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;; SRFI-19: Time Data Types and Procedures.
;;
;; Modified by Derick Eddington to be included into the (srfi :19 time) R6RS library.
;; TODO: For implementations which have threads,
;; the thread timing stuff can probably be made to work.
;;
;; Copyright (C) I/NET, Inc. (2000, 2002, 2003). All Rights Reserved.
;;
;; This document and translations of it may be copied and furnished to others,
;; and derivative works that comment on or otherwise explain it or assist in its
;; implementation may be prepared, copied, published and distributed, in whole or
;; in part, without restriction of any kind, provided that the above copyright
;; notice and this paragraph are included on all such copies and derivative works.
;; However, this document itself may not be modified in any way, such as by
;; removing the copyright notice or references to the Scheme Request For
;; Implementation process or editors, except as needed for the purpose of
;; developing SRFIs in which case the procedures for copyrights defined in the SRFI
;; process must be followed, or as required to translate it into languages other
;; than English.
;;
;; The limited permissions granted above are perpetual and will not be revoked
;; by the authors or their successors or assigns.
;;
;; This document and the information contained herein is provided on an "AS IS"
;; basis and THE AUTHOR AND THE SRFI EDITORS DISCLAIM ALL WARRANTIES, EXPRESS OR
;; IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
;; INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
;; MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
;; -- Bug fixes.
;;
;; MAKE-TIME had parameters seconds and nanoseconds reversed; change all
;; references in file to match. Will F: 2002-10-15
;;
;; DATE-YEAR-DAY returned the wrong day; tm:year-day fixed to do the right
;; thing. Will F: 2002-10-15
;; It also called an undefined error procedure.
;;
;; DISPLAYING procedure removed. Will F: 2002-10-15.
;;
;; TM:NANO constant corrected. 2002-11-04.
;;
;; The following fixes by Will Fitzgerald, February, 2003.
;; -- Thanks to Steven Ma and others.
;;
;; (CURRENT-TIME 'TIME-THREAD) added.
;;
;; TIME-RESOLUTION for TIME-PROCESS added.
;;
;; TIME comparison procedures (time=?, etc. fixed.
;;
;; Corrected errors in converting between TAI and UTC time.
;;
;; TAI and UTC date converters no longer look at leap seconds,
;; which was an error.
;;
;; corrections to calls to tm:time-error
;;
;; timezone offset not used in date->time-utc and date->julian-day
;;
;; typos in tm:integer-reader-exact, tm:string->date,
;; time-monotonic->time-utc!, tm:char->int fixed
;;
;; corrected "~k", "~f" formatting for date->string (includes fix for
;; "~4"
;;
;; 'split-real' fixed.
;;
;; fixed julian-day->time-utc and variants.
;;
;; changes 2003-02-26, based on comments by Martin Gasbichler.
;;
;; moronic, overly complicated COPY-TIME procedure changed
;; to simple version suggested by Martin Gasbichler.
;;
;; To provide more portability, changed #\Space to #\space
;; and #\tab to #\Tab to (integer->char 9)
;;
;; changed arity-3 calls to / and - to arity 2 calls (again,
;; for more general portability).
;;
;; split-real fixed again -- by removing it, and using
;; 'fractional part'. Will Fitzgerald 5/16/2003.
;; --------------------------------------------------------------
(define-syntax receive
(syntax-rules ()
((receive formals expression body ...)
(call-with-values (lambda () expression)
(lambda formals body ...)))))
;;; -- we want receive later on for a couple of small things
;;
;; :OPTIONAL is nice, too
(define-syntax :optional
(syntax-rules ()
((_ val default-value)
(if (null? val) default-value (car val)))))
(define time-tai 'time-tai)
(define time-utc 'time-utc)
(define time-monotonic 'time-monotonic)
#|(define time-thread 'time-thread)
(define time-process 'time-process)|#
(define time-duration 'time-duration)
;; example of extension (MZScheme specific)
;(define time-gc 'time-gc)
;;-- LOCALE dependent constants
(define tm:locale-number-separator ".")
(define tm:locale-abbr-weekday-vector (vector "Sun" "Mon" "Tue" "Wed"
"Thu" "Fri" "Sat"))
(define tm:locale-long-weekday-vector (vector "Sunday" "Monday"
"Tuesday" "Wednesday"
"Thursday" "Friday"
"Saturday"))
;; note empty string in 0th place.
(define tm:locale-abbr-month-vector (vector "" "Jan" "Feb" "Mar"
"Apr" "May" "Jun" "Jul"
"Aug" "Sep" "Oct" "Nov"
"Dec"))
(define tm:locale-long-month-vector (vector "" "January" "February"
"March" "April" "May"
"June" "July" "August"
"September" "October"
"November" "December"))
(define tm:locale-pm "PM")
(define tm:locale-am "AM")
;; See date->string
(define tm:locale-date-time-format "~a ~b ~d ~H:~M:~S~z ~Y")
(define tm:locale-short-date-format "~m/~d/~y")
(define tm:locale-time-format "~H:~M:~S")
(define tm:iso-8601-date-time-format "~Y-~m-~dT~H:~M:~S~z")
;;-- Miscellaneous Constants.
;;-- only the tm:tai-epoch-in-jd might need changing if
;; a different epoch is used.
(define tm:nano (expt 10 9))
(define tm:sid 86400) ; seconds in a day
(define tm:sihd 43200) ; seconds in a half day
(define tm:tai-epoch-in-jd 4881175/2) ; julian day number for 'the epoch'
;;; A Very simple Error system for the time procedures
;;;
(define tm:time-error-types
'((invalid-clock-type . "invalid clock type")
(unsupported-clock-type . "unsupported clock type")
(incompatible-time-types . "incompatible time types")
(not-duration . "not duration")
(dates-are-immutable . "dates are immutable")
(bad-date-format-string . "bad date format string")
(bad-date-template-string . "bad date template string")
(invalid-month-specification . "invalid month specification")
))
(define (tm:time-error caller type value)
(cond
[(assoc type tm:time-error-types)
=>
(lambda (p)
(if value
(error caller (cdr p) value)
(error caller (cdr p))))]
[else
(error caller "(library (srfi :19 time)) internal error: unsupported error type" type)]))
;; A table of leap seconds
;; See ftp://maia.usno.navy.mil/ser7/tai-utc.dat
;; and update as necessary.
;; this procedures reads the file in the abover
;; format and creates the leap second table
;; it also calls the almost standard, but not R5 procedures read-line
;; & open-input-string
;; ie (set! tm:leap-second-table (tm:read-tai-utc-date "tai-utc.dat"))
(define (tm:read-tai-utc-data filename)
(define (convert-jd jd)
(* (- (inexact->exact jd) tm:tai-epoch-in-jd) tm:sid))
(define (convert-sec sec)
(inexact->exact sec))
(let ( (port (open-input-file filename))
(table '()) )
(let loop ((line (read-line port)))
(if (not (eq? line eof))
(begin
(let* ( (data (read (open-input-string (string-append "(" line ")"))))
(year (car data))
(jd (cadddr (cdr data)))
(secs (cadddr (cdddr data))) )
(if (>= year 1972)
(set! table (cons (cons (convert-jd jd) (convert-sec secs)) table)))
(loop (read-line port))))))
table))
;; each entry is ( utc seconds since epoch . # seconds to add for tai )
;; note they go higher to lower, and end in 1972.
(define tm:leap-second-table
'((1136073600 . 33)
(915148800 . 32)
(867715200 . 31)
(820454400 . 30)
(773020800 . 29)
(741484800 . 28)
(709948800 . 27)
(662688000 . 26)
(631152000 . 25)
(567993600 . 24)
(489024000 . 23)
(425865600 . 22)
(394329600 . 21)
(362793600 . 20)
(315532800 . 19)
(283996800 . 18)
(252460800 . 17)
(220924800 . 16)
(189302400 . 15)
(157766400 . 14)
(126230400 . 13)
(94694400 . 12)
(78796800 . 11)
(63072000 . 10)))
(define (read-leap-second-table filename)
(set! tm:leap-second-table (tm:read-tai-utc-data filename))
(values))
(define (tm:leap-second-delta utc-seconds)
(letrec ( (lsd (lambda (table)
(cond
((>= utc-seconds (caar table))
(cdar table))
(else (lsd (cdr table)))))) )
(if (< utc-seconds (* (- 1972 1970) 365 tm:sid)) 0
(lsd tm:leap-second-table))))
;; going from tai seconds to utc seconds ...
(define (tm:leap-second-neg-delta tai-seconds)
(letrec ( (lsd (lambda (table)
(cond ((null? table) 0)
((<= (cdar table) (- tai-seconds (caar table)))
(cdar table))
(else (lsd (cdr table)))))) )
(if (< tai-seconds (* (- 1972 1970) 365 tm:sid)) 0
(lsd tm:leap-second-table))))
;;; the time structure; creates the accessors, too.
;;; wf: changed to match srfi documentation.
(define-record-type time
(fields
(mutable type)
(mutable nanosecond)
(mutable second)))
;; thanks, Martin Gasbichler ...
(define (copy-time time)
(make-time (time-type time)
(time-nanosecond time) ; original had this mistakenly swapped with time-second
(time-second time)))
;;; current-time
;;; specific time getters.
;; I'm not sure why the original was using time-nanoseconds
;; as 10000 * the milliseconds
(define (tm:get-time-of-day)
(let ([ct (host:current-time)])
(values (host:time-second ct)
(host:time-nanosecond ct))))
(define (tm:current-time-utc)
(receive (seconds nanos) (tm:get-time-of-day)
(make-time time-utc nanos seconds)))
(define (tm:current-time-tai)
(receive (seconds nanos) (tm:get-time-of-day)
(make-time time-tai
nanos
(+ seconds (tm:leap-second-delta seconds)) )))
#|(define (tm:current-time-ms-time time-type proc)
(let ((current-ms (proc)))
(make-time time-type
XXX
ZZZ
))) |#
;; -- we define it to be the same as tai.
;; a different implemation of current-time-montonic
;; will require rewriting all of the time-monotonic converters,
;; of course.
(define (tm:current-time-monotonic)
(receive (seconds nanos) (tm:get-time-of-day)
(make-time time-monotonic
nanos
(+ seconds (tm:leap-second-delta seconds)) )))
#|(define (tm:current-time-thread)
(tm:current-time-ms-time time-process current-process-milliseconds))
(define (tm:current-time-process)
(tm:current-time-ms-time time-process current-process-milliseconds))
(define (tm:current-time-gc)
(tm:current-time-ms-time time-gc current-gc-milliseconds)) |#
(define (current-time . clock-type)
(let ( (clock-type (:optional clock-type time-utc)) )
(cond
((eq? clock-type time-tai) (tm:current-time-tai))
((eq? clock-type time-utc) (tm:current-time-utc))
((eq? clock-type time-monotonic) (tm:current-time-monotonic))
#|((eq? clock-type time-thread) (tm:current-time-thread))
((eq? clock-type time-process) (tm:current-time-process))
((eq? clock-type time-gc) (tm:current-time-gc))|#
(else (tm:time-error 'current-time 'invalid-clock-type clock-type)))))
;; -- time resolution
;; this is the resolution of the clock in nanoseconds.
;; this will be implementation specific.
(define (time-resolution . clock-type)
(let ((clock-type (:optional clock-type time-utc)))
(cond
((eq? clock-type time-tai) host:time-resolution)
((eq? clock-type time-utc) host:time-resolution)
((eq? clock-type time-monotonic) host:time-resolution)
#|((eq? clock-type time-thread) host:time-resolution)
((eq? clock-type time-process) host:time-resolution)
((eq? clock-type time-gc) host:time-resolution)|#
(else (tm:time-error 'time-resolution 'invalid-clock-type clock-type)))))
;; -- time comparisons
(define (tm:time-compare-check time1 time2 caller)
(if (or (not (and (time? time1) (time? time2)))
(not (eq? (time-type time1) (time-type time2))))
(tm:time-error caller 'incompatible-time-types #f)
#t))
(define (time=? time1 time2)
(tm:time-compare-check time1 time2 'time=?)
(and (= (time-second time1) (time-second time2))
(= (time-nanosecond time1) (time-nanosecond time2))))
(define (time>? time1 time2)
(tm:time-compare-check time1 time2 'time>?)
(or (> (time-second time1) (time-second time2))
(and (= (time-second time1) (time-second time2))
(> (time-nanosecond time1) (time-nanosecond time2)))))
(define (time<? time1 time2)
(tm:time-compare-check time1 time2 'time<?)
(or (< (time-second time1) (time-second time2))
(and (= (time-second time1) (time-second time2))
(< (time-nanosecond time1) (time-nanosecond time2)))))
(define (time>=? time1 time2)
(tm:time-compare-check time1 time2 'time>=?)
(or (>= (time-second time1) (time-second time2))
(and (= (time-second time1) (time-second time2))
(>= (time-nanosecond time1) (time-nanosecond time2)))))
(define (time<=? time1 time2)
(tm:time-compare-check time1 time2 'time<=?)
(or (<= (time-second time1) (time-second time2))
(and (= (time-second time1) (time-second time2))
(<= (time-nanosecond time1) (time-nanosecond time2)))))
;; -- time arithmetic
(define (tm:time->nanoseconds time)
#|(define (sign1 n) ; must be code rot
(if (negative? n) -1 1))|#
(+ (* (time-second time) tm:nano)
(time-nanosecond time)))
(define (tm:nanoseconds->time time-type nanoseconds)
(make-time time-type
(remainder nanoseconds tm:nano)
(quotient nanoseconds tm:nano)))
(define (tm:nanoseconds->values nanoseconds)
(div-and-mod nanoseconds tm:nano))
(define (tm:time-difference time1 time2 time3)
(if (or (not (and (time? time1) (time? time2)))
(not (eq? (time-type time1) (time-type time2))))
(tm:time-error 'time-difference 'incompatible-time-types #f))
(time-type-set! time3 time-duration)
(if (time=? time1 time2)
(begin
(time-second-set! time3 0)
(time-nanosecond-set! time3 0))
(receive
(secs nanos)
(tm:nanoseconds->values (- (tm:time->nanoseconds time1)
(tm:time->nanoseconds time2)))
(time-second-set! time3 secs)
(time-nanosecond-set! time3 nanos)))
time3)
(define (time-difference time1 time2)
(tm:time-difference time1 time2 (make-time #f #f #f)))
(define (time-difference! time1 time2)
(tm:time-difference time1 time2 time1))
(define (tm:add-duration time1 duration time3)
(if (not (and (time? time1) (time? duration)))
(tm:time-error 'add-duration 'incompatible-time-types #f))
(if (not (eq? (time-type duration) time-duration))
(tm:time-error 'add-duration 'not-duration duration)
(let ( (sec-plus (+ (time-second time1) (time-second duration)))
(nsec-plus (+ (time-nanosecond time1) (time-nanosecond duration))) )
(let ((r (remainder nsec-plus tm:nano))
(q (quotient nsec-plus tm:nano)))
; (time-type-set! time3 (time-type time1))
(if (negative? r)
(begin
(time-second-set! time3 (+ sec-plus q -1))
(time-nanosecond-set! time3 (+ tm:nano r)))
(begin
(time-second-set! time3 (+ sec-plus q))
(time-nanosecond-set! time3 r)))
time3))))
(define (add-duration time1 duration)
(tm:add-duration time1 duration (make-time (time-type time1) #f #f)))
(define (add-duration! time1 duration)
(tm:add-duration time1 duration time1))
(define (tm:subtract-duration time1 duration time3)
(if (not (and (time? time1) (time? duration)))
(tm:time-error 'add-duration 'incompatible-time-types #f))
(if (not (eq? (time-type duration) time-duration))
(tm:time-error 'tm:subtract-duration 'not-duration duration)
(let ( (sec-minus (- (time-second time1) (time-second duration)))
(nsec-minus (- (time-nanosecond time1) (time-nanosecond duration))) )
(let ((r (remainder nsec-minus tm:nano))
(q (quotient nsec-minus tm:nano)))
(if (negative? r)
(begin
(time-second-set! time3 (- sec-minus q 1))
(time-nanosecond-set! time3 (+ tm:nano r)))
(begin
(time-second-set! time3 (- sec-minus q))
(time-nanosecond-set! time3 r)))
time3))))
(define (subtract-duration time1 duration)
(tm:subtract-duration time1 duration (make-time (time-type time1) #f #f)))
(define (subtract-duration! time1 duration)
(tm:subtract-duration time1 duration time1))
;; -- converters between types.
(define (tm:time-tai->time-utc! time-in time-out caller)
(if (not (eq? (time-type time-in) time-tai))
(tm:time-error caller 'incompatible-time-types time-in))
(time-type-set! time-out time-utc)
(time-nanosecond-set! time-out (time-nanosecond time-in))
(time-second-set! time-out (- (time-second time-in)
(tm:leap-second-neg-delta
(time-second time-in))))
time-out)
(define (time-tai->time-utc time-in)
(tm:time-tai->time-utc! time-in (make-time #f #f #f) 'time-tai->time-utc))
(define (time-tai->time-utc! time-in)
(tm:time-tai->time-utc! time-in time-in 'time-tai->time-utc!))
(define (tm:time-utc->time-tai! time-in time-out caller)
(if (not (eq? (time-type time-in) time-utc))
(tm:time-error caller 'incompatible-time-types time-in))
(time-type-set! time-out time-tai)
(time-nanosecond-set! time-out (time-nanosecond time-in))
(time-second-set! time-out (+ (time-second time-in)
(tm:leap-second-delta
(time-second time-in))))
time-out)
(define (time-utc->time-tai time-in)
(tm:time-utc->time-tai! time-in (make-time #f #f #f) 'time-utc->time-tai))
(define (time-utc->time-tai! time-in)
(tm:time-utc->time-tai! time-in time-in 'time-utc->time-tai!))
;; -- these depend on time-monotonic having the same definition as time-tai!
(define (time-monotonic->time-utc time-in)
(if (not (eq? (time-type time-in) time-monotonic))
(tm:time-error 'time-monotoinc->time-utc 'incompatible-time-types time-in))
(let ((ntime (copy-time time-in)))
(time-type-set! ntime time-tai)
(tm:time-tai->time-utc! ntime ntime 'time-monotonic->time-utc)))
(define (time-monotonic->time-utc! time-in)
(if (not (eq? (time-type time-in) time-monotonic))
(tm:time-error 'time-monotonic->time-utc! 'incompatible-time-types time-in))
(time-type-set! time-in time-tai)
(tm:time-tai->time-utc! time-in time-in 'time-monotonic->time-utc))
(define (time-monotonic->time-tai time-in)
(if (not (eq? (time-type time-in) time-monotonic))
(tm:time-error 'time-monotonic->time-tai 'incompatible-time-types time-in))
(let ((ntime (copy-time time-in)))
(time-type-set! ntime time-tai)
ntime))
(define (time-monotonic->time-tai! time-in)
(if (not (eq? (time-type time-in) time-monotonic))
(tm:time-error 'time-monotonic->time-tai! 'incompatible-time-types time-in))
(time-type-set! time-in time-tai)
time-in)
(define (time-utc->time-monotonic time-in)
(if (not (eq? (time-type time-in) time-utc))
(tm:time-error 'time-utc->time-monotonic 'incompatible-time-types time-in))
(let ((ntime (tm:time-utc->time-tai! time-in (make-time #f #f #f)
'time-utc->time-monotonic)))
(time-type-set! ntime time-monotonic)
ntime))
(define (time-utc->time-monotonic! time-in)
(if (not (eq? (time-type time-in) time-utc))
(tm:time-error 'time-utc->time-montonic! 'incompatible-time-types time-in))
(let ((ntime (tm:time-utc->time-tai! time-in time-in
'time-utc->time-monotonic!)))
(time-type-set! ntime time-monotonic)
ntime))
(define (time-tai->time-monotonic time-in)
(if (not (eq? (time-type time-in) time-tai))
(tm:time-error 'time-tai->time-monotonic 'incompatible-time-types time-in))
(let ((ntime (copy-time time-in)))
(time-type-set! ntime time-monotonic)
ntime))
(define (time-tai->time-monotonic! time-in)
(if (not (eq? (time-type time-in) time-tai))
(tm:time-error 'time-tai->time-monotonic! 'incompatible-time-types time-in))
(time-type-set! time-in time-monotonic)
time-in)
;; -- date structures
(define-record-type date
(fields
(mutable nanosecond)
(mutable second)
(mutable minute)
(mutable hour)
(mutable day)
(mutable month)
(mutable year)
(mutable zone-offset)))
;; redefine setters (in Ikarus version, only to keep names the same in below code)
(define tm:set-date-nanosecond! date-nanosecond-set!)
(define tm:set-date-second! date-second-set!)
(define tm:set-date-minute! date-minute-set!)
(define tm:set-date-hour! date-hour-set!)
(define tm:set-date-day! date-day-set!)
(define tm:set-date-month! date-month-set!)
(define tm:set-date-year! date-year-set!)
(define tm:set-date-zone-offset! date-zone-offset-set!)
;; gives the julian day which starts at noon.
(define (tm:encode-julian-day-number day month year)
(let* ((a (quotient (- 14 month) 12))
(y (- (- (+ year 4800) a) (if (negative? year) -1 0)))
(m (- (+ month (* 12 a)) 3)))
(+ day
(quotient (+ (* 153 m) 2) 5)
(* 365 y)
(quotient y 4)
(- (quotient y 100))
(quotient y 400)
-32045)))
(define (tm:char-pos char str index len)
(cond
((>= index len) #f)
((char=? (string-ref str index) char)
index)
(else
(tm:char-pos char str (+ index 1) len))))
(define (tm:fractional-part r)
(if (integer? r) "0"
(let ((str (number->string (exact->inexact r))))
(let ((ppos (tm:char-pos #\. str 0 (string-length str))))
(substring str (+ ppos 1) (string-length str))))))
;; gives the seconds/date/month/year
(define (tm:decode-julian-day-number jdn)
(let* ((days (truncate jdn))
(a (+ days 32044))
(b (quotient (+ (* 4 a) 3) 146097))
(c (- a (quotient (* 146097 b) 4)))
(d (quotient (+ (* 4 c) 3) 1461))
(e (- c (quotient (* 1461 d) 4)))
(m (quotient (+ (* 5 e) 2) 153))
(y (+ (* 100 b) d -4800 (quotient m 10))))
(values ; seconds date month year
(* (- jdn days) tm:sid)
(+ e (- (quotient (+ (* 153 m) 2) 5)) 1)
(+ m 3 (* -12 (quotient m 10)))
(if (>= 0 y) (- y 1) y))
))
(define (tm:local-tz-offset)
(host:time-gmt-offset (host:current-time)))
;; special thing -- ignores nanos
(define (tm:time->julian-day-number seconds tz-offset)
(+ (/ (+ seconds
tz-offset
tm:sihd)
tm:sid)
tm:tai-epoch-in-jd))
(define (tm:find proc l)
(if (null? l)
#f
(if (proc (car l))
#t
(tm:find proc (cdr l)))))
(define (tm:tai-before-leap-second? second)
(tm:find (lambda (x)
(= second (- (+ (car x) (cdr x)) 1)))
tm:leap-second-table))
(define (tm:time->date time tz-offset ttype)
(if (not (eq? (time-type time) ttype))
(tm:time-error 'time->date 'incompatible-time-types time))
(let* ( (offset (:optional tz-offset (tm:local-tz-offset))) )
(receive (secs date month year)
(tm:decode-julian-day-number
(tm:time->julian-day-number (time-second time) offset))
(let* ( (hours (quotient secs (* 60 60)))
(rem (remainder secs (* 60 60)))
(minutes (quotient rem 60))
(seconds (remainder rem 60)) )
(make-date (time-nanosecond time)
seconds
minutes
hours
date
month
year
offset)))))
(define (time-tai->date time . tz-offset)
(if (tm:tai-before-leap-second? (time-second time))
;; if it's *right* before the leap, we need to pretend to subtract a second ...
(let ((d (tm:time->date (subtract-duration! (time-tai->time-utc time) (make-time time-duration 0 1)) tz-offset time-utc)))
(tm:set-date-second! d 60)
d)
(tm:time->date (time-tai->time-utc time) tz-offset time-utc)))
(define (time-utc->date time . tz-offset)
(tm:time->date time tz-offset time-utc))
;; again, time-monotonic is the same as time tai
(define (time-monotonic->date time . tz-offset)
(tm:time->date time tz-offset time-monotonic))
(define (date->time-utc date)
(let ( (nanosecond (date-nanosecond date))
(second (date-second date))
(minute (date-minute date))
(hour (date-hour date))
(day (date-day date))
(month (date-month date))
(year (date-year date))
(offset (date-zone-offset date)) )
(let ( (jdays (- (tm:encode-julian-day-number day month year)
tm:tai-epoch-in-jd)) )
(make-time
time-utc
nanosecond
(+ (* (- jdays 1/2) 24 60 60)
(* hour 60 60)
(* minute 60)
second
(- offset))
))))
(define (date->time-tai d)
(if (= (date-second d) 60)
(subtract-duration! (time-utc->time-tai! (date->time-utc d)) (make-time time-duration 0 1))
(time-utc->time-tai! (date->time-utc d))))
(define (date->time-monotonic date)
(time-utc->time-monotonic! (date->time-utc date)))
(define (tm:leap-year? year)
(or (= (modulo year 400) 0)
(and (= (modulo year 4) 0) (not (= (modulo year 100) 0)))))
(define (leap-year? date)
(tm:leap-year? (date-year date)))
;; tm:year-day fixed: adding wrong number of days.
(define tm:month-assoc '((0 . 0) (1 . 31) (2 . 59) (3 . 90) (4 . 120)
(5 . 151) (6 . 181) (7 . 212) (8 . 243)
(9 . 273) (10 . 304) (11 . 334)))
(define (tm:year-day day month year)
(let ((days-pr (assoc (- month 1) tm:month-assoc)))
(if (not days-pr)
(tm:time-error 'date-year-day 'invalid-month-specification month))
(if (and (tm:leap-year? year) (> month 2))
(+ day (cdr days-pr) 1)
(+ day (cdr days-pr)))))
(define (date-year-day date)
(tm:year-day (date-day date) (date-month date) (date-year date)))
;; from calendar faq
(define (tm:week-day day month year)
(let* ((a (quotient (- 14 month) 12))
(y (- year a))
(m (+ month (* 12 a) -2)))
(modulo (+ day y (quotient y 4) (- (quotient y 100))
(quotient y 400) (quotient (* 31 m) 12))
7)))
(define (date-week-day date)
(tm:week-day (date-day date) (date-month date) (date-year date)))
(define (tm:days-before-first-week date day-of-week-starting-week)
(let* ( (first-day (make-date 0 0 0 0
1
1
(date-year date)
#f))
(fdweek-day (date-week-day first-day)) )
(modulo (- day-of-week-starting-week fdweek-day)
7)))
(define (date-week-number date day-of-week-starting-week)
(quotient (- (date-year-day date)
(tm:days-before-first-week date day-of-week-starting-week))
7))
(define (current-date . tz-offset)
(time-utc->date (current-time time-utc)
(:optional tz-offset (tm:local-tz-offset))))
;; given a 'two digit' number, find the year within 50 years +/-
(define (tm:natural-year n)
(let* ( (current-year (date-year (current-date)))
(current-century (* (quotient current-year 100) 100)) )
(cond
((>= n 100) n)
((< n 0) n)
((<= (- (+ current-century n) current-year) 50)
(+ current-century n))
(else
(+ (- current-century 100) n)))))
(define (date->julian-day date)
(let ( (nanosecond (date-nanosecond date))
(second (date-second date))
(minute (date-minute date))
(hour (date-hour date))
(day (date-day date))
(month (date-month date))
(year (date-year date))
(offset (date-zone-offset date)) )
(+ (tm:encode-julian-day-number day month year)
(- 1/2)
(+ (/ (+ (* hour 60 60)
(* minute 60)
second
(/ nanosecond tm:nano)
(- offset))
tm:sid)))))
(define (date->modified-julian-day date)
(- (date->julian-day date)
4800001/2))
(define (time-utc->julian-day time)
(if (not (eq? (time-type time) time-utc))
(tm:time-error 'time-utc->julian-day 'incompatible-time-types time))
(+ (/ (+ (time-second time) (/ (time-nanosecond time) tm:nano))
tm:sid)
tm:tai-epoch-in-jd))
(define (time-utc->modified-julian-day time)
(- (time-utc->julian-day time)
4800001/2))
(define (time-tai->julian-day time)
(if (not (eq? (time-type time) time-tai))
(tm:time-error 'time-tai->julian-day 'incompatible-time-types time))
(+ (/ (+ (- (time-second time)
(tm:leap-second-delta (time-second time)))
(/ (time-nanosecond time) tm:nano))
tm:sid)
tm:tai-epoch-in-jd))
(define (time-tai->modified-julian-day time)
(- (time-tai->julian-day time)
4800001/2))
;; this is the same as time-tai->julian-day
(define (time-monotonic->julian-day time)
(if (not (eq? (time-type time) time-monotonic))
(tm:time-error 'time-monotonic->julian-day 'incompatible-time-types time))
(+ (/ (+ (- (time-second time)
(tm:leap-second-delta (time-second time)))
(/ (time-nanosecond time) tm:nano))
tm:sid)
tm:tai-epoch-in-jd))
(define (time-monotonic->modified-julian-day time)
(- (time-monotonic->julian-day time)
4800001/2))
(define (julian-day->time-utc jdn)
(let ( (nanosecs (* tm:nano tm:sid (- jdn tm:tai-epoch-in-jd))) )
(make-time time-utc
(remainder nanosecs tm:nano)
(floor (/ nanosecs tm:nano)))))
(define (julian-day->time-tai jdn)
(time-utc->time-tai! (julian-day->time-utc jdn)))
(define (julian-day->time-monotonic jdn)
(time-utc->time-monotonic! (julian-day->time-utc jdn)))
(define (julian-day->date jdn . tz-offset)
(let ((offset (:optional tz-offset (tm:local-tz-offset))))
(time-utc->date (julian-day->time-utc jdn) offset)))
(define (modified-julian-day->date jdn . tz-offset)
(let ((offset (:optional tz-offset (tm:local-tz-offset))))
(julian-day->date (+ jdn 4800001/2) offset)))
(define (modified-julian-day->time-utc jdn)
(julian-day->time-utc (+ jdn 4800001/2)))
(define (modified-julian-day->time-tai jdn)
(julian-day->time-tai (+ jdn 4800001/2)))
(define (modified-julian-day->time-monotonic jdn)
(julian-day->time-monotonic (+ jdn 4800001/2)))
(define (current-julian-day)
(time-utc->julian-day (current-time time-utc)))
(define (current-modified-julian-day)
(time-utc->modified-julian-day (current-time time-utc)))
;; returns a string rep. of number N, of minimum LENGTH,
;; padded with character PAD-WITH. If PAD-WITH if #f,
;; no padding is done, and it's as if number->string was used.
;; if string is longer than LENGTH, it's as if number->string was used.
(define (tm:padding n pad-with length)
(let* ( (str (number->string n))
(str-len (string-length str)) )
(if (or (> str-len length)
(not pad-with))
str
(let* ( (new-str (make-string length pad-with))
(new-str-offset (- (string-length new-str)
str-len)) )
(do ((i 0 (+ i 1)))
((>= i (string-length str)))
(string-set! new-str (+ new-str-offset i)
(string-ref str i)))
new-str))))
(define (tm:last-n-digits i n)
(abs (remainder i (expt 10 n))))
(define (tm:locale-abbr-weekday n)
(vector-ref tm:locale-abbr-weekday-vector n))
(define (tm:locale-long-weekday n)
(vector-ref tm:locale-long-weekday-vector n))
(define (tm:locale-abbr-month n)
(vector-ref tm:locale-abbr-month-vector n))
(define (tm:locale-long-month n)
(vector-ref tm:locale-long-month-vector n))
(define (tm:vector-find needle haystack comparator)
(let ((len (vector-length haystack)))
(define (tm:vector-find-int index)
(cond
((>= index len) #f)
((comparator needle (vector-ref haystack index)) index)
(else (tm:vector-find-int (+ index 1)))))
(tm:vector-find-int 0)))
(define (tm:locale-abbr-weekday->index string)
(tm:vector-find string tm:locale-abbr-weekday-vector string=?))
(define (tm:locale-long-weekday->index string)
(tm:vector-find string tm:locale-long-weekday-vector string=?))
(define (tm:locale-abbr-month->index string)
(tm:vector-find string tm:locale-abbr-month-vector string=?))
(define (tm:locale-long-month->index string)
(tm:vector-find string tm:locale-long-month-vector string=?))
;; do nothing.
;; Your implementation might want to do something...
;;
(define (tm:locale-print-time-zone date port)
(values))
;; Again, locale specific.
(define (tm:locale-am/pm hr)
(if (> hr 11) tm:locale-pm tm:locale-am))
(define (tm:tz-printer offset port)
(cond
((= offset 0) (display "Z" port))
((negative? offset) (display "-" port))
(else (display "+" port)))
(if (not (= offset 0))
(let ( (hours (abs (quotient offset (* 60 60))))
(minutes (abs (quotient (remainder offset (* 60 60)) 60))) )
(display (tm:padding hours #\0 2) port)
(display (tm:padding minutes #\0 2) port))))
;; A table of output formatting directives.
;; the first time is the format char.
;; the second is a procedure that takes the date, a padding character
;; (which might be #f), and the output port.
;;
(define tm:directives
(list
(cons #\~ (lambda (date pad-with port) (display #\~ port)))
(cons #\a (lambda (date pad-with port)
(display (tm:locale-abbr-weekday (date-week-day date))
port)))
(cons #\A (lambda (date pad-with port)
(display (tm:locale-long-weekday (date-week-day date))
port)))
(cons #\b (lambda (date pad-with port)
(display (tm:locale-abbr-month (date-month date))
port)))
(cons #\B (lambda (date pad-with port)
(display (tm:locale-long-month (date-month date))
port)))
(cons #\c (lambda (date pad-with port)
(display (date->string date tm:locale-date-time-format) port)))
(cons #\d (lambda (date pad-with port)
(display (tm:padding (date-day date)
#\0 2)
port)))
(cons #\D (lambda (date pad-with port)
(display (date->string date "~m/~d/~y") port)))
(cons #\e (lambda (date pad-with port)
(display (tm:padding (date-day date)
#\space 2)
port)))
(cons #\f (lambda (date pad-with port)
(if (> (date-nanosecond date)
tm:nano)
(display (tm:padding (+ (date-second date) 1)
pad-with 2)
port)
(display (tm:padding (date-second date)
pad-with 2)
port))
(let* ((ns (tm:fractional-part (/
(date-nanosecond date)
tm:nano 1.0)))
(le (string-length ns)))
(if (> le 2)
(begin
(display tm:locale-number-separator port)
(display (substring ns 2 le) port))))))
(cons #\h (lambda (date pad-with port)
(display (date->string date "~b") port)))
(cons #\H (lambda (date pad-with port)
(display (tm:padding (date-hour date)
pad-with 2)
port)))
(cons #\I (lambda (date pad-with port)
(let ((hr (date-hour date)))
(if (> hr 12)
(display (tm:padding (- hr 12)
pad-with 2)
port)
(display (tm:padding hr
pad-with 2)
port)))))
(cons #\j (lambda (date pad-with port)
(display (tm:padding (date-year-day date)
pad-with 3)
port)))
(cons #\k (lambda (date pad-with port)
(display (tm:padding (date-hour date)
#\0 2)
port)))
(cons #\l (lambda (date pad-with port)
(let ((hr (if (> (date-hour date) 12)
(- (date-hour date) 12) (date-hour date))))
(display (tm:padding hr #\space 2)
port))))
(cons #\m (lambda (date pad-with port)
(display (tm:padding (date-month date)
pad-with 2)
port)))
(cons #\M (lambda (date pad-with port)
(display (tm:padding (date-minute date)
pad-with 2)
port)))
(cons #\n (lambda (date pad-with port)
(newline port)))
(cons #\N (lambda (date pad-with port)
(display (tm:padding (date-nanosecond date)
pad-with 9)
port)))
(cons #\p (lambda (date pad-with port)
(display (tm:locale-am/pm (date-hour date)) port)))
(cons #\r (lambda (date pad-with port)
(display (date->string date "~I:~M:~S ~p") port)))
(cons #\s (lambda (date pad-with port)
(display (time-second (date->time-utc date)) port)))
(cons #\S (lambda (date pad-with port)
(if (> (date-nanosecond date)
tm:nano)
(display (tm:padding (+ (date-second date) 1)
pad-with 2)
port)
(display (tm:padding (date-second date)
pad-with 2)
port))))
(cons #\t (lambda (date pad-with port)
(display (integer->char 9) port)))
(cons #\T (lambda (date pad-with port)
(display (date->string date "~H:~M:~S") port)))
(cons #\U (lambda (date pad-with port)
(if (> (tm:days-before-first-week date 0) 0)
(display (tm:padding (+ (date-week-number date 0) 1)
#\0 2) port)
(display (tm:padding (date-week-number date 0)
#\0 2) port))))
(cons #\V (lambda (date pad-with port)
(display (tm:padding (date-week-number date 1)
#\0 2) port)))
(cons #\w (lambda (date pad-with port)
(display (date-week-day date) port)))
(cons #\x (lambda (date pad-with port)
(display (date->string date tm:locale-short-date-format) port)))
(cons #\X (lambda (date pad-with port)
(display (date->string date tm:locale-time-format) port)))
(cons #\W (lambda (date pad-with port)
(if (> (tm:days-before-first-week date 1) 0)
(display (tm:padding (+ (date-week-number date 1) 1)
#\0 2) port)
(display (tm:padding (date-week-number date 1)
#\0 2) port))))
(cons #\y (lambda (date pad-with port)
(display (tm:padding (tm:last-n-digits
(date-year date) 2)
pad-with
2)
port)))
(cons #\Y (lambda (date pad-with port)
(display (date-year date) port)))
(cons #\z (lambda (date pad-with port)
(tm:tz-printer (date-zone-offset date) port)))
(cons #\Z (lambda (date pad-with port)
(tm:locale-print-time-zone date port)))
(cons #\1 (lambda (date pad-with port)
(display (date->string date "~Y-~m-~d") port)))
(cons #\2 (lambda (date pad-with port)
(display (date->string date "~k:~M:~S~z") port)))
(cons #\3 (lambda (date pad-with port)
(display (date->string date "~k:~M:~S") port)))
(cons #\4 (lambda (date pad-with port)
(display (date->string date "~Y-~m-~dT~k:~M:~S~z") port)))
(cons #\5 (lambda (date pad-with port)
(display (date->string date "~Y-~m-~dT~k:~M:~S") port)))
))
(define (tm:get-formatter char)
(let ( (associated (assoc char tm:directives)) )
(if associated (cdr associated) #f)))
(define (tm:date-printer date index format-string str-len port)
(if (>= index str-len)
(values)
(let ( (current-char (string-ref format-string index)) )
(if (not (char=? current-char #\~))
(begin
(display current-char port)
(tm:date-printer date (+ index 1) format-string str-len port))
(if (= (+ index 1) str-len) ; bad format string.
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(let ( (pad-char? (string-ref format-string (+ index 1))) )
(cond
((char=? pad-char? #\-)
(if (= (+ index 2) str-len) ; bad format string.
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(let ( (formatter (tm:get-formatter
(string-ref format-string
(+ index 2)))) )
(if (not formatter)
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(begin
(formatter date #f port)
(tm:date-printer date (+ index 3)
format-string str-len port))))))
((char=? pad-char? #\_)
(if (= (+ index 2) str-len) ; bad format string.
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(let ( (formatter (tm:get-formatter
(string-ref format-string
(+ index 2)))) )
(if (not formatter)
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(begin
(formatter date #\space port)
(tm:date-printer date (+ index 3)
format-string str-len port))))))
(else
(let ( (formatter (tm:get-formatter
(string-ref format-string
(+ index 1)))) )
(if (not formatter)
(tm:time-error 'tm:date-printer 'bad-date-format-string
format-string)
(begin
(formatter date #\0 port)
(tm:date-printer date (+ index 2)
format-string str-len port))))))))))))
(define (date->string date . format-string)
(let ( (str-port (open-output-string))
(fmt-str (:optional format-string "~c")) )
(tm:date-printer date 0 fmt-str (string-length fmt-str) str-port)
(get-output-string str-port)))
(define (tm:char->int ch)
(cond
((char=? ch #\0) 0)
((char=? ch #\1) 1)
((char=? ch #\2) 2)
((char=? ch #\3) 3)
((char=? ch #\4) 4)
((char=? ch #\5) 5)
((char=? ch #\6) 6)
((char=? ch #\7) 7)
((char=? ch #\8) 8)
((char=? ch #\9) 9)
(else (tm:time-error 'string->date 'bad-date-template-string
(list "Non-integer character" ch )))))
;; read an integer upto n characters long on port; upto -> #f if any length
(define (tm:integer-reader upto port)
(define (accum-int port accum nchars)
(let ((ch (peek-char port)))
(if (or (eof-object? ch)
(not (char-numeric? ch))
(and upto (>= nchars upto )))
accum
(accum-int port (+ (* accum 10) (tm:char->int (read-char
port))) (+
nchars 1)))))
(accum-int port 0 0))
(define (tm:make-integer-reader upto)
(lambda (port)
(tm:integer-reader upto port)))
;; read an fractional integer upto n characters long on port; upto -> #f if any length
;;
;; The return value is normalized to upto decimal places. For example, if upto is 9 and
;; the string read is "123", the return value is 123000000.
(define (tm:fractional-integer-reader upto port)
(define (accum-int port accum nchars)
(let ((ch (peek-char port)))
(if (or (eof-object? ch)
(not (char-numeric? ch))
(and upto (>= nchars upto )))
(* accum (expt 10 (- upto nchars)))
(accum-int port (+ (* accum 10) (tm:char->int (read-char port))) (+ nchars 1)))))
(accum-int port 0 0))
(define (tm:make-fractional-integer-reader upto)
(lambda (port)
(tm:fractional-integer-reader upto port)))
;; read *exactly* n characters and convert to integer; could be padded
(define (tm:integer-reader-exact n port)
(let ( (padding-ok #t) )
(define (accum-int port accum nchars)
(let ((ch (peek-char port)))
(cond
((>= nchars n) accum)
((eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
"Premature ending to integer read."))
((char-numeric? ch)
(set! padding-ok #f)
(accum-int port (+ (* accum 10) (tm:char->int (read-char
port)))
(+ nchars 1)))
(padding-ok
(read-char port) ; consume padding
(accum-int port accum (+ nchars 1)))
(else ; padding where it shouldn't be
(tm:time-error 'string->date 'bad-date-template-string
"Non-numeric characters in integer read.")))))
(accum-int port 0 0)))
(define (tm:make-integer-exact-reader n)
(lambda (port)
(tm:integer-reader-exact n port)))
(define (tm:zone-reader port)
(let ( (offset 0)
(positive? #f) )
(let ( (ch (read-char port)) )
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone +/-" ch)))
(if (or (char=? ch #\Z) (char=? ch #\z))
0
(begin
(cond
((char=? ch #\+) (set! positive? #t))
((char=? ch #\-) (set! positive? #f))
(else
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone +/-" ch))))
(let ((ch (read-char port)))
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone number" ch)))
(set! offset (* (tm:char->int ch)
10 60 60)))
(let ((ch (read-char port)))
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone number" ch)))
(set! offset (+ offset (* (tm:char->int ch)
60 60))))
(let ((ch (read-char port)))
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone number" ch)))
(set! offset (+ offset (* (tm:char->int ch)
10 60))))
(let ((ch (read-char port)))
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-template-string
(list "Invalid time zone number" ch)))
(set! offset (+ offset (* (tm:char->int ch)
60))))
(if positive? offset (- offset)))))))
;; looking at a char, read the char string, run thru indexer, return index
(define (tm:locale-reader port indexer)
(let ( (string-port (open-output-string)) )
(define (read-char-string)
(let ((ch (peek-char port)))
(if (char-alphabetic? ch)
(begin (write-char (read-char port) string-port)
(read-char-string))
(get-output-string string-port))))
(let* ( (str (read-char-string))
(index (indexer str)) )
(if index index (tm:time-error 'string->date
'bad-date-template-string
(list "Invalid string for " indexer))))))
(define (tm:make-locale-reader indexer)
(lambda (port)
(tm:locale-reader port indexer)))
(define (tm:make-char-id-reader char)
(lambda (port)
(if (char=? char (read-char port))
char
(tm:time-error 'string->date
'bad-date-template-string
"Invalid character match."))))
;; A List of formatted read directives.
;; Each entry is a list.
;; 1. the character directive;
;; a procedure, which takes a character as input & returns
;; 2. #t as soon as a character on the input port is acceptable
;; for input,
;; 3. a port reader procedure that knows how to read the current port
;; for a value. Its one parameter is the port.
;; 4. a action procedure, that takes the value (from 3.) and some
;; object (here, always the date) and (probably) side-effects it.
;; In some cases (e.g., ~A) the action is to do nothing
(define tm:read-directives
(let ( (ireader4 (tm:make-integer-reader 4))
(ireader2 (tm:make-integer-reader 2))
(fireader9 (tm:make-fractional-integer-reader 9))
(ireaderf (tm:make-integer-reader #f))
(eireader2 (tm:make-integer-exact-reader 2))
(eireader4 (tm:make-integer-exact-reader 4))
(locale-reader-abbr-weekday (tm:make-locale-reader
tm:locale-abbr-weekday->index))
(locale-reader-long-weekday (tm:make-locale-reader
tm:locale-long-weekday->index))
(locale-reader-abbr-month (tm:make-locale-reader
tm:locale-abbr-month->index))
(locale-reader-long-month (tm:make-locale-reader
tm:locale-long-month->index))
(char-fail (lambda (ch) #t))
(do-nothing (lambda (val object) (values)))
)
(list
(list #\~ char-fail (tm:make-char-id-reader #\~) do-nothing)
(list #\a char-alphabetic? locale-reader-abbr-weekday do-nothing)
(list #\A char-alphabetic? locale-reader-long-weekday do-nothing)
(list #\b char-alphabetic? locale-reader-abbr-month
(lambda (val object)
(tm:set-date-month! object val)))
(list #\B char-alphabetic? locale-reader-long-month
(lambda (val object)
(tm:set-date-month! object val)))
(list #\d char-numeric? ireader2 (lambda (val object)
(tm:set-date-day!
object val)))
(list #\e char-fail eireader2 (lambda (val object)
(tm:set-date-day! object val)))
(list #\h char-alphabetic? locale-reader-abbr-month
(lambda (val object)
(tm:set-date-month! object val)))
(list #\H char-numeric? ireader2 (lambda (val object)
(tm:set-date-hour! object val)))
(list #\k char-fail eireader2 (lambda (val object)
(tm:set-date-hour! object val)))
(list #\m char-numeric? ireader2 (lambda (val object)
(tm:set-date-month! object val)))
(list #\M char-numeric? ireader2 (lambda (val object)
(tm:set-date-minute!
object val)))
(list #\N char-numeric? fireader9 (lambda (val object)
(tm:set-date-nanosecond! object val)))
(list #\S char-numeric? ireader2 (lambda (val object)
(tm:set-date-second! object val)))
(list #\y char-fail eireader2
(lambda (val object)
(tm:set-date-year! object (tm:natural-year val))))
(list #\Y char-numeric? ireader4 (lambda (val object)
(tm:set-date-year! object val)))
(list #\z (lambda (c)
(or (char=? c #\Z)
(char=? c #\z)
(char=? c #\+)
(char=? c #\-)))
tm:zone-reader (lambda (val object)
(tm:set-date-zone-offset! object val)))
)))
(define (tm:string->date date index format-string str-len port template-string)
(define (skip-until port skipper)
(let ((ch (peek-char port)))
(if (eof-object? ch)
(tm:time-error 'string->date 'bad-date-format-string template-string)
(if (not (skipper ch))
(begin (read-char port) (skip-until port skipper))))))
(if (>= index str-len)
(begin
(values))
(let ( (current-char (string-ref format-string index)) )
(if (not (char=? current-char #\~))
(let ((port-char (read-char port)))
(if (or (eof-object? port-char)
(not (char=? current-char port-char)))
(tm:time-error 'string->date 'bad-date-format-string template-string))
(tm:string->date date (+ index 1) format-string str-len port template-string))
;; otherwise, it's an escape, we hope
(if (> (+ index 1) str-len)
(tm:time-error 'string->date 'bad-date-format-string template-string)
(let* ( (format-char (string-ref format-string (+ index 1)))
(format-info (assoc format-char tm:read-directives)) )
(if (not format-info)
(tm:time-error 'string->date 'bad-date-format-string template-string)
(begin
(let ((skipper (cadr format-info))
(reader (caddr format-info))
(actor (cadddr format-info)))
(skip-until port skipper)
(let ((val (reader port)))
(if (eof-object? val)
(tm:time-error 'string->date 'bad-date-format-string template-string)
(actor val date)))
(tm:string->date date (+ index 2) format-string str-len port template-string))))))))))
(define (string->date input-string template-string)
(define (tm:date-ok? date)
(and (date-nanosecond date)
(date-second date)
(date-minute date)
(date-hour date)
(date-day date)
(date-month date)
(date-year date)
(date-zone-offset date)))
(let ( (newdate (make-date 0 0 0 0 #f #f #f (tm:local-tz-offset))) )
(tm:string->date newdate
0
template-string
(string-length template-string)
(open-input-string input-string)
template-string)
(if (tm:date-ok? newdate)
newdate
(tm:time-error 'string->date 'bad-date-format-string (list "Incomplete date read. " newdate template-string)))))
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