Module org.tquadrat.foundation.util

Package org.tquadrat.foundation.util.internal

Class KeyBasedComparator<T,K>

java.lang.Object

org.tquadrat.foundation.util.internal.KeyBasedComparator<T,K>

Type Parameters:

T - The type to order.

K - The key type that is used to determine the order; this may be the same as the type itself.

All Implemented Interfaces:

Comparator<T>

@ClassVersion(sourceVersion="$Id: KeyBasedComparator.java 820 2020-12-29 20:34:22Z tquadrat $")
@API(status=INTERNAL,
     since="0.0.5")
public class KeyBasedComparator<T,K>
extends Object
implements Comparator<T>

Sometimes a special sort key is used to order elements, and instead of hiding the generation of that key inside the method compare() of an implementation of Comparator, this implementation expects an instance of Comparators.KeyProvider as an argument to its constructor.

Author:

Thomas Thrien (thomas.thrien@tquadrat.org)

Version:

$Id: KeyBasedComparator.java 820 2020-12-29 20:34:22Z tquadrat $

Since:

0.0.5

UML Diagram

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UML Diagram for "org.tquadrat.foundation.util.internal.KeyBasedComparator"

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Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	m_CacheKeys	A flag that determines whether the keys are to be cached internally; true means they are kept, false means that the keys are generated newly for each comparison.
private final Map<T,K>	m_KeyCache	The cache for the keys.
private final Comparator<K>	m_KeyComparator	The comparator that determines the sort order for the keys.
private final Comparators.KeyProvider<T,K>	m_KeyProvider	The method that generates the key for the given element.

Constructor Summary

Constructors

Constructor	Description
KeyBasedComparator(Comparators.KeyProvider<T,K> keyProvider, Comparator<K> keyComparator, boolean cacheKeys)	Creates a new KeyBasedComparator instance.

Method Summary

Modifier and Type	Method	Description
final int	compare(T o1, T o2)
private final K	retrieveKey(T o)	Provides the key for the given element, either from the cache or freshly generated.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Details

m_CacheKeys

private final boolean m_CacheKeys

A flag that determines whether the keys are to be cached internally; true means they are kept, false means that the keys are generated newly for each comparison.

m_KeyCache

private final Map<T,K> m_KeyCache

The cache for the keys.

m_KeyComparator

private final Comparator<K> m_KeyComparator

The comparator that determines the sort order for the keys.

m_KeyProvider

private final Comparators.KeyProvider<T,K> m_KeyProvider

The method that generates the key for the given element.

Constructor Details

KeyBasedComparator

public KeyBasedComparator(Comparators.KeyProvider<T,K> keyProvider,
 Comparator<K> keyComparator,
 boolean cacheKeys)

Creates a new KeyBasedComparator instance.

Parameters:

keyProvider - The method that generates the key for a given element.

keyComparator - The comparator that determines the sort order for the keys.

cacheKeys - A flag that determines whether the keys are to be cached internally; true means they are kept, false means that the keys are generated newly for each comparison.

Method Details

compare

public final int compare(T o1,
 T o2)

Specified by:

compare in interface Comparator<T>

retrieveKey

private final K retrieveKey(T o)

Provides the key for the given element, either from the cache or freshly generated.

Parameters:

o - The element.

Returns:

The sort key for the element.