// 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.util.Predicate;
import com.google.ical.util.TimeUtils;
import com.google.ical.values.Frequency;
import com.google.ical.values.TimeValue;
import com.google.ical.values.Weekday;
import com.google.ical.values.DateValue;
import java.util.ArrayList;
import java.util.List;
/**
* factory for generators that operate on groups of generators to generate full
* dates.
*
* @author mikesamuel+svn@gmail.com (Mike Samuel)
*/
class InstanceGenerators {
/**
* a collector that yields each date in the period without doing any set
* collecting.
*/
static Generator serialInstanceGenerator(
final Predicate<? super DateValue> filter,
final Generator yearGenerator, final Generator monthGenerator,
final Generator dayGenerator, final Generator hourGenerator,
final Generator minuteGenerator, final Generator secondGenerator) {
if (skipSubDayGenerators(hourGenerator, minuteGenerator, secondGenerator)) {
// Fast case for generators that are not more frequent than daily.
return new Generator() {
@Override
public boolean generate(DTBuilder builder)
throws IteratorShortCircuitingException {
// cascade through periods to compute the next date
do {
// until we run out of days in the current month
while (!dayGenerator.generate(builder)) {
// until we run out of months in the current year
while (!monthGenerator.generate(builder)) {
// if there are more years available fetch one
if (!yearGenerator.generate(builder)) {
// otherwise the recurrence is exhausted
return false;
}
}
}
// apply filters to generated dates
} while (!filter.apply(builder.toDateTime()));
return true;
}
};
} else {
return new Generator() {
@Override
public boolean generate(DTBuilder builder)
throws IteratorShortCircuitingException {
// cascade through periods to compute the next date
do {
// until we run out of seconds in the current minute
while (!secondGenerator.generate(builder)) {
// until we run out of minutes in the current hour
while (!minuteGenerator.generate(builder)) {
// until we run out of hours in the current day
while (!hourGenerator.generate(builder)) {
// until we run out of days in the current month
while (!dayGenerator.generate(builder)) {
// until we run out of months in the current year
while (!monthGenerator.generate(builder)) {
// if there are more years available fetch one
if (!yearGenerator.generate(builder)) {
// otherwise the recurrence is exhausted
return false;
}
}
}
}
}
}
// apply filters to generated dates
} while (!filter.apply(builder.toDateTime()));
// TODO: maybe group the filters into different kinds so we don't
// apply filters that only affect days to every second.
return true;
}
};
}
}
static Generator bySetPosInstanceGenerator(
int[] setPos, final Frequency freq, final Weekday wkst,
final Predicate<? super DateValue> filter,
final Generator yearGenerator, final Generator monthGenerator,
final Generator dayGenerator, final Generator hourGenerator,
final Generator minuteGenerator, final Generator secondGenerator) {
final int[] uSetPos = Util.uniquify(setPos);
final Generator serialInstanceGenerator = serialInstanceGenerator(
filter, yearGenerator, monthGenerator, dayGenerator,
hourGenerator, minuteGenerator, secondGenerator);
final boolean allPositive;
final int maxPos;
if (false) {
int mp = 0;
boolean ap = true;
for (int i = setPos.length; --i >= 0;) {
if (setPos[i] < 0) {
ap = false;
break;
}
mp = Math.max(setPos[i], mp);
}
maxPos = mp;
allPositive = ap;
} else {
// TODO(msamuel): does this work?
maxPos = uSetPos[uSetPos.length - 1];
allPositive = uSetPos[0] > 0;
}
return new Generator() {
DateValue pushback = null;
/**
* Is this the first instance we generate?
* We need to know so that we don't clobber dtStart.
*/
boolean first = true;
/** Do we need to halt iteration once the current set has been used? */
boolean done = false;
/** The elements in the current set, filtered by set pos */
List<DateValue> candidates;
/**
* index into candidates. The number of elements in candidates already
* consumed.
*/
int i;
@Override
public boolean generate(DTBuilder builder)
throws IteratorShortCircuitingException {
while (null == candidates || i >= candidates.size()) {
if (done) { return false; }
// (1) Make sure that builder is appropriately initialized so that
// we only generate instances in the next set
DateValue d0 = null;
if (null != pushback) {
d0 = pushback;
builder.year = d0.year();
builder.month = d0.month();
builder.day = d0.day();
pushback = null;
} else if (!first) {
// we need to skip ahead to the next item since we didn't exhaust
// the last period
switch (freq) {
case YEARLY:
if (!yearGenerator.generate(builder)) { return false; }
// $FALL-THROUGH$
case MONTHLY:
while (!monthGenerator.generate(builder)) {
if (!yearGenerator.generate(builder)) { return false; }
}
break;
case WEEKLY:
// consume because just incrementing date doesn't do anything
DateValue nextWeek =
Util.nextWeekStart(builder.toDateTime(), wkst);
do {
if (!serialInstanceGenerator.generate(builder)) {
return false;
}
} while (builder.compareTo(nextWeek) < 0);
d0 = builder.toDateTime();
break;
default:
break;
}
} else {
first = false;
}
// (2) Build a set of the dates in the year/month/week that match
// the other rule.
List<DateValue> dates = new ArrayList<DateValue>();
if (null != d0) { dates.add(d0); }
// Optimization: if min(bySetPos) > 0 then we already have absolute
// positions, so we don't need to generate all of the instances for
// the period.
// This speeds up things like the first weekday of the year:
// RRULE:FREQ=YEARLY;BYDAY=MO,TU,WE,TH,FR,BYSETPOS=1
// that would otherwise generate 260+ instances per one emitted
// TODO(msamuel): this may be premature. If needed, We could
// improve more generally by inferring a BYMONTH generator based on
// distribution of set positions within the year.
int limit = allPositive ? maxPos : Integer.MAX_VALUE;
while (limit > dates.size()) {
if (!serialInstanceGenerator.generate(builder)) {
// If we can't generate any, then make sure we return false
// once the instances we have generated are exhausted.
// If this is returning false due to some artificial limit, such
// as the 100 year limit in serialYearGenerator, then we exit
// via an exception because otherwise we would pick the wrong
// elements for some uSetPoses that contain negative elements.
done = true;
break;
}
DateValue d = builder.toDateTime();
boolean contained = false;
if (null == d0) {
d0 = d;
contained = true;
} else {
switch (freq) {
case WEEKLY:
int nb = TimeUtils.daysBetween(d, d0);
// Two dates (d, d0) are in the same week
// if there isn't a whole week in between them and the
// later day is later in the week than the earlier day.
contained =
nb < 7
&& ((7 + Weekday.valueOf(d).javaDayNum
- wkst.javaDayNum) % 7)
> ((7 + Weekday.valueOf(d0).javaDayNum
- wkst.javaDayNum) % 7);
break;
case MONTHLY:
contained =
d0.month() == d.month() && d0.year() == d.year();
break;
case YEARLY:
contained = d0.year() == d.year();
break;
default:
done = true;
return false;
}
}
if (contained) {
dates.add(d);
} else {
// reached end of the set
pushback = d; // save d so we can use it later
break;
}
}
// (3) Resolve the positions to absolute positions and order them
int[] absSetPos;
if (allPositive) {
absSetPos = uSetPos;
} else {
IntSet uAbsSetPos = new IntSet();
for (int j = 0; j < uSetPos.length; ++j) {
int p = uSetPos[j];
if (p < 0) { p = dates.size() + p + 1; }
uAbsSetPos.add(p);
}
absSetPos = uAbsSetPos.toIntArray();
}
candidates = new ArrayList<DateValue>();
for (int p : absSetPos) {
if (p >= 1 && p <= dates.size()) { // p is 1-indexed
candidates.add(dates.get(p - 1));
}
}
i = 0;
if (candidates.isEmpty()) {
// none in this region, so keep looking
candidates = null;
continue;
}
}
// (5) Emit a date. It will be checked against the end condition and
// dtStart elsewhere
DateValue d = candidates.get(i++);
builder.year = d.year();
builder.month = d.month();
builder.day = d.day();
if (d instanceof TimeValue) {
TimeValue t = (TimeValue) d;
builder.hour = t.hour();
builder.minute = t.minute();
builder.second = t.second();
}
return true;
}
};
}
static boolean skipSubDayGenerators(
Generator hourGenerator, Generator minuteGenerator,
Generator secondGenerator) {
return secondGenerator instanceof SingleValueGenerator
&& minuteGenerator instanceof SingleValueGenerator
&& hourGenerator instanceof SingleValueGenerator;
}
private InstanceGenerators() {
// uninstantiable
}
}