sql/time.lisp

   1 ;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10 -*-
   2 ;;;; *************************************************************************
   3 ;;;;
   4 ;;;; $Id$
   5 ;;;;
   6 ;;;; A variety of structures and function for creating and
   7 ;;;; manipulating dates, times, durations and intervals for
   8 ;;;; CLSQL.
   9 ;;;;
  10 ;;;; This file was originally part of ODCL and is Copyright (c) 2002 -
  11 ;;;; 2003 onShore Development, Inc.
  12 ;;;;
  13 ;;;; CLSQL users are granted the rights to distribute and use this software
  14 ;;;; as governed by the terms of the Lisp Lesser GNU Public License
  15 ;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
  16 ;;;; *************************************************************************
  17
  18 (in-package #:clsql-sys)
  19
  20 ;; ------------------------------------------------------------
  21 ;; Months
  22
  23 (defvar *month-keywords*
  24   '(:january :february :march :april :may :june :july :august :september
  25     :october :november :december))
  26
  27 (defvar *month-names*
  28   '("" "January" "February" "March" "April" "May" "June" "July" "August"
  29     "September" "October" "November" "December"))
  30
  31 (defun month-name (month-index)
  32   (nth month-index *month-names*))
  33
  34 (defun ordinal-month (month-keyword)
  35   "Return the zero-based month number for the given MONTH keyword."
  36   (position month-keyword *month-keywords*))
  37
  38
  39 ;; ------------------------------------------------------------
  40 ;; Days
  41
  42 (defvar *day-keywords*
  43   '(:sunday :monday :tuesday :wednesday :thursday :friday :saturday))
  44
  45 (defvar *day-names*
  46   '("Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"))
  47
  48 (defun day-name (day-index)
  49   (nth day-index *day-names*))
  50
  51 (defun ordinal-day (day-keyword)
  52   "Return the zero-based day number for the given DAY keyword."
  53   (position day-keyword *day-keywords*))
  54
  55
  56 ;; ------------------------------------------------------------
  57 ;; time classes: wall-time, duration
  58
  59 (eval-when (:compile-toplevel :load-toplevel)
  60
  61 (defstruct (wall-time (:conc-name time-)
  62                       (:constructor %make-wall-time)
  63                       (:print-function %print-wall-time))
  64   (mjd 0 :type fixnum)
  65   (second 0 :type fixnum)
  66   (usec 0 :type fixnum))
  67
  68 (defun %print-wall-time (time stream depth)
  69   (declare (ignore depth))
  70   (if *print-escape*
  71       (format stream "#<WALL-TIME: ~a>" (format-time nil time))
  72       (format-time stream time :format :pretty)))
  73
  74 (defstruct (duration (:constructor %make-duration)
  75                      (:print-function %print-duration))
  76   (year 0 :type fixnum)
  77   (month 0 :type fixnum)
  78   (day 0 :type fixnum)
  79   (hour 0 :type fixnum)
  80   (second 0 :type fixnum)
  81   (minute 0 :type fixnum)
  82   (usec 0 :type fixnum))
  83
  84 (defun %print-duration (duration stream depth)
  85   (declare (ignore depth))
  86   (if *print-escape*
  87       (format stream "#<DURATION: ~a>"
  88               (format-duration nil duration :precision :second))
  89       (format-duration stream duration :precision :second)))
  90
  91 (defstruct (date (:constructor %make-date)
  92                  (:print-function %print-date))
  93   (mjd 0 :type fixnum))
  94
  95 (defun %print-date (date stream depth)
  96   (declare (ignore depth))
  97   (if *print-escape*
  98       (format stream "#<DATE: ~a>" (format-date nil date))
  99       (format-date stream date :format :pretty)))
 100
 101 );eval-when
 102
 103 (defun duration-timestring (duration)
 104   (let ((second (duration-second duration))
 105         (minute (duration-minute duration))
 106         (hour (duration-hour duration))
 107         (day (duration-day duration))
 108         (month (duration-month duration))
 109         (year (duration-year duration)))
 110     (format nil "P~dY~dM~dD~dH~dM~dS" year month day hour minute second)))
 111
 112
 113 ;; ------------------------------------------------------------
 114 ;; Constructors
 115
 116 (defun make-time (&key (year 0) (month 1) (day 1) (hour 0) (minute 0)
 117                        (second 0) (usec 0) (offset 0))
 118   (let ((mjd (gregorian-to-mjd month day year))
 119         (sec (+ (* hour 60 60)
 120                 (* minute 60)
 121                 second (- offset))))
 122     (multiple-value-bind (day-add raw-sec)
 123         (floor sec (* 60 60 24))
 124       (%make-wall-time :mjd (+ mjd day-add) :second raw-sec :usec usec))))
 125
 126 (defun make-date (&key (year 0) (month 1) (day 1) (hour 0) (minute 0)
 127                        (second 0) (usec 0) (offset 0))
 128   (time->date (make-time :year year :month month :day day :hour hour
 129                          :minute minute :second second :usec usec :offset offset)))
 130
 131 (defun copy-time (time)
 132   (%make-wall-time :mjd (time-mjd time)
 133                    :second (time-second time)))
 134
 135 (defun utime->time (utime)
 136   "Return a pair: (GREGORIAN DAY . TIME-OF-DAY)"
 137   (multiple-value-bind (second minute hour day mon year)
 138       (decode-universal-time utime)
 139     (make-time :year year :month mon :day day :hour hour :minute minute
 140                :second second)))
 141
 142 (defun date->time (date)
 143   "Returns a walltime for the given date"
 144   (%make-wall-time :mjd (date-mjd date)))
 145
 146 (defun time->date (time)
 147   "Returns a date for the given wall time (obvious loss in resolution)"
 148   (%make-date :mjd (time-mjd time)))
 149
 150 (defun get-time ()
 151   "Return a pair: (GREGORIAN DAY . TIME-OF-DAY)"
 152   (utime->time (get-universal-time)))
 153
 154 (defun get-date ()
 155   "Returns a date for today"
 156   (time->date (get-time)))
 157
 158 (defun make-duration (&key (year 0) (month 0) (day 0) (hour 0) (minute 0)
 159                       (second 0) (usec 0))
 160   (multiple-value-bind (second-add usec-1000000)
 161       (floor usec 1000000)
 162     (multiple-value-bind (minute-add second-60)
 163         (floor (+ second second-add) 60)
 164       (multiple-value-bind (hour-add minute-60)
 165           (floor (+ minute minute-add) 60)
 166         (multiple-value-bind (day-add hour-24)
 167             (floor (+ hour hour-add) 24)
 168           (%make-duration :year year :month month :day (+ day day-add)
 169                           :hour hour-24
 170                           :minute minute-60
 171                           :second second-60
 172                           :usec usec-1000000))))))
 173
 174
 175 ;; ------------------------------------------------------------
 176 ;; Accessors
 177
 178 (defun time-hms (time)
 179   (multiple-value-bind (hourminute second)
 180       (floor (time-second time) 60)
 181     (multiple-value-bind (hour minute)
 182         (floor hourminute 60)
 183       (values hour minute second))))
 184
 185 (defun time-ymd (time)
 186   (destructuring-bind (month day year)
 187       (mjd-to-gregorian (time-mjd time))
 188     (values year month day)))
 189
 190 (defun time-dow (time)
 191   "Return the 0 indexed Day of the week starting with Sunday"
 192   (mod (+ 3 (time-mjd time)) 7))
 193
 194 (defun decode-time (time)
 195   "returns the decoded time as multiple values: usec, second, minute, hour,
 196   day, month, year, integer day-of-week"
 197   (multiple-value-bind (year month day)
 198       (time-ymd time)
 199     (multiple-value-bind (hour minute second)
 200         (time-hms time)
 201       (values (time-usec time) second minute hour day month year (mod (+ (time-mjd time) 3) 7)))))
 202
 203 (defun date-ymd (date)
 204   (time-ymd (date->time date)))
 205
 206 (defun date-dow (date)
 207   (time-dow (date->time date)))
 208
 209 (defun decode-date (date)
 210   "returns the decoded date as multiple values: day month year integer day-of-week"
 211   (multiple-value-bind (year month day)
 212       (time-ymd (date->time date))
 213     (values day month year (date-dow date))))
 214
 215 ;; duration specific
 216 (defun duration-reduce (duration precision &optional round)
 217   (ecase precision
 218     (:usec
 219      (+ (duration-usec duration)
 220         (* (duration-reduce duration :second) 1000000)))
 221     (:second
 222      (+ (if round
 223             (floor (duration-usec duration) 500000)
 224             0)
 225         (duration-second duration)
 226         (* (duration-reduce duration :minute) 60)))
 227     (:minute
 228      (+ (if round
 229             (floor (duration-second duration) 30)
 230             0)
 231         (duration-minute duration)
 232         (* (duration-reduce duration :hour) 60)))
 233     (:hour
 234      (+ (if round
 235             (floor (duration-minute duration) 30)
 236             0)
 237         (duration-hour duration)
 238         (* (duration-reduce duration :day) 24)))
 239     (:day
 240      (+ (if round
 241             (floor (duration-hour duration) 12)
 242             0)
 243         (duration-day duration)))))
 244
 245
 246 ;; ------------------------------------------------------------
 247 ;; Arithemetic and comparators
 248
 249 (defun duration= (duration-a duration-b)
 250   (= (duration-reduce duration-a :usec)
 251      (duration-reduce duration-b :usec)))
 252
 253 (defun duration< (duration-a duration-b)
 254   (< (duration-reduce duration-a :usec)
 255      (duration-reduce duration-b :usec)))
 256
 257 (defun duration<= (duration-a duration-b)
 258   (<= (duration-reduce duration-a :usec)
 259       (duration-reduce duration-b :usec)))
 260
 261 (defun duration>= (x y)
 262   (duration<= y x))
 263
 264 (defun duration> (x y)
 265   (duration< y x))
 266
 267 (defun %time< (x y)
 268   (let ((mjd-x (time-mjd x))
 269         (mjd-y (time-mjd y)))
 270     (if (/= mjd-x mjd-y)
 271         (< mjd-x mjd-y)
 272         (if (/= (time-second x) (time-second y))
 273             (< (time-second x) (time-second y))
 274             (< (time-usec x) (time-usec y))))))
 275
 276 (defun %time>= (x y)
 277   (if (/= (time-mjd x) (time-mjd y))
 278       (>= (time-mjd x) (time-mjd y))
 279       (if (/= (time-second x) (time-second y))
 280           (>= (time-second x) (time-second y))
 281           (>= (time-usec x) (time-usec y)))))
 282
 283 (defun %time<= (x y)
 284   (if (/= (time-mjd x) (time-mjd y))
 285       (<= (time-mjd x) (time-mjd y))
 286       (if (/= (time-second x) (time-second y))
 287           (<= (time-second x) (time-second y))
 288           (<= (time-usec x) (time-usec y)))))
 289
 290 (defun %time> (x y)
 291   (if (/= (time-mjd x) (time-mjd y))
 292       (> (time-mjd x) (time-mjd y))
 293       (if (/= (time-second x) (time-second y))
 294           (> (time-second x) (time-second y))
 295           (> (time-usec x) (time-usec y)))))
 296
 297 (defun %time= (x y)
 298   (and (= (time-mjd x) (time-mjd y))
 299        (= (time-second x) (time-second y))
 300        (= (time-usec x) (time-usec y))))
 301
 302 (defun time= (number &rest more-numbers)
 303   "Returns T if all of its arguments are numerically equal, NIL otherwise."
 304   (do ((nlist more-numbers (cdr nlist)))
 305       ((atom nlist) t)
 306      (declare (list nlist))
 307      (if (not (%time= (car nlist) number)) (return nil))))
 308
 309 (defun time/= (number &rest more-numbers)
 310   "Returns T if no two of its arguments are numerically equal, NIL otherwise."
 311   (do* ((head number (car nlist))
 312         (nlist more-numbers (cdr nlist)))
 313        ((atom nlist) t)
 314      (declare (list nlist))
 315      (unless (do* ((nl nlist (cdr nl)))
 316                   ((atom nl) t)
 317                (declare (list nl))
 318                (if (%time= head (car nl)) (return nil)))
 319        (return nil))))
 320
 321 (defun time< (number &rest more-numbers)
 322   "Returns T if its arguments are in strictly increasing order, NIL otherwise."
 323   (do* ((n number (car nlist))
 324         (nlist more-numbers (cdr nlist)))
 325        ((atom nlist) t)
 326      (declare (list nlist))
 327      (if (not (%time< n (car nlist))) (return nil))))
 328
 329 (defun time> (number &rest more-numbers)
 330   "Returns T if its arguments are in strictly decreasing order, NIL otherwise."
 331   (do* ((n number (car nlist))
 332         (nlist more-numbers (cdr nlist)))
 333        ((atom nlist) t)
 334      (declare (list nlist))
 335      (if (not (%time> n (car nlist))) (return nil))))
 336
 337 (defun time<= (number &rest more-numbers)
 338   "Returns T if arguments are in strictly non-decreasing order, NIL otherwise."
 339   (do* ((n number (car nlist))
 340         (nlist more-numbers (cdr nlist)))
 341        ((atom nlist) t)
 342      (declare (list nlist))
 343      (if (not (%time<= n (car nlist))) (return nil))))
 344
 345 (defun time>= (number &rest more-numbers)
 346   "Returns T if arguments are in strictly non-increasing order, NIL otherwise."
 347   (do* ((n number (car nlist))
 348         (nlist more-numbers (cdr nlist)))
 349        ((atom nlist) t)
 350      (declare (list nlist))
 351      (if (not (%time>= n (car nlist))) (return nil))))
 352
 353 (defun time-max (number &rest more-numbers)
 354   "Returns the greatest of its arguments."
 355   (do ((nlist more-numbers (cdr nlist))
 356        (result number))
 357       ((null nlist) (return result))
 358      (declare (list nlist))
 359      (if (%time> (car nlist) result) (setf result (car nlist)))))
 360
 361 (defun time-min (number &rest more-numbers)
 362   "Returns the least of its arguments."
 363   (do ((nlist more-numbers (cdr nlist))
 364        (result number))
 365       ((null nlist) (return result))
 366      (declare (list nlist))
 367      (if (%time< (car nlist) result) (setf result (car nlist)))))
 368
 369 (defun time-compare (time-a time-b)
 370   (let ((mjd-a (time-mjd time-a))
 371         (mjd-b (time-mjd time-b))
 372         (sec-a (time-second time-a))
 373         (sec-b (time-second time-b))
 374         (usec-a (time-usec time-a))
 375         (usec-b (time-usec time-b)))
 376     (if (= mjd-a mjd-b)
 377         (if (= sec-a sec-b)
 378             (if (= usec-a usec-b)
 379                 :equal
 380                 (if (< usec-a usec-b)
 381                     :less-than
 382                     :greater-than))
 383             (if (< sec-a sec-b)
 384                 :less-than
 385                 :greater-than))
 386         (if (< mjd-a mjd-b)
 387             :less-than
 388             :greater-than))))
 389
 390 ; now the same for dates
 391 (eval-when (:compile-toplevel :load-toplevel)
 392 (defun replace-string (string1 search-string replace-string &key (test #'string=))
 393   "Search within string1 for search-string, replace with replace-string, non-destructively."
 394   (let ((replace-string-length (length replace-string))
 395         (search-string-length  (length search-string)))
 396     (labels ((sub-replace-string (current-string position)
 397                (let ((found-position (search search-string current-string :test test :start2 position)))
 398                  (if (null found-position)
 399                      current-string
 400                      (sub-replace-string (concatenate 'string
 401                                                       (subseq current-string 0 found-position)
 402                                                       replace-string
 403                                                       (subseq current-string (+ found-position search-string-length)))
 404                                          (+ position replace-string-length))))))
 405       (sub-replace-string string1 0))))
 406 );eval-when
 407
 408 (defmacro wrap-time-for-date (time-func &key (result-func))
 409   (let ((date-func (intern (replace-string (symbol-name time-func) "TIME" "DATE"))))
 410     `(defun ,date-func (number &rest more-numbers)
 411       (let ((result (apply #',time-func (mapcar #'date->time (cons number more-numbers)))))
 412         ,(if result-func
 413              `(funcall #',result-func result)
 414              'result)))))
 415
 416 (wrap-time-for-date time=)
 417 (wrap-time-for-date time/=)
 418 (wrap-time-for-date time<)
 419 (wrap-time-for-date time>)
 420 (wrap-time-for-date time<=)
 421 (wrap-time-for-date time>=)
 422 (wrap-time-for-date time-max :result-func time->date)
 423 (wrap-time-for-date time-min :result-func time->date)
 424
 425 (defun date-compare (date-a date-b)
 426   (time-compare (date->time date-a) (date->time date-b)))
 427
 428 ;; ------------------------------------------------------------
 429 ;; Formatting and output
 430
 431 (defvar +decimal-printer+ #(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9))
 432
 433 (defun db-timestring (time)
 434   "return the string to store the given time in the database"
 435   (declare (optimize (speed 3)))
 436   (let ((output (copy-seq "'XXXX-XX-XX XX:XX:XX.")))
 437     (flet ((inscribe-base-10 (output offset size decimal)
 438              (declare (type fixnum offset size decimal)
 439                       (type (simple-vector 10) +decimal-printer+))
 440              (dotimes (x size)
 441                (declare (type fixnum x)
 442                         (optimize (safety 0)))
 443                (multiple-value-bind (next this)
 444                    (floor decimal 10)
 445                  (setf (aref output (+ (- size x 1) offset))
 446                        (aref +decimal-printer+ this))
 447                  (setf decimal next)))))
 448       (multiple-value-bind (usec second minute hour day month year)
 449           (decode-time time)
 450         (inscribe-base-10 output 1 4 year)
 451         (inscribe-base-10 output 6 2 month)
 452         (inscribe-base-10 output 9 2 day)
 453         (inscribe-base-10 output 12 2 hour)
 454         (inscribe-base-10 output 15 2 minute)
 455         (inscribe-base-10 output 18 2 second)
 456         (format nil "~a~d'" output usec)))))
 457
 458 (defun iso-timestring (time)
 459   "return the string to store the given time in the database"
 460   (declare (optimize (speed 3)))
 461   (let ((output (copy-seq "XXXX-XX-XX XX:XX:XX,")))
 462     (flet ((inscribe-base-10 (output offset size decimal)
 463              (declare (type fixnum offset size decimal)
 464                       (type (simple-vector 10) +decimal-printer+))
 465              (dotimes (x size)
 466                (declare (type fixnum x)
 467                         (optimize (safety 0)))
 468                (multiple-value-bind (next this)
 469                    (floor decimal 10)
 470                  (setf (aref output (+ (- size x 1) offset))
 471                        (aref +decimal-printer+ this))
 472                  (setf decimal next)))))
 473       (multiple-value-bind (usec second minute hour day month year)
 474           (decode-time time)
 475         (inscribe-base-10 output 0 4 year)
 476         (inscribe-base-10 output 5 2 month)
 477         (inscribe-base-10 output 8 2 day)
 478         (inscribe-base-10 output 11 2 hour)
 479         (inscribe-base-10 output 14 2 minute)
 480         (inscribe-base-10 output 17 2 second)
 481         (format nil "~a,~d" output usec)))))
 482
 483 (defun db-datestring (date)
 484   (db-timestring (date->time date)))
 485 (defun iso-datestring (date)
 486   (iso-timestring (date->time date)))
 487
 488
 489 ;; ------------------------------------------------------------
 490 ;; Intervals
 491
 492 (defstruct interval
 493   (start nil)
 494   (end nil)
 495   (name nil)
 496   (contained nil)
 497   (type nil)
 498   (data nil))
 499
 500 ;; fix : should also return :contains / :contained
 501
 502 (defun interval-relation (x y)
 503   "Compare the relationship of node x to node y. Returns either
 504 :contained :contains :follows :overlaps or :precedes."
 505   (let ((xst  (interval-start x))
 506         (xend (interval-end x))
 507         (yst  (interval-start y))
 508         (yend (interval-end y)))
 509     (case (time-compare xst yst)
 510       (:equal
 511        (case (time-compare xend yend)
 512          (:less-than
 513           :contained)
 514          ((:equal :greater-than)
 515           :contains)))
 516       (:greater-than
 517        (case (time-compare xst yend)
 518          ((:equal :greater-than)
 519           :follows)
 520          (:less-than
 521           (case (time-compare xend yend)
 522             ((:less-than :equal)
 523              :contained)
 524             ((:greater-than)
 525              :overlaps)))))
 526       (:less-than
 527        (case (time-compare xend yst)
 528          ((:equal :less-than)
 529           :precedes)
 530          (:greater-than
 531           (case (time-compare xend yend)
 532             (:less-than
 533              :overlaps)
 534             ((:equal :greater-than)
 535              :contains))))))))
 536
 537 ;; ------------------------------------------------------------
 538 ;; interval lists
 539
 540 (defun sort-interval-list (list)
 541   (sort list (lambda (x y)
 542                (case (interval-relation x y)
 543                  ((:precedes :contains) t)
 544                  ((:follows :overlaps :contained) nil)))))
 545
 546 ;; interval push will return its list of intervals in strict order.
 547 (defun interval-push (interval-list interval &optional container-rule)
 548   (declare (ignore container-rule))
 549   (let ((sorted-list (sort-interval-list interval-list)))
 550     (dotimes (x (length sorted-list))
 551       (let ((elt (nth x sorted-list)))
 552         (case (interval-relation elt interval)
 553           (:follows
 554            (return-from interval-push (insert-at-index x sorted-list interval)))
 555           (:contains
 556            (return-from interval-push
 557              (replace-at-index x sorted-list
 558                                (make-interval :start (interval-start elt)
 559                                               :end (interval-end elt)
 560                                               :type (interval-type elt)
 561                                               :contained (interval-push (interval-contained elt) interval)
 562                                               :data (interval-data elt)))))
 563           ((:overlaps :contained)
 564            (error "Overlap")))))
 565     (append sorted-list (list interval))))
 566
 567 ;; interval lists
 568
 569 (defun interval-match (list time)
 570   "Return the index of the first interval in list containing time"
 571   ;; this depends on ordering of intervals!
 572   (let ((list (sort-interval-list list)))
 573     (dotimes (x (length list))
 574       (let ((elt (nth x list)))
 575         (when (and (time<= (interval-start elt) time)
 576                    (time< time (interval-end elt)))
 577           (return-from interval-match x))))))
 578
 579 (defun interval-clear (list time)
 580   (dotimes (x (length list))
 581     (let ((elt (nth x list)))
 582       (when (and (time<= (interval-start elt) time)
 583                  (time< time (interval-end elt)))
 584         (if (interval-match (interval-contained elt) time)
 585             (return-from interval-clear
 586               (replace-at-index x list
 587                                 (make-interval :start (interval-start elt)
 588                                                :end (interval-end elt)
 589                                                :type (interval-type elt)
 590                                                :contained (interval-clear (interval-contained elt) time)
 591                                                :data (interval-data elt))))
 592             (return-from interval-clear
 593               (delete-at-index x list)))))))
 594
 595 (defun interval-edit (list time start end &optional tag)
 596   "Attempts to modify the most deeply nested interval in list which
 597 begins at time.  If no changes are made, returns nil."
 598   ;; function required sorted interval list
 599   (let ((list (sort-interval-list list)))
 600     (if (null list) nil
 601       (dotimes (x (length list))
 602         (let ((elt (nth x list)))
 603           (when (and (time<= (interval-start elt) time)
 604                      (time< time (interval-end elt)))
 605             (or (interval-edit (interval-contained elt) time start end tag)
 606                 (cond ((and (< 0 x)
 607                             (time< start (interval-end (nth (1- x) list))))
 608                        (error "Overlap of previous interval"))
 609                       ((and (< x (1- (length list)))
 610                             (time< (interval-start (nth (1+ x) list)) end))
 611                        (error "~S ~S ~S ~S Overlap of next interval" x (length list) (interval-start (nth (1+ x) list)) end ))
 612                       ((time= (interval-start elt) time)
 613                        (return-from interval-edit
 614                          (replace-at-index x list
 615                                            (make-interval :start start
 616                                                           :end end
 617                                                           :type (interval-type elt)
 618                                                           :contained (restrict-intervals (interval-contained elt) start end)
 619                                                           :data (or tag (interval-data elt))))))))))))))
 620
 621 (defun restrict-intervals (list start end &aux newlist)
 622   (let ((test-interval (make-interval :start start :end end)))
 623     (dolist (elt list)
 624       (when (equal :contained
 625                    (interval-relation elt test-interval))
 626         (push elt newlist)))
 627     (nreverse newlist)))
 628
 629 ;;; utils from odcl/list.lisp
 630
 631 (defun replace-at-index (idx list elt)
 632   (cond ((= idx 0)
 633          (cons elt (cdr list)))
 634         ((= idx (1- (length list)))
 635          (append (butlast list) (list elt)))
 636         (t
 637          (append (subseq list 0 idx)
 638                  (list elt)
 639                  (subseq list (1+ idx))))))
 640
 641 (defun insert-at-index (idx list elt)
 642   (cond ((= idx 0)
 643          (cons elt list))
 644         ((= idx (1- (length list)))
 645          (append list (list elt)))
 646         (t
 647          (append (subseq list 0 idx)
 648                  (list elt)
 649                  (subseq list idx)))))
 650
 651 (defun delete-at-index (idx list)
 652   (cond ((= idx 0)
 653          (cdr list))
 654         ((= idx (1- (length list)))
 655          (butlast list))
 656         (t
 657          (append (subseq list 0 idx)
 658                  (subseq list (1+ idx))))))
 659
 660
 661 ;; ------------------------------------------------------------
 662 ;; return MJD for Gregorian date
 663
 664 (defun gregorian-to-mjd (month day year)
 665   (let ((b 0)
 666         (month-adj month)
 667         (year-adj (if (< year 0)
 668                       (+ year 1)
 669                       year))
 670         d
 671         c)
 672     (when (< month 3)
 673       (incf month-adj 12)
 674       (decf year-adj))
 675     (unless (or (< year 1582)
 676                 (and (= year 1582)
 677                      (or (< month 10)
 678                          (and (= month 10)
 679                               (< day 15)))))
 680       (let ((a (floor (/ year-adj 100))))
 681         (setf b (+ (- 2 a) (floor (/ a 4))))))
 682     (if (< year-adj 0)
 683         (setf c (floor (- (* 365.25d0 year-adj) 679006.75d0)))
 684         (setf c (floor (- (* 365.25d0 year-adj) 679006d0))))
 685     (setf d (floor (* 30.6001 (+ 1 month-adj))))
 686     ;; (cmsg "b ~s c ~s d ~s day ~s" b c d day)
 687     (+ b c d day)))
 688
 689 ;; convert MJD to Gregorian date
 690
 691 (defun mjd-to-gregorian (mjd)
 692   (let (z r g a b c year month day)
 693     (setf z (floor (+ mjd 678882)))
 694     (setf r (- (+ mjd 678882) z))
 695     (setf g (- z .25))
 696     (setf a (floor (/ g 36524.25)))
 697     (setf b (- a (floor (/ a 4))))
 698     (setf year (floor (/ (+ b g) 365.25)))
 699     (setf c (- (+ b z) (floor (* 365.25 year))))
 700     (setf month (truncate (/ (+ (* 5 c) 456) 153)))
 701     (setf day (+ (- c (truncate (/ (- (* 153 month) 457) 5))) r))
 702     (when (> month 12)
 703       (incf year)
 704       (decf month 12))
 705     (list month day year)))
 706
 707 (defun duration+ (time &rest durations)
 708   "Add each DURATION to TIME, returning a new wall-time value."
 709   (let ((year   (duration-year time))
 710         (month  (duration-month time))
 711         (day    (duration-day time))
 712         (hour   (duration-hour time))
 713         (minute (duration-minute time))
 714         (second (duration-second time))
 715         (usec   (duration-usec time)))
 716     (dolist (duration durations)
 717       (incf year    (duration-year duration))
 718       (incf month   (duration-month duration))
 719       (incf day     (duration-day duration))
 720       (incf hour    (duration-hour duration))
 721       (incf minute  (duration-minute duration))
 722       (incf second  (duration-second duration))
 723       (incf usec    (duration-usec duration)))
 724     (make-duration :year year :month month :day day :hour hour :minute minute
 725                    :second second :usec usec)))
 726
 727 (defun duration- (duration &rest durations)
 728     "Subtract each DURATION from TIME, returning a new duration value."
 729   (let ((year   (duration-year duration))
 730         (month  (duration-month duration))
 731         (day    (duration-day duration))
 732         (hour   (duration-hour duration))
 733         (minute (duration-minute duration))
 734         (second (duration-second duration))
 735         (usec   (duration-usec duration)))
 736     (dolist (duration durations)
 737       (decf year    (duration-year duration))
 738       (decf month   (duration-month duration))
 739       (decf day     (duration-day duration))
 740       (decf hour    (duration-hour duration))
 741       (decf minute  (duration-minute duration))
 742       (decf second  (duration-second duration))
 743       (decf usec    (duration-usec duration)))
 744     (make-duration :year year :month month :day day :hour hour :minute minute
 745                    :second second :usec usec)))
 746
 747 ;; Date + Duration
 748
 749 (defun time+ (time &rest durations)
 750   "Add each DURATION to TIME, returning a new wall-time value."
 751   (let ((new-time (copy-time time)))
 752     (dolist (duration durations)
 753       (roll new-time
 754             :year (duration-year duration)
 755             :month (duration-month duration)
 756             :day (duration-day duration)
 757             :hour (duration-hour duration)
 758             :minute (duration-minute duration)
 759             :second (duration-second duration)
 760             :usec (duration-usec duration)
 761             :destructive t))
 762     new-time))
 763
 764 (defun date+ (date &rest durations)
 765   "Add each DURATION to DATE, returning a new date value.
 766 Note that (barring daylight saving time) 12h + 12h will result in a new day, but doing
 767 it as separate calculations will not, as the time is chopped to a date before being returned."
 768   (time->date (apply #'time+ (cons (date->time date) durations))))
 769
 770 (defun time- (time &rest durations)
 771   "Subtract each DURATION from TIME, returning a new wall-time value."
 772   (let ((new-time (copy-time time)))
 773     (dolist (duration durations)
 774       (roll new-time
 775             :year (- (duration-year duration))
 776             :month (- (duration-month duration))
 777             :day (- (duration-day duration))
 778             :hour (- (duration-hour duration))
 779             :minute (- (duration-minute duration))
 780             :second (- (duration-second duration))
 781             :usec (- (duration-usec duration))
 782             :destructive t))
 783     new-time))
 784
 785 (defun date- (date &rest durations)
 786   "Subtract each DURATION to DATE, returning a new date value.
 787 Note that (barring daylight saving time) 12h + 12h will result in a new day, but doing
 788 it as separate calculations will not, as the time is chopped to a date before being returned."
 789   (time->date (apply #'time- (cons (date->time date) durations))))
 790
 791 (defun time-difference (time1 time2)
 792   "Returns a DURATION representing the difference between TIME1 and
 793 TIME2."
 794   (flet ((do-diff (time1 time2)
 795
 796   (let (day-diff sec-diff)
 797     (setf day-diff (- (time-mjd time2)
 798                       (time-mjd time1)))
 799     (if (> day-diff 0)
 800         (progn (decf day-diff)
 801                (setf sec-diff (+ (time-second time2)
 802                                  (- (* 60 60 24)
 803                                     (time-second time1)))))
 804       (setf sec-diff (- (time-second time2)
 805                         (time-second time1))))
 806      (make-duration :day day-diff
 807                    :second sec-diff))))
 808     (if (time< time1 time2)
 809         (do-diff time1 time2)
 810       (do-diff time2 time1))))
 811
 812 (defun date-difference (date1 date2)
 813   "Returns a DURATION representing the difference between TIME1 and
 814 TIME2."
 815   (time-difference (date->time date1) (date->time date2)))
 816
 817 (defun format-date (stream date &key format
 818                     (date-separator "-")
 819                     (internal-separator " "))
 820   "produces on stream the datestring corresponding to the date
 821 with the given options"
 822   (format-time stream (date->time date)
 823                :format format
 824                :date-separator date-separator
 825                :internal-separator internal-separator))
 826
 827 (defun format-time (stream time &key format
 828                     (date-separator "-")
 829                     (time-separator ":")
 830                     (internal-separator " "))
 831   "produces on stream the timestring corresponding to the wall-time
 832 with the given options"
 833   (let ((*print-circle* nil))
 834     (multiple-value-bind (usec second minute hour day month year dow)
 835         (decode-time time)
 836       (case format
 837         (:pretty
 838          (format stream "~A ~A, ~A ~D, ~D"
 839                  (pretty-time hour minute)
 840                  (day-name dow)
 841                  (month-name month)
 842                  day
 843                  year))
 844         (:short-pretty
 845          (format stream "~A, ~D/~D/~D"
 846                  (pretty-time hour minute)
 847                  month day year))
 848         (:iso
 849          (let ((string (iso-timestring time)))
 850            (if stream
 851                (write-string string stream)
 852              string)))
 853         (t
 854          (format stream "~2,'0D~A~2,'0D~A~2,'0D~A~2,'0D~A~2,'0D~A~2,'0D.~6,'0D"
 855                  year date-separator month date-separator day
 856                  internal-separator hour time-separator minute time-separator
 857                  second usec))))))
 858
 859 (defun pretty-time (hour minute)
 860   (cond
 861    ((eq hour 0)
 862     (format nil "12:~2,'0D AM" minute))
 863    ((eq hour 12)
 864     (format nil "12:~2,'0D PM" minute))
 865    ((< hour 12)
 866     (format nil "~D:~2,'0D AM" hour minute))
 867    ((and (> hour 12) (< hour 24))
 868     (format nil "~D:~2,'0D PM" (- hour 12) minute))
 869    (t
 870     (error "pretty-time got bad hour"))))
 871
 872 (defun leap-days-in-days (days)
 873   ;; return the number of leap days between Mar 1 2000 and
 874   ;; (Mar 1 2000) + days, where days can be negative
 875   (if (< days 0)
 876       (ceiling (/ (- days) (* 365 4)))
 877       (floor (/ days (* 365 4)))))
 878
 879 (defun current-year ()
 880   (third (mjd-to-gregorian (time-mjd (get-time)))))
 881
 882 (defun current-month ()
 883   (first (mjd-to-gregorian (time-mjd (get-time)))))
 884
 885 (defun current-day ()
 886   (second (mjd-to-gregorian (time-mjd (get-time)))))
 887
 888 (defun parse-date-time (string)
 889   "parses date like 08/08/01, 8.8.2001, eg"
 890   (when (> (length string) 1)
 891     (let ((m (current-month))
 892           (d (current-day))
 893           (y (current-year)))
 894       (let ((integers (mapcar #'parse-integer (hork-integers string))))
 895         (case (length integers)
 896           (1
 897            (setf y (car integers)))
 898           (2
 899            (setf m (car integers))
 900            (setf y (cadr integers)))
 901           (3
 902            (setf m (car integers))
 903            (setf d (cadr integers))
 904            (setf y (caddr integers)))
 905           (t
 906            (return-from parse-date-time))))
 907       (when (< y 100)
 908         (incf y 2000))
 909       (make-time :year y :month m :day d))))
 910
 911 (defun hork-integers (input)
 912   (let ((output '())
 913         (start 0))
 914     (dotimes (x (length input))
 915       (unless (<= 48 (char-code (aref input x)) 57)
 916         (push (subseq input start x) output)
 917         (setf start (1+ x))))
 918     (nreverse (push (subseq input start) output))))
 919
 920 (defun merged-time (day time-of-day)
 921   (%make-wall-time :mjd (time-mjd day)
 922                    :second (time-second time-of-day)))
 923
 924 (defun time-meridian (hours)
 925   (cond ((= hours 0)
 926          (values 12 "AM"))
 927         ((= hours 12)
 928          (values 12 "PM"))
 929         ((< 12 hours)
 930          (values (- hours 12) "PM"))
 931         (t
 932          (values hours "AM"))))
 933
 934 (defgeneric to-string (val &rest keys)
 935   )
 936
 937 (defmethod to-string ((time wall-time) &rest keys)
 938   (destructuring-bind (&key (style :daytime) &allow-other-keys)
 939       keys
 940     (print-date time style)))
 941
 942 (defun print-date (time &optional (style :daytime))
 943   (multiple-value-bind (usec second minute hour day month year dow)
 944       (decode-time time)
 945     (declare (ignore usec second))
 946     (multiple-value-bind (hours meridian)
 947         (time-meridian hour)
 948       (ecase style
 949         (:time-of-day
 950          ;; 2:00 PM
 951          (format nil "~d:~2,'0d ~a" hours minute meridian))
 952         (:long-day
 953          ;; October 11th, 2000
 954          (format nil "~a ~d, ~d" (month-name month) day year))
 955         (:month
 956          ;; October
 957          (month-name month))
 958         (:month-year
 959          ;; October 2000
 960          (format nil "~a ~d" (month-name month) year))
 961         (:full
 962          ;; 11:08 AM, November 22, 2002
 963          (format nil "~d:~2,'0d ~a, ~a ~d, ~d"
 964                  hours minute meridian (month-name month) day year))
 965         (:full+weekday
 966          ;; 11:09 AM Friday, November 22, 2002
 967          (format nil "~d:~2,'0d ~a ~a, ~a ~d, ~d"
 968                  hours minute meridian (nth dow *day-names*)
 969                  (month-name month) day year))
 970         (:daytime
 971          ;; 11:09 AM, 11/22/2002
 972          (format-time nil time :format :short-pretty))
 973         (:day
 974          ;; 11/22/2002
 975          (format nil "~d/~d/~d" month day year))))))
 976
 977 (defun time-element (time element)
 978   (multiple-value-bind (usec second minute hour day month year dow)
 979       (decode-time time)
 980     (declare (ignore usec))
 981     (ecase element
 982       (:seconds
 983        second)
 984       (:minutes
 985        minute)
 986       (:hours
 987        hour)
 988       (:day-of-month
 989        day)
 990       (:integer-day-of-week
 991        dow)
 992       (:day-of-week
 993        (nth dow *day-keywords*))
 994       (:month
 995        month)
 996       (:year
 997        year))))
 998
 999 (defun date-element (date element)
1000   (time-element (date->time date) element))
1001
1002 (defun format-duration (stream duration &key (precision :minute))
1003   (let ((second (duration-second duration))
1004         (minute (duration-minute duration))
1005         (hour (duration-hour duration))
1006         (day (duration-day duration))
1007         (month (duration-month duration))
1008         (year (duration-year duration))
1009         (return (null stream))
1010         (stream (or stream (make-string-output-stream))))
1011     (ecase precision
1012       (:day
1013        (setf hour 0 second 0 minute 0))
1014       (:hour
1015        (setf second 0 minute 0))
1016       (:minute
1017        (setf second 0))
1018       (:second
1019        t))
1020     (if (= 0 year month day hour minute)
1021         (format stream "0 minutes")
1022         (let ((sent? nil))
1023           (when (< 0 year)
1024             (format stream "~d year~p" year year)
1025             (setf sent? t))
1026           (when (< 0 month)
1027             (when sent?
1028               (write-char #\Space stream))
1029             (format stream "~d month~p" month month)
1030             (setf sent? t))
1031           (when (< 0 day)
1032             (when sent?
1033               (write-char #\Space stream))
1034             (format stream "~d day~p" day day)
1035             (setf sent? t))
1036           (when (< 0 hour)
1037             (when sent?
1038               (write-char #\Space stream))
1039             (format stream "~d hour~p" hour hour)
1040             (setf sent? t))
1041           (when (< 0 minute)
1042             (when sent?
1043               (write-char #\Space stream))
1044             (format stream "~d min~p" minute minute)
1045             (setf sent? t))
1046           (when (< 0 second)
1047             (when sent?
1048               (write-char #\Space stream))
1049             (format stream "~d sec~p" second second))))
1050     (when return
1051       (get-output-stream-string stream))))
1052
1053 (defgeneric midnight (self))
1054 (defmethod midnight ((self wall-time))
1055   "truncate hours, minutes and seconds"
1056   (%make-wall-time :mjd (time-mjd self)))
1057
1058 (defun roll (date &key (year 0) (month 0) (day 0) (second 0) (hour 0)
1059              (minute 0) (usec 0) (destructive nil))
1060   (unless (= 0 year month)
1061     (multiple-value-bind (year-orig month-orig day-orig)
1062         (time-ymd date)
1063       (multiple-value-bind (new-year new-month)
1064          (floor (+ month month-orig (* 12 (+ year year-orig))) 12)
1065        (let ((new-date (make-time :year new-year
1066                                   :month new-month
1067                                   :day day-orig
1068                                   :second (time-second date)
1069                                   :usec usec)))
1070          (if destructive
1071              (setf (time-mjd date) (time-mjd new-date))
1072              (setq date new-date))))))
1073   (let ((mjd (time-mjd date))
1074         (sec (time-second date))
1075         (usec (time-usec date)))
1076     (multiple-value-bind (sec-new usec-new)
1077         (floor (+ usec
1078                   (* 1000000
1079                      (+ sec second
1080                         (* 60 minute)
1081                         (* 60 60 hour))))
1082                1000000)
1083       (multiple-value-bind (mjd-new sec-new)
1084           (floor sec-new (* 60 60 24))
1085         (if destructive
1086             (progn
1087               (setf (time-mjd date) (+ mjd mjd-new day)
1088                     (time-second date) sec-new
1089                     (time-usec date) usec-new)
1090               date)
1091             (%make-wall-time :mjd (+ mjd mjd-new day)
1092                              :second sec-new
1093                              :usec usec-new))))))
1094
1095 (defun roll-to (date size position)
1096   (ecase size
1097     (:month
1098      (ecase position
1099        (:beginning
1100         (roll date :day (+ 1
1101                            (- (time-element date :day-of-month)))))
1102        (:end
1103         (roll date :day (+ (days-in-month (time-element date :month)
1104                                           (time-element date :year))
1105                            (- (time-element date :day-of-month)))))))))
1106
1107 (defun week-containing (time)
1108   (let* ((midn (midnight time))
1109          (dow (time-element midn :integer-day-of-week)))
1110     (list (roll midn :day (- dow))
1111           (roll midn :day (- 7 dow)))))
1112
1113 (defun leap-year? (year)
1114   "t if YEAR is a leap yeap in the Gregorian calendar"
1115   (and (= 0 (mod year 4))
1116        (or (not (= 0 (mod year 100)))
1117            (= 0 (mod year 400)))))
1118
1119 (defun valid-month-p (month)
1120   "t if MONTH exists in the Gregorian calendar"
1121   (<= 1 month 12))
1122
1123 (defun valid-gregorian-date-p (date)
1124   "t if DATE (year month day) exists in the Gregorian calendar"
1125   (let ((max-day (days-in-month (nth 1 date) (nth 0 date))))
1126     (<= 1 (nth 2 date) max-day)))
1127
1128 (defun days-in-month (month year &key (careful t))
1129   "the number of days in MONTH of YEAR, observing Gregorian leap year
1130 rules"
1131   (declare (type fixnum month year))
1132   (when careful
1133     (check-type month (satisfies valid-month-p)
1134                 "between 1 (January) and 12 (December)"))
1135   (if (eql month 2)                     ; feb
1136       (if (leap-year? year)
1137           29 28)
1138       (let ((even (mod (1- month) 2)))
1139         (if (< month 8)                 ; aug
1140             (- 31 even)
1141             (+ 30 even)))))
1142
1143 (defun day-of-year (year month day &key (careful t))
1144   "the day number within the year of the date DATE.  For example,
1145 1987 1 1 returns 1"
1146   (declare (type fixnum year month day))
1147   (when careful
1148     (let ((date (list year month day)))
1149     (check-type date (satisfies valid-gregorian-date-p)
1150                 "a valid Gregorian date")))
1151   (let ((doy (+ day (* 31 (1- month)))))
1152     (declare (type fixnum doy))
1153     (when (< 2 month)
1154       (setf doy (- doy (floor (+ 23 (* 4 month)) 10)))
1155       (when (leap-year? year)
1156         (incf doy)))
1157     doy))
1158
1159 (defun parse-yearstring (string)
1160   (let ((year (or (parse-integer-insensitively string)
1161                   (extract-roman string))))
1162     (when (and year (< 1500 year 2500))
1163       (make-time :year year))))
1164
1165 (defun parse-integer-insensitively (string)
1166   (let ((start (position-if #'digit-char-p string))
1167         (end   (position-if #'digit-char-p string :from-end t)))
1168     (when (and start end)
1169       (parse-integer (subseq string start (1+ end)) :junk-allowed t))))
1170
1171 (defvar *roman-digits*
1172   '((#\M . 1000)
1173     (#\D . 500)
1174     (#\C . 100)
1175     (#\L . 50)
1176     (#\X . 10)
1177     (#\V . 5)
1178     (#\I . 1)))
1179
1180 (defun extract-roman (string &aux parse)
1181   (dotimes (x (length string))
1182     (let ((val (cdr (assoc (aref string x) *roman-digits*))))
1183       (when (and val parse (< (car parse) val))
1184         (push (- (pop parse)) parse))
1185       (push val parse)))
1186   (apply #'+ parse))
1187
1188
1189 ;; ------------------------------------------------------------
1190 ;; Parsing iso-8601 timestrings
1191
1192 (define-condition iso-8601-syntax-error (sql-user-error)
1193   ((bad-component;; year, month whatever
1194     :initarg :bad-component
1195     :reader bad-component))
1196   (:report (lambda (c stream)
1197              (format stream "Bad component: ~A " (bad-component c)))))
1198
1199 (defun parse-timestring (timestring &key (start 0) end junk-allowed)
1200   "parse a timestring and return the corresponding wall-time.  If the
1201 timestring starts with P, read a duration; otherwise read an ISO 8601
1202 formatted date string."
1203   (declare (ignore junk-allowed))
1204   (let ((string (subseq timestring start end)))
1205     (if (char= (aref string 0) #\P)
1206         (parse-iso-8601-duration string)
1207       (parse-iso-8601-time string))))
1208
1209 (defun parse-datestring (datestring &key (start 0) end junk-allowed)
1210   "parse a ISO 8601 timestring and return the corresponding date.
1211 Will throw a hissy fit if the date string is a duration. Will ignore any precision beyond day (hour/min/sec/usec)."
1212   (let ((parsed-value (parse-timestring datestring :start start :end end :junk-allowed junk-allowed)))
1213     (ecase (type-of parsed-value)
1214       (wall-time (%make-date :mjd (time-mjd parsed-value))))))
1215
1216
1217 (defvar *iso-8601-duration-delimiters*
1218   '((#\Y . :years)
1219     (#\D . :days)
1220     (#\H . :hours)
1221     (#\M . :months/minutes)
1222     (#\S . :seconds)))
1223
1224 (defun iso-8601-delimiter (elt)
1225   (cdr (assoc elt *iso-8601-duration-delimiters*)))
1226
1227 (defun iso-8601-duration-subseq (string end)
1228   (let* ((pos (position-if #'iso-8601-delimiter string :end end :from-end t))
1229          (pos2 (when pos
1230                  (position-if-not #'digit-char-p string :end pos :from-end t)))
1231          (number (when pos2
1232                    (parse-integer
1233                     (subseq string (1+ pos2) pos) :junk-allowed t))))
1234     (when number
1235       (values number
1236               (1+ pos)
1237               (1+ pos2)
1238               (iso-8601-delimiter (aref string pos))))))
1239
1240 (defun parse-iso-8601-duration (string)
1241   "return a wall-time from a duration string"
1242   (block parse
1243     (let ((years 0)
1244           (months 0)
1245           (days 0)
1246           (secs 0)
1247           (hours 0)
1248           (minutes 0)
1249           (index (length string))
1250           (months/minutes nil))
1251       (loop
1252        (multiple-value-bind (duration next-index duration-type)
1253            (iso-8601-duration-subseq string index)
1254          (case duration-type
1255            (:years
1256             (incf years duration))
1257            (:months/minutes
1258             (if months/minutes
1259                 (incf months duration)
1260                 (progn
1261                   (setq months/minutes t)
1262                   (incf minutes duration))))
1263            (:days
1264             (setq months/minutes t)
1265             (incf days duration))
1266            (:hours
1267             (setq months/minutes t)
1268             (incf hours duration))
1269            (:seconds
1270             (incf secs duration))
1271            (t
1272             (return-from parse
1273               (make-duration
1274                :year years :month months :day days :hour hours
1275                :minute minutes :second secs))))
1276          (setf index next-index))))))
1277
1278 ;; e.g. 2000-11-11 00:00:00-06
1279
1280 (defun parse-iso-8601-time (string)
1281   "return the wall-time corresponding to the given ISO 8601 datestring"
1282   (multiple-value-bind (year month day hour minute second usec offset)
1283       (syntax-parse-iso-8601 string)
1284     (make-time :year year
1285                :month month
1286                :day day
1287                :hour hour
1288                :minute minute
1289                :second second
1290                :usec usec
1291                :offset offset)))
1292
1293
1294 (defun syntax-parse-iso-8601 (string)
1295   ;; use strlen to determine if fractional seconds are present in timestamp
1296   (let ((strlen (length string))
1297         year month day hour minute second usec gmt-sec-offset)
1298     (handler-case
1299         (progn
1300           (setf year           (parse-integer string :start 0 :end 4)
1301                 month          (parse-integer string :start 5 :end 7)
1302                 day            (parse-integer string :start 8 :end 10)
1303                 hour           (if (<= 13 strlen)
1304                                    (parse-integer string :start 11 :end 13)
1305                                    0)
1306                 minute         (if (<= 16 strlen)
1307                                    (parse-integer string :start 14 :end 16)
1308                                    0)
1309                 second         (if (<= 19 strlen)
1310                                    (parse-integer string :start 17 :end 19)
1311                                    0))
1312           (cond
1313             ((and (> strlen 19)
1314                   (or (char= #\, (char string 19))
1315                       (char= #\. (char string 19))))
1316              (multiple-value-bind (parsed-usec usec-end)
1317                  (parse-integer string :start 20 :junk-allowed t)
1318                (setf usec          (or parsed-usec 0)
1319                      gmt-sec-offset (if (<= (+ 3 usec-end)  strlen)
1320                                         (let ((skip-to (or (position #\+ string :start 19)
1321                                                            (position #\- string :start 19))))
1322                                           (if skip-to
1323                                               (* 60 60
1324                                                  (parse-integer string :start skip-to
1325                                                                 :end (+ skip-to 3)))
1326                                               0))
1327                                         0))))
1328             (t
1329              (setf usec           0
1330                    gmt-sec-offset (if (<= 22  strlen)
1331                                       (let ((skip-to (or (position #\+ string :start 19)
1332                                                          (position #\- string :start 19))))
1333                                         (if skip-to
1334                                             (* 60 60
1335                                                (parse-integer string :start skip-to
1336                                                               :end (+ skip-to 3)))
1337                                             0))
1338                                       0))))
1339           (unless (< 0 year)
1340             (error 'iso-8601-syntax-error
1341                    :bad-component '(year . 0)))
1342           (unless (< 0 month)
1343             (error 'iso-8601-syntax-error
1344                    :bad-component '(month . 0)))
1345           (unless (< 0 day)
1346             (error 'iso-8601-syntax-error
1347                    :bad-component '(month . 0)))
1348           (values year month day hour minute second usec gmt-sec-offset))
1349       (simple-error ()
1350         (error 'iso-8601-syntax-error
1351                :bad-component
1352                (car (find-if (lambda (pair) (null (cdr pair)))
1353                              `((year . ,year) (month . ,month)
1354                                (day . ,day) (hour . ,hour)
1355                                (minute . ,minute) (second . ,second)
1356                                (usec . ,usec)
1357                                (timezone . ,gmt-sec-offset)))))))))