;;;; -- WHN 20000127
(declaim (maybe-inline
- tree-equal nth %setnth nthcdr last make-list append
- nconc member member-if member-if-not tailp adjoin union
+ tree-equal nth %setnth nthcdr last last1 make-list append
+ nconc nconc2 member member-if member-if-not tailp adjoin union
nunion intersection nintersection set-difference nset-difference
set-exclusive-or nset-exclusive-or subsetp acons assoc
assoc-if assoc-if-not rassoc rassoc-if rassoc-if-not subst subst-if
(fast-nthcdr (mod n i) r-i))
(declare (type index i)))))))
+(defun last1 (list)
+ #!+sb-doc
+ "Return the last cons (not the last element) of a list"
+ (let ((rest list)
+ (list list))
+ (loop (unless (consp rest) (return list))
+ (shiftf list rest (cdr rest)))))
+
(defun last (list &optional (n 1))
#!+sb-doc
"Return the last N conses (not the last element!) of a list."
- (if (typep n 'index)
- (do ((checked-list list (cdr checked-list))
- (returned-list list)
- (index 0 (1+ index)))
- ((atom checked-list) returned-list)
- (declare (type index index))
- (if (>= index n)
- (pop returned-list)))
- list))
+ (if (eql n 1)
+ (last1 list)
+ (if (typep n 'index)
+ (do ((checked-list list (cdr checked-list))
+ (returned-list list)
+ (index 0 (1+ index)))
+ ((atom checked-list) returned-list)
+ (declare (type index index))
+ (if (>= index n)
+ (pop returned-list)))
+ list)))
(defun list (&rest args)
#!+sb-doc
(declare (type index size))
(do ((count size (1- count))
(result '() (cons initial-element result)))
- ((zerop count) result)
+ ((<= count 0) result)
(declare (type index count))))
\f
(defun append (&rest lists)
(return top-of-top)))
(t (fail top-of-top)))))))
+(defun nconc2 (x y)
+ (if (null x) y
+ (let ((z x)
+ (rest (cdr x)))
+ (loop
+ (unless (consp rest)
+ (rplacd z y)
+ (return x))
+ (shiftf z rest (cdr rest))))))
+
(defun nreconc (x y)
#!+sb-doc
"Return (NCONC (NREVERSE X) Y)."