1.0.12.29: optimize POSITION & FIND families for strings

[sbcl/simd.git] / src / code / seq.lisp

;;;; generic SEQUENCEs
;;;;
;;;; KLUDGE: comment from original CMU CL source:
;;;;   Be careful when modifying code. A lot of the structure of the
;;;;   code is affected by the fact that compiler transforms use the
;;;;   lower level support functions. If transforms are written for
;;;;   some sequence operation, note how the END argument is handled
;;;;   in other operations with transforms.

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!IMPL")
\f
;;;; utilities

(defun %check-generic-sequence-bounds (seq start end)
  (let ((length (sb!sequence:length seq)))
    (if (<= 0 start (or end length) length)
        (or end length)
        (sequence-bounding-indices-bad-error seq start end))))

(eval-when (:compile-toplevel :load-toplevel :execute)

(defparameter *sequence-keyword-info*
  ;; (name default supplied-p adjustment new-type)
  `((count nil
           nil
           (etypecase count
             (null (1- most-positive-fixnum))
             (fixnum (max 0 count))
             (integer (if (minusp count)
                          0
                          (1- most-positive-fixnum))))
           (mod #.sb!xc:most-positive-fixnum))
    ,@(mapcan (lambda (names)
                (destructuring-bind (start end length sequence) names
                  (list
                   `(,start
                     0
                     nil
                     (if (<= 0 ,start ,length)
                         ,start
                         (sequence-bounding-indices-bad-error ,sequence ,start ,end))
                     index)
                  `(,end
                    nil
                    nil
                    (if (or (null ,end) (<= ,start ,end ,length))
                        ;; Defaulting of NIL is done inside the
                        ;; bodies, for ease of sharing with compiler
                        ;; transforms.
                        ;;
                        ;; FIXME: defend against non-number non-NIL
                        ;; stuff?
                        ,end
                        (sequence-bounding-indices-bad-error ,sequence ,start ,end))
                    (or null index)))))
              '((start end length sequence)
                (start1 end1 length1 sequence1)
                (start2 end2 length2 sequence2)))
    (key nil
         nil
         (and key (%coerce-callable-to-fun key))
         (or null function))
    (test #'eql
          nil
          (%coerce-callable-to-fun test)
          function)
    (test-not nil
              nil
              (and test-not (%coerce-callable-to-fun test-not))
              (or null function))
    ))

(sb!xc:defmacro define-sequence-traverser (name args &body body)
  (multiple-value-bind (body declarations docstring)
      (parse-body body :doc-string-allowed t)
    (collect ((new-args) (new-declarations) (adjustments))
      (dolist (arg args)
        (case arg
          ;; FIXME: make this robust.  And clean.
          ((sequence)
           (new-args arg)
           (adjustments '(length (length sequence)))
           (new-declarations '(type index length)))
          ((sequence1)
           (new-args arg)
           (adjustments '(length1 (length sequence1)))
           (new-declarations '(type index length1)))
          ((sequence2)
           (new-args arg)
           (adjustments '(length2 (length sequence2)))
           (new-declarations '(type index length2)))
          ((function predicate)
           (new-args arg)
           (adjustments `(,arg (%coerce-callable-to-fun ,arg))))
          (t (let ((info (cdr (assoc arg *sequence-keyword-info*))))
               (cond (info
                      (destructuring-bind (default supplied-p adjuster type) info
                        (new-args `(,arg ,default ,@(when supplied-p (list supplied-p))))
                        (adjustments `(,arg ,adjuster))
                        (new-declarations `(type ,type ,arg))))
                     (t (new-args arg)))))))
      `(defun ,name ,(new-args)
         ,@(when docstring (list docstring))
         ,@declarations
         (let* (,@(adjustments))
           (declare ,@(new-declarations))
           ,@body)))))

;;; SEQ-DISPATCH does an efficient type-dispatch on the given SEQUENCE.
;;;
;;; FIXME: It might be worth making three cases here, LIST,
;;; SIMPLE-VECTOR, and VECTOR, instead of the current LIST and VECTOR.
;;; It tends to make code run faster but be bigger; some benchmarking
;;; is needed to decide.
(sb!xc:defmacro seq-dispatch
    (sequence list-form array-form &optional other-form)
  `(if (listp ,sequence)
       (let ((,sequence (truly-the list ,sequence)))
         (declare (ignorable ,sequence))
         ,list-form)
       ,@(if other-form
             `((if (arrayp ,sequence)
                   (let ((,sequence (truly-the vector ,sequence)))
                     (declare (ignorable ,sequence))
                     ,array-form)
                   ,other-form))
             `((let ((,sequence (truly-the vector ,sequence)))
                 (declare (ignorable ,sequence))
                 ,array-form)))))

(sb!xc:defmacro %make-sequence-like (sequence length)
  #!+sb-doc
  "Return a sequence of the same type as SEQUENCE and the given LENGTH."
  `(seq-dispatch ,sequence
     (make-list ,length)
     (make-array ,length :element-type (array-element-type ,sequence))
     (sb!sequence:make-sequence-like ,sequence ,length)))

(sb!xc:defmacro bad-sequence-type-error (type-spec)
  `(error 'simple-type-error
          :datum ,type-spec
          :expected-type '(satisfies is-a-valid-sequence-type-specifier-p)
          :format-control "~S is a bad type specifier for sequences."
          :format-arguments (list ,type-spec)))

(sb!xc:defmacro sequence-type-length-mismatch-error (type length)
  `(error 'simple-type-error
          :datum ,length
          :expected-type (cond ((array-type-p ,type)
                                `(eql ,(car (array-type-dimensions ,type))))
                               ((type= ,type (specifier-type 'null))
                                '(eql 0))
                               ((cons-type-p ,type)
                                '(integer 1))
                               (t (bug "weird type in S-T-L-M-ERROR")))
          ;; FIXME: this format control causes ugly printing.  There's
          ;; probably some ~<~@:_~> incantation that would make it
          ;; nicer. -- CSR, 2002-10-18
          :format-control "The length requested (~S) does not match the type restriction in ~S."
          :format-arguments (list ,length (type-specifier ,type))))

(sb!xc:defmacro sequence-type-too-hairy (type-spec)
  ;; FIXME: Should this be a BUG? I'm inclined to think not; there are
  ;; words that give some but not total support to this position in
  ;; ANSI.  Essentially, we are justified in throwing this on
  ;; e.g. '(OR SIMPLE-VECTOR (VECTOR FIXNUM)), but maybe not (by ANSI)
  ;; on '(CONS * (CONS * NULL)) -- CSR, 2002-10-18

  ;; On the other hand, I'm not sure it deserves to be a type-error,
  ;; either. -- bem, 2005-08-10
  `(error 'simple-program-error
          :format-control "~S is too hairy for sequence functions."
          :format-arguments (list ,type-spec)))
) ; EVAL-WHEN

(defun is-a-valid-sequence-type-specifier-p (type)
  (let ((type (specifier-type type)))
    (or (csubtypep type (specifier-type 'list))
        (csubtypep type (specifier-type 'vector)))))

;;; It's possible with some sequence operations to declare the length
;;; of a result vector, and to be safe, we really ought to verify that
;;; the actual result has the declared length.
(defun vector-of-checked-length-given-length (vector declared-length)
  (declare (type vector vector))
  (declare (type index declared-length))
  (let ((actual-length (length vector)))
    (unless (= actual-length declared-length)
      (error 'simple-type-error
             :datum vector
             :expected-type `(vector ,declared-length)
             :format-control
             "Vector length (~W) doesn't match declared length (~W)."
             :format-arguments (list actual-length declared-length))))
  vector)
(defun sequence-of-checked-length-given-type (sequence result-type)
  (let ((ctype (specifier-type result-type)))
    (if (not (array-type-p ctype))
        sequence
        (let ((declared-length (first (array-type-dimensions ctype))))
          (if (eq declared-length '*)
              sequence
              (vector-of-checked-length-given-length sequence
                                                     declared-length))))))

(declaim (ftype (function (sequence index) nil) signal-index-too-large-error))
(defun signal-index-too-large-error (sequence index)
  (let* ((length (length sequence))
         (max-index (and (plusp length)
                         (1- length))))
    (error 'index-too-large-error
           :datum index
           :expected-type (if max-index
                              `(integer 0 ,max-index)
                              ;; This seems silly, is there something better?
                              '(integer 0 (0))))))

(defun sequence-bounding-indices-bad-error (sequence start end)
  (let ((size (length sequence)))
    (error 'bounding-indices-bad-error
           :datum (cons start end)
           :expected-type `(cons (integer 0 ,size)
                                 (integer ,start ,size))
           :object sequence)))

(defun array-bounding-indices-bad-error (array start end)
  (let ((size (array-total-size array)))
    (error 'bounding-indices-bad-error
           :datum (cons start end)
           :expected-type `(cons (integer 0 ,size)
                                 (integer ,start ,size))
           :object array)))
\f
(defun elt (sequence index)
  #!+sb-doc "Return the element of SEQUENCE specified by INDEX."
  (seq-dispatch sequence
                (do ((count index (1- count))
                     (list sequence (cdr list)))
                    ((= count 0)
                     (if (endp list)
                         (signal-index-too-large-error sequence index)
                         (car list)))
                  (declare (type (integer 0) count)))
                (progn
                  (when (>= index (length sequence))
                    (signal-index-too-large-error sequence index))
                  (aref sequence index))
                (sb!sequence:elt sequence index)))

(defun %setelt (sequence index newval)
  #!+sb-doc "Store NEWVAL as the component of SEQUENCE specified by INDEX."
  (seq-dispatch sequence
                (do ((count index (1- count))
                     (seq sequence))
                    ((= count 0) (rplaca seq newval) newval)
                  (declare (fixnum count))
                  (if (atom (cdr seq))
                      (signal-index-too-large-error sequence index)
                      (setq seq (cdr seq))))
                (progn
                  (when (>= index (length sequence))
                    (signal-index-too-large-error sequence index))
                  (setf (aref sequence index) newval))
                (setf (sb!sequence:elt sequence index) newval)))

(defun length (sequence)
  #!+sb-doc "Return an integer that is the length of SEQUENCE."
  (seq-dispatch sequence
                (length sequence)
                (length sequence)
                (sb!sequence:length sequence)))

(defun make-sequence (type length &key (initial-element nil iep))
  #!+sb-doc
  "Return a sequence of the given TYPE and LENGTH, with elements initialized
  to INITIAL-ELEMENT."
  (declare (fixnum length))
  (let* ((adjusted-type
          (typecase type
            (atom (cond
                    ((eq type 'string) '(vector character))
                    ((eq type 'simple-string) '(simple-array character (*)))
                    (t type)))
            (cons (cond
                    ((eq (car type) 'string) `(vector character ,@(cdr type)))
                    ((eq (car type) 'simple-string)
                     `(simple-array character ,(if (cdr type)
                                                   (cdr type)
                                                   '(*))))
                    (t type)))
            (t type)))
         (type (specifier-type adjusted-type)))
    (cond ((csubtypep type (specifier-type 'list))
           (cond
             ((type= type (specifier-type 'list))
              (make-list length :initial-element initial-element))
             ((eq type *empty-type*)
              (bad-sequence-type-error nil))
             ((type= type (specifier-type 'null))
              (if (= length 0)
                  'nil
                  (sequence-type-length-mismatch-error type length)))
             ((cons-type-p type)
              (multiple-value-bind (min exactp)
                  (sb!kernel::cons-type-length-info type)
                (if exactp
                    (unless (= length min)
                      (sequence-type-length-mismatch-error type length))
                    (unless (>= length min)
                      (sequence-type-length-mismatch-error type length)))
                (make-list length :initial-element initial-element)))
             ;; We'll get here for e.g. (OR NULL (CONS INTEGER *)),
             ;; which may seem strange and non-ideal, but then I'd say
             ;; it was stranger to feed that type in to MAKE-SEQUENCE.
             (t (sequence-type-too-hairy (type-specifier type)))))
          ((csubtypep type (specifier-type 'vector))
           (cond
             (;; is it immediately obvious what the result type is?
              (typep type 'array-type)
              (progn
                (aver (= (length (array-type-dimensions type)) 1))
                (let* ((etype (type-specifier
                               (array-type-specialized-element-type type)))
                       (etype (if (eq etype '*) t etype))
                       (type-length (car (array-type-dimensions type))))
                  (unless (or (eq type-length '*)
                              (= type-length length))
                    (sequence-type-length-mismatch-error type length))
                  ;; FIXME: These calls to MAKE-ARRAY can't be
                  ;; open-coded, as the :ELEMENT-TYPE argument isn't
                  ;; constant.  Probably we ought to write a
                  ;; DEFTRANSFORM for MAKE-SEQUENCE.  -- CSR,
                  ;; 2002-07-22
                  (if iep
                      (make-array length :element-type etype
                                  :initial-element initial-element)
                      (make-array length :element-type etype)))))
             (t (sequence-type-too-hairy (type-specifier type)))))
          ((and (csubtypep type (specifier-type 'sequence))
                (find-class adjusted-type nil))
           (let* ((class (find-class adjusted-type nil)))
             (unless (sb!mop:class-finalized-p class)
               (sb!mop:finalize-inheritance class))
             (if iep
                 (sb!sequence:make-sequence-like
                  (sb!mop:class-prototype class) length
                  :initial-element initial-element)
                 (sb!sequence:make-sequence-like
                  (sb!mop:class-prototype class) length))))
          (t (bad-sequence-type-error (type-specifier type))))))
\f
;;;; SUBSEQ
;;;;
;;;; The support routines for SUBSEQ are used by compiler transforms,
;;;; so we worry about dealing with END being supplied or defaulting
;;;; to NIL at this level.

(defun string-subseq* (sequence start end)
  (with-array-data ((data sequence)
                    (start start)
                    (end end)
                    :force-inline t
                    :check-fill-pointer t)
    (declare (optimize (speed 3) (safety 0)))
    (string-dispatch ((simple-array character (*))
                      (simple-array base-char (*))
                      (vector nil))
        data
        (subseq data start end))))

(defun vector-subseq* (sequence start end)
  (declare (type vector sequence))
  (declare (type index start)
           (type (or null index) end))
  (with-array-data ((data sequence)
                    (start start)
                    (end end)
                    :check-fill-pointer t
                    :force-inline t)
    (let* ((copy (%make-sequence-like sequence (- end start)))
           (setter (!find-data-vector-setter copy))
           (reffer (!find-data-vector-reffer data)))
      (declare (optimize (speed 3) (safety 0)))
      (do ((old-index start (1+ old-index))
           (new-index 0 (1+ new-index)))
          ((= old-index end) copy)
        (declare (index old-index new-index))
        (funcall setter copy new-index
                 (funcall reffer data old-index))))))

(defun list-subseq* (sequence start end)
  (declare (type list sequence)
           (type unsigned-byte start)
           (type (or null unsigned-byte) end))
  (flet ((oops ()
           (sequence-bounding-indices-bad-error sequence start end)))
    (let ((pointer sequence))
      (unless (zerop start)
        ;; If START > 0 the list cannot be empty. So CDR down to
        ;; it START-1 times, check that we still have something, then
        ;; CDR the final time.
        ;;
        ;; If START was zero, the list may be empty if END is NIL or
        ;; also zero.
        (when (> start 1)
          (setf pointer (nthcdr (1- start) pointer)))
        (if pointer
            (pop pointer)
            (oops)))
      (if end
          (let ((n (- end start)))
            (declare (integer n))
            (when (minusp n)
              (oops))
            (when (plusp n)
              (let* ((head (list nil))
                     (tail head))
                (macrolet ((pop-one ()
                             `(let ((tmp (list (pop pointer))))
                                (setf (cdr tail) tmp
                                      tail tmp))))
                  ;; Bignum case
                  (loop until (fixnump n)
                        do (pop-one)
                           (decf n))
                  ;; Fixnum case, but leave last element, so we should
                  ;; still have something left in the sequence.
                  (let ((m (1- n)))
                    (declare (fixnum m))
                    (loop repeat m
                          do (pop-one)))
                  (unless pointer
                    (oops))
                  ;; OK, pop the last one.
                  (pop-one)
                  (cdr head)))))
            (loop while pointer
                  collect (pop pointer))))))

(defun subseq (sequence start &optional end)
  #!+sb-doc
  "Return a copy of a subsequence of SEQUENCE starting with element number
   START and continuing to the end of SEQUENCE or the optional END."
  (seq-dispatch sequence
    (list-subseq* sequence start end)
    (vector-subseq* sequence start end)
    (sb!sequence:subseq sequence start end)))
\f
;;;; COPY-SEQ

(defun copy-seq (sequence)
  #!+sb-doc "Return a copy of SEQUENCE which is EQUAL to SEQUENCE but not EQ."
  (seq-dispatch sequence
    (list-copy-seq* sequence)
    (vector-subseq* sequence 0 nil)
    (sb!sequence:copy-seq sequence)))

(defun list-copy-seq* (sequence)
  (!copy-list-macro sequence :check-proper-list t))
\f
;;;; FILL

(defun list-fill* (sequence item start end)
  (declare (type list sequence)
           (type unsigned-byte start)
           (type (or null unsigned-byte) end))
  (flet ((oops ()
           (sequence-bounding-indices-bad-error sequence start end)))
    (let ((pointer sequence))
      (unless (zerop start)
        ;; If START > 0 the list cannot be empty. So CDR down to it
        ;; START-1 times, check that we still have something, then CDR
        ;; the final time.
        ;;
        ;; If START was zero, the list may be empty if END is NIL or
        ;; also zero.
        (unless (= start 1)
          (setf pointer (nthcdr (1- start) pointer)))
        (if pointer
            (pop pointer)
            (oops)))
      (if end
          (let ((n (- end start)))
            (declare (integer n))
            (when (minusp n)
              (oops))
            (when (plusp n)
              (loop repeat n
                    do (setf pointer (cdr (rplaca pointer item))))))
          (loop while pointer
                do (setf pointer (cdr (rplaca pointer item))))))))

(defun vector-fill* (sequence item start end)
  (with-array-data ((data sequence)
                    (start start)
                    (end end)
                    :force-inline t
                    :check-fill-pointer t)
    (let ((setter (!find-data-vector-setter data)))
      (declare (optimize (speed 3) (safety 0)))
      (do ((index start (1+ index)))
          ((= index end) sequence)
        (declare (index index))
        (funcall setter data index item)))))

(defun string-fill* (sequence item start end)
  (declare (string sequence))
  (with-array-data ((data sequence)
                    (start start)
                    (end end)
                    :force-inline t
                    :check-fill-pointer t)
    (macrolet ((frob ()
                 `(locally (declare (optimize (safety 0) (speed 3)))
                    (do ((i start (1+ i)))
                        ((= i end) sequence)
                     (declare (index i))
                     (setf (aref data i) item)))))
      (etypecase data
        #!+sb-unicode
        ((simple-array character (*))
         (let ((item (locally (declare (optimize (safety 3)))
                       (the character item))))
           (frob)))
        ((simple-array base-char (*))
         (let ((item (locally (declare (optimize (safety 3)))
                       (the base-char item))))
           (frob)))))))

(defun fill (sequence item &key (start 0) end)
  #!+sb-doc
  "Replace the specified elements of SEQUENCE with ITEM."
  (seq-dispatch sequence
   (list-fill* sequence item start end)
   (vector-fill* sequence item start end)
   (sb!sequence:fill sequence item
                     :start start
                     :end (%check-generic-sequence-bounds sequence start end))))
\f
;;;; REPLACE

(eval-when (:compile-toplevel :execute)

;;; If we are copying around in the same vector, be careful not to copy the
;;; same elements over repeatedly. We do this by copying backwards.
(sb!xc:defmacro mumble-replace-from-mumble ()
  `(if (and (eq target-sequence source-sequence) (> target-start source-start))
       (let ((nelts (min (- target-end target-start)
                         (- source-end source-start))))
         (do ((target-index (+ (the fixnum target-start) (the fixnum nelts) -1)
                            (1- target-index))
              (source-index (+ (the fixnum source-start) (the fixnum nelts) -1)
                            (1- source-index)))
             ((= target-index (the fixnum (1- target-start))) target-sequence)
           (declare (fixnum target-index source-index))
           ;; disable bounds checking
           (declare (optimize (safety 0)))
           (setf (aref target-sequence target-index)
                 (aref source-sequence source-index))))
       (do ((target-index target-start (1+ target-index))
            (source-index source-start (1+ source-index)))
           ((or (= target-index (the fixnum target-end))
                (= source-index (the fixnum source-end)))
            target-sequence)
         (declare (fixnum target-index source-index))
         ;; disable bounds checking
         (declare (optimize (safety 0)))
         (setf (aref target-sequence target-index)
               (aref source-sequence source-index)))))

(sb!xc:defmacro list-replace-from-list ()
  `(if (and (eq target-sequence source-sequence) (> target-start source-start))
       (let ((new-elts (subseq source-sequence source-start
                               (+ (the fixnum source-start)
                                  (the fixnum
                                       (min (- (the fixnum target-end)
                                               (the fixnum target-start))
                                            (- (the fixnum source-end)
                                               (the fixnum source-start))))))))
         (do ((n new-elts (cdr n))
              (o (nthcdr target-start target-sequence) (cdr o)))
             ((null n) target-sequence)
           (rplaca o (car n))))
       (do ((target-index target-start (1+ target-index))
            (source-index source-start (1+ source-index))
            (target-sequence-ref (nthcdr target-start target-sequence)
                                 (cdr target-sequence-ref))
            (source-sequence-ref (nthcdr source-start source-sequence)
                                 (cdr source-sequence-ref)))
           ((or (= target-index (the fixnum target-end))
                (= source-index (the fixnum source-end))
                (null target-sequence-ref) (null source-sequence-ref))
            target-sequence)
         (declare (fixnum target-index source-index))
         (rplaca target-sequence-ref (car source-sequence-ref)))))

(sb!xc:defmacro list-replace-from-mumble ()
  `(do ((target-index target-start (1+ target-index))
        (source-index source-start (1+ source-index))
        (target-sequence-ref (nthcdr target-start target-sequence)
                             (cdr target-sequence-ref)))
       ((or (= target-index (the fixnum target-end))
            (= source-index (the fixnum source-end))
            (null target-sequence-ref))
        target-sequence)
     (declare (fixnum source-index target-index))
     (rplaca target-sequence-ref (aref source-sequence source-index))))

(sb!xc:defmacro mumble-replace-from-list ()
  `(do ((target-index target-start (1+ target-index))
        (source-index source-start (1+ source-index))
        (source-sequence (nthcdr source-start source-sequence)
                         (cdr source-sequence)))
       ((or (= target-index (the fixnum target-end))
            (= source-index (the fixnum source-end))
            (null source-sequence))
        target-sequence)
     (declare (fixnum target-index source-index))
     (setf (aref target-sequence target-index) (car source-sequence))))

) ; EVAL-WHEN

;;;; The support routines for REPLACE are used by compiler transforms, so we
;;;; worry about dealing with END being supplied or defaulting to NIL
;;;; at this level.

(defun list-replace-from-list* (target-sequence source-sequence target-start
                                target-end source-start source-end)
  (when (null target-end) (setq target-end (length target-sequence)))
  (when (null source-end) (setq source-end (length source-sequence)))
  (list-replace-from-list))

(defun list-replace-from-vector* (target-sequence source-sequence target-start
                                  target-end source-start source-end)
  (when (null target-end) (setq target-end (length target-sequence)))
  (when (null source-end) (setq source-end (length source-sequence)))
  (list-replace-from-mumble))

(defun vector-replace-from-list* (target-sequence source-sequence target-start
                                  target-end source-start source-end)
  (when (null target-end) (setq target-end (length target-sequence)))
  (when (null source-end) (setq source-end (length source-sequence)))
  (mumble-replace-from-list))

(defun vector-replace-from-vector* (target-sequence source-sequence
                                    target-start target-end source-start
                                    source-end)
  (when (null target-end) (setq target-end (length target-sequence)))
  (when (null source-end) (setq source-end (length source-sequence)))
  (mumble-replace-from-mumble))

#!+sb-unicode
(defun simple-character-string-replace-from-simple-character-string*
    (target-sequence source-sequence
     target-start target-end source-start source-end)
  (declare (type (simple-array character (*)) target-sequence source-sequence))
  (when (null target-end) (setq target-end (length target-sequence)))
  (when (null source-end) (setq source-end (length source-sequence)))
  (mumble-replace-from-mumble))

(define-sequence-traverser replace
    (sequence1 sequence2 &rest args &key start1 end1 start2 end2)
  #!+sb-doc
  "The target sequence is destructively modified by copying successive
   elements into it from the source sequence."
  (declare (dynamic-extent args))
  (let* (;; KLUDGE: absent either rewriting FOO-REPLACE-FROM-BAR, or
         ;; excessively polluting DEFINE-SEQUENCE-TRAVERSER, we rebind
         ;; these things here so that legacy code gets the names it's
         ;; expecting.  We could use &AUX instead :-/.
         (target-sequence sequence1)
         (source-sequence sequence2)
         (target-start start1)
         (source-start start2)
         (target-end (or end1 length1))
         (source-end (or end2 length2)))
    (seq-dispatch target-sequence
      (seq-dispatch source-sequence
        (list-replace-from-list)
        (list-replace-from-mumble)
        (apply #'sb!sequence:replace sequence1 sequence2 args))
      (seq-dispatch source-sequence
        (mumble-replace-from-list)
        (mumble-replace-from-mumble)
        (apply #'sb!sequence:replace sequence1 sequence2 args))
      (apply #'sb!sequence:replace sequence1 sequence2 args))))
\f
;;;; REVERSE

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro vector-reverse (sequence)
  `(let ((length (length ,sequence)))
     (declare (fixnum length))
     (do ((forward-index 0 (1+ forward-index))
          (backward-index (1- length) (1- backward-index))
          (new-sequence (%make-sequence-like sequence length)))
         ((= forward-index length) new-sequence)
       (declare (fixnum forward-index backward-index))
       (setf (aref new-sequence forward-index)
             (aref ,sequence backward-index)))))

(sb!xc:defmacro list-reverse-macro (sequence)
  `(do ((new-list ()))
       ((endp ,sequence) new-list)
     (push (pop ,sequence) new-list)))

) ; EVAL-WHEN

(defun reverse (sequence)
  #!+sb-doc
  "Return a new sequence containing the same elements but in reverse order."
  (seq-dispatch sequence
    (list-reverse* sequence)
    (vector-reverse* sequence)
    (sb!sequence:reverse sequence)))

;;; internal frobs

(defun list-reverse* (sequence)
  (list-reverse-macro sequence))

(defun vector-reverse* (sequence)
  (vector-reverse sequence))
\f
;;;; NREVERSE

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro vector-nreverse (sequence)
  `(let ((length (length (the vector ,sequence))))
     (when (>= length 2)
       (do ((left-index 0 (1+ left-index))
            (right-index (1- length) (1- right-index)))
           ((<= right-index left-index))
         (declare (type index left-index right-index))
         (rotatef (aref ,sequence left-index)
                  (aref ,sequence right-index))))
     ,sequence))

(sb!xc:defmacro list-nreverse-macro (list)
  `(do ((1st (cdr ,list) (if (endp 1st) 1st (cdr 1st)))
        (2nd ,list 1st)
        (3rd '() 2nd))
       ((atom 2nd) 3rd)
     (rplacd 2nd 3rd)))

) ; EVAL-WHEN

(defun list-nreverse* (sequence)
  (list-nreverse-macro sequence))

(defun vector-nreverse* (sequence)
  (vector-nreverse sequence))

(defun nreverse (sequence)
  #!+sb-doc
  "Return a sequence of the same elements in reverse order; the argument
   is destroyed."
  (seq-dispatch sequence
    (list-nreverse* sequence)
    (vector-nreverse* sequence)
    (sb!sequence:nreverse sequence)))
\f
;;;; CONCATENATE

(defmacro sb!sequence:dosequence ((e sequence &optional return) &body body)
  (multiple-value-bind (forms decls) (parse-body body :doc-string-allowed nil)
    (let ((s sequence)
          (sequence (gensym "SEQUENCE")))
      `(block nil
        (let ((,sequence ,s))
          (seq-dispatch ,sequence
            (dolist (,e ,sequence ,return) ,@body)
            (dovector (,e ,sequence ,return) ,@body)
            (multiple-value-bind (state limit from-end step endp elt)
                (sb!sequence:make-sequence-iterator ,sequence)
              (do ((state state (funcall step ,sequence state from-end)))
                  ((funcall endp ,sequence state limit from-end)
                   (let ((,e nil))
                     ,@(filter-dolist-declarations decls)
                     ,e
                     ,return))
                (let ((,e (funcall elt ,sequence state)))
                  ,@decls
                  (tagbody
                     ,@forms))))))))))

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro concatenate-to-list (sequences)
  `(let ((result (list nil)))
     (do ((sequences ,sequences (cdr sequences))
          (splice result))
         ((null sequences) (cdr result))
       (let ((sequence (car sequences)))
         (sb!sequence:dosequence (e sequence)
           (setq splice (cdr (rplacd splice (list e)))))))))

(sb!xc:defmacro concatenate-to-mumble (output-type-spec sequences)
  `(do ((seqs ,sequences (cdr seqs))
        (total-length 0)
        (lengths ()))
       ((null seqs)
        (do ((sequences ,sequences (cdr sequences))
             (lengths lengths (cdr lengths))
             (index 0)
             (result (make-sequence ,output-type-spec total-length)))
            ((= index total-length) result)
          (declare (fixnum index))
          (let ((sequence (car sequences)))
            (sb!sequence:dosequence (e sequence)
              (setf (aref result index) e)
              (incf index)))))
     (let ((length (length (car seqs))))
       (declare (fixnum length))
       (setq lengths (nconc lengths (list length)))
       (setq total-length (+ total-length length)))))

) ; EVAL-WHEN
\f
(defun concatenate (output-type-spec &rest sequences)
  #!+sb-doc
  "Return a new sequence of all the argument sequences concatenated together
  which shares no structure with the original argument sequences of the
  specified OUTPUT-TYPE-SPEC."
  (let ((type (specifier-type output-type-spec)))
  (cond
    ((csubtypep type (specifier-type 'list))
     (cond
       ((type= type (specifier-type 'list))
        (apply #'concat-to-list* sequences))
       ((eq type *empty-type*)
        (bad-sequence-type-error nil))
       ((type= type (specifier-type 'null))
        (if (every (lambda (x) (or (null x)
                                   (and (vectorp x) (= (length x) 0))))
                   sequences)
            'nil
            (sequence-type-length-mismatch-error
             type
             ;; FIXME: circular list issues.
             (reduce #'+ sequences :key #'length))))
       ((cons-type-p type)
        (multiple-value-bind (min exactp)
            (sb!kernel::cons-type-length-info type)
          (let ((length (reduce #'+ sequences :key #'length)))
            (if exactp
                (unless (= length min)
                  (sequence-type-length-mismatch-error type length))
                (unless (>= length min)
                  (sequence-type-length-mismatch-error type length)))
            (apply #'concat-to-list* sequences))))
       (t (sequence-type-too-hairy (type-specifier type)))))
    ((csubtypep type (specifier-type 'vector))
     (apply #'concat-to-simple* output-type-spec sequences))
    ((and (csubtypep type (specifier-type 'sequence))
          (find-class output-type-spec nil))
     (coerce (apply #'concat-to-simple* 'vector sequences) output-type-spec))
    (t
     (bad-sequence-type-error output-type-spec)))))

;;; internal frobs
;;; FIXME: These are weird. They're never called anywhere except in
;;; CONCATENATE. It seems to me that the macros ought to just
;;; be expanded directly in CONCATENATE, or in CONCATENATE-STRING
;;; and CONCATENATE-LIST variants. Failing that, these ought to be local
;;; functions (FLET).
(defun concat-to-list* (&rest sequences)
  (concatenate-to-list sequences))
(defun concat-to-simple* (type &rest sequences)
  (concatenate-to-mumble type sequences))
\f
;;;; MAP and MAP-INTO

;;; helper functions to handle arity-1 subcases of MAP
(declaim (ftype (function (function sequence) list) %map-list-arity-1))
(declaim (ftype (function (function sequence) simple-vector)
                %map-simple-vector-arity-1))
(defun %map-to-list-arity-1 (fun sequence)
  (let ((reversed-result nil)
        (really-fun (%coerce-callable-to-fun fun)))
    (sb!sequence:dosequence (element sequence)
      (push (funcall really-fun element)
            reversed-result))
    (nreverse reversed-result)))
(defun %map-to-simple-vector-arity-1 (fun sequence)
  (let ((result (make-array (length sequence)))
        (index 0)
        (really-fun (%coerce-callable-to-fun fun)))
    (declare (type index index))
    (sb!sequence:dosequence (element sequence)
      (setf (aref result index)
            (funcall really-fun element))
      (incf index))
    result))
(defun %map-for-effect-arity-1 (fun sequence)
  (let ((really-fun (%coerce-callable-to-fun fun)))
    (sb!sequence:dosequence (element sequence)
      (funcall really-fun element)))
  nil)

(declaim (maybe-inline %map-for-effect))
(defun %map-for-effect (fun sequences)
  (declare (type function fun) (type list sequences))
  (let ((%sequences sequences)
        (%iters (mapcar (lambda (s)
                          (seq-dispatch s
                            s
                            0
                            (multiple-value-list
                             (sb!sequence:make-sequence-iterator s))))
                        sequences))
        (%apply-args (make-list (length sequences))))
    ;; this is almost efficient (except in the general case where we
    ;; trampoline to MAKE-SEQUENCE-ITERATOR; if we had DX allocation
    ;; of MAKE-LIST, the whole of %MAP would be cons-free.
    (declare (type list %sequences %iters %apply-args))
    (loop
     (do ((in-sequences  %sequences  (cdr in-sequences))
          (in-iters      %iters      (cdr in-iters))
          (in-apply-args %apply-args (cdr in-apply-args)))
         ((null in-sequences) (apply fun %apply-args))
       (let ((i (car in-iters)))
         (declare (type (or list index) i))
         (cond
           ((listp (car in-sequences))
            (if (null i)
                (return-from %map-for-effect nil)
                (setf (car in-apply-args) (car i)
                      (car in-iters) (cdr i))))
           ((typep i 'index)
            (let ((v (the vector (car in-sequences))))
              (if (>= i (length v))
                  (return-from %map-for-effect nil)
                  (setf (car in-apply-args) (aref v i)
                        (car in-iters) (1+ i)))))
           (t
            (destructuring-bind (state limit from-end step endp elt &rest ignore)
                i
              (declare (type function step endp elt)
                       (ignore ignore))
              (let ((s (car in-sequences)))
                (if (funcall endp s state limit from-end)
                    (return-from %map-for-effect nil)
                    (progn
                      (setf (car in-apply-args) (funcall elt s state))
                      (setf (caar in-iters) (funcall step s state from-end)))))))))))))
(defun %map-to-list (fun sequences)
  (declare (type function fun)
           (type list sequences))
  (let ((result nil))
    (flet ((f (&rest args)
             (declare (dynamic-extent args))
             (push (apply fun args) result)))
      (declare (dynamic-extent #'f))
      (%map-for-effect #'f sequences))
    (nreverse result)))
(defun %map-to-vector (output-type-spec fun sequences)
  (declare (type function fun)
           (type list sequences))
  (let ((min-len 0))
    (flet ((f (&rest args)
             (declare (dynamic-extent args))
             (declare (ignore args))
             (incf min-len)))
      (declare (dynamic-extent #'f))
      (%map-for-effect #'f sequences))
    (let ((result (make-sequence output-type-spec min-len))
          (i 0))
      (declare (type (simple-array * (*)) result))
      (flet ((f (&rest args)
               (declare (dynamic-extent args))
               (setf (aref result i) (apply fun args))
               (incf i)))
        (declare (dynamic-extent #'f))
        (%map-for-effect #'f sequences))
      result)))
(defun %map-to-sequence (result-type fun sequences)
  (declare (type function fun)
           (type list sequences))
  (let ((min-len 0))
    (flet ((f (&rest args)
             (declare (dynamic-extent args))
             (declare (ignore args))
             (incf min-len)))
      (declare (dynamic-extent #'f))
      (%map-for-effect #'f sequences))
    (let ((result (make-sequence result-type min-len)))
      (multiple-value-bind (state limit from-end step endp elt setelt)
          (sb!sequence:make-sequence-iterator result)
        (declare (ignore limit endp elt))
        (flet ((f (&rest args)
                 (declare (dynamic-extent args))
                 (funcall setelt (apply fun args) result state)
                 (setq state (funcall step result state from-end))))
          (declare (dynamic-extent #'f))
          (%map-for-effect #'f sequences)))
      result)))

;;; %MAP is just MAP without the final just-to-be-sure check that
;;; length of the output sequence matches any length specified
;;; in RESULT-TYPE.
(defun %map (result-type function first-sequence &rest more-sequences)
  (let ((really-fun (%coerce-callable-to-fun function))
        (type (specifier-type result-type)))
    ;; Handle one-argument MAP NIL specially, using ETYPECASE to turn
    ;; it into something which can be DEFTRANSFORMed away. (It's
    ;; fairly important to handle this case efficiently, since
    ;; quantifiers like SOME are transformed into this case, and since
    ;; there's no consing overhead to dwarf our inefficiency.)
    (if (and (null more-sequences)
             (null result-type))
        (%map-for-effect-arity-1 really-fun first-sequence)
        ;; Otherwise, use the industrial-strength full-generality
        ;; approach, consing O(N-ARGS) temporary storage (which can have
        ;; DYNAMIC-EXTENT), then using O(N-ARGS * RESULT-LENGTH) time.
        (let ((sequences (cons first-sequence more-sequences)))
          (cond
            ((eq type *empty-type*) (%map-for-effect really-fun sequences))
            ((csubtypep type (specifier-type 'list))
             (%map-to-list really-fun sequences))
            ((csubtypep type (specifier-type 'vector))
             (%map-to-vector result-type really-fun sequences))
            ((and (csubtypep type (specifier-type 'sequence))
                  (find-class result-type nil))
             (%map-to-sequence result-type really-fun sequences))
            (t
             (bad-sequence-type-error result-type)))))))

(defun map (result-type function first-sequence &rest more-sequences)
  (apply #'%map
         result-type
         function
         first-sequence
         more-sequences))

;;; KLUDGE: MAP has been rewritten substantially since the fork from
;;; CMU CL in order to give reasonable performance, but this
;;; implementation of MAP-INTO still has the same problems as the old
;;; MAP code. Ideally, MAP-INTO should be rewritten to be efficient in
;;; the same way that the corresponding cases of MAP have been
;;; rewritten. Instead of doing it now, though, it's easier to wait
;;; until we have DYNAMIC-EXTENT, at which time it should become
;;; extremely easy to define a reasonably efficient MAP-INTO in terms
;;; of (MAP NIL ..). -- WHN 20000920
(defun map-into (result-sequence function &rest sequences)
  (let* ((fp-result
          (and (arrayp result-sequence)
               (array-has-fill-pointer-p result-sequence)))
         (len (apply #'min
                     (if fp-result
                         (array-dimension result-sequence 0)
                         (length result-sequence))
                     (mapcar #'length sequences))))

    (when fp-result
      (setf (fill-pointer result-sequence) len))

    (let ((really-fun (%coerce-callable-to-fun function)))
      (dotimes (index len)
        (setf (elt result-sequence index)
              (apply really-fun
                     (mapcar (lambda (seq) (elt seq index))
                             sequences))))))
  result-sequence)
\f
;;;; quantifiers

;;; We borrow the logic from (MAP NIL ..) to handle iteration over
;;; arbitrary sequence arguments, both in the full call case and in
;;; the open code case.
(macrolet ((defquantifier (name found-test found-result
                                &key doc (unfound-result (not found-result)))
             `(progn
                ;; KLUDGE: It would be really nice if we could simply
                ;; do something like this
                ;;  (declaim (inline ,name))
                ;;  (defun ,name (pred first-seq &rest more-seqs)
                ;;    ,doc
                ;;    (flet ((map-me (&rest rest)
                ;;             (let ((pred-value (apply pred rest)))
                ;;               (,found-test pred-value
                ;;                 (return-from ,name
                ;;                   ,found-result)))))
                ;;      (declare (inline map-me))
                ;;      (apply #'map nil #'map-me first-seq more-seqs)
                ;;      ,unfound-result))
                ;; but Python doesn't seem to be smart enough about
                ;; inlining and APPLY to recognize that it can use
                ;; the DEFTRANSFORM for MAP in the resulting inline
                ;; expansion. I don't have any appetite for deep
                ;; compiler hacking right now, so I'll just work
                ;; around the apparent problem by using a compiler
                ;; macro instead. -- WHN 20000410
                (defun ,name (pred first-seq &rest more-seqs)
                  #!+sb-doc ,doc
                  (flet ((map-me (&rest rest)
                           (let ((pred-value (apply pred rest)))
                             (,found-test pred-value
                                          (return-from ,name
                                            ,found-result)))))
                    (declare (inline map-me))
                    (apply #'map nil #'map-me first-seq more-seqs)
                    ,unfound-result))
                ;; KLUDGE: It would be more obviously correct -- but
                ;; also significantly messier -- for PRED-VALUE to be
                ;; a gensym. However, a private symbol really does
                ;; seem to be good enough; and anyway the really
                ;; obviously correct solution is to make Python smart
                ;; enough that we can use an inline function instead
                ;; of a compiler macro (as above). -- WHN 20000410
                ;;
                ;; FIXME: The DEFINE-COMPILER-MACRO here can be
                ;; important for performance, and it'd be good to have
                ;; it be visible throughout the compilation of all the
                ;; target SBCL code. That could be done by defining
                ;; SB-XC:DEFINE-COMPILER-MACRO and using it here,
                ;; moving this DEFQUANTIFIER stuff (and perhaps other
                ;; inline definitions in seq.lisp as well) into a new
                ;; seq.lisp, and moving remaining target-only stuff
                ;; from the old seq.lisp into target-seq.lisp.
                (define-compiler-macro ,name (pred first-seq &rest more-seqs)
                  (let ((elements (make-gensym-list (1+ (length more-seqs))))
                        (blockname (gensym "BLOCK")))
                    (once-only ((pred pred))
                      `(block ,blockname
                         (map nil
                              (lambda (,@elements)
                                (let ((pred-value (funcall ,pred ,@elements)))
                                  (,',found-test pred-value
                                    (return-from ,blockname
                                      ,',found-result))))
                              ,first-seq
                              ,@more-seqs)
                         ,',unfound-result)))))))
  (defquantifier some when pred-value :unfound-result nil :doc
  "Apply PREDICATE to the 0-indexed elements of the sequences, then
   possibly to those with index 1, and so on. Return the first
   non-NIL value encountered, or NIL if the end of any sequence is reached.")
  (defquantifier every unless nil :doc
  "Apply PREDICATE to the 0-indexed elements of the sequences, then
   possibly to those with index 1, and so on. Return NIL as soon
   as any invocation of PREDICATE returns NIL, or T if every invocation
   is non-NIL.")
  (defquantifier notany when nil :doc
  "Apply PREDICATE to the 0-indexed elements of the sequences, then
   possibly to those with index 1, and so on. Return NIL as soon
   as any invocation of PREDICATE returns a non-NIL value, or T if the end
   of any sequence is reached.")
  (defquantifier notevery unless t :doc
  "Apply PREDICATE to 0-indexed elements of the sequences, then
   possibly to those with index 1, and so on. Return T as soon
   as any invocation of PREDICATE returns NIL, or NIL if every invocation
   is non-NIL."))
\f
;;;; REDUCE

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro mumble-reduce (function
                               sequence
                               key
                               start
                               end
                               initial-value
                               ref)
  `(do ((index ,start (1+ index))
        (value ,initial-value))
       ((>= index ,end) value)
     (setq value (funcall ,function value
                          (apply-key ,key (,ref ,sequence index))))))

(sb!xc:defmacro mumble-reduce-from-end (function
                                        sequence
                                        key
                                        start
                                        end
                                        initial-value
                                        ref)
  `(do ((index (1- ,end) (1- index))
        (value ,initial-value)
        (terminus (1- ,start)))
       ((<= index terminus) value)
     (setq value (funcall ,function
                          (apply-key ,key (,ref ,sequence index))
                          value))))

(sb!xc:defmacro list-reduce (function
                             sequence
                             key
                             start
                             end
                             initial-value
                             ivp)
  `(let ((sequence (nthcdr ,start ,sequence)))
     (do ((count (if ,ivp ,start (1+ ,start))
                 (1+ count))
          (sequence (if ,ivp sequence (cdr sequence))
                    (cdr sequence))
          (value (if ,ivp ,initial-value (apply-key ,key (car sequence)))
                 (funcall ,function value (apply-key ,key (car sequence)))))
         ((>= count ,end) value))))

(sb!xc:defmacro list-reduce-from-end (function
                                      sequence
                                      key
                                      start
                                      end
                                      initial-value
                                      ivp)
  `(let ((sequence (nthcdr (- (length ,sequence) ,end)
                           (reverse ,sequence))))
     (do ((count (if ,ivp ,start (1+ ,start))
                 (1+ count))
          (sequence (if ,ivp sequence (cdr sequence))
                    (cdr sequence))
          (value (if ,ivp ,initial-value (apply-key ,key (car sequence)))
                 (funcall ,function (apply-key ,key (car sequence)) value)))
         ((>= count ,end) value))))

) ; EVAL-WHEN

(define-sequence-traverser reduce (function sequence &rest args &key key
                                   from-end start end (initial-value nil ivp))
  (declare (type index start))
  (declare (dynamic-extent args))
  (let ((start start)
        (end (or end length)))
    (declare (type index start end))
    (seq-dispatch sequence
      (if (= end start)
          (if ivp initial-value (funcall function))
          (if from-end
              (list-reduce-from-end function sequence key start end
                                    initial-value ivp)
              (list-reduce function sequence key start end
                           initial-value ivp)))
      (if (= end start)
          (if ivp initial-value (funcall function))
          (if from-end
              (progn
                (when (not ivp)
                  (setq end (1- (the fixnum end)))
                  (setq initial-value (apply-key key (aref sequence end))))
                (mumble-reduce-from-end function sequence key start end
                                        initial-value aref))
              (progn
                (when (not ivp)
                  (setq initial-value (apply-key key (aref sequence start)))
                  (setq start (1+ start)))
                (mumble-reduce function sequence key start end
                               initial-value aref))))
      (apply #'sb!sequence:reduce function sequence args))))
\f
;;;; DELETE

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro mumble-delete (pred)
  `(do ((index start (1+ index))
        (jndex start)
        (number-zapped 0))
       ((or (= index (the fixnum end)) (= number-zapped count))
        (do ((index index (1+ index))           ; Copy the rest of the vector.
             (jndex jndex (1+ jndex)))
            ((= index (the fixnum length))
             (shrink-vector sequence jndex))
          (declare (fixnum index jndex))
          (setf (aref sequence jndex) (aref sequence index))))
     (declare (fixnum index jndex number-zapped))
     (setf (aref sequence jndex) (aref sequence index))
     (if ,pred
         (incf number-zapped)
         (incf jndex))))

(sb!xc:defmacro mumble-delete-from-end (pred)
  `(do ((index (1- (the fixnum end)) (1- index)) ; Find the losers.
        (number-zapped 0)
        (losers ())
        this-element
        (terminus (1- start)))
       ((or (= index terminus) (= number-zapped count))
        (do ((losers losers)                     ; Delete the losers.
             (index start (1+ index))
             (jndex start))
            ((or (null losers) (= index (the fixnum end)))
             (do ((index index (1+ index))       ; Copy the rest of the vector.
                  (jndex jndex (1+ jndex)))
                 ((= index (the fixnum length))
                  (shrink-vector sequence jndex))
               (declare (fixnum index jndex))
               (setf (aref sequence jndex) (aref sequence index))))
          (declare (fixnum index jndex))
          (setf (aref sequence jndex) (aref sequence index))
          (if (= index (the fixnum (car losers)))
              (pop losers)
              (incf jndex))))
     (declare (fixnum index number-zapped terminus))
     (setq this-element (aref sequence index))
     (when ,pred
       (incf number-zapped)
       (push index losers))))

(sb!xc:defmacro normal-mumble-delete ()
  `(mumble-delete
    (if test-not
        (not (funcall test-not item (apply-key key (aref sequence index))))
        (funcall test item (apply-key key (aref sequence index))))))

(sb!xc:defmacro normal-mumble-delete-from-end ()
  `(mumble-delete-from-end
    (if test-not
        (not (funcall test-not item (apply-key key this-element)))
        (funcall test item (apply-key key this-element)))))

(sb!xc:defmacro list-delete (pred)
  `(let ((handle (cons nil sequence)))
     (do ((current (nthcdr start sequence) (cdr current))
          (previous (nthcdr start handle))
          (index start (1+ index))
          (number-zapped 0))
         ((or (= index (the fixnum end)) (= number-zapped count))
          (cdr handle))
       (declare (fixnum index number-zapped))
       (cond (,pred
              (rplacd previous (cdr current))
              (incf number-zapped))
             (t
              (setq previous (cdr previous)))))))

(sb!xc:defmacro list-delete-from-end (pred)
  `(let* ((reverse (nreverse (the list sequence)))
          (handle (cons nil reverse)))
     (do ((current (nthcdr (- (the fixnum length) (the fixnum end)) reverse)
                   (cdr current))
          (previous (nthcdr (- (the fixnum length) (the fixnum end)) handle))
          (index start (1+ index))
          (number-zapped 0))
         ((or (= index (the fixnum end)) (= number-zapped count))
          (nreverse (cdr handle)))
       (declare (fixnum index number-zapped))
       (cond (,pred
              (rplacd previous (cdr current))
              (incf number-zapped))
             (t
              (setq previous (cdr previous)))))))

(sb!xc:defmacro normal-list-delete ()
  '(list-delete
    (if test-not
        (not (funcall test-not item (apply-key key (car current))))
        (funcall test item (apply-key key (car current))))))

(sb!xc:defmacro normal-list-delete-from-end ()
  '(list-delete-from-end
    (if test-not
        (not (funcall test-not item (apply-key key (car current))))
        (funcall test item (apply-key key (car current))))))

) ; EVAL-WHEN

(define-sequence-traverser delete
    (item sequence &rest args &key from-end test test-not start
     end count key)
  #!+sb-doc
  "Return a sequence formed by destructively removing the specified ITEM from
  the given SEQUENCE."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (normal-list-delete-from-end)
          (normal-list-delete))
      (if from-end
          (normal-mumble-delete-from-end)
          (normal-mumble-delete))
      (apply #'sb!sequence:delete item sequence args))))

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro if-mumble-delete ()
  `(mumble-delete
    (funcall predicate (apply-key key (aref sequence index)))))

(sb!xc:defmacro if-mumble-delete-from-end ()
  `(mumble-delete-from-end
    (funcall predicate (apply-key key this-element))))

(sb!xc:defmacro if-list-delete ()
  '(list-delete
    (funcall predicate (apply-key key (car current)))))

(sb!xc:defmacro if-list-delete-from-end ()
  '(list-delete-from-end
    (funcall predicate (apply-key key (car current)))))

) ; EVAL-WHEN

(define-sequence-traverser delete-if
    (predicate sequence &rest args &key from-end start key end count)
  #!+sb-doc
  "Return a sequence formed by destructively removing the elements satisfying
  the specified PREDICATE from the given SEQUENCE."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (if-list-delete-from-end)
          (if-list-delete))
      (if from-end
          (if-mumble-delete-from-end)
          (if-mumble-delete))
      (apply #'sb!sequence:delete-if predicate sequence args))))

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro if-not-mumble-delete ()
  `(mumble-delete
    (not (funcall predicate (apply-key key (aref sequence index))))))

(sb!xc:defmacro if-not-mumble-delete-from-end ()
  `(mumble-delete-from-end
    (not (funcall predicate (apply-key key this-element)))))

(sb!xc:defmacro if-not-list-delete ()
  '(list-delete
    (not (funcall predicate (apply-key key (car current))))))

(sb!xc:defmacro if-not-list-delete-from-end ()
  '(list-delete-from-end
    (not (funcall predicate (apply-key key (car current))))))

) ; EVAL-WHEN

(define-sequence-traverser delete-if-not
    (predicate sequence &rest args &key from-end start end key count)
  #!+sb-doc
  "Return a sequence formed by destructively removing the elements not
  satisfying the specified PREDICATE from the given SEQUENCE."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (if-not-list-delete-from-end)
          (if-not-list-delete))
      (if from-end
          (if-not-mumble-delete-from-end)
          (if-not-mumble-delete))
      (apply #'sb!sequence:delete-if-not predicate sequence args))))
\f
;;;; REMOVE

(eval-when (:compile-toplevel :execute)

;;; MUMBLE-REMOVE-MACRO does not include (removes) each element that
;;; satisfies the predicate.
(sb!xc:defmacro mumble-remove-macro (bump left begin finish right pred)
  `(do ((index ,begin (,bump index))
        (result
         (do ((index ,left (,bump index))
              (result (%make-sequence-like sequence length)))
             ((= index (the fixnum ,begin)) result)
           (declare (fixnum index))
           (setf (aref result index) (aref sequence index))))
        (new-index ,begin)
        (number-zapped 0)
        (this-element))
       ((or (= index (the fixnum ,finish))
            (= number-zapped count))
        (do ((index index (,bump index))
             (new-index new-index (,bump new-index)))
            ((= index (the fixnum ,right)) (%shrink-vector result new-index))
          (declare (fixnum index new-index))
          (setf (aref result new-index) (aref sequence index))))
     (declare (fixnum index new-index number-zapped))
     (setq this-element (aref sequence index))
     (cond (,pred (incf number-zapped))
           (t (setf (aref result new-index) this-element)
              (setq new-index (,bump new-index))))))

(sb!xc:defmacro mumble-remove (pred)
  `(mumble-remove-macro 1+ 0 start end length ,pred))

(sb!xc:defmacro mumble-remove-from-end (pred)
  `(let ((sequence (copy-seq sequence)))
     (mumble-delete-from-end ,pred)))

(sb!xc:defmacro normal-mumble-remove ()
  `(mumble-remove
    (if test-not
        (not (funcall test-not item (apply-key key this-element)))
        (funcall test item (apply-key key this-element)))))

(sb!xc:defmacro normal-mumble-remove-from-end ()
  `(mumble-remove-from-end
    (if test-not
        (not (funcall test-not item (apply-key key this-element)))
        (funcall test item (apply-key key this-element)))))

(sb!xc:defmacro if-mumble-remove ()
  `(mumble-remove (funcall predicate (apply-key key this-element))))

(sb!xc:defmacro if-mumble-remove-from-end ()
  `(mumble-remove-from-end (funcall predicate (apply-key key this-element))))

(sb!xc:defmacro if-not-mumble-remove ()
  `(mumble-remove (not (funcall predicate (apply-key key this-element)))))

(sb!xc:defmacro if-not-mumble-remove-from-end ()
  `(mumble-remove-from-end
    (not (funcall predicate (apply-key key this-element)))))

;;; LIST-REMOVE-MACRO does not include (removes) each element that satisfies
;;; the predicate.
(sb!xc:defmacro list-remove-macro (pred reverse?)
  `(let* ((sequence ,(if reverse?
                         '(reverse (the list sequence))
                         'sequence))
          (%start ,(if reverse? '(- length end) 'start))
          (%end ,(if reverse? '(- length start) 'end))
          (splice (list nil))
          (results (do ((index 0 (1+ index))
                        (before-start splice))
                       ((= index (the fixnum %start)) before-start)
                     (declare (fixnum index))
                     (setq splice
                           (cdr (rplacd splice (list (pop sequence))))))))
     (do ((index %start (1+ index))
          (this-element)
          (number-zapped 0))
         ((or (= index (the fixnum %end)) (= number-zapped count))
          (do ((index index (1+ index)))
              ((null sequence)
               ,(if reverse?
                    '(nreverse (the list (cdr results)))
                    '(cdr results)))
            (declare (fixnum index))
            (setq splice (cdr (rplacd splice (list (pop sequence)))))))
       (declare (fixnum index number-zapped))
       (setq this-element (pop sequence))
       (if ,pred
           (setq number-zapped (1+ number-zapped))
           (setq splice (cdr (rplacd splice (list this-element))))))))

(sb!xc:defmacro list-remove (pred)
  `(list-remove-macro ,pred nil))

(sb!xc:defmacro list-remove-from-end (pred)
  `(list-remove-macro ,pred t))

(sb!xc:defmacro normal-list-remove ()
  `(list-remove
    (if test-not
        (not (funcall test-not item (apply-key key this-element)))
        (funcall test item (apply-key key this-element)))))

(sb!xc:defmacro normal-list-remove-from-end ()
  `(list-remove-from-end
    (if test-not
        (not (funcall test-not item (apply-key key this-element)))
        (funcall test item (apply-key key this-element)))))

(sb!xc:defmacro if-list-remove ()
  `(list-remove
    (funcall predicate (apply-key key this-element))))

(sb!xc:defmacro if-list-remove-from-end ()
  `(list-remove-from-end
    (funcall predicate (apply-key key this-element))))

(sb!xc:defmacro if-not-list-remove ()
  `(list-remove
    (not (funcall predicate (apply-key key this-element)))))

(sb!xc:defmacro if-not-list-remove-from-end ()
  `(list-remove-from-end
    (not (funcall predicate (apply-key key this-element)))))

) ; EVAL-WHEN

(define-sequence-traverser remove
    (item sequence &rest args &key from-end test test-not start
     end count key)
  #!+sb-doc
  "Return a copy of SEQUENCE with elements satisfying the test (default is
   EQL) with ITEM removed."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (normal-list-remove-from-end)
          (normal-list-remove))
      (if from-end
          (normal-mumble-remove-from-end)
          (normal-mumble-remove))
      (apply #'sb!sequence:remove item sequence args))))

(define-sequence-traverser remove-if
    (predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a copy of sequence with elements satisfying PREDICATE removed."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (if-list-remove-from-end)
          (if-list-remove))
      (if from-end
          (if-mumble-remove-from-end)
          (if-mumble-remove))
      (apply #'sb!sequence:remove-if predicate sequence args))))

(define-sequence-traverser remove-if-not
    (predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a copy of sequence with elements not satisfying PREDICATE removed."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (if-not-list-remove-from-end)
          (if-not-list-remove))
      (if from-end
          (if-not-mumble-remove-from-end)
          (if-not-mumble-remove))
      (apply #'sb!sequence:remove-if-not predicate sequence args))))
\f
;;;; REMOVE-DUPLICATES

;;; Remove duplicates from a list. If from-end, remove the later duplicates,
;;; not the earlier ones. Thus if we check from-end we don't copy an item
;;; if we look into the already copied structure (from after :start) and see
;;; the item. If we check from beginning we check into the rest of the
;;; original list up to the :end marker (this we have to do by running a
;;; do loop down the list that far and using our test.
(defun list-remove-duplicates* (list test test-not start end key from-end)
  (declare (fixnum start))
  (let* ((result (list ())) ; Put a marker on the beginning to splice with.
         (splice result)
         (current list)
         (end (or end (length list)))
         (hash (and (> (- end start) 20)
                    test
                    (not key)
                    (not test-not)
                    (or (eql test #'eql)
                        (eql test #'eq)
                        (eql test #'equal)
                        (eql test #'equalp))
                    (make-hash-table :test test :size (- end start)))))
    (do ((index 0 (1+ index)))
        ((= index start))
      (declare (fixnum index))
      (setq splice (cdr (rplacd splice (list (car current)))))
      (setq current (cdr current)))
    (if hash
        (do ((index start (1+ index)))
            ((or (and end (= index (the fixnum end)))
                 (atom current)))
          (declare (fixnum index))
          ;; The hash table contains links from values that are
          ;; already in result to the cons cell *preceding* theirs
          ;; in the list.  That is, for each value v in the list,
          ;; v and (cadr (gethash v hash)) are equal under TEST.
          (let ((prev (gethash (car current) hash)))
            (cond
             ((not prev)
              (setf (gethash (car current) hash) splice)
              (setq splice (cdr (rplacd splice (list (car current))))))
             ((not from-end)
              (let* ((old (cdr prev))
                     (next (cdr old)))
                (if next
                  (let ((next-val (car next)))
                    ;; (assert (eq (gethash next-val hash) old))
                    (setf (cdr prev) next
                          (gethash next-val hash) prev
                          (gethash (car current) hash) splice
                          splice (cdr (rplacd splice (list (car current))))))
                  (setf (car old) (car current)))))))
          (setq current (cdr current)))
      (do ((index start (1+ index)))
          ((or (and end (= index (the fixnum end)))
               (atom current)))
        (declare (fixnum index))
        (if (or (and from-end
                     (not (if test-not
                              (member (apply-key key (car current))
                                      (nthcdr (1+ start) result)
                                      :test-not test-not
                                      :key key)
                            (member (apply-key key (car current))
                                    (nthcdr (1+ start) result)
                                    :test test
                                    :key key))))
                (and (not from-end)
                     (not (do ((it (apply-key key (car current)))
                               (l (cdr current) (cdr l))
                               (i (1+ index) (1+ i)))
                              ((or (atom l) (and end (= i (the fixnum end))))
                               ())
                            (declare (fixnum i))
                            (if (if test-not
                                    (not (funcall test-not
                                                  it
                                                  (apply-key key (car l))))
                                  (funcall test it (apply-key key (car l))))
                                (return t))))))
            (setq splice (cdr (rplacd splice (list (car current))))))
        (setq current (cdr current))))
    (do ()
        ((atom current))
      (setq splice (cdr (rplacd splice (list (car current)))))
      (setq current (cdr current)))
    (cdr result)))

(defun vector-remove-duplicates* (vector test test-not start end key from-end
                                         &optional (length (length vector)))
  (declare (vector vector) (fixnum start length))
  (when (null end) (setf end (length vector)))
  (let ((result (%make-sequence-like vector length))
        (index 0)
        (jndex start))
    (declare (fixnum index jndex))
    (do ()
        ((= index start))
      (setf (aref result index) (aref vector index))
      (setq index (1+ index)))
    (do ((elt))
        ((= index end))
      (setq elt (aref vector index))
      (unless (or (and from-end
                       (if test-not
                           (position (apply-key key elt) result
                                     :start start :end jndex
                                     :test-not test-not :key key)
                           (position (apply-key key elt) result
                                     :start start :end jndex
                                     :test test :key key)))
                  (and (not from-end)
                       (if test-not
                           (position (apply-key key elt) vector
                                     :start (1+ index) :end end
                                     :test-not test-not :key key)
                           (position (apply-key key elt) vector
                                     :start (1+ index) :end end
                                     :test test :key key))))
        (setf (aref result jndex) elt)
        (setq jndex (1+ jndex)))
      (setq index (1+ index)))
    (do ()
        ((= index length))
      (setf (aref result jndex) (aref vector index))
      (setq index (1+ index))
      (setq jndex (1+ jndex)))
    (%shrink-vector result jndex)))

(define-sequence-traverser remove-duplicates
    (sequence &rest args &key test test-not start end from-end key)
  #!+sb-doc
  "The elements of SEQUENCE are compared pairwise, and if any two match,
   the one occurring earlier is discarded, unless FROM-END is true, in
   which case the one later in the sequence is discarded. The resulting
   sequence is returned.

   The :TEST-NOT argument is deprecated."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (if sequence
        (list-remove-duplicates* sequence test test-not
                                 start end key from-end))
    (vector-remove-duplicates* sequence test test-not start end key from-end)
    (apply #'sb!sequence:remove-duplicates sequence args)))
\f
;;;; DELETE-DUPLICATES

(defun list-delete-duplicates* (list test test-not key from-end start end)
  (declare (fixnum start))
  (let ((handle (cons nil list)))
    (do ((current (nthcdr start list) (cdr current))
         (previous (nthcdr start handle))
         (index start (1+ index)))
        ((or (and end (= index (the fixnum end))) (null current))
         (cdr handle))
      (declare (fixnum index))
      (if (do ((x (if from-end
                      (nthcdr (1+ start) handle)
                      (cdr current))
                  (cdr x))
               (i (1+ index) (1+ i)))
              ((or (null x)
                   (and (not from-end) end (= i (the fixnum end)))
                   (eq x current))
               nil)
            (declare (fixnum i))
            (if (if test-not
                    (not (funcall test-not
                                  (apply-key key (car current))
                                  (apply-key key (car x))))
                    (funcall test
                             (apply-key key (car current))
                             (apply-key key (car x))))
                (return t)))
          (rplacd previous (cdr current))
          (setq previous (cdr previous))))))

(defun vector-delete-duplicates* (vector test test-not key from-end start end
                                         &optional (length (length vector)))
  (declare (vector vector) (fixnum start length))
  (when (null end) (setf end (length vector)))
  (do ((index start (1+ index))
       (jndex start))
      ((= index end)
       (do ((index index (1+ index))            ; copy the rest of the vector
            (jndex jndex (1+ jndex)))
           ((= index length)
            (shrink-vector vector jndex))
         (setf (aref vector jndex) (aref vector index))))
    (declare (fixnum index jndex))
    (setf (aref vector jndex) (aref vector index))
    (unless (if test-not
                (position (apply-key key (aref vector index)) vector :key key
                          :start (if from-end start (1+ index))
                          :end (if from-end jndex end)
                          :test-not test-not)
                (position (apply-key key (aref vector index)) vector :key key
                          :start (if from-end start (1+ index))
                          :end (if from-end jndex end)
                          :test test))
      (setq jndex (1+ jndex)))))

(define-sequence-traverser delete-duplicates
    (sequence &rest args &key test test-not start end from-end key)
  #!+sb-doc
  "The elements of SEQUENCE are examined, and if any two match, one is
   discarded. The resulting sequence, which may be formed by destroying the
   given sequence, is returned.

   The :TEST-NOT argument is deprecated."
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (if sequence
        (list-delete-duplicates* sequence test test-not
                                 key from-end start end))
    (vector-delete-duplicates* sequence test test-not key from-end start end)
    (apply #'sb!sequence:delete-duplicates sequence args)))
\f
;;;; SUBSTITUTE

(defun list-substitute* (pred new list start end count key test test-not old)
  (declare (fixnum start end count))
  (let* ((result (list nil))
         elt
         (splice result)
         (list list))      ; Get a local list for a stepper.
    (do ((index 0 (1+ index)))
        ((= index start))
      (declare (fixnum index))
      (setq splice (cdr (rplacd splice (list (car list)))))
      (setq list (cdr list)))
    (do ((index start (1+ index)))
        ((or (= index end) (null list) (= count 0)))
      (declare (fixnum index))
      (setq elt (car list))
      (setq splice
            (cdr (rplacd splice
                         (list
                          (cond
                           ((case pred
                                   (normal
                                    (if test-not
                                        (not
                                         (funcall test-not old (apply-key key elt)))
                                        (funcall test old (apply-key key elt))))
                                   (if (funcall test (apply-key key elt)))
                                   (if-not (not (funcall test (apply-key key elt)))))
                            (decf count)
                            new)
                                (t elt))))))
      (setq list (cdr list)))
    (do ()
        ((null list))
      (setq splice (cdr (rplacd splice (list (car list)))))
      (setq list (cdr list)))
    (cdr result)))

;;; Replace old with new in sequence moving from left to right by incrementer
;;; on each pass through the loop. Called by all three substitute functions.
(defun vector-substitute* (pred new sequence incrementer left right length
                           start end count key test test-not old)
  (declare (fixnum start count end incrementer right))
  (let ((result (%make-sequence-like sequence length))
        (index left))
    (declare (fixnum index))
    (do ()
        ((= index start))
      (setf (aref result index) (aref sequence index))
      (setq index (+ index incrementer)))
    (do ((elt))
        ((or (= index end) (= count 0)))
      (setq elt (aref sequence index))
      (setf (aref result index)
            (cond ((case pred
                          (normal
                            (if test-not
                                (not (funcall test-not old (apply-key key elt)))
                                (funcall test old (apply-key key elt))))
                          (if (funcall test (apply-key key elt)))
                          (if-not (not (funcall test (apply-key key elt)))))
                   (setq count (1- count))
                   new)
                  (t elt)))
      (setq index (+ index incrementer)))
    (do ()
        ((= index right))
      (setf (aref result index) (aref sequence index))
      (setq index (+ index incrementer)))
    result))

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro subst-dispatch (pred)
  `(seq-dispatch sequence
     (if from-end
         (nreverse (list-substitute* ,pred
                                     new
                                     (reverse sequence)
                                     (- (the fixnum length)
                                        (the fixnum end))
                                     (- (the fixnum length)
                                        (the fixnum start))
                                     count key test test-not old))
         (list-substitute* ,pred
                           new sequence start end count key test test-not
                           old))
    (if from-end
        (vector-substitute* ,pred new sequence -1 (1- (the fixnum length))
                            -1 length (1- (the fixnum end))
                            (1- (the fixnum start))
                            count key test test-not old)
        (vector-substitute* ,pred new sequence 1 0 length length
                            start end count key test test-not old))
    ;; FIXME: wow, this is an odd way to implement the dispatch.  PRED
    ;; here is (QUOTE [NORMAL|IF|IF-NOT]).  Not only is this pretty
    ;; pointless, but also LIST-SUBSTITUTE* and VECTOR-SUBSTITUTE*
    ;; dispatch once per element on PRED's run-time identity.
    ,(ecase (cadr pred)
       ((normal) `(apply #'sb!sequence:substitute new old sequence args))
       ((if) `(apply #'sb!sequence:substitute-if new predicate sequence args))
       ((if-not) `(apply #'sb!sequence:substitute-if-not new predicate sequence args)))))
) ; EVAL-WHEN

(define-sequence-traverser substitute
    (new old sequence &rest args &key from-end test test-not
         start count end key)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements,
  except that all elements equal to OLD are replaced with NEW."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (type index end))
    (subst-dispatch 'normal)))
\f
;;;; SUBSTITUTE-IF, SUBSTITUTE-IF-NOT

(define-sequence-traverser substitute-if
    (new predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements
  except that all elements satisfying the PRED are replaced with NEW."
  (declare (dynamic-extent args))
  (declare (fixnum start))
  (let ((end (or end length))
        (test predicate)
        (test-not nil)
        old)
    (declare (type index length end))
    (subst-dispatch 'if)))

(define-sequence-traverser substitute-if-not
    (new predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements
  except that all elements not satisfying the PRED are replaced with NEW."
  (declare (dynamic-extent args))
  (declare (fixnum start))
  (let ((end (or end length))
        (test predicate)
        (test-not nil)
        old)
    (declare (type index length end))
    (subst-dispatch 'if-not)))
\f
;;;; NSUBSTITUTE

(define-sequence-traverser nsubstitute
    (new old sequence &rest args &key from-end test test-not
         end count key start)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements
  except that all elements equal to OLD are replaced with NEW. SEQUENCE
  may be destructively modified."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (seq-dispatch sequence
      (if from-end
          (let ((length (length sequence)))
            (nreverse (nlist-substitute*
                       new old (nreverse (the list sequence))
                       test test-not (- length end) (- length start)
                       count key)))
          (nlist-substitute* new old sequence
                             test test-not start end count key))
      (if from-end
          (nvector-substitute* new old sequence -1
                               test test-not (1- end) (1- start) count key)
          (nvector-substitute* new old sequence 1
                               test test-not start end count key))
      (apply #'sb!sequence:nsubstitute new old sequence args))))

(defun nlist-substitute* (new old sequence test test-not start end count key)
  (declare (fixnum start count end))
  (do ((list (nthcdr start sequence) (cdr list))
       (index start (1+ index)))
      ((or (= index end) (null list) (= count 0)) sequence)
    (declare (fixnum index))
    (when (if test-not
              (not (funcall test-not old (apply-key key (car list))))
              (funcall test old (apply-key key (car list))))
      (rplaca list new)
      (setq count (1- count)))))

(defun nvector-substitute* (new old sequence incrementer
                            test test-not start end count key)
  (declare (fixnum start incrementer count end))
  (do ((index start (+ index incrementer)))
      ((or (= index end) (= count 0)) sequence)
    (declare (fixnum index))
    (when (if test-not
              (not (funcall test-not
                            old
                            (apply-key key (aref sequence index))))
              (funcall test old (apply-key key (aref sequence index))))
      (setf (aref sequence index) new)
      (setq count (1- count)))))
\f
;;;; NSUBSTITUTE-IF, NSUBSTITUTE-IF-NOT

(define-sequence-traverser nsubstitute-if
    (new predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements
   except that all elements satisfying PREDICATE are replaced with NEW.
   SEQUENCE may be destructively modified."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (fixnum end))
    (seq-dispatch sequence
      (if from-end
          (let ((length (length sequence)))
            (nreverse (nlist-substitute-if*
                       new predicate (nreverse (the list sequence))
                       (- length end) (- length start) count key)))
          (nlist-substitute-if* new predicate sequence
                                start end count key))
      (if from-end
          (nvector-substitute-if* new predicate sequence -1
                                  (1- end) (1- start) count key)
          (nvector-substitute-if* new predicate sequence 1
                                  start end count key))
      (apply #'sb!sequence:nsubstitute-if new predicate sequence args))))

(defun nlist-substitute-if* (new test sequence start end count key)
  (declare (fixnum end))
  (do ((list (nthcdr start sequence) (cdr list))
       (index start (1+ index)))
      ((or (= index end) (null list) (= count 0)) sequence)
    (when (funcall test (apply-key key (car list)))
      (rplaca list new)
      (setq count (1- count)))))

(defun nvector-substitute-if* (new test sequence incrementer
                               start end count key)
  (do ((index start (+ index incrementer)))
      ((or (= index end) (= count 0)) sequence)
    (when (funcall test (apply-key key (aref sequence index)))
      (setf (aref sequence index) new)
      (setq count (1- count)))))

(define-sequence-traverser nsubstitute-if-not
    (new predicate sequence &rest args &key from-end start end count key)
  #!+sb-doc
  "Return a sequence of the same kind as SEQUENCE with the same elements
   except that all elements not satisfying PREDICATE are replaced with NEW.
   SEQUENCE may be destructively modified."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length)))
    (declare (fixnum end))
    (seq-dispatch sequence
      (if from-end
          (let ((length (length sequence)))
            (nreverse (nlist-substitute-if-not*
                       new predicate (nreverse (the list sequence))
                       (- length end) (- length start) count key)))
          (nlist-substitute-if-not* new predicate sequence
                                    start end count key))
      (if from-end
          (nvector-substitute-if-not* new predicate sequence -1
                                      (1- end) (1- start) count key)
          (nvector-substitute-if-not* new predicate sequence 1
                                      start end count key))
      (apply #'sb!sequence:nsubstitute-if-not new predicate sequence args))))

(defun nlist-substitute-if-not* (new test sequence start end count key)
  (declare (fixnum end))
  (do ((list (nthcdr start sequence) (cdr list))
       (index start (1+ index)))
      ((or (= index end) (null list) (= count 0)) sequence)
    (when (not (funcall test (apply-key key (car list))))
      (rplaca list new)
      (decf count))))

(defun nvector-substitute-if-not* (new test sequence incrementer
                                   start end count key)
  (do ((index start (+ index incrementer)))
      ((or (= index end) (= count 0)) sequence)
    (when (not (funcall test (apply-key key (aref sequence index))))
      (setf (aref sequence index) new)
      (decf count))))
\f
;;;; FIND, POSITION, and their -IF and -IF-NOT variants

(defun effective-find-position-test (test test-not)
  (effective-find-position-test test test-not))
(defun effective-find-position-key (key)
  (effective-find-position-key key))

;;; shared guts of out-of-line FIND, POSITION, FIND-IF, and POSITION-IF
(macrolet (;; shared logic for defining %FIND-POSITION and
           ;; %FIND-POSITION-IF in terms of various inlineable cases
           ;; of the expression defined in FROB and VECTOR*-FROB
           (frobs ()
             `(seq-dispatch sequence-arg
               (frob sequence-arg from-end)
               (with-array-data ((sequence sequence-arg :offset-var offset)
                                 (start start)
                                 (end end)
                                 :check-fill-pointer t)
                 (multiple-value-bind (f p)
                     (macrolet ((frob2 () '(if from-end
                                            (frob sequence t)
                                            (frob sequence nil))))
                       (typecase sequence
                         #!+sb-unicode
                         ((simple-array character (*)) (frob2))
                         ((simple-array base-char (*)) (frob2))
                         (t (vector*-frob sequence))))
                   (declare (type (or index null) p))
                   (values f (and p (the index (- p offset)))))))))
  (defun %find-position (item sequence-arg from-end start end key test)
    (macrolet ((frob (sequence from-end)
                 `(%find-position item ,sequence
                                  ,from-end start end key test))
               (vector*-frob (sequence)
                 `(%find-position-vector-macro item ,sequence
                                               from-end start end key test)))
      (frobs)))
  (defun %find-position-if (predicate sequence-arg from-end start end key)
    (macrolet ((frob (sequence from-end)
                 `(%find-position-if predicate ,sequence
                                     ,from-end start end key))
               (vector*-frob (sequence)
                 `(%find-position-if-vector-macro predicate ,sequence
                                                  from-end start end key)))
      (frobs)))
  (defun %find-position-if-not (predicate sequence-arg from-end start end key)
    (macrolet ((frob (sequence from-end)
                 `(%find-position-if-not predicate ,sequence
                                         ,from-end start end key))
               (vector*-frob (sequence)
                 `(%find-position-if-not-vector-macro predicate ,sequence
                                                  from-end start end key)))
      (frobs))))

(defun find
    (item sequence &rest args &key from-end (start 0) end key test test-not)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 0 (%find-position
                  item sequence from-end start end
                  (effective-find-position-key key)
                  (effective-find-position-test test test-not)))
    (nth-value 0 (%find-position
                  item sequence from-end start end
                  (effective-find-position-key key)
                  (effective-find-position-test test test-not)))
    (apply #'sb!sequence:find item sequence args)))
(defun position
    (item sequence &rest args &key from-end (start 0) end key test test-not)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 1 (%find-position
                  item sequence from-end start end
                  (effective-find-position-key key)
                  (effective-find-position-test test test-not)))
    (nth-value 1 (%find-position
                  item sequence from-end start end
                  (effective-find-position-key key)
                  (effective-find-position-test test test-not)))
    (apply #'sb!sequence:position item sequence args)))

(defun find-if (predicate sequence &rest args &key from-end (start 0) end key)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 0 (%find-position-if
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (nth-value 0 (%find-position-if
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (apply #'sb!sequence:find-if predicate sequence args)))
(defun position-if
    (predicate sequence &rest args &key from-end (start 0) end key)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 1 (%find-position-if
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (nth-value 1 (%find-position-if
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (apply #'sb!sequence:position-if predicate sequence args)))

(defun find-if-not
    (predicate sequence &rest args &key from-end (start 0) end key)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 0 (%find-position-if-not
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (nth-value 0 (%find-position-if-not
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (apply #'sb!sequence:find-if-not predicate sequence args)))
(defun position-if-not
    (predicate sequence &rest args &key from-end (start 0) end key)
  (declare (dynamic-extent args))
  (seq-dispatch sequence
    (nth-value 1 (%find-position-if-not
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (nth-value 1 (%find-position-if-not
                  (%coerce-callable-to-fun predicate)
                  sequence from-end start end
                  (effective-find-position-key key)))
    (apply #'sb!sequence:position-if-not predicate sequence args)))
\f
;;;; COUNT-IF, COUNT-IF-NOT, and COUNT

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro vector-count-if (notp from-end-p predicate sequence)
  (let ((next-index (if from-end-p '(1- index) '(1+ index)))
        (pred `(funcall ,predicate (apply-key key (aref ,sequence index)))))
    `(let ((%start ,(if from-end-p '(1- end) 'start))
           (%end ,(if from-end-p '(1- start) 'end)))
      (do ((index %start ,next-index)
           (count 0))
          ((= index (the fixnum %end)) count)
        (declare (fixnum index count))
        (,(if notp 'unless 'when) ,pred
          (setq count (1+ count)))))))

(sb!xc:defmacro list-count-if (notp from-end-p predicate sequence)
  (let ((pred `(funcall ,predicate (apply-key key (pop sequence)))))
    `(let ((%start ,(if from-end-p '(- length end) 'start))
           (%end ,(if from-end-p '(- length start) 'end))
           (sequence ,(if from-end-p '(reverse sequence) 'sequence)))
      (do ((sequence (nthcdr %start ,sequence))
           (index %start (1+ index))
           (count 0))
          ((or (= index (the fixnum %end)) (null sequence)) count)
        (declare (fixnum index count))
        (,(if notp 'unless 'when) ,pred
          (setq count (1+ count)))))))


) ; EVAL-WHEN

(define-sequence-traverser count-if
    (pred sequence &rest args &key from-end start end key)
  #!+sb-doc
  "Return the number of elements in SEQUENCE satisfying PRED(el)."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length))
        (pred (%coerce-callable-to-fun pred)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (list-count-if nil t pred sequence)
          (list-count-if nil nil pred sequence))
      (if from-end
          (vector-count-if nil t pred sequence)
          (vector-count-if nil nil pred sequence))
      (apply #'sb!sequence:count-if pred sequence args))))

(define-sequence-traverser count-if-not
    (pred sequence &rest args &key from-end start end key)
  #!+sb-doc
  "Return the number of elements in SEQUENCE not satisfying TEST(el)."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (let ((end (or end length))
        (pred (%coerce-callable-to-fun pred)))
    (declare (type index end))
    (seq-dispatch sequence
      (if from-end
          (list-count-if t t pred sequence)
          (list-count-if t nil pred sequence))
      (if from-end
          (vector-count-if t t pred sequence)
          (vector-count-if t nil pred sequence))
      (apply #'sb!sequence:count-if-not pred sequence args))))

(define-sequence-traverser count
    (item sequence &rest args &key from-end start end
          key (test #'eql test-p) (test-not nil test-not-p))
  #!+sb-doc
  "Return the number of elements in SEQUENCE satisfying a test with ITEM,
   which defaults to EQL."
  (declare (fixnum start))
  (declare (dynamic-extent args))
  (when (and test-p test-not-p)
    ;; ANSI Common Lisp has left the behavior in this situation unspecified.
    ;; (CLHS 17.2.1)
    (error ":TEST and :TEST-NOT are both present."))
  (let ((end (or end length)))
    (declare (type index end))
    (let ((%test (if test-not-p
                     (lambda (x)
                       (not (funcall test-not item x)))
                     (lambda (x)
                       (funcall test item x)))))
      (seq-dispatch sequence
        (if from-end
            (list-count-if nil t %test sequence)
            (list-count-if nil nil %test sequence))
        (if from-end
            (vector-count-if nil t %test sequence)
            (vector-count-if nil nil %test sequence))
        (apply #'sb!sequence:count item sequence args)))))
\f
;;;; MISMATCH

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro match-vars (&rest body)
  `(let ((inc (if from-end -1 1))
         (start1 (if from-end (1- (the fixnum end1)) start1))
         (start2 (if from-end (1- (the fixnum end2)) start2))
         (end1 (if from-end (1- (the fixnum start1)) end1))
         (end2 (if from-end (1- (the fixnum start2)) end2)))
     (declare (fixnum inc start1 start2 end1 end2))
     ,@body))

(sb!xc:defmacro matchify-list ((sequence start length end) &body body)
  (declare (ignore end)) ;; ### Should END be used below?
  `(let ((,sequence (if from-end
                        (nthcdr (- (the fixnum ,length) (the fixnum ,start) 1)
                                (reverse (the list ,sequence)))
                        (nthcdr ,start ,sequence))))
     (declare (type list ,sequence))
     ,@body))

) ; EVAL-WHEN

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro if-mismatch (elt1 elt2)
  `(cond ((= (the fixnum index1) (the fixnum end1))
          (return (if (= (the fixnum index2) (the fixnum end2))
                      nil
                      (if from-end
                          (1+ (the fixnum index1))
                          (the fixnum index1)))))
         ((= (the fixnum index2) (the fixnum end2))
          (return (if from-end (1+ (the fixnum index1)) index1)))
         (test-not
          (if (funcall test-not (apply-key key ,elt1) (apply-key key ,elt2))
              (return (if from-end (1+ (the fixnum index1)) index1))))
         (t (if (not (funcall test (apply-key key ,elt1)
                              (apply-key key ,elt2)))
                (return (if from-end (1+ (the fixnum index1)) index1))))))

(sb!xc:defmacro mumble-mumble-mismatch ()
  `(do ((index1 start1 (+ index1 (the fixnum inc)))
        (index2 start2 (+ index2 (the fixnum inc))))
       (())
     (declare (fixnum index1 index2))
     (if-mismatch (aref sequence1 index1) (aref sequence2 index2))))

(sb!xc:defmacro mumble-list-mismatch ()
  `(do ((index1 start1 (+ index1 (the fixnum inc)))
        (index2 start2 (+ index2 (the fixnum inc))))
       (())
     (declare (fixnum index1 index2))
     (if-mismatch (aref sequence1 index1) (pop sequence2))))
\f
(sb!xc:defmacro list-mumble-mismatch ()
  `(do ((index1 start1 (+ index1 (the fixnum inc)))
        (index2 start2 (+ index2 (the fixnum inc))))
       (())
     (declare (fixnum index1 index2))
     (if-mismatch (pop sequence1) (aref sequence2 index2))))

(sb!xc:defmacro list-list-mismatch ()
  `(do ((sequence1 sequence1)
        (sequence2 sequence2)
        (index1 start1 (+ index1 (the fixnum inc)))
        (index2 start2 (+ index2 (the fixnum inc))))
       (())
     (declare (fixnum index1 index2))
     (if-mismatch (pop sequence1) (pop sequence2))))

) ; EVAL-WHEN

(define-sequence-traverser mismatch
    (sequence1 sequence2 &rest args &key from-end test test-not
     start1 end1 start2 end2 key)
  #!+sb-doc
  "The specified subsequences of SEQUENCE1 and SEQUENCE2 are compared
   element-wise. If they are of equal length and match in every element, the
   result is NIL. Otherwise, the result is a non-negative integer, the index
   within SEQUENCE1 of the leftmost position at which they fail to match; or,
   if one is shorter than and a matching prefix of the other, the index within
   SEQUENCE1 beyond the last position tested is returned. If a non-NIL
   :FROM-END argument is given, then one plus the index of the rightmost
   position in which the sequences differ is returned."
  (declare (fixnum start1 start2))
  (declare (dynamic-extent args))
  (let* ((end1 (or end1 length1))
         (end2 (or end2 length2)))
    (declare (type index end1 end2))
    (match-vars
     (seq-dispatch sequence1
       (seq-dispatch sequence2
         (matchify-list (sequence1 start1 length1 end1)
           (matchify-list (sequence2 start2 length2 end2)
             (list-list-mismatch)))
         (matchify-list (sequence1 start1 length1 end1)
           (list-mumble-mismatch))
         (apply #'sb!sequence:mismatch sequence1 sequence2 args))
       (seq-dispatch sequence2
         (matchify-list (sequence2 start2 length2 end2)
           (mumble-list-mismatch))
         (mumble-mumble-mismatch)
         (apply #'sb!sequence:mismatch sequence1 sequence2 args))
       (apply #'sb!sequence:mismatch sequence1 sequence2 args)))))
\f
;;; search comparison functions

(eval-when (:compile-toplevel :execute)

;;; Compare two elements and return if they don't match.
(sb!xc:defmacro compare-elements (elt1 elt2)
  `(if test-not
       (if (funcall test-not (apply-key key ,elt1) (apply-key key ,elt2))
           (return nil)
           t)
       (if (not (funcall test (apply-key key ,elt1) (apply-key key ,elt2)))
           (return nil)
           t)))

(sb!xc:defmacro search-compare-list-list (main sub)
  `(do ((main ,main (cdr main))
        (jndex start1 (1+ jndex))
        (sub (nthcdr start1 ,sub) (cdr sub)))
       ((or (endp main) (endp sub) (<= end1 jndex))
        t)
     (declare (type (integer 0) jndex))
     (compare-elements (car sub) (car main))))

(sb!xc:defmacro search-compare-list-vector (main sub)
  `(do ((main ,main (cdr main))
        (index start1 (1+ index)))
       ((or (endp main) (= index end1)) t)
     (compare-elements (aref ,sub index) (car main))))

(sb!xc:defmacro search-compare-vector-list (main sub index)
  `(do ((sub (nthcdr start1 ,sub) (cdr sub))
        (jndex start1 (1+ jndex))
        (index ,index (1+ index)))
       ((or (<= end1 jndex) (endp sub)) t)
     (declare (type (integer 0) jndex))
     (compare-elements (car sub) (aref ,main index))))

(sb!xc:defmacro search-compare-vector-vector (main sub index)
  `(do ((index ,index (1+ index))
        (sub-index start1 (1+ sub-index)))
       ((= sub-index end1) t)
     (compare-elements (aref ,sub sub-index) (aref ,main index))))

(sb!xc:defmacro search-compare (main-type main sub index)
  (if (eq main-type 'list)
      `(seq-dispatch ,sub
         (search-compare-list-list ,main ,sub)
         (search-compare-list-vector ,main ,sub)
         ;; KLUDGE: just hack it together so that it works
         (return-from search (apply #'sb!sequence:search sequence1 sequence2 args)))
      `(seq-dispatch ,sub
         (search-compare-vector-list ,main ,sub ,index)
         (search-compare-vector-vector ,main ,sub ,index)
         (return-from search (apply #'sb!sequence:search sequence1 sequence2 args)))))

) ; EVAL-WHEN
\f
;;;; SEARCH

(eval-when (:compile-toplevel :execute)

(sb!xc:defmacro list-search (main sub)
  `(do ((main (nthcdr start2 ,main) (cdr main))
        (index2 start2 (1+ index2))
        (terminus (- end2 (the (integer 0) (- end1 start1))))
        (last-match ()))
       ((> index2 terminus) last-match)
     (declare (type (integer 0) index2))
     (if (search-compare list main ,sub index2)
         (if from-end
             (setq last-match index2)
             (return index2)))))

(sb!xc:defmacro vector-search (main sub)
  `(do ((index2 start2 (1+ index2))
        (terminus (- end2 (the (integer 0) (- end1 start1))))
        (last-match ()))
       ((> index2 terminus) last-match)
     (declare (type (integer 0) index2))
     (if (search-compare vector ,main ,sub index2)
         (if from-end
             (setq last-match index2)
             (return index2)))))

) ; EVAL-WHEN

(define-sequence-traverser search
    (sequence1 sequence2 &rest args &key
     from-end test test-not start1 end1 start2 end2 key)
  (declare (fixnum start1 start2))
  (declare (dynamic-extent args))
  (let ((end1 (or end1 length1))
        (end2 (or end2 length2)))
    (seq-dispatch sequence2
      (list-search sequence2 sequence1)
      (vector-search sequence2 sequence1)
      (apply #'sb!sequence:search sequence1 sequence2 args))))

;;; FIXME: this was originally in array.lisp; it might be better to
;;; put it back there, and make DOSEQUENCE and SEQ-DISPATCH be in
;;; a new early-seq.lisp file.
(defun fill-data-vector (vector dimensions initial-contents)
  (let ((index 0))
    (labels ((frob (axis dims contents)
               (cond ((null dims)
                      (setf (aref vector index) contents)
                      (incf index))
                     (t
                      (unless (typep contents 'sequence)
                        (error "malformed :INITIAL-CONTENTS: ~S is not a ~
                                sequence, but ~W more layer~:P needed."
                               contents
                               (- (length dimensions) axis)))
                      (unless (= (length contents) (car dims))
                        (error "malformed :INITIAL-CONTENTS: Dimension of ~
                                axis ~W is ~W, but ~S is ~W long."
                               axis (car dims) contents (length contents)))
                      (sb!sequence:dosequence (content contents)
                        (frob (1+ axis) (cdr dims) content))))))
      (frob 0 dimensions initial-contents))))