/*
* Copyright (C) 2002-2017 Sebastiano Vigna
*
* 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 PACKAGE;
import java.util.Iterator;
import java.util.NoSuchElementException;
/** A class providing static methods and objects that do useful things with type-specific iterators.
*
* @see Iterator
*/
public final class BIG_LIST_ITERATORS {
private BIG_LIST_ITERATORS() {}
/** A class returning no elements and a type-specific big list iterator interface.
*
* <p>This class may be useful to implement your own in case you subclass
* a type-specific iterator.
*/
public static class EmptyBigListIterator KEY_GENERIC implements KEY_BIG_LIST_ITERATOR KEY_GENERIC, java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptyBigListIterator() {}
@Override
public boolean hasNext() { return false; }
@Override
public boolean hasPrevious() { return false; }
@Override
public KEY_GENERIC_TYPE NEXT_KEY() { throw new NoSuchElementException(); }
@Override
public KEY_GENERIC_TYPE PREV_KEY() { throw new NoSuchElementException(); }
@Override
public long nextIndex() { return 0; }
@Override
public long previousIndex() { return -1; }
@Override
public long skip(long n) { return 0; };
@Override
public long back(long n) { return 0; };
@Override
public Object clone() { return EMPTY_BIG_LIST_ITERATOR; }
private Object readResolve() { return EMPTY_BIG_LIST_ITERATOR; }
}
/** An empty iterator (immutable). It is serializable and cloneable.
*
* <p>The class of this objects represent an abstract empty iterator
* that can iterate as a type-specific (list) iterator.
*/
SUPPRESS_WARNINGS_KEY_RAWTYPES
public static final EmptyBigListIterator EMPTY_BIG_LIST_ITERATOR = new EmptyBigListIterator();
/** An iterator returning a single element. */
private static class SingletonBigListIterator KEY_GENERIC implements KEY_BIG_LIST_ITERATOR KEY_GENERIC {
private final KEY_GENERIC_TYPE element;
private int curr;
public SingletonBigListIterator(final KEY_GENERIC_TYPE element) {
this.element = element;
}
@Override
public boolean hasNext() { return curr == 0; }
@Override
public boolean hasPrevious() { return curr == 1; }
@Override
public KEY_GENERIC_TYPE NEXT_KEY() {
if (! hasNext()) throw new NoSuchElementException();
curr = 1;
return element;
}
@Override
public KEY_GENERIC_TYPE PREV_KEY() {
if (! hasPrevious()) throw new NoSuchElementException();
curr = 0;
return element;
}
@Override
public long nextIndex() {
return curr;
}
@Override
public long previousIndex() {
return curr - 1;
}
}
/** Returns an iterator that iterates just over the given element.
*
* @param element the only element to be returned by a type-specific list iterator.
* @return an iterator that iterates just over {@code element}.
*/
public static KEY_GENERIC KEY_BIG_LIST_ITERATOR KEY_GENERIC singleton(final KEY_GENERIC_TYPE element) {
return new SingletonBigListIterator KEY_GENERIC_DIAMOND(element);
}
/** An unmodifiable wrapper class for big list iterators. */
public static class UnmodifiableBigListIterator KEY_GENERIC implements KEY_BIG_LIST_ITERATOR KEY_GENERIC {
protected final KEY_BIG_LIST_ITERATOR KEY_GENERIC i;
public UnmodifiableBigListIterator(final KEY_BIG_LIST_ITERATOR KEY_GENERIC i) {
this.i = i;
}
@Override
public boolean hasNext() { return i.hasNext(); }
@Override
public boolean hasPrevious() { return i.hasPrevious(); }
@Override
public KEY_GENERIC_TYPE NEXT_KEY() { return i.NEXT_KEY(); }
@Override
public KEY_GENERIC_TYPE PREV_KEY() { return i.PREV_KEY(); }
@Override
public long nextIndex() { return i.nextIndex(); }
@Override
public long previousIndex() { return i.previousIndex(); }
}
/** Returns an unmodifiable list iterator backed by the specified list iterator.
*
* @param i the list iterator to be wrapped in an unmodifiable list iterator.
* @return an unmodifiable view of the specified list iterator.
*/
public static KEY_GENERIC KEY_BIG_LIST_ITERATOR KEY_GENERIC unmodifiable(final KEY_BIG_LIST_ITERATOR KEY_GENERIC i) { return new UnmodifiableBigListIterator KEY_GENERIC_DIAMOND(i); }
/** A class exposing a list iterator as a big-list iterator.. */
public static class BigListIteratorListIterator KEY_GENERIC implements KEY_BIG_LIST_ITERATOR KEY_GENERIC {
protected final KEY_LIST_ITERATOR KEY_GENERIC i;
protected BigListIteratorListIterator(final KEY_LIST_ITERATOR KEY_GENERIC i) {
this.i = i;
}
private int intDisplacement(long n) {
if (n < Integer.MIN_VALUE || n > Integer.MAX_VALUE) throw new IndexOutOfBoundsException("This big iterator is restricted to 32-bit displacements");
return (int)n;
}
@Override
public void set(KEY_GENERIC_TYPE ok) { i.set(ok); }
@Override
public void add(KEY_GENERIC_TYPE ok) { i.add(ok); }
@Override
public int back(int n) { return i.back(n); }
@Override
public long back(long n) { return i.back(intDisplacement(n)); }
@Override
public void remove() { i.remove(); }
@Override
public int skip(int n) { return i.skip(n); }
@Override
public long skip(long n) { return i.skip(intDisplacement(n)); }
@Override
public boolean hasNext() { return i.hasNext(); }
@Override
public boolean hasPrevious() { return i.hasPrevious(); }
@Override
public KEY_GENERIC_TYPE NEXT_KEY() { return i.NEXT_KEY(); }
@Override
public KEY_GENERIC_TYPE PREV_KEY() { return i.PREV_KEY(); }
@Override
public long nextIndex() { return i.nextIndex(); }
@Override
public long previousIndex() { return i.previousIndex(); }
}
/** Returns a big-list iterator backed by the specified list iterator.
*
* @param i the list iterator to adapted to the big-list-iterator interface.
* @return a big-list iterator backed by the specified list iterator.
*/
public static KEY_GENERIC KEY_BIG_LIST_ITERATOR KEY_GENERIC asBigListIterator(final KEY_LIST_ITERATOR KEY_GENERIC i) { return new BigListIteratorListIterator KEY_GENERIC_DIAMOND(i); }
}