Package eu.bandm.tools.util.java

Class Iterators

java.lang.Object

eu.bandm.tools.util.java.Iterators

public final class Iterators
extends Object

Library of combinators for classes implementing Iterator.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Iterators.FilterIterator<A>
static interface	Iterators.LookaheadIterator<A>
(package private) static class	Iterators.LookaheadIteratorImpl<A>
static class	Iterators.MultipleLookaheadIterator<T>	An iterator which allows arbitrary deep look-ahead for an underlying iterator.
static class	Iterators.Pairwise<T>	Visitor which performs the method Iterators.Pairwise.first(Object) for the first element of an Iterable; afterwards the methodIterators.Pairwise.pairwise(Object,Object) for each pair of adjacent elements, and at last the method Iterators.Pairwise.last(Object).
static interface	Iterators.PushbackIterator<A>
(package private) static class	Iterators.PushbackIteratorImpl<A>
static class	Iterators.Triplewise<T>	Visitor which performs the method Iterators.Triplewise.action(Object,Object,Object) for triples of adjacent elements of an Iterable.

Method Summary

Modifier and Type	Method	Description
static <E, F> Iterator<F>	bind(Function<? super E,? extends Iterator<? extends F>> fun, Iterator<E> things)
static <A> Iterator<A>	cacheHasNext(Iterator<A> i)
static <A> Iterator<A>	cast(Iterator<? extends A> iterator)	Forgets a wildcard in the element type of a given iterator.
static <A, B> Iterator<B>	comprehend(Iterator<A> gen, Function<? super A,? extends Iterator<B>> fun)	Deprecated. use streams instead
static <A, B> Iterator<B>	comprehend(Iterator<A> gen, Predicate<? super A> filter, Function<? super A,? extends B> map)	Deprecated. use streams instead
static <E> Iterator<E>	concat(Iterator<? extends E> first, Iterator<? extends E> second)	Returns an iterator consisting of the combined elements of two given iterators in order.
static <E> Iterator<E>	cons(E first, Iterator<E> rest)	Returns an iterator consisting of the given first element preceding the remaining elements of a given iterator.
static <A> Iterator<A>	drop(int n, Iterator<A> things)
static <A> void	elementwise(Consumer<? super A> sink, Iterator<A> it)
static <E> Iterator<E>	empty()	Returns an iterator consisting of no elements.
static <E> Iterator<E>	filter(Predicate<? super E> pred, Iterator<E> i)	Returns an iterator consisting of the remaining elements of a given iterator that match the given predicate.
static <A, B> Iterator<A>	filterWithConstraint(BiPredicate<? super A,? super B> rel, Iterator<A> things, Iterator<B> constraints)
static <E> Iterator<E>	flatten(Iterator<? extends Iterator<? extends E>> iterators)	Returns an iterator consisting of the combined elements of all iterators returned by a given iterator in order.
static <A> Iterators.LookaheadIterator<A>	lookahead(Iterator<? extends A> things)
static <A, B> Iterator<B>	map(Function<? super A,? extends B> fun, Iterator<A> it)	Returns an iterator consisting of the results of applying the given function to the remaining elements of a given iterator.
static <A> Iterator<A>	merge(Comparator<? super A> order, boolean removeDuplicates, Iterator<? extends A> left, Iterator<? extends A> right)
static <E> Iterator<E>	of(E... things)	Returns an iterator consisting of exactly the given elements.
static <A> Iterators.PushbackIterator<A>	pushback(Iterator<? extends A> things)
static <E> Iterator<E>	singleton(E value)	Returns an iterator consisting of exactly one given element.
static <A> Iterator<A>	take(int n, Iterator<A> things)
static <A> Iterator<A>	unmodifiableIterator(Iterator<A> i)

Methods inherited from class java.lang.Object

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

Method Details

cast

public static <A> Iterator<A> cast(Iterator<? extends A> iterator)

Forgets a wildcard in the element type of a given iterator.

Parameters:

iterator - an iterator

Returns:

the same iterator

empty

public static <E> Iterator<E> empty()

Returns an iterator consisting of no elements.

Type Parameters:

E - the type of elements returned by the returned iterator

Returns:

an iterator that has no elements

singleton

public static <E> Iterator<E> singleton(E value)

Returns an iterator consisting of exactly one given element. The element is not removable.

Type Parameters:

E - the type of elements returned by the returned iterator

Parameters:

value - the single element of the returned iterator

Returns:

an iterator that has exactly the given element

of

@SafeVarargs
public static <E> Iterator<E> of(E... things)

Returns an iterator consisting of exactly the given elements. Elements are not removable.

Type Parameters:

E - the type of elements returned by the returned iterator

Parameters:

things - the elements of the returned iterator

Returns:

an iterator that has exactly the given elements

cons

public static <E> Iterator<E> cons(E first,
 Iterator<E> rest)

Returns an iterator consisting of the given first element preceding the remaining elements of a given iterator. The first element is not removable. Further removal requests are passed through to the underlying iterator.

Type Parameters:

E - the type of elements returned by the returned iterator

Parameters:

first - the first element

rest - the iterator of the succeeding elements

Returns:

an iterator that returns the first element followed by the remaining elements of rest

Throws:

NullPointerException - if rest == null

concat

public static <E> Iterator<E> concat(Iterator<? extends E> first,
 Iterator<? extends E> second)

Returns an iterator consisting of the combined elements of two given iterators in order. Removal requests are passed through to the underlying iterators.

Type Parameters:

E - the type of elements returned by the returned iterator

Parameters:

first - the first iterator to consult for elements

second - the second iterator to consult for elements

Returns:

an iterator that returns all remaining elements of first, followed by all remaining elements of second

Throws:

NullPointerException - if first == null or second == null

flatten

public static <E> Iterator<E> flatten(Iterator<? extends Iterator<? extends E>> iterators)

Returns an iterator consisting of the combined elements of all iterators returned by a given iterator in order. Removal requests are passed through to the underlying iterators.

Type Parameters:

E - the type of elements returned by the returned iterator

Parameters:

iterators - the iterators to be combined

Returns:

the combined interator

Throws:

NullPointerException - if iterators == null or one in the list is ==null.

bind

@Undocumented
public static <E,
F> Iterator<F> bind(Function<? super E,? extends Iterator<? extends F>> fun,
 Iterator<E> things)

filter

public static <E> Iterator<E> filter(Predicate<? super E> pred,
 Iterator<E> i)

Returns an iterator consisting of the remaining elements of a given iterator that match the given predicate. Removal requests are passed through to the underlying iterator.

map

public static <A,
B> Iterator<B> map(Function<? super A,? extends B> fun,
 Iterator<A> it)

Returns an iterator consisting of the results of applying the given function to the remaining elements of a given iterator. Removal requests are passed through to the underlying iterator.

comprehend

@Deprecated(since="0.0")
public static <A,
B> Iterator<B> comprehend(Iterator<A> gen,
 Predicate<? super A> filter,
 Function<? super A,? extends B> map)

Deprecated.

use streams instead

First apply filter, than map, and collect results.

comprehend

@Deprecated(since="0.0")
public static <A,
B> Iterator<B> comprehend(Iterator<A> gen,
 Function<? super A,? extends Iterator<B>> fun)

Deprecated.

use streams instead

Apply function and collect results.

unmodifiableIterator

@Undocumented
public static <A> Iterator<A> unmodifiableIterator(Iterator<A> i)

lookahead

@Undocumented
public static <A> Iterators.LookaheadIterator<A> lookahead(Iterator<? extends A> things)

pushback

@Undocumented
public static <A> Iterators.PushbackIterator<A> pushback(Iterator<? extends A> things)

merge

@Undocumented
public static <A> Iterator<A> merge(Comparator<? super A> order,
 boolean removeDuplicates,
 Iterator<? extends A> left,
 Iterator<? extends A> right)

filterWithConstraint

@Undocumented
public static <A,
B> Iterator<A> filterWithConstraint(BiPredicate<? super A,? super B> rel,
 Iterator<A> things,
 Iterator<B> constraints)

cacheHasNext

@Undocumented
public static <A> Iterator<A> cacheHasNext(Iterator<A> i)

drop

@Undocumented
public static <A> Iterator<A> drop(int n,
 Iterator<A> things)

take

@Undocumented
public static <A> Iterator<A> take(int n,
 Iterator<A> things)

elementwise

@Undocumented
public static <A> void elementwise(Consumer<? super A> sink,
 Iterator<A> it)