140 lines
6.6 KiB
Rexx
Executable File
140 lines
6.6 KiB
Rexx
Executable File
#!/usr/bin/env rexx
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/*----------------------------------------------------------------------------*/
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/* */
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/* Copyright (c) 1995, 2004 IBM Corporation. All rights reserved. */
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/* Copyright (c) 2005-2014 Rexx Language Association. All rights reserved. */
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/* */
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/* This program and the accompanying materials are made available under */
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/* the terms of the Common Public License v1.0 which accompanies this */
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/* distribution. A copy is also available at the following address: */
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/* https://www.oorexx.org/license.html */
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/* */
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/* Redistribution and use in source and binary forms, with or */
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/* without modification, are permitted provided that the following */
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/* conditions are met: */
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/* */
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/* Redistributions of source code must retain the above copyright */
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/* notice, this list of conditions and the following disclaimer. */
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/* Redistributions in binary form must reproduce the above copyright */
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/* notice, this list of conditions and the following disclaimer in */
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/* the documentation and/or other materials provided with the distribution. */
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/* */
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/* Neither the name of Rexx Language Association nor the names */
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/* of its contributors may be used to endorse or promote products */
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/* derived from this software without specific prior written permission. */
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/* */
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/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS */
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/* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT */
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/* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS */
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/* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT */
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/* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
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/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED */
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/* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, */
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/* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY */
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/* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING */
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/* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS */
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/* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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/* */
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/*----------------------------------------------------------------------------*/
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/******************************************************************************/
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/* */
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/* Description: */
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/* Display a date and moon phase in English */
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/* */
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/******************************************************************************/
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/* -- get the current time */
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date = .datetime~new
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/* -- get a phase calculator for this date */
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date = .MoonPhase~new
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say date~moonPhase
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say date~englishDate
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Exit /*** END OF REXX ***/
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/* -- A subclass of the date time class that knows about moon phases, and
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-- can also display the date using English conventions */
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::class "MoonPhase" subclass DateTime
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/* -- December 31, 1899...a known date for a new moon */
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::constant knownNewMoon 18991231
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/* -- the number of days in a lunar cycle */
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::constant lunation 29.5305889
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/* -- The fraction of a cycle for one day, defined as the
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-- the reciprical of a lunation (1 / lunation) */
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::constant dayPhase 0.0338631907
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/* -- Within this fraction, considered new (dayPhase / 2) */
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::constant newPhase 0.0169315954
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/* -- Phase position for waxing moon (.25 + newPhase) */
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::constant waxPhase 0.266931595
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/* -- Fractional position for a full moon phase (.50 + newPhase) */
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::constant fullPhase 0.516931595
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/* -- and finally the fractional position for a waning moon (.75 + newPhase) */
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::constant wanePhase 0.766931595
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/* -- return the phase of the moon for this date */
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::method moonPhase
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/* -- get the difference from the given date and January 1, 1900, which is
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-- the known date of a */
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delta = self - .datetime~fromStandardDate(self~knownNewMoon)
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deltaDays = delta~days
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moonphase = (deltaDays / self~lunation) // 1
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/* -- get the essential phase range we are sitting in */
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select
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when self~newphase <= moonphase & moonphase < self~waxphase
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then do
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targetPhase = self~waxphase
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phaseName = "waxing half"
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end
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when self~waxphase <= moonphase & moonphase < self~fullphase
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then do
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targetPhase = self~fullphase
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phaseName = "full"
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end
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when self~fullphase <= moonphase & moonphase < self~wanephase
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then do
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targetPhase = self~wanephase
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phaseName = "waning half"
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end
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when ((self~wanephase <= moonphase & moonphase <= 1) |,
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(0 <= moonphase & moonphase < self~newphase))
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then do
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targetPhase = self~newphase
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phaseName = "new"
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end
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otherwise /* Should never get here. */
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nop
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end
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/* -- now calculate the days we are off from being exactly on the phase */
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if moonphase > targetPhase
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then extradays = trunc( (1 + targetphase - moonphase ) * self~lunation )
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else extradays = trunc( (targetphase - moonphase) * self~lunation )
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select
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when extradays = 0
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then return 'There will be a' phaseName 'moon tonight.'
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when extradays = 1
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then return 'There will be a' phaseName 'moon tomorrow.'
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otherwise
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dayNames = .array~of('one', 'two', 'three', 'four', 'five', 'six', 'seven')
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return 'There will be a' phaseName 'moon in' dayNames[extradays] 'days.'
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end
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/* -- return the date as a proper English form */
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::method englishDate
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day = self~day
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unit = day //10
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select
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when day % 10 = 1 then day = day'th'
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when unit=1 then day = day'st'
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when unit=2 then day = day'nd'
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when unit=3 then day = day'rd'
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otherwise day = day'th'
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end
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return "It's" self~dayName 'the' day 'of' self~monthName',' self~year'.'
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