// implement Comparator
public int compare(SargInterval i1, SargInterval i2) {
int c = i1.getLowerBound().compareTo(i2.getLowerBound());
if (c != 0) {
return c;
}
return i1.getUpperBound().compareTo(i2.getUpperBound());
}
private void intersectSequences(SargIntervalSequence targetSeq, SargIntervalSequence sourceSeq) {
ListIterator<SargInterval> targetIter = targetSeq.list.listIterator();
if (!targetIter.hasNext()) {
// No target intervals at all, so quit.
return;
}
ListIterator<SargInterval> sourceIter = sourceSeq.list.listIterator();
if (!sourceIter.hasNext()) {
// No source intervals at all, so result is empty
targetSeq.list.clear();
return;
}
// Start working on first source and target intervals
SargInterval target = targetIter.next();
SargInterval source = sourceIter.next();
// loop invariant: both source and target are non-null on entry
for (; ; ) {
if (source.getUpperBound().compareTo(target.getLowerBound()) < 0) {
// Source is completely below target; discard it and
// move on to next one.
if (!sourceIter.hasNext()) {
// No more sources.
break;
}
source = sourceIter.next();
continue;
}
if (target.getUpperBound().compareTo(source.getLowerBound()) < 0) {
// Target is completely below source; discard it and
// move on to next one.
targetIter.remove();
if (!targetIter.hasNext()) {
// All done.
return;
}
target = targetIter.next();
continue;
}
// Overlap case: perform intersection of the two intervals.
if (source.getLowerBound().compareTo(target.getLowerBound()) > 0) {
// Source starts after target starts, so trim the target.
target.setLower(
source.getLowerBound().getCoordinate(), source.getLowerBound().getStrictness());
}
int c = source.getUpperBound().compareTo(target.getUpperBound());
if (c < 0) {
// The source ends before the target ends, so split the target
// into two parts. The first part will be kept for sure; the
// second part will be compared against further source ranges.
SargInterval newTarget = new SargInterval(factory, dataType);
newTarget.setLower(
source.getUpperBound().getCoordinate(),
source.getUpperBound().getStrictnessComplement());
if (target.getUpperBound().isFinite()) {
newTarget.setUpper(
target.getUpperBound().getCoordinate(), target.getUpperBound().getStrictness());
}
// Trim current target to exclude the part of the range
// which will move to newTarget.
target.setUpper(
source.getUpperBound().getCoordinate(), source.getUpperBound().getStrictness());
// Insert newTarget after target. This makes newTarget
// into previous().
targetIter.add(newTarget);
// Next time through, work on newTarget.
// targetIter.previous() is pointing at the newTarget.
target = targetIter.previous();
// Now targetIter.next() is also pointing at the newTarget;
// need to do this redundant step to get targetIter in sync
// with target.
target = targetIter.next();
// Advance source.
if (!sourceIter.hasNext()) {
break;
}
source = sourceIter.next();
} else if (c == 0) {
// Source and target ends coincide, so advance both source and
// target.
if (!targetIter.hasNext()) {
return;
}
target = targetIter.next();
if (!sourceIter.hasNext()) {
break;
}
source = sourceIter.next();
} else {
// Source ends after target ends, so advance target.
assert (c > 0);
if (!targetIter.hasNext()) {
return;
}
target = targetIter.next();
}
}
// Discard any remaining targets since they didn't have corresponding
// sources.
for (; ; ) {
targetIter.remove();
if (!targetIter.hasNext()) {
break;
}
targetIter.next();
}
}
private SargIntervalSequence evaluateUnion(List<SargIntervalSequence> list) {
SargIntervalSequence seq = new SargIntervalSequence();
// Toss all entries from each sequence in the list into one big sorted
// set.
SortedSet<SargInterval> intervals = new TreeSet<SargInterval>(new IntervalComparator());
for (SargIntervalSequence childSeq : list) {
intervals.addAll(childSeq.getList());
}
// Now, overlapping ranges are consecutive in the set. Merge them by
// increasing the upper bound of the first; discard the others. In the
// example, [4, 6] and [5, 7) are combined to form [4, 7). (7, 8] is
// not merged with the new range because neither range contains the
// value 7.
//
// Input:
// 1 2 3 4 5 6 7 8 9
// 1 [1, 3] [-----]
// 2 [4, 6] [-----]
// 3 [5, 7) [-----)
// 4 (7, 8] (--]
//
// Output:
// 1 [1, 3] [-----]
// 2 [4, 7) [--------)
// 3 (7, 8] (--]
SargInterval accumulator = null;
for (SargInterval interval : intervals) {
// Empty intervals should have been previously filtered out.
assert (!interval.isEmpty());
if (accumulator == null) {
// The very first interval: start accumulating.
accumulator = new SargInterval(factory, getDataType());
accumulator.copyFrom(interval);
seq.addInterval(accumulator);
continue;
}
if (accumulator.contains(interval)) {
// Just drop new interval because it's already covered
// by accumulator.
continue;
}
// Test for overlap.
int c = interval.getLowerBound().compareTo(accumulator.getUpperBound());
// If no overlap, test for touching instead.
if (c > 0) {
if (interval.getLowerBound().isTouching(accumulator.getUpperBound())) {
// Force test below to pass.
c = -1;
}
}
if (c <= 0) {
// Either touching or overlap: grow the accumulator.
accumulator.upperBound.copyFrom(interval.getUpperBound());
} else {
// Disjoint: start accumulating a new interval
accumulator = new SargInterval(factory, getDataType());
accumulator.copyFrom(interval);
seq.addInterval(accumulator);
}
}
return seq;
}
