org.apache.lucene.util

Class RadixSelector

java.lang.Object

org.apache.lucene.util.Selector

org.apache.lucene.util.RadixSelector

public abstract class RadixSelector
extends Selector

Radix selector.

This implementation works similarly to a MSB radix sort except that it only recurses into the sub partition that contains the desired value.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RadixSelector(int maxLength) Sole constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract int	byteAt(int i, int k) Return the k-th byte of the entry at index i, or -1 if its length is less than or equal to k.
protected Selector	getFallbackSelector(int d) Get a fall-back selector which may assume that the first d bytes of all compared strings are equal.
void	select(int from, int to, int k) Reorder elements so that the element at position k is the same as if all elements were sorted and all other elements are partitioned around it: [from, k) only contains elements that are less than or equal to k and (k, to) only contains elements that are greater than or equal to k.

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

swap

Methods inherited from class java.lang.Object

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

Constructor Detail

RadixSelector

protected RadixSelector(int maxLength)

Sole constructor.

Parameters:

maxLength - the maximum length of keys, pass Integer.MAX_VALUE if unknown.

Method Detail

byteAt

protected abstract int byteAt(int i,
                              int k)

Return the k-th byte of the entry at index i, or -1 if its length is less than or equal to k. This may only be called with a value of i between 0 included and maxLength excluded.

getFallbackSelector

protected Selector getFallbackSelector(int d)

Get a fall-back selector which may assume that the first d bytes of all compared strings are equal. This fallback selector is used when the range becomes narrow or when the maximum level of recursion has been exceeded.

select

public void select(int from,
                   int to,
                   int k)

Description copied from class: Selector

Reorder elements so that the element at position k is the same as if all elements were sorted and all other elements are partitioned around it: [from, k) only contains elements that are less than or equal to k and (k, to) only contains elements that are greater than or equal to k.

Specified by:

select in class Selector