/**
* Will allocate a row number to every extent in the list that may overlap the horizon. Row
* numbers are assumed to begin at 0. This algorithm ensures that no temporal overlap occurs on
* any given row and that the minimum number of rows are required. Extents whcih do not overlap
* the horizon defined by horizonStart and horizonEnd will be given a row of -1.
*
* @param horizonStart Will ignore rows that cannot occur at or after this time.
* @param horizonEnd Will ignore rows that cannot occur at or before this time.
* @param extents A list of objects implementing the Extent interface whose rows are to be set
* (thus may be changed)
* @return A susbet of extents which intersected the time horizon, and for which rows have been
* assigned.
*/
public static List allocateRows(int horizonStart, int horizonEnd, List extents) {
List results = new ArrayList();
LinkedList source = new LinkedList(extents);
Collections.sort(source, new ExtentComparator());
// Check the sort worked
if (DEBUG_ON) {
System.out.println("Debug version");
int max = 0; // Not safe for negative horizon start value.
for (Iterator it = source.iterator(); it.hasNext(); ) {
Extent extent = (Extent) it.next();
if (max > extent.getStart()) {
System.out.println("Bad sort");
System.exit(-1);
}
max = extent.getStart();
}
}
int lastCount = extents.size();
int rowCount = 0;
while (source.size() > 0) {
boolean passedHorizon = false;
int currentTime = horizonStart;
Iterator it = source.iterator();
while (currentTime <= horizonEnd && it.hasNext()) {
Extent extent = (Extent) it.next();
// If it is totally outside the horizon - ret rid of it and set row to NO_ROW
if (extent.getEnd() < horizonStart || extent.getStart() > horizonEnd) {
System.out.println("Removing element " + extent.toString() + " - outside horizon");
System.out.println(
" start "
+ extent.getStart()
+ " end "
+ extent.getEnd()
+ " horizonStart "
+ horizonStart
+ " horizonEnd "
+ horizonEnd);
extent.setRow(NO_ROW);
it.remove();
continue;
}
// If it overlaps already placed extents, then just skip it
if (extent.getStart() < currentTime
&& passedHorizon) // Also check to make sure it is not initial entry
continue;
// Otherwise, we will insert it in this row, and remove it from further consideration
extent.setRow(rowCount);
results.add(extent);
it.remove();
// Update currentTime
currentTime = extent.getEnd();
// Indicate we have inserted something and thus passed the Horizon
passedHorizon = true;
}
rowCount++;
if (DEBUG_ON) {
if (source.size() >= lastCount) {
System.out.println("Bug in the loop - should be converging but isn't");
System.exit(-1);
}
lastCount = source.size();
}
}
return results;
}
public void add(Extent e) {
e.setRow(n);
latestEnd = e.getEnd();
}
