org.apache.lucene.util

Class IntroSorter

java.lang.Object

org.apache.lucene.util.Sorter

org.apache.lucene.util.IntroSorter

Direct Known Subclasses:

ArrayIntroSorter, CollectionUtil.ListIntroSorter

public abstract class IntroSorter
extends Sorter

Sorter implementation based on a variant of the quicksort algorithm called introsort: when the recursion level exceeds the log of the length of the array to sort, it falls back to heapsort. This prevents quicksort from running into its worst-case quadratic runtime. Small arrays are sorted with insertion sort.

Field Summary

Fields inherited from class org.apache.lucene.util.Sorter

BINARY_SORT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
IntroSorter() Create a new IntroSorter.

Method Summary

Modifier and Type	Method and Description
protected int	compare(int i, int j) Compare entries found in slots i and j.
protected abstract int	comparePivot(int j) Compare the pivot with the slot at j, similarly to compare(i, j).
(package private) void	quicksort(int from, int to, int maxDepth)
protected abstract void	setPivot(int i) Save the value at slot i so that it can later be used as a pivot, see Sorter.comparePivot(int).
void	sort(int from, int to) Sort the slice which starts at from (inclusive) and ends at to (exclusive).

Methods inherited from class org.apache.lucene.util.Sorter

binarySort, binarySort, checkRange, doRotate, heapChild, heapify, heapParent, heapSort, lower, lower2, mergeInPlace, reverse, rotate, siftDown, swap, upper, upper2

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IntroSorter

public IntroSorter()

Create a new IntroSorter.

Method Detail

sort

public final void sort(int from,
                       int to)

Description copied from class: Sorter

Sort the slice which starts at from (inclusive) and ends at to (exclusive).

Specified by:

sort in class Sorter

quicksort

void quicksort(int from,
               int to,
               int maxDepth)

setPivot

protected abstract void setPivot(int i)

Description copied from class: Sorter

Save the value at slot i so that it can later be used as a pivot, see Sorter.comparePivot(int).

Overrides:

setPivot in class Sorter

comparePivot

protected abstract int comparePivot(int j)

Description copied from class: Sorter

Compare the pivot with the slot at j, similarly to compare(i, j).

Overrides:

comparePivot in class Sorter

compare

protected int compare(int i,
                      int j)

Description copied from class: Sorter

Compare entries found in slots i and j. The contract for the returned value is the same as Comparator.compare(Object, Object).

Specified by:

compare in class Sorter