Module org.tquadrat.foundation.util

Package org.tquadrat.foundation.util.internal

Class ListBasedComparator<T,K>

java.lang.Object

org.tquadrat.foundation.util.internal.ListBasedComparator<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: ListBasedComparator.java 1032 2022-04-10 17:27:44Z tquadrat $")
@API(status=INTERNAL,
     since="0.0.5")
public class ListBasedComparator<T,K>
extends Object
implements Comparator<T>

A comparator that works on a list of sort keys.

Sometimes, a special sort order is required that cannot be defined as a rule based on the values themselves. Instead an ordered list of value defines their sequence.

The implementation first determines the key for a given value, then it looks up that key in the key list to determine the sort order. Values whose keys are not in the key list are placed on the list, will be ordered based on the order implied by the given comparator according their keys.

Author:

Thomas Thrien (thomas.thrien@tquadrat.org)

Version:

$Id: ListBasedComparator.java 1032 2022-04-10 17:27:44Z tquadrat $

Since:

0.0.5

UML Diagram

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

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Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ListBasedComparator.SimpleKeyProvider<T,K extends T>	A simple implementation of Comparators.KeyProvider that returns the instance itself as the sort order key.

Field Summary

Fields

Modifier and Type	Field	Description
private final Comparator<? super K>	m_Comparator	The comparator that is used to determine the sort order for instances that do not have their keys in the list; may be null.
private final Comparators.KeyProvider<T,K>	m_KeyProvider	The key provider.
private final K[]	m_Keys	The list with the sort order keys.

Constructor Summary

Constructors

Constructor	Description
ListBasedComparator(Comparators.KeyProvider<T,K> keyProvider, Comparator<? super K> comparator, K[] keys)	Creates a new ListBasedComparator instance.

Method Summary

Modifier and Type	Method	Description
final int	compare(T o1, T o2)
private int	searchKey(K key)	Searches the given key in the list.

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_Comparator

private final Comparator<? super K> m_Comparator

The comparator that is used to determine the sort order for instances that do not have their keys in the list; may be null.

m_KeyProvider

private final Comparators.KeyProvider<T,K> m_KeyProvider

The key provider.

m_Keys

private final K[] m_Keys

The list with the sort order keys.

Constructor Details

ListBasedComparator

public ListBasedComparator(Comparators.KeyProvider<T,K> keyProvider,
 Comparator<? super K> comparator,
 K[] keys)

Creates a new ListBasedComparator instance.

Parameters:

keyProvider - The implementation of Comparators.KeyProvider that returns the sort keys for the instances to compare.

comparator - The comparator that is used to order the instances that are not listed.

keys - The sort order keys.

Method Details

compare

public final int compare(T o1,
 T o2)

Specified by:

compare in interface Comparator<T>

searchKey

private int searchKey(K key)

Searches the given key in the list.

Parameters:

key - The key.

Returns:

The index in the list or CommonConstants.NOT_FOUND (-1) if the key is not in the list.