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package bjc.utils.funcutils;
import java.util.function.Consumer;
import java.util.function.Function;
import bjc.funcdata.FunctionalList;
import bjc.funcdata.IList;
/**
* Implements a single group partitioning pass on a list.
*
* @author ben
*
* @param <E>
* The type of element in the list being partitioned
*/
final class GroupPartIteration<E> implements Consumer<E> {
/* The list we're returning. */
private final IList<IList<E>> returnedList;
/* The current partition of the list. */
public IList<E> currentPartition;
/* The items rejected from the current partition. */
private final IList<E> rejectedItems;
/* The number of items in the current partition. */
private int numberInCurrentPartition;
/* The number of items in each partition. */
private final int numberPerPartition;
/* The function to use to count an item. */
private final Function<E, Integer> elementCounter;
/**
* Create a new group partitioning iteration.
*
* @param returned
* The list containing all of the existing partitions.
*
* @param rejects
* The items that have been rejected from a partition for being
* too large.
*
* @param nPerPart
* The combined value of items that should go into each
* partition.
*
* @param eleCount
* The function to use to determine the value of an item.
*/
public GroupPartIteration(final IList<IList<E>> returned, final IList<E> rejects,
final int nPerPart, final Function<E, Integer> eleCount) {
this.returnedList = returned;
this.rejectedItems = rejects;
this.numberPerPartition = nPerPart;
this.elementCounter = eleCount;
this.currentPartition = new FunctionalList<>();
this.numberInCurrentPartition = 0;
}
@Override
public void accept(final E value) {
final boolean shouldStartPartition
= numberInCurrentPartition >= numberPerPartition;
if (shouldStartPartition) {
returnedList.add(currentPartition);
currentPartition = new FunctionalList<>();
numberInCurrentPartition = 0;
} else {
final int currentElementCount = elementCounter.apply(value);
final boolean shouldReject = (numberInCurrentPartition + currentElementCount)
>= numberPerPartition;
if (shouldReject) {
rejectedItems.add(value);
} else {
currentPartition.add(value);
numberInCurrentPartition += currentElementCount;
}
}
}
}
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