reverse (build-list old list))))
  19
  20 (defun insert-before-all (new old list)
  21   (labels ((build-list (old c &optional newlist)
  22              (if c
  23                  (if (eq old (car c))
  24                      (build-list old (cdr c) (cons (car c) (cons new newlist)))
  25                      (build-list old (cdr c) (cons (car c) newlist)))
  26                  newlist)))
  27     (reverse (build-list old list))))
  28
  29 (defun flatten (l)
  30   (mapcan #'(lambda (x)
  31               (cond ((null x) nil)
  32                     ((atom x) (list x))
  33                     (t (flatten x))))
  34           l))
  35