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/*
* Copyright (C) 2002-2023 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 it.unimi.dsi.fastutil.objects;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.RandomAccess;
import java.util.NoSuchElementException;
import java.lang.reflect.Array;
import java.util.Comparator;
import java.util.stream.Collector;
import java.util.function.Consumer;
/**
* A type-specific array-based list; provides some additional methods that use polymorphism to avoid
* (un)boxing.
*
*
* This class implements a lightweight, fast, open, optimized, reuse-oriented version of array-based
* lists. Instances of this class represent a list with an array that is enlarged as needed when new
* entries are created (by increasing its current length by 50%), but is never made smaller
* (even on a {@link #clear()}). A family of {@linkplain #trim() trimming methods} lets you control
* the size of the backing array; this is particularly useful if you reuse instances of this class.
* Range checks are equivalent to those of {@link java.util}'s classes, but they are delayed as much
* as possible.
*
*
* The backing array is exposed by the {@link #elements()} method. If an instance of this class was
* created {@linkplain #wrap(Object[],int) by wrapping}, backing-array reallocations will be
* performed using reflection, so that {@link #elements()} can return an array of the same type of
* the original array: the comments about efficiency made in
* {@link it.unimi.dsi.fastutil.objects.ObjectArrays} apply here. Moreover, you must take into
* consideration that assignment to an array not of type {@code Object[]} is slower due to type
* checking.
*
*
* This class implements the bulk methods {@code removeElements()}, {@code addElements()} and
* {@code getElements()} using high-performance system calls (e.g.,
* {@link System#arraycopy(Object,int,Object,int,int) System.arraycopy()}) instead of expensive
* loops.
*
* @see java.util.ArrayList
*/
public class ObjectArrayList extends AbstractObjectList implements RandomAccess, Cloneable, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353131L;
/** The initial default capacity of an array list. */
public static final int DEFAULT_INITIAL_CAPACITY = 10;
/**
* Whether the backing array was passed to {@code wrap()}. In this case, we must reallocate with the
* same type of array.
*/
protected final boolean wrapped;
/** The backing array. */
protected transient K a[];
/** The current actual size of the list (never greater than the backing-array length). */
protected int size;
/**
* Ensures that the component type of the given array is the proper type. This is irrelevant for
* primitive types, so it will just do a trivial copy. But for Reference types, you can have a
* {@code String[]} masquerading as an {@code Object[]}, which is a case we need to prepare for
* because we let the user give an array to use directly with {@link #wrap}.
*/
@SuppressWarnings("unchecked")
private static final K[] copyArraySafe(K[] a, int length) {
if (length == 0) return (K[])ObjectArrays.EMPTY_ARRAY;
return (K[])java.util.Arrays.copyOf(a, length, Object[].class);
}
private static final K[] copyArrayFromSafe(ObjectArrayList l) {
return copyArraySafe(l.a, l.size);
}
/**
* Creates a new array list using a given array.
*
*
* This constructor is only meant to be used by the wrapping methods.
*
* @param a the array that will be used to back this array list.
*/
protected ObjectArrayList(final K a[], @SuppressWarnings("unused") boolean wrapped) {
this.a = a;
this.wrapped = wrapped;
}
@SuppressWarnings("unchecked")
private void initArrayFromCapacity(final int capacity) {
if (capacity < 0) throw new IllegalArgumentException("Initial capacity (" + capacity + ") is negative");
if (capacity == 0) a = (K[])ObjectArrays.EMPTY_ARRAY;
else a = (K[])new Object[capacity];
}
/**
* Creates a new array list with given capacity.
*
* @param capacity the initial capacity of the array list (may be 0).
*/
public ObjectArrayList(final int capacity) {
initArrayFromCapacity(capacity);
this.wrapped = false;
}
/** Creates a new array list with {@link #DEFAULT_INITIAL_CAPACITY} capacity. */
@SuppressWarnings("unchecked")
public ObjectArrayList() {
a = (K[])ObjectArrays.DEFAULT_EMPTY_ARRAY; // We delay allocation
wrapped = false;
}
/**
* Creates a new array list and fills it with a given collection.
*
* @param c a collection that will be used to fill the array list.
*/
public ObjectArrayList(final Collection c) {
if (c instanceof ObjectArrayList) {
a = copyArrayFromSafe((ObjectArrayList)c);
size = a.length;
} else {
initArrayFromCapacity(c.size());
if (c instanceof ObjectList) {
((ObjectList)c).getElements(0, a, 0, size = c.size());
} else {
size = ObjectIterators.unwrap(c.iterator(), a);
}
}
this.wrapped = false;
}
/**
* Creates a new array list and fills it with a given type-specific collection.
*
* @param c a type-specific collection that will be used to fill the array list.
*/
public ObjectArrayList(final ObjectCollection c) {
if (c instanceof ObjectArrayList) {
a = copyArrayFromSafe((ObjectArrayList)c);
size = a.length;
} else {
initArrayFromCapacity(c.size());
if (c instanceof ObjectList) {
((ObjectList)c).getElements(0, a, 0, size = c.size());
} else {
size = ObjectIterators.unwrap(c.iterator(), a);
}
}
this.wrapped = false;
}
/**
* Creates a new array list and fills it with a given type-specific list.
*
* @param l a type-specific list that will be used to fill the array list.
*/
public ObjectArrayList(final ObjectList l) {
if (l instanceof ObjectArrayList) {
a = copyArrayFromSafe((ObjectArrayList)l);
size = a.length;
} else {
initArrayFromCapacity(l.size());
l.getElements(0, a, 0, size = l.size());
}
this.wrapped = false;
}
/**
* Creates a new array list and fills it with the elements of a given array.
*
* @param a an array whose elements will be used to fill the array list.
*/
public ObjectArrayList(final K a[]) {
this(a, 0, a.length);
}
/**
* Creates a new array list and fills it with the elements of a given array.
*
* @param a an array whose elements will be used to fill the array list.
* @param offset the first element to use.
* @param length the number of elements to use.
*/
public ObjectArrayList(final K a[], final int offset, final int length) {
this(length);
System.arraycopy(a, offset, this.a, 0, length);
size = length;
}
/**
* Creates a new array list and fills it with the elements returned by an iterator..
*
* @param i an iterator whose returned elements will fill the array list.
*/
public ObjectArrayList(final Iterator i) {
this();
while (i.hasNext()) this.add((i.next()));
}
/**
* Creates a new array list and fills it with the elements returned by a type-specific iterator..
*
* @param i a type-specific iterator whose returned elements will fill the array list.
*/
public ObjectArrayList(final ObjectIterator i) {
this();
while (i.hasNext()) this.add(i.next());
}
/**
* Returns the backing array of this list.
*
*
* If this array list was created by wrapping a given array, it is guaranteed that the type of the
* returned array will be the same. Otherwise, the returned array will be of type {@link Object
* Object[]} (in spite of the declared return type).
*
*
* Warning: This behaviour may cause (unfathomable) run-time errors if a method
* expects an array actually of type {@code K[]}, but this methods returns an array of type
* {@link Object Object[]}.
*
* @return the backing array.
*/
public K[] elements() {
return a;
}
/**
* Wraps a given array into an array list of given size.
*
*
* Note it is guaranteed that the type of the array returned by {@link #elements()} will be the same
* (see the comments in the class documentation).
*
* @param a an array to wrap.
* @param length the length of the resulting array list.
* @return a new array list of the given size, wrapping the given array.
*/
public static ObjectArrayList wrap(final K a[], final int length) {
if (length > a.length) throw new IllegalArgumentException("The specified length (" + length + ") is greater than the array size (" + a.length + ")");
final ObjectArrayList l = new ObjectArrayList<>(a, true);
l.size = length;
return l;
}
/**
* Wraps a given array into an array list.
*
*
* Note it is guaranteed that the type of the array returned by {@link #elements()} will be the same
* (see the comments in the class documentation).
*
* @param a an array to wrap.
* @return a new array list wrapping the given array.
*/
public static ObjectArrayList wrap(final K a[]) {
return wrap(a, a.length);
}
/**
* Creates a new empty array list.
*
* @return a new empty array list.
*/
public static ObjectArrayList of() {
return new ObjectArrayList<>();
}
/**
* Creates an array list using an array of elements.
*
* @param init a the array the will become the new backing array of the array list.
* @return a new array list backed by the given array.
* @see #wrap
*/
@SafeVarargs
public static ObjectArrayList of(final K... init) {
return wrap(init);
}
// Collector wants a function that returns the collection being added to.
ObjectArrayList combine(ObjectArrayList toAddFrom) {
addAll(toAddFrom);
return this;
}
private static final Collector> TO_LIST_COLLECTOR = Collector.of(ObjectArrayList::new, ObjectArrayList::add, ObjectArrayList::combine);
/** Returns a {@link Collector} that collects a {@code Stream}'s elements into a new ArrayList. */
@SuppressWarnings({ "unchecked", "rawtypes" })
public static Collector> toList() {
return (Collector)TO_LIST_COLLECTOR;
}
/**
* Returns a {@link Collector} that collects a {@code Stream}'s elements into a new ArrayList,
* potentially pre-allocated to handle the given size.
*/
public static Collector> toListWithExpectedSize(int expectedSize) {
if (expectedSize <= DEFAULT_INITIAL_CAPACITY) {
// Already below default capacity. Just use all default construction instead of fiddling with
// atomics in SizeDecreasingSupplier
return toList();
}
return Collector.of(new ObjectCollections.SizeDecreasingSupplier>(expectedSize, (int size) -> size <= DEFAULT_INITIAL_CAPACITY ? new ObjectArrayList() : new ObjectArrayList(size)), ObjectArrayList::add, ObjectArrayList::combine);
}
/**
* Ensures that this array list can contain the given number of entries without resizing.
*
* @param capacity the new minimum capacity for this array list.
*/
@SuppressWarnings("unchecked")
public void ensureCapacity(final int capacity) {
if (capacity <= a.length || (a == ObjectArrays.DEFAULT_EMPTY_ARRAY && capacity <= DEFAULT_INITIAL_CAPACITY)) return;
if (wrapped) a = ObjectArrays.ensureCapacity(a, capacity, size);
else {
if (capacity > a.length) {
final Object t[] = new Object[capacity];
System.arraycopy(a, 0, t, 0, size);
a = (K[])t;
}
}
assert size <= a.length;
}
/**
* Grows this array list, ensuring that it can contain the given number of entries without resizing,
* and in case increasing the current capacity at least by a factor of 50%.
*
* @param capacity the new minimum capacity for this array list.
*/
@SuppressWarnings("unchecked")
private void grow(int capacity) {
if (capacity <= a.length) return;
if (a != ObjectArrays.DEFAULT_EMPTY_ARRAY) capacity = (int)Math.max(Math.min((long)a.length + (a.length >> 1), it.unimi.dsi.fastutil.Arrays.MAX_ARRAY_SIZE), capacity);
else if (capacity < DEFAULT_INITIAL_CAPACITY) capacity = DEFAULT_INITIAL_CAPACITY;
if (wrapped) a = ObjectArrays.forceCapacity(a, capacity, size);
else {
final Object t[] = new Object[capacity];
System.arraycopy(a, 0, t, 0, size);
a = (K[])t;
}
assert size <= a.length;
}
@Override
public void add(final int index, final K k) {
ensureIndex(index);
grow(size + 1);
if (index != size) System.arraycopy(a, index, a, index + 1, size - index);
a[index] = k;
size++;
assert size <= a.length;
}
@Override
public boolean add(final K k) {
grow(size + 1);
a[size++] = k;
assert size <= a.length;
return true;
}
@Override
public K get(final int index) {
if (index >= size) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than or equal to list size (" + size + ")");
return a[index];
}
@Override
public int indexOf(final Object k) {
for (int i = 0; i < size; i++) if (java.util.Objects.equals(k, a[i])) return i;
return -1;
}
@Override
public int lastIndexOf(final Object k) {
for (int i = size; i-- != 0;) if (java.util.Objects.equals(k, a[i])) return i;
return -1;
}
@Override
public K remove(final int index) {
if (index >= size) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than or equal to list size (" + size + ")");
final K old = a[index];
size--;
if (index != size) System.arraycopy(a, index + 1, a, index, size - index);
a[size] = null;
assert size <= a.length;
return old;
}
@Override
public boolean remove(final Object k) {
int index = indexOf(k);
if (index == -1) return false;
remove(index);
assert size <= a.length;
return true;
}
@Override
public K set(final int index, final K k) {
if (index >= size) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than or equal to list size (" + size + ")");
K old = a[index];
a[index] = k;
return old;
}
@Override
public void clear() {
Arrays.fill(a, 0, size, null);
size = 0;
assert size <= a.length;
}
@Override
public int size() {
return size;
}
@Override
public void size(final int size) {
if (size > a.length) a = ObjectArrays.forceCapacity(a, size, this.size);
if (size > this.size) Arrays.fill(a, this.size, size, (null));
else Arrays.fill(a, size, this.size, (null));
this.size = size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
/**
* Trims this array list so that the capacity is equal to the size.
*
* @see java.util.ArrayList#trimToSize()
*/
public void trim() {
trim(0);
}
/**
* Trims the backing array if it is too large.
*
* If the current array length is smaller than or equal to {@code n}, this method does nothing.
* Otherwise, it trims the array length to the maximum between {@code n} and {@link #size()}.
*
*
* This method is useful when reusing lists. {@linkplain #clear() Clearing a list} leaves the array
* length untouched. If you are reusing a list many times, you can call this method with a typical
* size to avoid keeping around a very large array just because of a few large transient lists.
*
* @param n the threshold for the trimming.
*/
@SuppressWarnings("unchecked")
public void trim(final int n) {
// TODO: use Arrays.trim() and preserve type only if necessary
if (n >= a.length || size == a.length) return;
final K t[] = (K[])new Object[Math.max(n, size)];
System.arraycopy(a, 0, t, 0, size);
a = t;
assert size <= a.length;
}
private class SubList extends AbstractObjectList.ObjectRandomAccessSubList {
private static final long serialVersionUID = -3185226345314976296L;
protected SubList(int from, int to) {
super(ObjectArrayList.this, from, to);
}
// Most of the inherited methods should be fine, but we can override a few of them for performance.
// Needed because we can't access the parent class' instance variables directly in a different
// instance of SubList.
private K[] getParentArray() {
return a;
}
@Override
public K get(int i) {
ensureRestrictedIndex(i);
return a[i + from];
}
private final class SubListIterator extends ObjectIterators.AbstractIndexBasedListIterator {
// We are using pos == 0 to be 0 relative to SubList.from (meaning you need to do a[from + i] when
// accessing array).
SubListIterator(int index) {
super(0, index);
}
@Override
protected final K get(int i) {
return a[from + i];
}
@Override
protected final void add(int i, K k) {
SubList.this.add(i, k);
}
@Override
protected final void set(int i, K k) {
SubList.this.set(i, k);
}
@Override
protected final void remove(int i) {
SubList.this.remove(i);
}
@Override
protected final int getMaxPos() {
return to - from;
}
@Override
public K next() {
if (!hasNext()) throw new NoSuchElementException();
return a[from + (lastReturned = pos++)];
}
@Override
public K previous() {
if (!hasPrevious()) throw new NoSuchElementException();
return a[from + (lastReturned = --pos)];
}
@Override
public void forEachRemaining(final Consumer action) {
final int max = to - from;
while (pos < max) {
action.accept(a[from + (lastReturned = pos++)]);
}
}
}
@Override
public ObjectListIterator listIterator(int index) {
return new SubListIterator(index);
}
private final class SubListSpliterator extends ObjectSpliterators.LateBindingSizeIndexBasedSpliterator {
// We are using pos == 0 to be 0 relative to real array 0
SubListSpliterator() {
super(from);
}
private SubListSpliterator(int pos, int maxPos) {
super(pos, maxPos);
}
@Override
protected final int getMaxPosFromBackingStore() {
return to;
}
@Override
protected final K get(int i) {
return a[i];
}
@Override
protected final SubListSpliterator makeForSplit(int pos, int maxPos) {
return new SubListSpliterator(pos, maxPos);
}
@Override
public boolean tryAdvance(final Consumer action) {
if (pos >= getMaxPos()) return false;
action.accept(a[pos++]);
return true;
}
@Override
public void forEachRemaining(final Consumer action) {
final int max = getMaxPos();
while (pos < max) {
action.accept(a[pos++]);
}
}
}
@Override
public ObjectSpliterator spliterator() {
return new SubListSpliterator();
}
boolean contentsEquals(K[] otherA, int otherAFrom, int otherATo) {
if (a == otherA && from == otherAFrom && to == otherATo) return true;
if (otherATo - otherAFrom != size()) {
return false;
}
int pos = from, otherPos = otherAFrom;
// We have already assured that the two ranges are the same size, so we only need to check one
// bound.
// TODO When minimum version of Java becomes Java 9, use the Arrays.equals which takes bounds, which
// is vectorized.
// Make sure to split out the reference equality case when you do this.
while (pos < to) if (!java.util.Objects.equals(a[pos++], otherA[otherPos++])) return false;
return true;
}
@Override
public boolean equals(Object o) {
if (o == this) return true;
if (o == null) return false;
if (!(o instanceof java.util.List)) return false;
if (o instanceof ObjectArrayList) {
@SuppressWarnings("unchecked")
ObjectArrayList other = (ObjectArrayList)o;
return contentsEquals(other.a, 0, other.size());
}
if (o instanceof ObjectArrayList.SubList) {
@SuppressWarnings("unchecked")
ObjectArrayList.SubList other = (ObjectArrayList.SubList)o;
return contentsEquals(other.getParentArray(), other.from, other.to);
}
return super.equals(o);
}
@SuppressWarnings("unchecked")
int contentsCompareTo(K[] otherA, int otherAFrom, int otherATo) {
// TODO When minimum version of Java becomes Java 9, use Arrays.compare, which vectorizes.
K e1, e2;
int r, i, j;
for (i = from, j = otherAFrom; i < to && i < otherATo; i++, j++) {
e1 = a[i];
e2 = otherA[j];
if ((r = (((Comparable)(e1)).compareTo(e2))) != 0) return r;
}
return i < otherATo ? -1 : (i < to ? 1 : 0);
}
@SuppressWarnings("unchecked")
@Override
public int compareTo(final java.util.List l) {
if (l instanceof ObjectArrayList) {
@SuppressWarnings("unchecked")
ObjectArrayList other = (ObjectArrayList)l;
return contentsCompareTo(other.a, 0, other.size());
}
if (l instanceof ObjectArrayList.SubList) {
@SuppressWarnings("unchecked")
ObjectArrayList.SubList other = (ObjectArrayList.SubList)l;
return contentsCompareTo(other.getParentArray(), other.from, other.to);
}
return super.compareTo(l);
}
// We don't override subList as we want AbstractList's "sub-sublist" nesting handling,
// which would be tricky to do here.
// TODO Do override it so array access isn't sent through N indirections.
// This will likely mean making this class static.
}
@Override
public ObjectList subList(int from, int to) {
if (from == 0 && to == size()) return this;
ensureIndex(from);
ensureIndex(to);
if (from > to) throw new IndexOutOfBoundsException("Start index (" + from + ") is greater than end index (" + to + ")");
return new SubList(from, to);
}
/**
* Copies element of this type-specific list into the given array using optimized system calls.
*
* @param from the start index (inclusive).
* @param a the destination array.
* @param offset the offset into the destination array where to store the first element copied.
* @param length the number of elements to be copied.
*/
@Override
public void getElements(final int from, final Object[] a, final int offset, final int length) {
ObjectArrays.ensureOffsetLength(a, offset, length);
System.arraycopy(this.a, from, a, offset, length);
}
/**
* Removes elements of this type-specific list using optimized system calls.
*
* @param from the start index (inclusive).
* @param to the end index (exclusive).
*/
@Override
public void removeElements(final int from, final int to) {
it.unimi.dsi.fastutil.Arrays.ensureFromTo(size, from, to);
System.arraycopy(a, to, a, from, size - to);
size -= (to - from);
int i = to - from;
while (i-- != 0) a[size + i] = null;
}
/**
* Adds elements to this type-specific list using optimized system calls.
*
* @param index the index at which to add elements.
* @param a the array containing the elements.
* @param offset the offset of the first element to add.
* @param length the number of elements to add.
*/
@Override
public void addElements(final int index, final K a[], final int offset, final int length) {
ensureIndex(index);
ObjectArrays.ensureOffsetLength(a, offset, length);
grow(size + length);
System.arraycopy(this.a, index, this.a, index + length, size - index);
System.arraycopy(a, offset, this.a, index, length);
size += length;
}
/**
* Sets elements to this type-specific list using optimized system calls.
*
* @param index the index at which to start setting elements.
* @param a the array containing the elements.
* @param offset the offset of the first element to add.
* @param length the number of elements to add.
*/
@Override
public void setElements(final int index, final K a[], final int offset, final int length) {
ensureIndex(index);
ObjectArrays.ensureOffsetLength(a, offset, length);
if (index + length > size) throw new IndexOutOfBoundsException("End index (" + (index + length) + ") is greater than list size (" + size + ")");
System.arraycopy(a, offset, this.a, index, length);
}
@Override
public void forEach(final Consumer action) {
for (int i = 0; i < size; ++i) {
action.accept(a[i]);
}
}
@Override
public boolean addAll(int index, final Collection c) {
if (c instanceof ObjectList) {
return addAll(index, (ObjectList)c);
}
ensureIndex(index);
int n = c.size();
if (n == 0) return false;
grow(size + n);
System.arraycopy(a, index, a, index + n, size - index);
final Iterator i = c.iterator();
size += n;
while (n-- != 0) a[index++] = i.next();
assert size <= a.length;
return true;
}
@Override
public boolean addAll(final int index, final ObjectList l) {
ensureIndex(index);
final int n = l.size();
if (n == 0) return false;
grow(size + n);
System.arraycopy(a, index, a, index + n, size - index);
l.getElements(0, a, index, n);
size += n;
assert size <= a.length;
return true;
}
@Override
public boolean removeAll(final Collection c) {
final Object[] a = this.a;
int j = 0;
for (int i = 0; i < size; i++) if (!c.contains(a[i])) a[j++] = a[i];
Arrays.fill(a, j, size, null);
final boolean modified = size != j;
size = j;
return modified;
}
@Override
public Object[] toArray() {
final int size = size();
// A subtle part of the spec says the returned array must be Object[] exactly.
if (size == 0) return it.unimi.dsi.fastutil.objects.ObjectArrays.EMPTY_ARRAY;
return Arrays.copyOf(a, size, Object[].class);
}
@SuppressWarnings("unchecked")
@Override
public T[] toArray(T[] a) {
if (a == null) {
a = (T[])new Object[size()];
} else if (a.length < size()) {
a = (T[])Array.newInstance(a.getClass().getComponentType(), size());
}
System.arraycopy(this.a, 0, a, 0, size());
if (a.length > size()) {
a[size()] = null;
}
return a;
}
@Override
public ObjectListIterator listIterator(final int index) {
ensureIndex(index);
return new ObjectListIterator() {
int pos = index, last = -1;
@Override
public boolean hasNext() {
return pos < size;
}
@Override
public boolean hasPrevious() {
return pos > 0;
}
@Override
public K next() {
if (!hasNext()) throw new NoSuchElementException();
return a[last = pos++];
}
@Override
public K previous() {
if (!hasPrevious()) throw new NoSuchElementException();
return a[last = --pos];
}
@Override
public int nextIndex() {
return pos;
}
@Override
public int previousIndex() {
return pos - 1;
}
@Override
public void add(K k) {
ObjectArrayList.this.add(pos++, k);
last = -1;
}
@Override
public void set(K k) {
if (last == -1) throw new IllegalStateException();
ObjectArrayList.this.set(last, k);
}
@Override
public void remove() {
if (last == -1) throw new IllegalStateException();
ObjectArrayList.this.remove(last);
/* If the last operation was a next(), we are removing an element *before* us, and we must decrease pos correspondingly. */
if (last < pos) pos--;
last = -1;
}
@Override
public void forEachRemaining(final Consumer action) {
while (pos < size) {
action.accept(a[last = pos++]);
}
}
@Override
public int back(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
final int remaining = size - pos;
if (n < remaining) {
pos -= n;
} else {
n = remaining;
pos = 0;
}
last = pos;
return n;
}
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
final int remaining = size - pos;
if (n < remaining) {
pos += n;
} else {
n = remaining;
pos = size;
}
last = pos - 1;
return n;
}
};
}
// If you update this, you will probably want to update ArraySet as well
private final class Spliterator implements ObjectSpliterator {
// Until we split, we will track the size of the list.
// Once we split, then we stop updating on structural modifications.
// Aka, size is late-binding.
boolean hasSplit = false;
int pos, max;
public Spliterator() {
this(0, ObjectArrayList.this.size, false);
}
private Spliterator(int pos, int max, boolean hasSplit) {
assert pos <= max : "pos " + pos + " must be <= max " + max;
this.pos = pos;
this.max = max;
this.hasSplit = hasSplit;
}
private int getWorkingMax() {
return hasSplit ? max : ObjectArrayList.this.size;
}
@Override
public int characteristics() {
return ObjectSpliterators.LIST_SPLITERATOR_CHARACTERISTICS;
}
@Override
public long estimateSize() {
return getWorkingMax() - pos;
}
@Override
public boolean tryAdvance(final Consumer action) {
if (pos >= getWorkingMax()) return false;
action.accept(a[pos++]);
return true;
}
@Override
public void forEachRemaining(final Consumer action) {
for (final int max = getWorkingMax(); pos < max; ++pos) {
action.accept(a[pos]);
}
}
@Override
public long skip(long n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
final int max = getWorkingMax();
if (pos >= max) return 0;
final int remaining = max - pos;
if (n < remaining) {
pos = it.unimi.dsi.fastutil.SafeMath.safeLongToInt(pos + n);
return n;
}
n = remaining;
pos = max;
return n;
}
@Override
public ObjectSpliterator trySplit() {
final int max = getWorkingMax();
int retLen = (max - pos) >> 1;
if (retLen <= 1) return null;
// Update instance max with the last seen list size (if needed) before continuing
this.max = max;
int myNewPos = pos + retLen;
int retMax = myNewPos;
int oldPos = pos;
this.pos = myNewPos;
this.hasSplit = true;
return new Spliterator(oldPos, retMax, true);
}
}
/**
* {@inheritDoc}
*
*
* The returned spliterator is late-binding; it will track structural changes after the current
* index, up until the first {@link java.util.Spliterator#trySplit() trySplit()}, at which point the
* maximum index will be fixed.
* Structural changes before the current index or after the first
* {@link java.util.Spliterator#trySplit() trySplit()} will result in unspecified behavior.
*/
@Override
public ObjectSpliterator spliterator() {
// If it wasn't for the possibility of the list being expanded or shrunk,
// we could return SPLITERATORS.wrap(a, 0, size).
return new Spliterator();
}
@SuppressWarnings("unchecked")
@Override
public void sort(final Comparator comp) {
if (comp == null) {
ObjectArrays.stableSort(a, 0, size);
} else {
ObjectArrays.stableSort(a, 0, size, comp);
}
}
@Override
public void unstableSort(final Comparator comp) {
if (comp == null) {
ObjectArrays.unstableSort(a, 0, size);
} else {
ObjectArrays.unstableSort(a, 0, size, comp);
}
}
@Override
@SuppressWarnings("unchecked")
public ObjectArrayList clone() {
ObjectArrayList cloned = null;
// Test for fastpath we can do if exactly an ArrayList
if (getClass() == ObjectArrayList.class) {
// Preserve backwards compatibility and make new list have Object[] even if it was wrapped from some
// subclass.
cloned = new ObjectArrayList<>(copyArraySafe(a, size), false);
cloned.size = size;
} else {
try {
cloned = (ObjectArrayList)super.clone();
} catch (CloneNotSupportedException err) {
// Can't happen
throw new InternalError(err);
}
// Preserve backwards compatibility and make new list have Object[] even if it was wrapped from some
// subclass.
cloned.a = copyArraySafe(a, size);
// We can't clear cloned.wrapped because it is final.
}
return cloned;
}
/**
* Compares this type-specific array list to another one.
*
* @apiNote This method exists only for sake of efficiency. The implementation inherited from the
* abstract implementation would already work.
*
* @param l a type-specific array list.
* @return true if the argument contains the same elements of this type-specific array list.
*/
public boolean equals(final ObjectArrayList l) {
// TODO When minimum version of Java becomes Java 9, use the Arrays.equals which takes bounds, which
// is vectorized.
if (l == this) return true;
int s = size();
if (s != l.size()) return false;
final K[] a1 = a;
final K[] a2 = l.a;
if (a1 == a2 && s == l.size()) return true;
while (s-- != 0) if (!java.util.Objects.equals(a1[s], a2[s])) return false;
return true;
}
@SuppressWarnings({ "unchecked", "unlikely-arg-type" })
@Override
public boolean equals(final Object o) {
if (o == this) return true;
if (o == null) return false;
if (!(o instanceof java.util.List)) return false;
if (o instanceof ObjectArrayList) {
// Safe cast because we are only going to take elements from other list, never give them
return equals((ObjectArrayList)o);
}
if (o instanceof ObjectArrayList.SubList) {
// Safe cast because we are only going to take elements from other list, never give them
// Sublist has an optimized sub-array based comparison, reuse that.
return ((ObjectArrayList.SubList)o).equals(this);
}
return super.equals(o);
}
/**
* Compares this array list to another array list.
*
* @apiNote This method exists only for sake of efficiency. The implementation inherited from the
* abstract implementation would already work.
*
* @param l an array list.
* @return a negative integer, zero, or a positive integer as this list is lexicographically less
* than, equal to, or greater than the argument.
*/
@SuppressWarnings("unchecked")
public int compareTo(final ObjectArrayList l) {
final int s1 = size(), s2 = l.size();
final K a1[] = a, a2[] = l.a;
// TODO When minimum version of Java becomes Java 9, use Arrays.compare, which vectorizes.
K e1, e2;
int r, i;
for (i = 0; i < s1 && i < s2; i++) {
e1 = a1[i];
e2 = a2[i];
if ((r = (((Comparable)(e1)).compareTo(e2))) != 0) return r;
}
return i < s2 ? -1 : (i < s1 ? 1 : 0);
}
@SuppressWarnings("unchecked")
@Override
public int compareTo(final java.util.List l) {
if (l instanceof ObjectArrayList) {
return compareTo((ObjectArrayList)l);
}
if (l instanceof ObjectArrayList.SubList) {
// Must negate because we are inverting the order of the comparison.
return -((ObjectArrayList.SubList)l).compareTo(this);
}
return super.compareTo(l);
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
s.defaultWriteObject();
for (int i = 0; i < size; i++) s.writeObject(a[i]);
}
@SuppressWarnings("unchecked")
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
a = (K[])new Object[size];
for (int i = 0; i < size; i++) a[i] = (K)s.readObject();
}
}