org.wildfly.security.util.ArrayIterator Maven / Gradle / Ivy
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* JBoss, Home of Professional Open Source.
* Copyright 2016 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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.wildfly.security.util;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import org.wildfly.common.Assert;
/**
* A read-only iterator over an array.
*
* @author David M. Lloyd
*/
public final class ArrayIterator implements ListIterator, EnumerationIterator {
private final E[] elements;
private final boolean descending;
private int idx;
/**
* Construct a new instance.
*
* @param elements the elements to iterate over
*/
public ArrayIterator(final E[] elements) {
this(elements, false);
}
/**
* Construct a new instance.
*
* @param elements the elements to iterate over
* @param descending {@code true} to iterate in descending order, {@code false} otherwise
*/
public ArrayIterator(final E[] elements, final boolean descending) {
this(elements, descending, descending ? elements.length : 0);
}
/**
* Construct a new instance.
*
* @param elements the elements to iterate over
* @param startIdx the starting index (must be within the bounds of {@code elements})
*/
public ArrayIterator(final E[] elements, final int startIdx) {
this(elements, false, startIdx);
}
/**
* Construct a new instance.
*
* @param elements the elements to iterate over
* @param descending {@code true} to iterate in descending order, {@code false} otherwise
* @param startIdx the starting index (must be within the bounds of {@code elements})
*/
public ArrayIterator(final E[] elements, final boolean descending, final int startIdx) {
Assert.checkNotNullParam("elements", elements);
Assert.checkMinimumParameter("startIdx", 0, startIdx);
Assert.checkMaximumParameter("startIdx", elements.length, startIdx);
this.elements = elements;
this.descending = descending;
this.idx = startIdx;
}
// ListIterator methods
/**
* Determine if there are more elements to iterate over in the reverse direction of this iterator.
*
* @return {@code true} if there are more elements, {@code false} otherwise
*/
public boolean hasPrevious() {
return descending ? idx < elements.length : idx > 0;
}
/**
* Determine if there are more elements to iterate over in the direction of this iterator.
*
* @return {@code true} if there are more elements, {@code false} otherwise
*/
public boolean hasNext() {
return descending ? idx > 0 : idx < elements.length;
}
/**
* Get the next element in the reverse direction of this iterator.
*
* @return the next element
*/
public E previous() {
if (! hasPrevious()) throw new NoSuchElementException();
return elements[descending ? idx ++ : -- idx];
}
/**
* Get the next element in the direction of this iterator.
*
* @return the next element
*/
public E next() {
if (! hasNext()) throw new NoSuchElementException();
return elements[descending ? -- idx : idx ++];
}
/**
* Get the next index in the direction of this iterator.
*
* @return the next index
*/
public int nextIndex() {
return descending ? idx - 1 : idx;
}
/**
* Get the next index in the reverse direction of this iterator.
*
* @return the next index
*/
public int previousIndex() {
return descending ? idx : idx - 1;
}
// Unsupported stuff
/**
* Unsupported.
*/
public void remove() {
throw Assert.unsupported();
}
/**
* Unsupported.
*
* @param e ignored
*/
public void set(final E e) {
throw Assert.unsupported();
}
/**
* Unsupported.
*
* @param e ignored
*/
public void add(final E e) {
throw Assert.unsupported();
}
}