com.google.ical.iter.Util Maven / Gradle / Ivy
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/**
* Copyright (C) 2015, 2016 Dirk Lemmermann Software & Consulting (dlsc.com)
*
* This file is part of CalendarFX.
*/
// Copyright (C) 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.ical.iter;
import com.google.ical.util.DTBuilder;
import com.google.ical.values.DateValue;
import com.google.ical.values.Weekday;
import com.google.ical.values.WeekdayNum;
/**
* a dumping ground for utility functions that don't fit anywhere else.
*
* @author [email protected] (Mike Samuel)
*/
class Util {
/**
* advances builder to the earliest day on or after builder that falls on
* wkst.
* @param builder non null.
* @param wkst the day of the week that the week starts on
*/
static void rollToNextWeekStart(DTBuilder builder, Weekday wkst) {
DateValue bd = builder.toDate();
builder.day += (7 - ((7 + (Weekday.valueOf(bd).javaDayNum
- wkst.javaDayNum))
% 7)) % 7;
builder.normalize();
}
/**
* the earliest day on or after d that falls on wkst.
* @param wkst the day of the week that the week starts on
*/
static DateValue nextWeekStart(DateValue d, Weekday wkst) {
DTBuilder builder = new DTBuilder(d);
builder.day += (7 - ((7 + (Weekday.valueOf(d).javaDayNum
- wkst.javaDayNum)) % 7))
% 7;
return builder.toDate();
}
/** returns a sorted unique copy of ints. */
static int[] uniquify(int[] ints) {
return uniquify(ints, 0, ints.length);
}
/** returns a sorted unique copy of ints. */
static int[] uniquify(int[] ints, int start, int end) {
IntSet iset = new IntSet();
for (int i = end; --i >= start; ) {
iset.add(ints[i]);
}
return iset.toIntArray();
}
/**
* given a weekday number, such as -1SU, returns the day of the month that it
* falls on.
* The weekday number may be refer to a week in the current month in some
* contexts or a week in the current year in other contexts.
* @param dow0 the day of week of the first day in the current year/month.
* @param nDays the number of days in the current year/month.
* In [28,29,30,31,365,366].
* @param weekNum -1SU in the example above.
* @param d0 the number of days between the 1st day of the current
* year/month and the current month.
* @param nDaysInMonth the number of days in the current month.
* @return 0 indicates no such day
*/
static int dayNumToDate(Weekday dow0, int nDays, int weekNum,
Weekday dow, int d0, int nDaysInMonth) {
// if dow is wednesday, then this is the date of the first wednesday
int firstDateOfGivenDow = 1 + ((7 + dow.javaDayNum - dow0.javaDayNum) % 7);
int date;
if (weekNum > 0) {
date = ((weekNum - 1) * 7) + firstDateOfGivenDow - d0;
} else { // count weeks from end of month
// calculate last day of the given dow.
// Since nDays <= 366, this should be > nDays
int lastDateOfGivenDow = firstDateOfGivenDow + (7 * 54);
lastDateOfGivenDow -= 7 * ((lastDateOfGivenDow - nDays + 6) / 7);
date = lastDateOfGivenDow + 7 * (weekNum + 1) - d0;
}
if (date <= 0 || date > nDaysInMonth) {
return 0;
}
return date;
}
/**
* Compute an absolute week number given a relative one.
* The day number -1SU refers to the last Sunday, so if there are 5 Sundays
* in a period that starts on dow0 with nDays, then -1SU is 5SU.
* Depending on where its used it may refer to the last Sunday of the year
* or of the month.
*
* @param weekdayNum -1SU in the example above.
* @param dow0 the day of the week of the first day of the week or month.
* One of the RRULE_WDAY_* constants.
* @param nDays the number of days in the month or year.
* @return an abolute week number, e.g. 5 in the example above.
* Valid if in [1,53].
*/
static int invertWeekdayNum(
WeekdayNum weekdayNum, Weekday dow0, int nDays) {
assert weekdayNum.num < 0;
// how many are there of that week?
return countInPeriod(weekdayNum.wday, dow0, nDays) + weekdayNum.num + 1;
}
/**
* the number of occurences of dow in a period nDays long where the first day
* of the period has day of week dow0.
*/
static int countInPeriod(Weekday dow, Weekday dow0, int nDays) {
// Two cases
// (1a) dow >= dow0: count === (nDays - (dow - dow0)) / 7
// (1b) dow < dow0: count === (nDays - (7 - dow0 - dow)) / 7
if (dow.javaDayNum >= dow0.javaDayNum) {
return 1 + ((nDays - (dow.javaDayNum - dow0.javaDayNum) - 1) / 7);
} else {
return 1 + ((nDays - (7 - (dow0.javaDayNum - dow.javaDayNum)) - 1) / 7);
}
}
private Util() {
// uninstantiable
}
}