93 lines
2.8 KiB
Plaintext
93 lines
2.8 KiB
Plaintext
/*
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* Copyright 2020 Adobe. All rights reserved.
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* This file is licensed to you under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License. You may obtain a copy
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* of the License at http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under
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* the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
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* OF ANY KIND, either express or implied. See the License for the specific language
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* governing permissions and limitations under the License.
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*/
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// Portions of the code in this file are based on code from ICU.
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// Original licensing can be found in the NOTICE file in the root directory of this source tree.
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import {AnyCalendarDate, Calendar} from '../types';
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import {CalendarDate} from '../CalendarDate';
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import {mod} from '../utils';
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const PERSIAN_EPOCH = 1948320;
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// Number of days from the start of the year to the start of each month.
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const MONTH_START = [
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0, // Farvardin
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31, // Ordibehesht
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62, // Khordad
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93, // Tir
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124, // Mordad
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155, // Shahrivar
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186, // Mehr
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216, // Aban
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246, // Azar
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276, // Dey
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306, // Bahman
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336 // Esfand
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];
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/**
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* The Persian calendar is the main calendar used in Iran and Afghanistan. It has 12 months
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* in each year, the first 6 of which have 31 days, and the next 5 have 30 days. The 12th month
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* has either 29 or 30 days depending on whether it is a leap year. The Persian year starts
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* around the March equinox.
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*/
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export class PersianCalendar implements Calendar {
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identifier = 'persian';
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fromJulianDay(jd: number): CalendarDate {
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let daysSinceEpoch = jd - PERSIAN_EPOCH;
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let year = 1 + Math.floor((33 * daysSinceEpoch + 3) / 12053);
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let farvardin1 = 365 * (year - 1) + Math.floor((8 * year + 21) / 33);
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let dayOfYear = daysSinceEpoch - farvardin1;
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let month = dayOfYear < 216
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? Math.floor(dayOfYear / 31)
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: Math.floor((dayOfYear - 6) / 30);
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let day = dayOfYear - MONTH_START[month] + 1;
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return new CalendarDate(this, year, month + 1, day);
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}
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toJulianDay(date: AnyCalendarDate): number {
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let jd = PERSIAN_EPOCH - 1 + 365 * (date.year - 1) + Math.floor((8 * date.year + 21) / 33);
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jd += MONTH_START[date.month - 1];
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jd += date.day;
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return jd;
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}
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getMonthsInYear(): number {
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return 12;
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}
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getDaysInMonth(date: AnyCalendarDate): number {
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if (date.month <= 6) {
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return 31;
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}
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if (date.month <= 11) {
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return 30;
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}
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let isLeapYear = mod(25 * date.year + 11, 33) < 8;
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return isLeapYear ? 30 : 29;
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}
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getEras() {
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return ['AP'];
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}
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getYearsInEra(): number {
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// 9378-10-10 persian is 9999-12-31 gregorian.
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// Round down to 9377 to set the maximum full year.
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return 9377;
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}
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}
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