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With inspiration from other libraries
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 1996-2010, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.util;
import java.util.Date;
/**
* Note: The Holiday framework is a technology preview.
* Despite its age, is still draft API, and clients should treat it as such.
*
* Simple implementation of DateRule.
* @draft ICU 2.8 (retainAll)
* @provisional This API might change or be removed in a future release.
*/
public class SimpleDateRule implements DateRule
{
/**
* Construct a rule for a fixed date within a month
*
* @param month The month in which this rule occurs (0-based).
* @param dayOfMonth The date in that month (1-based).
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public SimpleDateRule(int month, int dayOfMonth)
{
this.month = month;
this.dayOfMonth = dayOfMonth;
this.dayOfWeek = 0;
}
// temporary
/* package */SimpleDateRule(int month, int dayOfMonth, Calendar cal)
{
this.month = month;
this.dayOfMonth = dayOfMonth;
this.dayOfWeek = 0;
this.calendar = cal;
}
/**
* Construct a rule for a weekday within a month, e.g. the first Monday.
*
* @param month The month in which this rule occurs (0-based).
* @param dayOfMonth A date within that month (1-based).
* @param dayOfWeek The day of the week on which this rule occurs.
* @param after If true, this rule selects the first dayOfWeek
* on or after dayOfMonth. If false, the rule selects
* the first dayOfWeek on or before dayOfMonth.
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public SimpleDateRule(int month, int dayOfMonth, int dayOfWeek, boolean after)
{
this.month = month;
this.dayOfMonth = dayOfMonth;
this.dayOfWeek = after ? dayOfWeek : -dayOfWeek;
}
/**
* Return the first occurrance of the event represented by this rule
* that is on or after the given start date.
*
* @param start Only occurrances on or after this date are returned.
*
* @return The date on which this event occurs, or null if it
* does not occur on or after the start date.
*
* @see #firstBetween
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public Date firstAfter(Date start)
{
return doFirstBetween(start, null);
}
/**
* Return the first occurrance of the event represented by this rule
* that is on or after the given start date and before the given
* end date.
*
* @param start Only occurrances on or after this date are returned.
* @param end Only occurrances before this date are returned.
*
* @return The date on which this event occurs, or null if it
* does not occur between the start and end dates.
*
* @see #firstAfter
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public Date firstBetween(Date start, Date end)
{
// Pin to the min/max dates for this rule
return doFirstBetween(start, end);
}
/**
* Checks whether this event occurs on the given date. This does
* not take time of day into account; instead it checks
* whether this event and the given date are on the same day.
* This is useful for applications such as determining whether a given
* day is a holiday.
*
* @param date The date to check.
* @return true if this event occurs on the given date.
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public boolean isOn(Date date)
{
Calendar c = calendar;
synchronized(c) {
c.setTime(date);
int dayOfYear = c.get(Calendar.DAY_OF_YEAR);
c.setTime(computeInYear(c.get(Calendar.YEAR), c));
// System.out.println(" isOn: dayOfYear = " + dayOfYear);
// System.out.println(" holiday = " + c.get(Calendar.DAY_OF_YEAR));
return c.get(Calendar.DAY_OF_YEAR) == dayOfYear;
}
}
/**
* Check whether this event occurs at least once between the two
* dates given.
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
public boolean isBetween(Date start, Date end)
{
return firstBetween(start, end) != null; // TODO: optimize?
}
private Date doFirstBetween(Date start, Date end)
{
Calendar c = calendar;
synchronized(c) {
c.setTime(start);
int year = c.get(Calendar.YEAR);
int mon = c.get(Calendar.MONTH);
// If the rule is earlier in the year than the start date
// we have to go to the next year.
if (mon > this.month) {
year++;
}
// Figure out when the rule lands in the given year
Date result = computeInYear(year, c);
// If the rule is in the same month as the start date, it's possible
// to get a result that's before the start. If so, go to next year.
if (mon == this.month && result.before(start)) {
result = computeInYear(year+1, c);
}
if (end != null && result.after(end)) {
return null;
}
return result;
}
}
private Date computeInYear(int year, Calendar c)
{
synchronized(c) {
c.clear();
c.set(Calendar.ERA, c.getMaximum(Calendar.ERA));
c.set(Calendar.YEAR, year);
c.set(Calendar.MONTH, month);
c.set(Calendar.DATE, dayOfMonth);
//System.out.println(" computeInYear: start at " + c.getTime().toString());
if (dayOfWeek != 0) {
c.setTime(c.getTime()); // JDK 1.1.2 workaround
int weekday = c.get(Calendar.DAY_OF_WEEK);
//System.out.println(" weekday = " + weekday);
//System.out.println(" dayOfYear = " + c.get(Calendar.DAY_OF_YEAR));
int delta = 0;
if (dayOfWeek > 0) {
// We want the first occurrance of the given day of the week
// on or after the specified date in the month.
delta = (dayOfWeek - weekday + 7) % 7;
}
else {
// We want the first occurrance of the (-dayOfWeek)
// on or before the specified date in the month.
delta = -((dayOfWeek + weekday + 7) % 7);
}
//System.out.println(" adding " + delta + " days");
c.add(Calendar.DATE, delta);
}
return c.getTime();
}
}
/**
* @draft ICU 2.8
* @provisional This API might change or be removed in a future release.
*/
// public void setCalendar(Calendar c) {
// calendar = c;
// }
private Calendar calendar = new GregorianCalendar();
private int month;
private int dayOfMonth;
private int dayOfWeek;
}