Script Library: summer.r

Script Library: 1247 scripts
summer.r

REBOL [
    Title: "Daylight Saving Time function based on North American rules"
    Date: 30-Mar-2004
    Author: "Bohdan Lechnowsky"
    File: %summer.r
    Purpose: {
        Calculates whether a given date is in Daylight Saving Time or not, based on North American rules.  Rules vary by country.
    }
  Library: [
     level: 'intermediate
     platform: 'all
     type: [function]
     domain: [scientific]
     tested-under: none
     support: none
     license: none
     see-also: none
   ]
]

summer?: func [
    {Figures out Daylight Saving Time based on North American rules}
    d [date!] {Date to check}
    t [time!] {Time to check - DST occurs at 2AM}
    /local start end
][
    start: to-date reduce [1 4 d/year]
    start: start + 7 - start/weekday
    end: to-date reduce [25 10 d/year]
    end: end + 7 - end/weekday
    found? any [
        all [
            d > start
            d < end
        ]
        all [
            d = start
            t > 1:59:59
        ]
        all [
            d = end
            t < 2:00:00
        ]
    ]
]