Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $
You can buy this project and download/modify it how often you want.
org.glassfish.jersey.internal.guava.Iterators Maven / Gradle / Ivy
A bundle project producing JAX-RS RI bundles. The primary artifact is an "all-in-one" OSGi-fied JAX-RS RI bundle
(jaxrs-ri.jar).
Attached to that are two compressed JAX-RS RI archives. The first archive (jaxrs-ri.zip) consists of binary RI bits and
contains the API jar (under "api" directory), RI libraries (under "lib" directory) as well as all external
RI dependencies (under "ext" directory). The secondary archive (jaxrs-ri-src.zip) contains buildable JAX-RS RI source
bundle and contains the API jar (under "api" directory), RI sources (under "src" directory) as well as all external
RI dependencies (under "ext" directory). The second archive also contains "build.xml" ANT script that builds the RI
sources. To build the JAX-RS RI simply unzip the archive, cd to the created jaxrs-ri directory and invoke "ant" from
the command line.
/*
* Copyright (C) 2007 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.glassfish.jersey.internal.guava;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.function.Function;
import java.util.function.Predicate;
import static org.glassfish.jersey.internal.guava.Preconditions.checkArgument;
import static org.glassfish.jersey.internal.guava.Preconditions.checkNotNull;
import static org.glassfish.jersey.internal.guava.Preconditions.checkState;
import static org.glassfish.jersey.internal.guava.Predicates.in;
/**
* This class contains static utility methods that operate on or return objects
* of type {@link Iterator}. Except as noted, each method has a corresponding
* {@link Iterable}-based method in the {@link Iterables} class.
*
*
Performance notes: Unless otherwise noted, all of the iterators
* produced in this class are lazy , which means that they only advance
* the backing iteration when absolutely necessary.
*
*
See the Guava User Guide section on
* {@code Iterators} .
*
* @author Kevin Bourrillion
* @author Jared Levy
* @since 2.0 (imported from Google Collections Library)
*/
public final class Iterators {
private static final UnmodifiableListIterator EMPTY_LIST_ITERATOR
= new UnmodifiableListIterator() {
@Override
public boolean hasNext() {
return false;
}
@Override
public Object next() {
throw new NoSuchElementException();
}
@Override
public boolean hasPrevious() {
return false;
}
@Override
public Object previous() {
throw new NoSuchElementException();
}
@Override
public int nextIndex() {
return 0;
}
@Override
public int previousIndex() {
return -1;
}
};
private static final Iterator EMPTY_MODIFIABLE_ITERATOR =
new Iterator() {
@Override
public boolean hasNext() {
return false;
}
@Override
public Object next() {
throw new NoSuchElementException();
}
@Override
public void remove() {
CollectPreconditions.checkRemove(false);
}
};
private Iterators() {
}
/**
* Returns the empty iterator.
*
*
The {@link Iterable} equivalent of this method is {@link
* ImmutableSet#of()}.
*
* @deprecated Use {@code ImmutableSet.of().iterator()} instead; or for
* Java 7 or later, {@link Collections#emptyIterator}. This method is
* scheduled for removal in May 2016.
*/
@Deprecated
public static UnmodifiableIterator emptyIterator() {
return emptyListIterator();
}
/**
* Returns the empty iterator.
*
*
The {@link Iterable} equivalent of this method is {@link
* ImmutableSet#of()}.
*/
// Casting to any type is safe since there are no actual elements.
@SuppressWarnings("unchecked")
private static UnmodifiableListIterator emptyListIterator() {
return (UnmodifiableListIterator) EMPTY_LIST_ITERATOR;
}
/**
* Returns the empty {@code Iterator} that throws
* {@link IllegalStateException} instead of
* {@link UnsupportedOperationException} on a call to
* {@link Iterator#remove()}.
*/
// Casting to any type is safe since there are no actual elements.
@SuppressWarnings("unchecked")
static Iterator emptyModifiableIterator() {
return (Iterator) EMPTY_MODIFIABLE_ITERATOR;
}
/**
* Returns an unmodifiable view of {@code iterator}.
*/
public static UnmodifiableIterator unmodifiableIterator(
final Iterator iterator) {
checkNotNull(iterator);
if (iterator instanceof UnmodifiableIterator) {
return (UnmodifiableIterator) iterator;
}
return new UnmodifiableIterator() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public T next() {
return iterator.next();
}
};
}
/**
* Returns the number of elements remaining in {@code iterator}. The iterator
* will be left exhausted: its {@code hasNext()} method will return
* {@code false}.
*/
public static int size(Iterator iterator) {
int count = 0;
while (iterator.hasNext()) {
iterator.next();
count++;
}
return count;
}
/**
* Traverses an iterator and removes every element that belongs to the
* provided collection. The iterator will be left exhausted: its
* {@code hasNext()} method will return {@code false}.
*
* @param removeFrom the iterator to (potentially) remove elements from
* @param elementsToRemove the elements to remove
* @return {@code true} if any element was removed from {@code iterator}
*/
public static boolean removeAll(
Iterator removeFrom, Collection elementsToRemove) {
return removeIf(removeFrom, in(elementsToRemove));
}
/**
* Removes every element that satisfies the provided predicate from the
* iterator. The iterator will be left exhausted: its {@code hasNext()}
* method will return {@code false}.
*
* @param removeFrom the iterator to (potentially) remove elements from
* @param predicate a predicate that determines whether an element should
* be removed
* @return {@code true} if any elements were removed from the iterator
* @since 2.0
*/
public static boolean removeIf(
Iterator removeFrom, Predicate predicate) {
checkNotNull(predicate);
boolean modified = false;
while (removeFrom.hasNext()) {
if (predicate.test(removeFrom.next())) {
removeFrom.remove();
modified = true;
}
}
return modified;
}
/**
* Determines whether two iterators contain equal elements in the same order.
* More specifically, this method returns {@code true} if {@code iterator1}
* and {@code iterator2} contain the same number of elements and every element
* of {@code iterator1} is equal to the corresponding element of
* {@code iterator2}.
*
*
Note that this will modify the supplied iterators, since they will have
* been advanced some number of elements forward.
*/
public static boolean elementsEqual(
Iterator iterator1, Iterator iterator2) {
while (iterator1.hasNext()) {
if (!iterator2.hasNext()) {
return false;
}
Object o1 = iterator1.next();
Object o2 = iterator2.next();
if (!Objects.equals(o1, o2)) {
return false;
}
}
return !iterator2.hasNext();
}
/**
* Adds all elements in {@code iterator} to {@code collection}. The iterator
* will be left exhausted: its {@code hasNext()} method will return
* {@code false}.
*
* @return {@code true} if {@code collection} was modified as a result of this
* operation
*/
public static boolean addAll(
Collection addTo, Iterator iterator) {
checkNotNull(addTo);
checkNotNull(iterator);
boolean wasModified = false;
while (iterator.hasNext()) {
wasModified |= addTo.add(iterator.next());
}
return wasModified;
}
/**
* Returns {@code true} if every element returned by {@code iterator}
* satisfies the given predicate. If {@code iterator} is empty, {@code true}
* is returned.
*/
public static boolean all(
Iterator iterator, Predicate predicate) {
checkNotNull(predicate);
while (iterator.hasNext()) {
T element = iterator.next();
if (!predicate.test(element)) {
return false;
}
}
return true;
}
/**
* Returns the index in {@code iterator} of the first element that satisfies
* the provided {@code predicate}, or {@code -1} if the Iterator has no such
* elements.
*
*
More formally, returns the lowest index {@code i} such that
* {@code predicate.apply(Iterators.get(iterator, i))} returns {@code true},
* or {@code -1} if there is no such index.
*
*
If -1 is returned, the iterator will be left exhausted: its
* {@code hasNext()} method will return {@code false}. Otherwise,
* the iterator will be set to the element which satisfies the
* {@code predicate}.
*
* @since 2.0
*/
private static int indexOf(
Iterator iterator, Predicate predicate) {
checkNotNull(predicate, "predicate");
for (int i = 0; iterator.hasNext(); i++) {
T current = iterator.next();
if (predicate.test(current)) {
return i;
}
}
return -1;
}
/**
* Returns an iterator that applies {@code function} to each element of {@code
* fromIterator}.
*
*
The returned iterator supports {@code remove()} if the provided iterator
* does. After a successful {@code remove()} call, {@code fromIterator} no
* longer contains the corresponding element.
*/
public static Iterator transform(final Iterator fromIterator,
final Function function) {
checkNotNull(function);
return new TransformedIterator(fromIterator) {
@Override
T transform(F from) {
return function.apply(from);
}
};
}
/**
* Returns the next element in {@code iterator} or {@code defaultValue} if
* the iterator is empty. The {@link Iterables} analog to this method is
* {@link Iterables#getFirst}.
*
* @param defaultValue the default value to return if the iterator is empty
* @return the next element of {@code iterator} or the default value
* @since 7.0
*/
public static T getNext(Iterator iterator, T defaultValue) {
return iterator.hasNext() ? iterator.next() : defaultValue;
}
/**
* Deletes and returns the next value from the iterator, or returns
* {@code null} if there is no such value.
*/
static T pollNext(Iterator iterator) {
if (iterator.hasNext()) {
T result = iterator.next();
iterator.remove();
return result;
} else {
return null;
}
}
// Methods only in Iterators, not in Iterables
/**
* Clears the iterator using its remove method.
*/
static void clear(Iterator iterator) {
checkNotNull(iterator);
while (iterator.hasNext()) {
iterator.next();
iterator.remove();
}
}
/**
* Returns an iterator containing the elements of {@code array} in order. The
* returned iterator is a view of the array; subsequent changes to the array
* will be reflected in the iterator.
*
*
Note: It is often preferable to represent your data using a
* collection type, for example using {@link Arrays#asList(Object[])}, making
* this method unnecessary.
*
*
The {@code Iterable} equivalent of this method is either {@link
* Arrays#asList(Object[])}, {@link ImmutableList#copyOf(Object[])}},
* or {@link ImmutableList#of}.
*/
public static UnmodifiableIterator forArray(final T... array) {
return forArray(array, 0, array.length, 0);
}
/**
* Returns a list iterator containing the elements in the specified range of
* {@code array} in order, starting at the specified index.
*
*
The {@code Iterable} equivalent of this method is {@code
* Arrays.asList(array).subList(offset, offset + length).listIterator(index)}.
*/
static UnmodifiableListIterator forArray(
final T[] array, final int offset, int length, int index) {
checkArgument(length >= 0);
int end = offset + length;
// Technically we should give a slightly more descriptive error on overflow
Preconditions.checkPositionIndexes(offset, end, array.length);
Preconditions.checkPositionIndex(index, length);
if (length == 0) {
return emptyListIterator();
}
/*
* We can't use call the two-arg constructor with arguments (offset, end)
* because the returned Iterator is a ListIterator that may be moved back
* past the beginning of the iteration.
*/
return new AbstractIndexedListIterator(length, index) {
@Override
protected T get(int index) {
return array[offset + index];
}
};
}
/**
* Returns an iterator containing only {@code value}.
*
*
The {@link Iterable} equivalent of this method is {@link
* Collections#singleton}.
*/
public static UnmodifiableIterator singletonIterator(
final T value) {
return new UnmodifiableIterator() {
boolean done;
@Override
public boolean hasNext() {
return !done;
}
@Override
public T next() {
if (done) {
throw new NoSuchElementException();
}
done = true;
return value;
}
};
}
/**
* Returns a {@code PeekingIterator} backed by the given iterator.
*
*
Calls to the {@code peek} method with no intervening calls to {@code
* next} do not affect the iteration, and hence return the same object each
* time. A subsequent call to {@code next} is guaranteed to return the same
* object again. For example:
{@code
*
* PeekingIterator peekingIterator =
* Iterators.peekingIterator(Iterators.forArray("a", "b"));
* String a1 = peekingIterator.peek(); // returns "a"
* String a2 = peekingIterator.peek(); // also returns "a"
* String a3 = peekingIterator.next(); // also returns "a"}
*
*
Any structural changes to the underlying iteration (aside from those
* performed by the iterator's own {@link PeekingIterator#remove()} method)
* will leave the iterator in an undefined state.
*
*
The returned iterator does not support removal after peeking, as
* explained by {@link PeekingIterator#remove()}.
*
*
Note: If the given iterator is already a {@code PeekingIterator},
* it might be returned to the caller, although this is neither
* guaranteed to occur nor required to be consistent. For example, this
* method might choose to pass through recognized implementations of
* {@code PeekingIterator} when the behavior of the implementation is
* known to meet the contract guaranteed by this method.
*
*
There is no {@link Iterable} equivalent to this method, so use this
* method to wrap each individual iterator as it is generated.
*
* @param iterator the backing iterator. The {@link PeekingIterator} assumes
* ownership of this iterator, so users should cease making direct calls
* to it after calling this method.
* @return a peeking iterator backed by that iterator. Apart from the
* additional {@link PeekingIterator#peek()} method, this iterator behaves
* exactly the same as {@code iterator}.
*/
public static PeekingIterator peekingIterator(
Iterator iterator) {
if (iterator instanceof PeekingImpl) {
// Safe to cast to because PeekingImpl only uses T
// covariantly (and cannot be subclassed to add non-covariant uses).
@SuppressWarnings("unchecked")
PeekingImpl peeking = (PeekingImpl) iterator;
return peeking;
}
return new PeekingImpl(iterator);
}
/**
* Implementation of PeekingIterator that avoids peeking unless necessary.
*/
private static class PeekingImpl implements PeekingIterator {
private final Iterator iterator;
private boolean hasPeeked;
private E peekedElement;
public PeekingImpl(Iterator iterator) {
this.iterator = checkNotNull(iterator);
}
@Override
public boolean hasNext() {
return hasPeeked || iterator.hasNext();
}
@Override
public E next() {
if (!hasPeeked) {
return iterator.next();
}
E result = peekedElement;
hasPeeked = false;
peekedElement = null;
return result;
}
@Override
public void remove() {
checkState(!hasPeeked, "Can't remove after you've peeked at next");
iterator.remove();
}
@Override
public E peek() {
if (!hasPeeked) {
peekedElement = iterator.next();
hasPeeked = true;
}
return peekedElement;
}
}
}
