lisp/emacs-lisp/cl-extra.el

   1 ;;; cl-extra.el --- Common Lisp features, part 2  -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 1993, 2000-2012 Free Software Foundation, Inc.
   4
   5 ;; Author: Dave Gillespie <daveg@synaptics.com>
   6 ;; Keywords: extensions
   7 ;; Package: emacs
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; These are extensions to Emacs Lisp that provide a degree of
  27 ;; Common Lisp compatibility, beyond what is already built-in
  28 ;; in Emacs Lisp.
  29 ;;
  30 ;; This package was written by Dave Gillespie; it is a complete
  31 ;; rewrite of Cesar Quiroz's original cl.el package of December 1986.
  32 ;;
  33 ;; Bug reports, comments, and suggestions are welcome!
  34
  35 ;; This file contains portions of the Common Lisp extensions
  36 ;; package which are autoloaded since they are relatively obscure.
  37
  38 ;;; Code:
  39
  40 (require 'cl-lib)
  41
  42 ;;; Type coercion.
  43
  44 ;;;###autoload
  45 (defun cl-coerce (x type)
  46   "Coerce OBJECT to type TYPE.
  47 TYPE is a Common Lisp type specifier.
  48 \n(fn OBJECT TYPE)"
  49   (cond ((eq type 'list) (if (listp x) x (append x nil)))
  50         ((eq type 'vector) (if (vectorp x) x (vconcat x)))
  51         ((eq type 'string) (if (stringp x) x (concat x)))
  52         ((eq type 'array) (if (arrayp x) x (vconcat x)))
  53         ((and (eq type 'character) (stringp x) (= (length x) 1)) (aref x 0))
  54         ((and (eq type 'character) (symbolp x)) (cl-coerce (symbol-name x) type))
  55         ((eq type 'float) (float x))
  56         ((cl-typep x type) x)
  57         (t (error "Can't coerce %s to type %s" x type))))
  58
  59
  60 ;;; Predicates.
  61
  62 ;;;###autoload
  63 (defun cl-equalp (x y)
  64   "Return t if two Lisp objects have similar structures and contents.
  65 This is like `equal', except that it accepts numerically equal
  66 numbers of different types (float vs. integer), and also compares
  67 strings case-insensitively."
  68   (cond ((eq x y) t)
  69         ((stringp x)
  70          (and (stringp y) (= (length x) (length y))
  71               (or (string-equal x y)
  72                   (string-equal (downcase x) (downcase y)))))   ; lazy but simple!
  73         ((numberp x)
  74          (and (numberp y) (= x y)))
  75         ((consp x)
  76          (while (and (consp x) (consp y) (cl-equalp (car x) (car y)))
  77            (setq x (cdr x) y (cdr y)))
  78          (and (not (consp x)) (cl-equalp x y)))
  79         ((vectorp x)
  80          (and (vectorp y) (= (length x) (length y))
  81               (let ((i (length x)))
  82                 (while (and (>= (setq i (1- i)) 0)
  83                             (cl-equalp (aref x i) (aref y i))))
  84                 (< i 0))))
  85         (t (equal x y))))
  86
  87
  88 ;;; Control structures.
  89
  90 ;;;###autoload
  91 (defun cl--mapcar-many (cl-func cl-seqs)
  92   (if (cdr (cdr cl-seqs))
  93       (let* ((cl-res nil)
  94              (cl-n (apply 'min (mapcar 'length cl-seqs)))
  95              (cl-i 0)
  96              (cl-args (copy-sequence cl-seqs))
  97              cl-p1 cl-p2)
  98         (setq cl-seqs (copy-sequence cl-seqs))
  99         (while (< cl-i cl-n)
 100           (setq cl-p1 cl-seqs cl-p2 cl-args)
 101           (while cl-p1
 102             (setcar cl-p2
 103                     (if (consp (car cl-p1))
 104                         (prog1 (car (car cl-p1))
 105                           (setcar cl-p1 (cdr (car cl-p1))))
 106                       (aref (car cl-p1) cl-i)))
 107             (setq cl-p1 (cdr cl-p1) cl-p2 (cdr cl-p2)))
 108           (push (apply cl-func cl-args) cl-res)
 109           (setq cl-i (1+ cl-i)))
 110         (nreverse cl-res))
 111     (let ((cl-res nil)
 112           (cl-x (car cl-seqs))
 113           (cl-y (nth 1 cl-seqs)))
 114       (let ((cl-n (min (length cl-x) (length cl-y)))
 115             (cl-i -1))
 116         (while (< (setq cl-i (1+ cl-i)) cl-n)
 117           (push (funcall cl-func
 118                          (if (consp cl-x) (pop cl-x) (aref cl-x cl-i))
 119                          (if (consp cl-y) (pop cl-y) (aref cl-y cl-i)))
 120                 cl-res)))
 121       (nreverse cl-res))))
 122
 123 ;;;###autoload
 124 (defun cl-map (cl-type cl-func cl-seq &rest cl-rest)
 125   "Map a FUNCTION across one or more SEQUENCEs, returning a sequence.
 126 TYPE is the sequence type to return.
 127 \n(fn TYPE FUNCTION SEQUENCE...)"
 128   (let ((cl-res (apply 'cl-mapcar cl-func cl-seq cl-rest)))
 129     (and cl-type (cl-coerce cl-res cl-type))))
 130
 131 ;;;###autoload
 132 (defun cl-maplist (cl-func cl-list &rest cl-rest)
 133   "Map FUNCTION to each sublist of LIST or LISTs.
 134 Like `mapcar', except applies to lists and their cdr's rather than to
 135 the elements themselves.
 136 \n(fn FUNCTION LIST...)"
 137   (if cl-rest
 138       (let ((cl-res nil)
 139             (cl-args (cons cl-list (copy-sequence cl-rest)))
 140             cl-p)
 141         (while (not (memq nil cl-args))
 142           (push (apply cl-func cl-args) cl-res)
 143           (setq cl-p cl-args)
 144           (while cl-p (setcar cl-p (cdr (pop cl-p)) )))
 145         (nreverse cl-res))
 146     (let ((cl-res nil))
 147       (while cl-list
 148         (push (funcall cl-func cl-list) cl-res)
 149         (setq cl-list (cdr cl-list)))
 150       (nreverse cl-res))))
 151
 152 (defun cl-mapc (cl-func cl-seq &rest cl-rest)
 153   "Like `mapcar', but does not accumulate values returned by the function.
 154 \n(fn FUNCTION SEQUENCE...)"
 155   (if cl-rest
 156       (progn (apply 'cl-map nil cl-func cl-seq cl-rest)
 157              cl-seq)
 158     (mapc cl-func cl-seq)))
 159
 160 ;;;###autoload
 161 (defun cl-mapl (cl-func cl-list &rest cl-rest)
 162   "Like `cl-maplist', but does not accumulate values returned by the function.
 163 \n(fn FUNCTION LIST...)"
 164   (if cl-rest
 165       (apply 'cl-maplist cl-func cl-list cl-rest)
 166     (let ((cl-p cl-list))
 167       (while cl-p (funcall cl-func cl-p) (setq cl-p (cdr cl-p)))))
 168   cl-list)
 169
 170 ;;;###autoload
 171 (defun cl-mapcan (cl-func cl-seq &rest cl-rest)
 172   "Like `mapcar', but nconc's together the values returned by the function.
 173 \n(fn FUNCTION SEQUENCE...)"
 174   (apply 'nconc (apply 'cl-mapcar cl-func cl-seq cl-rest)))
 175
 176 ;;;###autoload
 177 (defun cl-mapcon (cl-func cl-list &rest cl-rest)
 178   "Like `cl-maplist', but nconc's together the values returned by the function.
 179 \n(fn FUNCTION LIST...)"
 180   (apply 'nconc (apply 'cl-maplist cl-func cl-list cl-rest)))
 181
 182 ;;;###autoload
 183 (defun cl-some (cl-pred cl-seq &rest cl-rest)
 184   "Return true if PREDICATE is true of any element of SEQ or SEQs.
 185 If so, return the true (non-nil) value returned by PREDICATE.
 186 \n(fn PREDICATE SEQ...)"
 187   (if (or cl-rest (nlistp cl-seq))
 188       (catch 'cl-some
 189         (apply 'cl-map nil
 190                (function (lambda (&rest cl-x)
 191                            (let ((cl-res (apply cl-pred cl-x)))
 192                              (if cl-res (throw 'cl-some cl-res)))))
 193                cl-seq cl-rest) nil)
 194     (let ((cl-x nil))
 195       (while (and cl-seq (not (setq cl-x (funcall cl-pred (pop cl-seq))))))
 196       cl-x)))
 197
 198 ;;;###autoload
 199 (defun cl-every (cl-pred cl-seq &rest cl-rest)
 200   "Return true if PREDICATE is true of every element of SEQ or SEQs.
 201 \n(fn PREDICATE SEQ...)"
 202   (if (or cl-rest (nlistp cl-seq))
 203       (catch 'cl-every
 204         (apply 'cl-map nil
 205                (function (lambda (&rest cl-x)
 206                            (or (apply cl-pred cl-x) (throw 'cl-every nil))))
 207                cl-seq cl-rest) t)
 208     (while (and cl-seq (funcall cl-pred (car cl-seq)))
 209       (setq cl-seq (cdr cl-seq)))
 210     (null cl-seq)))
 211
 212 ;;;###autoload
 213 (defun cl-notany (cl-pred cl-seq &rest cl-rest)
 214   "Return true if PREDICATE is false of every element of SEQ or SEQs.
 215 \n(fn PREDICATE SEQ...)"
 216   (not (apply 'cl-some cl-pred cl-seq cl-rest)))
 217
 218 ;;;###autoload
 219 (defun cl-notevery (cl-pred cl-seq &rest cl-rest)
 220   "Return true if PREDICATE is false of some element of SEQ or SEQs.
 221 \n(fn PREDICATE SEQ...)"
 222   (not (apply 'cl-every cl-pred cl-seq cl-rest)))
 223
 224 ;;;###autoload
 225 (defun cl--map-keymap-recursively (cl-func-rec cl-map &optional cl-base)
 226   (or cl-base
 227       (setq cl-base (copy-sequence [0])))
 228   (map-keymap
 229    (function
 230     (lambda (cl-key cl-bind)
 231       (aset cl-base (1- (length cl-base)) cl-key)
 232       (if (keymapp cl-bind)
 233           (cl--map-keymap-recursively
 234            cl-func-rec cl-bind
 235            (vconcat cl-base (list 0)))
 236         (funcall cl-func-rec cl-base cl-bind))))
 237    cl-map))
 238
 239 ;;;###autoload
 240 (defun cl--map-intervals (cl-func &optional cl-what cl-prop cl-start cl-end)
 241   (or cl-what (setq cl-what (current-buffer)))
 242   (if (bufferp cl-what)
 243       (let (cl-mark cl-mark2 (cl-next t) cl-next2)
 244         (with-current-buffer cl-what
 245           (setq cl-mark (copy-marker (or cl-start (point-min))))
 246           (setq cl-mark2 (and cl-end (copy-marker cl-end))))
 247         (while (and cl-next (or (not cl-mark2) (< cl-mark cl-mark2)))
 248           (setq cl-next (if cl-prop (next-single-property-change
 249                                      cl-mark cl-prop cl-what)
 250                           (next-property-change cl-mark cl-what))
 251                 cl-next2 (or cl-next (with-current-buffer cl-what
 252                                        (point-max))))
 253           (funcall cl-func (prog1 (marker-position cl-mark)
 254                              (set-marker cl-mark cl-next2))
 255                    (if cl-mark2 (min cl-next2 cl-mark2) cl-next2)))
 256         (set-marker cl-mark nil) (if cl-mark2 (set-marker cl-mark2 nil)))
 257     (or cl-start (setq cl-start 0))
 258     (or cl-end (setq cl-end (length cl-what)))
 259     (while (< cl-start cl-end)
 260       (let ((cl-next (or (if cl-prop (next-single-property-change
 261                                       cl-start cl-prop cl-what)
 262                            (next-property-change cl-start cl-what))
 263                          cl-end)))
 264         (funcall cl-func cl-start (min cl-next cl-end))
 265         (setq cl-start cl-next)))))
 266
 267 ;;;###autoload
 268 (defun cl--map-overlays (cl-func &optional cl-buffer cl-start cl-end cl-arg)
 269   (or cl-buffer (setq cl-buffer (current-buffer)))
 270   (if (fboundp 'overlay-lists)
 271
 272       ;; This is the preferred algorithm, though overlay-lists is undocumented.
 273       (let (cl-ovl)
 274         (with-current-buffer cl-buffer
 275           (setq cl-ovl (overlay-lists))
 276           (if cl-start (setq cl-start (copy-marker cl-start)))
 277           (if cl-end (setq cl-end (copy-marker cl-end))))
 278         (setq cl-ovl (nconc (car cl-ovl) (cdr cl-ovl)))
 279         (while (and cl-ovl
 280                     (or (not (overlay-start (car cl-ovl)))
 281                         (and cl-end (>= (overlay-start (car cl-ovl)) cl-end))
 282                         (and cl-start (<= (overlay-end (car cl-ovl)) cl-start))
 283                         (not (funcall cl-func (car cl-ovl) cl-arg))))
 284           (setq cl-ovl (cdr cl-ovl)))
 285         (if cl-start (set-marker cl-start nil))
 286         (if cl-end (set-marker cl-end nil)))
 287
 288     ;; This alternate algorithm fails to find zero-length overlays.
 289     (let ((cl-mark (with-current-buffer cl-buffer
 290                      (copy-marker (or cl-start (point-min)))))
 291           (cl-mark2 (and cl-end (with-current-buffer cl-buffer
 292                                   (copy-marker cl-end))))
 293           cl-pos cl-ovl)
 294       (while (save-excursion
 295                (and (setq cl-pos (marker-position cl-mark))
 296                     (< cl-pos (or cl-mark2 (point-max)))
 297                     (progn
 298                       (set-buffer cl-buffer)
 299                       (setq cl-ovl (overlays-at cl-pos))
 300                       (set-marker cl-mark (next-overlay-change cl-pos)))))
 301         (while (and cl-ovl
 302                     (or (/= (overlay-start (car cl-ovl)) cl-pos)
 303                         (not (and (funcall cl-func (car cl-ovl) cl-arg)
 304                                   (set-marker cl-mark nil)))))
 305           (setq cl-ovl (cdr cl-ovl))))
 306       (set-marker cl-mark nil) (if cl-mark2 (set-marker cl-mark2 nil)))))
 307
 308 ;;; Support for `setf'.
 309 ;;;###autoload
 310 (defun cl--set-frame-visible-p (frame val)
 311   (cond ((null val) (make-frame-invisible frame))
 312         ((eq val 'icon) (iconify-frame frame))
 313         (t (make-frame-visible frame)))
 314   val)
 315
 316
 317 ;;; Numbers.
 318
 319 ;;;###autoload
 320 (defun cl-gcd (&rest args)
 321   "Return the greatest common divisor of the arguments."
 322   (let ((a (abs (or (pop args) 0))))
 323     (while args
 324       (let ((b (abs (pop args))))
 325         (while (> b 0) (setq b (% a (setq a b))))))
 326     a))
 327
 328 ;;;###autoload
 329 (defun cl-lcm (&rest args)
 330   "Return the least common multiple of the arguments."
 331   (if (memq 0 args)
 332       0
 333     (let ((a (abs (or (pop args) 1))))
 334       (while args
 335         (let ((b (abs (pop args))))
 336           (setq a (* (/ a (cl-gcd a b)) b))))
 337       a)))
 338
 339 ;;;###autoload
 340 (defun cl-isqrt (x)
 341   "Return the integer square root of the argument."
 342   (if (and (integerp x) (> x 0))
 343       (let ((g (cond ((<= x 100) 10) ((<= x 10000) 100)
 344                      ((<= x 1000000) 1000) (t x)))
 345             g2)
 346         (while (< (setq g2 (/ (+ g (/ x g)) 2)) g)
 347           (setq g g2))
 348         g)
 349     (if (eq x 0) 0 (signal 'arith-error nil))))
 350
 351 ;;;###autoload
 352 (defun cl-floor (x &optional y)
 353   "Return a list of the floor of X and the fractional part of X.
 354 With two arguments, return floor and remainder of their quotient."
 355   (let ((q (floor x y)))
 356     (list q (- x (if y (* y q) q)))))
 357
 358 ;;;###autoload
 359 (defun cl-ceiling (x &optional y)
 360   "Return a list of the ceiling of X and the fractional part of X.
 361 With two arguments, return ceiling and remainder of their quotient."
 362   (let ((res (cl-floor x y)))
 363     (if (= (car (cdr res)) 0) res
 364       (list (1+ (car res)) (- (car (cdr res)) (or y 1))))))
 365
 366 ;;;###autoload
 367 (defun cl-truncate (x &optional y)
 368   "Return a list of the integer part of X and the fractional part of X.
 369 With two arguments, return truncation and remainder of their quotient."
 370   (if (eq (>= x 0) (or (null y) (>= y 0)))
 371       (cl-floor x y) (cl-ceiling x y)))
 372
 373 ;;;###autoload
 374 (defun cl-round (x &optional y)
 375   "Return a list of X rounded to the nearest integer and the remainder.
 376 With two arguments, return rounding and remainder of their quotient."
 377   (if y
 378       (if (and (integerp x) (integerp y))
 379           (let* ((hy (/ y 2))
 380                  (res (cl-floor (+ x hy) y)))
 381             (if (and (= (car (cdr res)) 0)
 382                      (= (+ hy hy) y)
 383                      (/= (% (car res) 2) 0))
 384                 (list (1- (car res)) hy)
 385               (list (car res) (- (car (cdr res)) hy))))
 386         (let ((q (round (/ x y))))
 387           (list q (- x (* q y)))))
 388     (if (integerp x) (list x 0)
 389       (let ((q (round x)))
 390         (list q (- x q))))))
 391
 392 ;;;###autoload
 393 (defun cl-mod (x y)
 394   "The remainder of X divided by Y, with the same sign as Y."
 395   (nth 1 (cl-floor x y)))
 396
 397 ;;;###autoload
 398 (defun cl-rem (x y)
 399   "The remainder of X divided by Y, with the same sign as X."
 400   (nth 1 (cl-truncate x y)))
 401
 402 ;;;###autoload
 403 (defun cl-signum (x)
 404   "Return 1 if X is positive, -1 if negative, 0 if zero."
 405   (cond ((> x 0) 1) ((< x 0) -1) (t 0)))
 406
 407
 408 ;; Random numbers.
 409
 410 ;;;###autoload
 411 (defun cl-random (lim &optional state)
 412   "Return a random nonnegative number less than LIM, an integer or float.
 413 Optional second arg STATE is a random-state object."
 414   (or state (setq state cl--random-state))
 415   ;; Inspired by "ran3" from Numerical Recipes.  Additive congruential method.
 416   (let ((vec (aref state 3)))
 417     (if (integerp vec)
 418         (let ((i 0) (j (- 1357335 (% (abs vec) 1357333))) (k 1))
 419           (aset state 3 (setq vec (make-vector 55 nil)))
 420           (aset vec 0 j)
 421           (while (> (setq i (% (+ i 21) 55)) 0)
 422             (aset vec i (setq j (prog1 k (setq k (- j k))))))
 423           (while (< (setq i (1+ i)) 200) (cl-random 2 state))))
 424     (let* ((i (aset state 1 (% (1+ (aref state 1)) 55)))
 425            (j (aset state 2 (% (1+ (aref state 2)) 55)))
 426            (n (logand 8388607 (aset vec i (- (aref vec i) (aref vec j))))))
 427       (if (integerp lim)
 428           (if (<= lim 512) (% n lim)
 429             (if (> lim 8388607) (setq n (+ (lsh n 9) (cl-random 512 state))))
 430             (let ((mask 1023))
 431               (while (< mask (1- lim)) (setq mask (1+ (+ mask mask))))
 432               (if (< (setq n (logand n mask)) lim) n (cl-random lim state))))
 433         (* (/ n '8388608e0) lim)))))
 434
 435 ;;;###autoload
 436 (defun cl-make-random-state (&optional state)
 437   "Return a copy of random-state STATE, or of the internal state if omitted.
 438 If STATE is t, return a new state object seeded from the time of day."
 439   (cond ((null state) (cl-make-random-state cl--random-state))
 440         ((vectorp state) (copy-tree state t))
 441         ((integerp state) (vector 'cl-random-state-tag -1 30 state))
 442         (t (cl-make-random-state (cl-random-time)))))
 443
 444 ;;;###autoload
 445 (defun cl-random-state-p (object)
 446   "Return t if OBJECT is a random-state object."
 447   (and (vectorp object) (= (length object) 4)
 448        (eq (aref object 0) 'cl-random-state-tag)))
 449
 450
 451 ;; Implementation limits.
 452
 453 (defun cl--finite-do (func a b)
 454   (condition-case _
 455       (let ((res (funcall func a b)))   ; check for IEEE infinity
 456         (and (numberp res) (/= res (/ res 2)) res))
 457     (arith-error nil)))
 458
 459 ;;;###autoload
 460 (defun cl-float-limits ()
 461   "Initialize the Common Lisp floating-point parameters.
 462 This sets the values of: `cl-most-positive-float', `cl-most-negative-float',
 463 `cl-least-positive-float', `cl-least-negative-float', `cl-float-epsilon',
 464 `cl-float-negative-epsilon', `cl-least-positive-normalized-float', and
 465 `cl-least-negative-normalized-float'."
 466   (or cl-most-positive-float (not (numberp '2e1))
 467       (let ((x '2e0) y z)
 468         ;; Find maximum exponent (first two loops are optimizations)
 469         (while (cl--finite-do '* x x) (setq x (* x x)))
 470         (while (cl--finite-do '* x (/ x 2)) (setq x (* x (/ x 2))))
 471         (while (cl--finite-do '+ x x) (setq x (+ x x)))
 472         (setq z x y (/ x 2))
 473         ;; Now cl-fill in 1's in the mantissa.
 474         (while (and (cl--finite-do '+ x y) (/= (+ x y) x))
 475           (setq x (+ x y) y (/ y 2)))
 476         (setq cl-most-positive-float x
 477               cl-most-negative-float (- x))
 478         ;; Divide down until mantissa starts rounding.
 479         (setq x (/ x z) y (/ 16 z) x (* x y))
 480         (while (condition-case _ (and (= x (* (/ x 2) 2)) (> (/ y 2) 0))
 481                  (arith-error nil))
 482           (setq x (/ x 2) y (/ y 2)))
 483         (setq cl-least-positive-normalized-float y
 484               cl-least-negative-normalized-float (- y))
 485         ;; Divide down until value underflows to zero.
 486         (setq x (/ 1 z) y x)
 487         (while (condition-case _ (> (/ x 2) 0) (arith-error nil))
 488           (setq x (/ x 2)))
 489         (setq cl-least-positive-float x
 490               cl-least-negative-float (- x))
 491         (setq x '1e0)
 492         (while (/= (+ '1e0 x) '1e0) (setq x (/ x 2)))
 493         (setq cl-float-epsilon (* x 2))
 494         (setq x '1e0)
 495         (while (/= (- '1e0 x) '1e0) (setq x (/ x 2)))
 496         (setq cl-float-negative-epsilon (* x 2))))
 497   nil)
 498
 499
 500 ;;; Sequence functions.
 501
 502 ;;;###autoload
 503 (defun cl-subseq (seq start &optional end)
 504   "Return the subsequence of SEQ from START to END.
 505 If END is omitted, it defaults to the length of the sequence.
 506 If START or END is negative, it counts from the end."
 507   (declare (gv-setter
 508             (lambda (new)
 509               `(progn (cl-replace ,seq ,new :start1 ,start :end1 ,end)
 510                       ,new))))
 511   (if (stringp seq) (substring seq start end)
 512     (let (len)
 513       (and end (< end 0) (setq end (+ end (setq len (length seq)))))
 514       (if (< start 0) (setq start (+ start (or len (setq len (length seq))))))
 515       (cond ((listp seq)
 516              (if (> start 0) (setq seq (nthcdr start seq)))
 517              (if end
 518                  (let ((res nil))
 519                    (while (>= (setq end (1- end)) start)
 520                      (push (pop seq) res))
 521                    (nreverse res))
 522                (copy-sequence seq)))
 523             (t
 524              (or end (setq end (or len (length seq))))
 525              (let ((res (make-vector (max (- end start) 0) nil))
 526                    (i 0))
 527                (while (< start end)
 528                  (aset res i (aref seq start))
 529                  (setq i (1+ i) start (1+ start)))
 530                res))))))
 531
 532 ;;;###autoload
 533 (defun cl-concatenate (type &rest seqs)
 534   "Concatenate, into a sequence of type TYPE, the argument SEQUENCEs.
 535 \n(fn TYPE SEQUENCE...)"
 536   (cond ((eq type 'vector) (apply 'vconcat seqs))
 537         ((eq type 'string) (apply 'concat seqs))
 538         ((eq type 'list) (apply 'append (append seqs '(nil))))
 539         (t (error "Not a sequence type name: %s" type))))
 540
 541
 542 ;;; List functions.
 543
 544 ;;;###autoload
 545 (defun cl-revappend (x y)
 546   "Equivalent to (append (reverse X) Y)."
 547   (nconc (reverse x) y))
 548
 549 ;;;###autoload
 550 (defun cl-nreconc (x y)
 551   "Equivalent to (nconc (nreverse X) Y)."
 552   (nconc (nreverse x) y))
 553
 554 ;;;###autoload
 555 (defun cl-list-length (x)
 556   "Return the length of list X.  Return nil if list is circular."
 557   (let ((n 0) (fast x) (slow x))
 558     (while (and (cdr fast) (not (and (eq fast slow) (> n 0))))
 559       (setq n (+ n 2) fast (cdr (cdr fast)) slow (cdr slow)))
 560     (if fast (if (cdr fast) nil (1+ n)) n)))
 561
 562 ;;;###autoload
 563 (defun cl-tailp (sublist list)
 564   "Return true if SUBLIST is a tail of LIST."
 565   (while (and (consp list) (not (eq sublist list)))
 566     (setq list (cdr list)))
 567   (if (numberp sublist) (equal sublist list) (eq sublist list)))
 568
 569 ;;; Property lists.
 570
 571 ;;;###autoload
 572 (defun cl-get (sym tag &optional def)
 573   "Return the value of SYMBOL's PROPNAME property, or DEFAULT if none.
 574 \n(fn SYMBOL PROPNAME &optional DEFAULT)"
 575   (declare (compiler-macro cl--compiler-macro-get)
 576            (gv-setter (lambda (store) `(put ,sym ,tag ,store))))
 577   (or (get sym tag)
 578       (and def
 579            ;; Make sure `def' is really absent as opposed to set to nil.
 580            (let ((plist (symbol-plist sym)))
 581              (while (and plist (not (eq (car plist) tag)))
 582                (setq plist (cdr (cdr plist))))
 583              (if plist (car (cdr plist)) def)))))
 584 (autoload 'cl--compiler-macro-get "cl-macs")
 585
 586 ;;;###autoload
 587 (defun cl-getf (plist tag &optional def)
 588   "Search PROPLIST for property PROPNAME; return its value or DEFAULT.
 589 PROPLIST is a list of the sort returned by `symbol-plist'.
 590 \n(fn PROPLIST PROPNAME &optional DEFAULT)"
 591   (declare (gv-expander
 592             (lambda (do)
 593               (gv-letplace (getter setter) plist
 594                 (macroexp-let2 nil k tag
 595                   (macroexp-let2 nil d def
 596                     (funcall do `(cl-getf ,getter ,k ,d)
 597                              (lambda (v)
 598                                (funcall setter
 599                                         `(cl--set-getf ,getter ,k ,v))))))))))
 600   (setplist '--cl-getf-symbol-- plist)
 601   (or (get '--cl-getf-symbol-- tag)
 602       ;; Originally we called cl-get here,
 603       ;; but that fails, because cl-get has a compiler macro
 604       ;; definition that uses getf!
 605       (when def
 606         ;; Make sure `def' is really absent as opposed to set to nil.
 607         (while (and plist (not (eq (car plist) tag)))
 608           (setq plist (cdr (cdr plist))))
 609         (if plist (car (cdr plist)) def))))
 610
 611 ;;;###autoload
 612 (defun cl--set-getf (plist tag val)
 613   (let ((p plist))
 614     (while (and p (not (eq (car p) tag))) (setq p (cdr (cdr p))))
 615     (if p (progn (setcar (cdr p) val) plist) (cl-list* tag val plist))))
 616
 617 ;;;###autoload
 618 (defun cl--do-remf (plist tag)
 619   (let ((p (cdr plist)))
 620     (while (and (cdr p) (not (eq (car (cdr p)) tag))) (setq p (cdr (cdr p))))
 621     (and (cdr p) (progn (setcdr p (cdr (cdr (cdr p)))) t))))
 622
 623 ;;;###autoload
 624 (defun cl-remprop (sym tag)
 625   "Remove from SYMBOL's plist the property PROPNAME and its value.
 626 \n(fn SYMBOL PROPNAME)"
 627   (let ((plist (symbol-plist sym)))
 628     (if (and plist (eq tag (car plist)))
 629         (progn (setplist sym (cdr (cdr plist))) t)
 630       (cl--do-remf plist tag))))
 631
 632 ;;; Some debugging aids.
 633
 634 (defun cl-prettyprint (form)
 635   "Insert a pretty-printed rendition of a Lisp FORM in current buffer."
 636   (let ((pt (point)) last)
 637     (insert "\n" (prin1-to-string form) "\n")
 638     (setq last (point))
 639     (goto-char (1+ pt))
 640     (while (search-forward "(quote " last t)
 641       (delete-char -7)
 642       (insert "'")
 643       (forward-sexp)
 644       (delete-char 1))
 645     (goto-char (1+ pt))
 646     (cl--do-prettyprint)))
 647
 648 (defun cl--do-prettyprint ()
 649   (skip-chars-forward " ")
 650   (if (looking-at "(")
 651       (let ((skip (or (looking-at "((") (looking-at "(prog")
 652                       (looking-at "(unwind-protect ")
 653                       (looking-at "(function (")
 654                       (looking-at "(cl--block-wrapper ")))
 655             (two (or (looking-at "(defun ") (looking-at "(defmacro ")))
 656             (let (or (looking-at "(let\\*? ") (looking-at "(while ")))
 657             (set (looking-at "(p?set[qf] ")))
 658         (if (or skip let
 659                 (progn
 660                   (forward-sexp)
 661                   (and (>= (current-column) 78) (progn (backward-sexp) t))))
 662             (let ((nl t))
 663               (forward-char 1)
 664               (cl--do-prettyprint)
 665               (or skip (looking-at ")") (cl--do-prettyprint))
 666               (or (not two) (looking-at ")") (cl--do-prettyprint))
 667               (while (not (looking-at ")"))
 668                 (if set (setq nl (not nl)))
 669                 (if nl (insert "\n"))
 670                 (lisp-indent-line)
 671                 (cl--do-prettyprint))
 672               (forward-char 1))))
 673     (forward-sexp)))
 674
 675 ;;;###autoload
 676 (defun cl-prettyexpand (form &optional full)
 677   (message "Expanding...")
 678   (let ((cl--compiling-file full)
 679         (byte-compile-macro-environment nil))
 680     (setq form (macroexpand-all form
 681                                 (and (not full) '((cl-block) (cl-eval-when)))))
 682     (message "Formatting...")
 683     (prog1 (cl-prettyprint form)
 684       (message ""))))
 685
 686
 687
 688 (run-hooks 'cl-extra-load-hook)
 689
 690 ;; Local variables:
 691 ;; byte-compile-dynamic: t
 692 ;; generated-autoload-file: "cl-loaddefs.el"
 693 ;; End:
 694
 695 ;;; cl-extra.el ends here