com.xenoamess.commons.primitive.iterators.LongRandomAccessSpliterator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of commonx Show documentation
Show all versions of commonx Show documentation
Commonx, a package of Java utility classes for common use.
/*
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.xenoamess.commons.primitive.iterators;
import com.xenoamess.commons.primitive.Primitive;
import com.xenoamess.commons.primitive.collections.lists.AbstractLongList;
import com.xenoamess.commons.primitive.collections.lists.LongList;
import com.xenoamess.commons.primitive.functions.LongConsumer;
import java.util.ConcurrentModificationException;
import java.util.Objects;
import java.util.RandomAccess;
import java.util.Spliterator;
import java.util.function.Consumer;
/**
* An index-based split-by-two, lazily initialized Spliterator covering
* a List that access elements via {@link java.util.List#get}.
*
* If access results in an IndexOutOfBoundsException then a
* ConcurrentModificationException is thrown instead (since the list has
* been structurally modified while traversing).
*
* If the List is an instance of AbstractList then concurrent modification
* checking is performed using the AbstractList's modCount field.
*
* @author XenoAmess
* @version 0.8.0
* @see LongSpliterator
*/
public class LongRandomAccessSpliterator implements LongSpliterator, Primitive {
private final LongList list;
private int index; // current index, modified on advance/split
private int fence; // -1 until used; then one past last index
// The following fields are valid if covering an AbstractList
private final AbstractLongList alist;
private int expectedModCount; // initialized when fence set
/**
*
Constructor for LongRandomAccessSpliterator.
*
* @param list a {@link com.xenoamess.commons.primitive.collections.lists.LongList} object.
*/
public LongRandomAccessSpliterator(LongList list) {
assert list instanceof RandomAccess;
this.list = list;
this.index = 0;
this.fence = -1;
this.alist = list instanceof AbstractLongList ? (AbstractLongList) list : null;
this.expectedModCount = alist != null ? alist.modCount : 0;
}
/**
* Create new spliterator covering the given range
*
* @param parent a {@link com.xenoamess.commons.primitive.iterators.LongRandomAccessSpliterator} object.
* @param origin a int.
* @param fence a int.
*/
public LongRandomAccessSpliterator(LongRandomAccessSpliterator parent,
int origin, int fence) {
this.list = parent.list;
this.index = origin;
this.fence = fence;
this.alist = parent.alist;
this.expectedModCount = parent.expectedModCount;
}
private int getFence() { // initialize fence to size on first use
int hi;
LongList lst = list;
if ((hi = fence) < 0) {
if (alist != null) {
expectedModCount = alist.modCount;
}
hi = fence = lst.size();
}
return hi;
}
/**
* {@inheritDoc}
*/
@Override
public LongSpliterator trySplit() {
int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
return (lo >= mid) ? null : // divide range in half unless too small
new LongRandomAccessSpliterator(this, lo, index = mid);
}
/**
* {@inheritDoc}
*/
@Override
public boolean tryAdvance(Consumer action) {
if (action == null) {
throw new NullPointerException();
}
int hi = getFence(), i = index;
if (i < hi) {
index = i + 1;
if (action instanceof LongConsumer) {
((LongConsumer) action).acceptPrimitive(getPrimitive(list, i));
} else {
action.accept(getPrimitive(list, i));
}
checkAbstractListModCount(alist, expectedModCount);
return true;
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public void forEachRemaining(Consumer action) {
Objects.requireNonNull(action);
LongList lst = list;
int hi = getFence();
int i = index;
index = hi;
if (action instanceof LongConsumer) {
LongConsumer actionLongConsumer = (LongConsumer) action;
for (; i < hi; i++) {
actionLongConsumer.acceptPrimitive(getPrimitive(lst, i));
}
} else {
for (; i < hi; i++) {
action.accept(getPrimitive(lst, i));
}
}
checkAbstractListModCount(alist, expectedModCount);
}
/**
* {@inheritDoc}
*/
@Override
public long estimateSize() {
return (long) (getFence() - index);
}
/**
* {@inheritDoc}
*/
@Override
public int characteristics() {
return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
}
private static long getPrimitive(LongList list, int i) {
try {
return list.getPrimitive(i);
} catch (IndexOutOfBoundsException ex) {
throw new ConcurrentModificationException();
}
}
static void checkAbstractListModCount(AbstractLongList alist, int expectedModCount) {
if (alist != null && alist.modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
}