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com.strobel.core.ReadOnlyList Maven / Gradle / Ivy
/*
* ReadOnlyList.java
*
* Copyright (c) 2012 Mike Strobel
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0.
* A copy of the license can be found in the License.html file at the root of this distribution.
* By using this source code in any fashion, you are agreeing to be bound by the terms of the
* Apache License, Version 2.0.
*
* You must not remove this notice, or any other, from this software.
*/
package com.strobel.core;
import com.strobel.annotations.NotNull;
import com.strobel.util.EmptyArrayCache;
import java.lang.reflect.Array;
import java.util.*;
/**
* @author Mike Strobel
*/
public class ReadOnlyList implements IReadOnlyList, List, RandomAccess {
private final static ReadOnlyList EMPTY = new ReadOnlyList();
private final static ReadOnlyCollectionIterator EMPTY_ITERATOR = new ReadOnlyCollectionIterator<>(EMPTY);
@SuppressWarnings("unchecked")
public static ReadOnlyList emptyList() {
return (ReadOnlyList)EMPTY;
}
private final int _offset;
private final int _length;
private final T[] _elements;
@SafeVarargs
@SuppressWarnings("unchecked")
public ReadOnlyList(final T... elements) {
VerifyArgument.notNull(elements, "elements");
_offset = 0;
_length = elements.length;
_elements = (T[])Arrays.copyOf(elements, elements.length, elements.getClass());
}
@SuppressWarnings("unchecked")
public ReadOnlyList(final Class elementType, final Collection elements) {
VerifyArgument.notNull(elementType, "elementType");
VerifyArgument.notNull(elements, "elements");
_offset = 0;
_length = elements.size();
_elements = elements.toArray((T[])Array.newInstance(elementType, _length));
}
@SuppressWarnings("unchecked")
public ReadOnlyList(final T[] elements, final int offset, final int length) {
VerifyArgument.notNull(elements, "elements");
_elements = (T[])Arrays.copyOf(elements, elements.length, elements.getClass());
subListRangeCheck(offset, offset + length, _elements.length);
_offset = offset;
_length = length;
}
protected ReadOnlyList newInstance() {
return new ReadOnlyList<>(_elements, _offset, _length);
}
private ReadOnlyList(final ReadOnlyList baseList, final int offset, final int length) {
VerifyArgument.notNull(baseList, "baseList");
final T[] elements = baseList._elements;
subListRangeCheck(offset, offset + length, elements.length);
_elements = elements;
_offset = offset;
_length = length;
}
protected final int getOffset() {
return _offset;
}
protected final T[] getElements() {
return _elements;
}
@Override
public final int size() {
return _length;
}
@Override
public final boolean isEmpty() {
return size() == 0;
}
@Override
public boolean containsAll(final Iterable c) {
VerifyArgument.notNull(c, "c");
for (final T element : c) {
if (!ArrayUtilities.contains(_elements, element)) {
return false;
}
}
return true;
}
@Override
public final boolean contains(final Object o) {
return indexOf(o) != -1;
}
@NotNull
@Override
@SuppressWarnings("unchecked")
public final Iterator iterator() {
if (isEmpty()) {
return (Iterator) EMPTY_ITERATOR;
}
return new ReadOnlyCollectionIterator(this);
}
@NotNull
@Override
@SuppressWarnings("unchecked")
public final T[] toArray() {
if (_length == 0) {
return EmptyArrayCache.fromArrayType(_elements.getClass());
}
return (T[])Arrays.copyOfRange(_elements, _offset, _offset + _length, _elements.getClass());
}
@NotNull
@Override
@SuppressWarnings({"unchecked", "SuspiciousSystemArraycopy"})
public final U[] toArray(@NotNull final U[] a) {
final int length = _length;
if (a.length < length) {
return (U[])Arrays.copyOfRange(_elements, _offset, _offset + _length, _elements.getClass());
}
System.arraycopy(_elements, _offset, a, 0, length);
if (a.length > length) {
a[length] = null;
}
return a;
}
@Override
public final boolean add(final T T) {
throw Error.unmodifiableCollection();
}
@Override
public final boolean remove(final Object o) {
throw Error.unmodifiableCollection();
}
@Override
public final boolean containsAll(@NotNull final Collection c) {
for (final Object o : c) {
if (!contains(o)) {
return false;
}
}
return true;
}
@Override
public final boolean addAll(@NotNull final Collection c) {
throw Error.unmodifiableCollection();
}
@Override
public final boolean addAll(final int index, @NotNull final Collection c) {
throw Error.unmodifiableCollection();
}
@Override
public final boolean removeAll(@NotNull final Collection c) {
throw Error.unmodifiableCollection();
}
@Override
public final boolean retainAll(@NotNull final Collection c) {
throw Error.unmodifiableCollection();
}
@Override
public final void clear() {
throw Error.unmodifiableCollection();
}
@Override
public final T get(final int index) {
return _elements[_offset + index];
}
@Override
public final T set(final int index, final T element) {
throw Error.unmodifiableCollection();
}
@Override
public final void add(final int index, final T element) {
throw Error.unmodifiableCollection();
}
@Override
public final T remove(final int index) {
throw Error.unmodifiableCollection();
}
@Override
public int hashCode() {
int hash = 0;
for (int i = _offset, n = _offset + _length; i < n ; i++) {
final T element = _elements[i];
if (element != null) {
hash = hash * 31 + element.hashCode();
}
}
return hash;
}
@Override
@SuppressWarnings("unchecked")
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof ReadOnlyList)) {
return false;
}
final ReadOnlyList other = (ReadOnlyList) obj;
return Arrays.equals(_elements, other._elements);
}
@Override
public final int indexOf(final Object o) {
final T[] elements = _elements;
final int start = _offset;
final int end = start + _length;
if (o == null) {
for (int i = start; i < end; i++) {
if (elements[i] == null) {
return i;
}
}
}
else {
for (int i = start; i < end; i++) {
if (o.equals(elements[i])) {
return i;
}
}
}
return -1;
}
@Override
public final int lastIndexOf(final Object o) {
final T[] elements = _elements;
final int start = _offset;
final int end = start + _length;
if (o == null) {
for (int i = end - 1; i >= start; i--) {
if (elements[i] == null) {
return i;
}
}
}
else {
for (int i = end - 1; i >= start; i--) {
if (o.equals(elements[i])) {
return i;
}
}
}
return -1;
}
@Override
public String toString() {
final Iterator it = iterator();
if (!it.hasNext()) {
return "[]";
}
final StringBuilder sb = new StringBuilder();
sb.append('[');
for (; ; ) {
final T e = it.next();
sb.append(e == this ? "(this Collection)" : e);
if (!it.hasNext()) {
return sb.append(']').toString();
}
sb.append(',').append(' ');
}
}
@NotNull
@Override
public final ListIterator listIterator() {
return new ReadOnlyCollectionIterator<>(this);
}
@NotNull
@Override
public final ListIterator listIterator(final int index) {
return new ReadOnlyCollectionIterator<>(this, index);
}
protected static void subListRangeCheck(final int fromIndex, final int toIndex, final int size) {
if (fromIndex < 0) {
throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
}
if (toIndex > size) {
throw new IndexOutOfBoundsException("toIndex = " + toIndex);
}
if (fromIndex > toIndex) {
throw new IllegalArgumentException("fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")");
}
}
@NotNull
@Override
public ReadOnlyList subList(final int fromIndex, final int toIndex) {
subListRangeCheck(fromIndex, toIndex, size());
return new ReadOnlyList<>(this, _offset + fromIndex, _offset + toIndex);
}
private static class ReadOnlyCollectionIterator implements ListIterator {
private final ReadOnlyList _list;
private int _position = -1;
ReadOnlyCollectionIterator(final ReadOnlyList list) {
this._list = list;
}
ReadOnlyCollectionIterator(final ReadOnlyList list, final int startPosition) {
if (startPosition < -1 || startPosition >= list.size()) {
throw new IllegalArgumentException();
}
_position = startPosition;
_list = list;
}
@Override
public final boolean hasNext() {
return _position + 1 < _list.size();
}
@Override
public final T next() {
if (!hasNext()) {
throw new IllegalStateException();
}
return _list.get(++_position);
}
@Override
public final boolean hasPrevious() {
return _position > 0;
}
@Override
public final T previous() {
if (!hasPrevious()) {
throw new IllegalStateException();
}
return _list.get(--_position);
}
@Override
public final int nextIndex() {
return _position + 1;
}
@Override
public final int previousIndex() {
return _position + 1;
}
@Override
public final void remove() {
throw Error.unmodifiableCollection();
}
@Override
public final void set(final T T) {
throw Error.unmodifiableCollection();
}
@Override
public final void add(@NotNull final T T) {
throw Error.unmodifiableCollection();
}
}
}
