Package org.apache.lucene.util
Class IntroSorter
java.lang.Object
org.apache.lucene.util.Sorter
org.apache.lucene.util.IntroSorter
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. Selects the pivot using Tukey's ninther
median-of-medians, and partitions using Bentley-McIlroy 3-way partitioning. Small ranges are
sorted with insertion sort.
This algorithm is NOT stable. It's fast on most data shapes, especially with low
cardinality. If the data to sort is known to be strictly ascending or descending, prefer TimSorter.
- NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected intcompare(int i, int j) Compare entries found in slotsiandj.protected abstract intcomparePivot(int j) Compare the pivot with the slot atj, similarly tocompare(i, j).protected abstract voidsetPivot(int i) Save the value at slotiso that it can later be used as a pivot, seeSorter.comparePivot(int).final voidsort(int from, int to) Sort the slice which starts atfrom(inclusive) and ends atto(exclusive).
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Constructor Details
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IntroSorter
public IntroSorter()Create a newIntroSorter.
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Method Details
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sort
public final void sort(int from, int to) Description copied from class:SorterSort the slice which starts atfrom(inclusive) and ends atto(exclusive). -
setPivot
protected abstract void setPivot(int i) Description copied from class:SorterSave the value at slotiso that it can later be used as a pivot, seeSorter.comparePivot(int). -
comparePivot
protected abstract int comparePivot(int j) Description copied from class:SorterCompare the pivot with the slot atj, similarly tocompare(i, j).- Overrides:
comparePivotin classSorter
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compare
protected int compare(int i, int j) Description copied from class:SorterCompare entries found in slotsiandj. The contract for the returned value is the same asComparator.compare(Object, Object).
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