Package net.hydromatic.morel.util

Class Pair<T1,T2>

java.lang.Object

net.hydromatic.morel.util.Pair<T1,T2>

Type Parameters:

T1 - Left-hand type

T2 - Right-hand type

All Implemented Interfaces:

Serializable, Comparable<Pair<T1,T2>>, Map.Entry<T1,T2>

public class Pair<T1,T2>
extends Object
implements Comparable<Pair<T1,T2>>, Map.Entry<T1,T2>, Serializable

Pair of objects.

Because a pair implements equals(Object), hashCode() and compareTo(Pair), it can be used in any kind of Collection.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	Pair.AdjacentIterator<E>	Iterator that returns consecutive pairs of elements from an underlying iterator.
private static class	Pair.FirstAndIterator<E>	Iterator that returns the first element of a collection paired with every other element.
private static class	Pair.LeftIterator<L,R>	Iterator that returns the left field of each pair.
private static class	Pair.MutableZipList<K,V>	A mutable list of pairs backed by a pair of mutable lists.
static interface	Pair.PairWithOrdinalConsumer<K,V>	Represents an operation that accepts two input arguments and an ordinal, and returns no result.
private static class	Pair.RightIterator<L,R>	Iterator that returns the right field of each pair.
private static class	Pair.ZipIterator<L,R>	Iterator that pairs elements from two iterators.
private static class	Pair.ZipList<K,V>	Unmodifiable list of pairs, backed by a pair of lists.

Field Summary

Fields

Modifier and Type	Field	Description
final T1	left
final T2	right

Constructor Summary

Constructors

Constructor	Description
Pair(T1 left, T2 right)	Creates a Pair.

Method Summary

Modifier and Type	Method	Description
static <T> Iterable<Pair<T,T>>	adjacents(Iterable<T> iterable)	Returns an iterator that iterates over (i, i + 1) pairs in an iterable.
static <K, V> boolean	allMatch(Iterable<K> ks, Iterable<V> vs, BiPredicate<K,V> predicate)	Returns whether all pairs match a given predicate.
static <K, V> boolean	anyMatch(Iterable<K> ks, Iterable<V> vs, BiPredicate<K,V> predicate)	Returns whether any pair matches a given predicate.
private static <C extends Comparable<C>> int	compare(C c1, C c2)	Compares a pair of comparable values of the same type.
int	compareTo(Pair<T1,T2> that)
boolean	equals(Object obj)
static <T> Iterable<Pair<T,T>>	firstAnd(Iterable<T> iterable)	Returns an iterator that iterates over (0, i) pairs in an iterable for i > 0.
static <K, V> void	forEach(Iterable<? extends Map.Entry<? extends K,? extends V>> entries, BiConsumer<K,V> consumer)	Applies an action to every element of an iterable of pairs.
static <K, V> void	forEach(Iterable<K> ks, Iterable<V> vs, BiConsumer<K,V> consumer)	Calls a consumer for each pair of items in two iterables.
static <K, V> void	forEachIndexed(Iterable<? extends Map.Entry<K,V>> pairs, Pair.PairWithOrdinalConsumer<K,V> consumer)	Calls a consumer with an ordinal for each pair of items in an iterable of pairs.
static <K, V> void	forEachIndexed(Iterable<K> ks, Iterable<V> vs, Pair.PairWithOrdinalConsumer<K,V> consumer)	Calls a consumer with an ordinal for each pair of items in two iterables.
static <K, V> void	forEachIndexed(Map<K,V> map, Pair.PairWithOrdinalConsumer<K,V> consumer)	Calls a consumer for each entry in a map.
T1	getKey()
T2	getValue()
int	hashCode()
static <L, R> Iterable<L>	left(Iterable<? extends Map.Entry<L,R>> iterable)	Returns an iterable over the left slice of an iterable.
static <K, V> List<K>	left(List<? extends Map.Entry<K,V>> pairs)
static <K, V> boolean	noneMatch(Iterable<K> ks, Iterable<V> vs, BiPredicate<K,V> predicate)	Returns whether no pair matches a given predicate.
static <K, V> Pair<K,V>	of(Map.Entry<K,V> entry)	Creates a Pair from a Map.Entry.
static <T1, T2> Pair<T1,T2>	of(T1 left, T2 right)	Creates a Pair of appropriate type.
static <L, R> Iterable<R>	right(Iterable<? extends Map.Entry<L,R>> iterable)	Returns an iterable over the right slice of an iterable.
static <K, V> List<V>	right(List<? extends Map.Entry<K,V>> pairs)
T2	setValue(T2 value)
static <K, V> Map<K,V>	toMap(Iterable<Pair<K,V>> pairs)	Converts a collection of Pairs into a Map.
String	toString()
static <K, V> Iterable<Pair<K,V>>	zip(Iterable<? extends K> ks, Iterable<? extends V> vs)	Converts two iterables into an iterable of Pairs.
static <K, V> List<Pair<K,V>>	zip(List<K> ks, List<V> vs)	Converts two lists into a list of Pairs, whose length is the lesser of the lengths of the source lists.
static <K, V> List<Pair<K,V>>	zip(List<K> ks, List<V> vs, boolean strict)	Converts two lists into a list of Pairs.
static <K, V> List<Pair<K,V>>	zip(K[] ks, V[] vs)	Converts two arrays into a list of Pairs.
static <K, V> List<Pair<K,V>>	zipMutable(List<K> ks, List<V> vs)	Returns a mutable list of pairs backed by a pair of mutable lists.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

left

public final T1 left

right

public final T2 right

Constructor Details

Pair

public Pair(T1 left,
 T2 right)

Creates a Pair.

Parameters:

left - left value

right - right value

Method Details

of

public static <T1,
T2> Pair<T1,T2> of(T1 left,
 T2 right)

Creates a Pair of appropriate type.

This is a shorthand that allows you to omit implicit types. For example, you can write:

return Pair.of(s, n);

instead of

return new Pair<String, Integer>(s, n);

Parameters:

left - left value

right - right value

Returns:

A Pair

of

public static <K,
V> Pair<K,V> of(Map.Entry<K,V> entry)

Creates a Pair from a Map.Entry.

equals

public boolean equals(Object obj)

Specified by:

equals in interface Map.Entry<T1,T2>

Overrides:

equals in class Object

hashCode

public int hashCode()

Computes hash code consistent with Map.Entry.hashCode().

Specified by:

hashCode in interface Map.Entry<T1,T2>

Overrides:

hashCode in class Object

compareTo

public int compareTo(@Nonnull
 Pair<T1,T2> that)

Specified by:

compareTo in interface Comparable<T1>

toString

public String toString()

Overrides:

toString in class Object

getKey

public T1 getKey()

Specified by:

getKey in interface Map.Entry<T1,T2>

getValue

public T2 getValue()

Specified by:

getValue in interface Map.Entry<T1,T2>

setValue

public T2 setValue(T2 value)

Specified by:

setValue in interface Map.Entry<T1,T2>

compare

private static <C extends Comparable<C>> int compare(C c1,
 C c2)

Compares a pair of comparable values of the same type. Null collates less than everything else, but equal to itself.

Parameters:

c1 - First value

c2 - Second value

Returns:

a negative integer, zero, or a positive integer if c1 is less than, equal to, or greater than c2.

toMap

public static <K,
V> Map<K,V> toMap(Iterable<Pair<K,V>> pairs)

Converts a collection of Pairs into a Map.

This is an obvious thing to do because Pair is similar in structure to Map.Entry.

The map contains a copy of the collection of Pairs; if you change the collection, the map does not change.

Parameters:

pairs - Collection of Pair objects

Returns:

map with the same contents as the collection

zip

public static <K,
V> List<Pair<K,V>> zip(List<K> ks,
 List<V> vs)

Converts two lists into a list of Pairs, whose length is the lesser of the lengths of the source lists.

Parameters:

ks - Left list

vs - Right list

Returns:

List of pairs

See Also:

• Ord.zip(java.util.List)

zip

public static <K,
V> List<Pair<K,V>> zip(List<K> ks,
 List<V> vs,
 boolean strict)

Converts two lists into a list of Pairs.

The length of the combined list is the lesser of the lengths of the source lists. But typically the source lists will be the same length.

Parameters:

ks - Left list

vs - Right list

strict - Whether to fail if lists have different size

Returns:

List of pairs

See Also:

• Ord.zip(java.util.List)

allMatch

public static <K,
V> boolean allMatch(Iterable<K> ks,
 Iterable<V> vs,
 BiPredicate<K,V> predicate)

Returns whether all pairs match a given predicate.

noneMatch

public static <K,
V> boolean noneMatch(Iterable<K> ks,
 Iterable<V> vs,
 BiPredicate<K,V> predicate)

Returns whether no pair matches a given predicate.

anyMatch

public static <K,
V> boolean anyMatch(Iterable<K> ks,
 Iterable<V> vs,
 BiPredicate<K,V> predicate)

Returns whether any pair matches a given predicate.

forEach

public static <K,
V> void forEach(Iterable<K> ks,
 Iterable<V> vs,
 BiConsumer<K,V> consumer)

Calls a consumer for each pair of items in two iterables.

forEachIndexed

public static <K,
V> void forEachIndexed(Iterable<K> ks,
 Iterable<V> vs,
 Pair.PairWithOrdinalConsumer<K,V> consumer)

Calls a consumer with an ordinal for each pair of items in two iterables.

forEachIndexed

public static <K,
V> void forEachIndexed(Iterable<? extends Map.Entry<K,V>> pairs,
 Pair.PairWithOrdinalConsumer<K,V> consumer)

Calls a consumer with an ordinal for each pair of items in an iterable of pairs.

forEachIndexed

public static <K,
V> void forEachIndexed(Map<K,V> map,
 Pair.PairWithOrdinalConsumer<K,V> consumer)

Calls a consumer for each entry in a map.

zip

public static <K,
V> Iterable<Pair<K,V>> zip(Iterable<? extends K> ks,
 Iterable<? extends V> vs)

Converts two iterables into an iterable of Pairs.

The resulting iterator ends whenever the first of the input iterators ends. But typically the source iterators will be the same length.

Parameters:

ks - Left iterable

vs - Right iterable

Returns:

Iterable over pairs

zip

public static <K,
V> List<Pair<K,V>> zip(K[] ks,
 V[] vs)

Converts two arrays into a list of Pairs.

The length of the combined list is the lesser of the lengths of the source arrays. But typically the source arrays will be the same length.

Parameters:

ks - Left array

vs - Right array

Returns:

List of pairs

zipMutable

public static <K,
V> List<Pair<K,V>> zipMutable(List<K> ks,
 List<V> vs)

Returns a mutable list of pairs backed by a pair of mutable lists.

Modifications to this list are reflected in the backing lists, and vice versa.

Type Parameters:

K - Key (left) value type

V - Value (right) value type

forEach

public static <K,
V> void forEach(Iterable<? extends Map.Entry<? extends K,? extends V>> entries,
 BiConsumer<K,V> consumer)

Applies an action to every element of an iterable of pairs.

Type Parameters:

K - Left type

V - Right type

Parameters:

entries - Pairs

consumer - The action to be performed for each element

See Also:

• Map.forEach(java.util.function.BiConsumer)

left

public static <L,
R> Iterable<L> left(Iterable<? extends Map.Entry<L,R>> iterable)

Returns an iterable over the left slice of an iterable.

Type Parameters:

L - Left type

R - Right type

Parameters:

iterable - Iterable over pairs

Returns:

Iterable over the left elements

right

public static <L,
R> Iterable<R> right(Iterable<? extends Map.Entry<L,R>> iterable)

Returns an iterable over the right slice of an iterable.

Type Parameters:

L - right type

R - Right type

Parameters:

iterable - Iterable over pairs

Returns:

Iterable over the right elements

left

public static <K,
V> List<K> left(List<? extends Map.Entry<K,V>> pairs)

right

public static <K,
V> List<V> right(List<? extends Map.Entry<K,V>> pairs)

adjacents

public static <T> Iterable<Pair<T,T>> adjacents(Iterable<T> iterable)

Returns an iterator that iterates over (i, i + 1) pairs in an iterable.

For example, adjacents([3, 5, 7]) returns [(3, 5), (5, 7)].

Type Parameters:

T - Element type

Parameters:

iterable - Source collection

Returns:

Iterable over adjacent element pairs

firstAnd

public static <T> Iterable<Pair<T,T>> firstAnd(Iterable<T> iterable)

Returns an iterator that iterates over (0, i) pairs in an iterable for i > 0.

For example, firstAnd([3, 5, 7]) returns [(3, 5), (3, 7)].

Type Parameters:

T - Element type

Parameters:

iterable - Source collection

Returns:

Iterable over pairs of the first element and all other elements