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/*
* Copyright (C) 2007-2020 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.Collection;
import java.util.NoSuchElementException;
import java.util.Set;
/** A simple, brute-force implementation of a set based on a backing array.
*
* The main purpose of this
* implementation is that of wrapping cleanly the brute-force approach to the storage of a very
* small number of items: just put them into an array and scan linearly to find an item.
*/
public class ARRAY_SET KEY_GENERIC extends ABSTRACT_SET KEY_GENERIC implements java.io.Serializable, Cloneable {
private static final long serialVersionUID = 1L;
/** The backing array (valid up to {@link #size}, excluded). */
private transient KEY_TYPE[] a;
/** The number of valid entries in {@link #a}. */
private int size;
/** Creates a new array set using the given backing array. The resulting set will have as many elements as the array.
*
*
It is responsibility of the caller that the elements of {@code a} are distinct.
*
* @param a the backing array.
*/
public ARRAY_SET(final KEY_TYPE[] a) {
this.a = a;
size = a.length;
}
/** Creates a new empty array set.
*/
public ARRAY_SET() { this.a = ARRAYS.EMPTY_ARRAY; }
/** Creates a new empty array set of given initial capacity.
*
* @param capacity the initial capacity.
*/
public ARRAY_SET(final int capacity) { this.a = new KEY_TYPE[capacity]; }
/** Creates a new array set copying the contents of a given collection.
* @param c a collection.
*/
public ARRAY_SET(COLLECTION KEY_GENERIC c) {
this(c.size ());
addAll(c);
}
/** Creates a new array set copying the contents of a given set.
* @param c a collection.
*/
public ARRAY_SET(final Collection c) {
this(c.size());
addAll(c);
}
/** Creates a new array set copying the contents of a given collection.
* @param c a collection.
*/
public ARRAY_SET(SET KEY_GENERIC c) {
this(c.size());
int i = 0;
for(KEY_TYPE x : c) {
a[i] = x;
i++;
}
size = i;
}
/** Creates a new array set copying the contents of a given set.
* @param c a collection.
*/
public ARRAY_SET(final Set c) {
this(c.size());
int i = 0;
for(KEY_GENERIC_CLASS x: c) {
a[i] = KEY_CLASS2TYPE(x);
i++;
}
size = i;
}
/** Creates a new array set using the given backing array and the given number of elements of the array.
*
*
It is responsibility of the caller that the first {@code size} elements of {@code a} are distinct.
*
* @param a the backing array.
* @param size the number of valid elements in {@code a}.
*/
public ARRAY_SET(final KEY_TYPE[] a, final int size) {
this.a = a;
this.size = size;
if (size > a.length) throw new IllegalArgumentException("The provided size (" + size + ") is larger than or equal to the array size (" + a.length + ")");
}
private int findKey(final KEY_TYPE o) {
for(int i = size; i-- != 0;) if (KEY_EQUALS(a[i], o)) return i;
return -1;
}
@Override
SUPPRESS_WARNINGS_KEY_UNCHECKED
public KEY_ITERATOR KEY_GENERIC iterator() {
return new KEY_ITERATOR KEY_GENERIC () {
int next = 0;
@Override
public boolean hasNext() { return next < size; }
@Override
public KEY_GENERIC_TYPE NEXT_KEY() {
if (! hasNext()) throw new NoSuchElementException();
return KEY_GENERIC_CAST a[next++];
}
@Override
public void remove() {
final int tail = size-- - next--;
System.arraycopy(a, next + 1, a, next, tail);
#if KEYS_REFERENCE
a[size] = null;
#endif
}
};
}
@Override
public boolean contains(final KEY_TYPE k) { return findKey(k) != -1; }
@Override
public int size() { return size; }
@Override
public boolean remove(final KEY_TYPE k) {
final int pos = findKey(k);
if (pos == -1) return false;
final int tail = size - pos - 1;
for(int i = 0; i < tail; i++) a[pos + i] = a[pos + i + 1];
size--;
#if KEYS_REFERENCE
a[size] = null;
#endif
return true;
}
@Override
public boolean add(final KEY_GENERIC_TYPE k) {
final int pos = findKey(k);
if (pos != -1) return false;
if (size == a.length) {
final KEY_TYPE[] b = new KEY_TYPE[size == 0 ? 2 : size * 2];
for(int i = size; i-- != 0;) b[i] = a[i];
a = b;
}
a[size++] = k;
return true;
}
@Override
public void clear() {
#if KEYS_REFERENCE
java.util.Arrays.fill(a, 0, size, null);
#endif
size = 0;
}
@Override
public boolean isEmpty() { return size == 0; }
/** Returns a deep copy of this set.
*
*
This method performs a deep copy of this array set; the data stored in the
* set, however, is not cloned. Note that this makes a difference only for object keys.
*
* @return a deep copy of this set.
*/
@Override
SUPPRESS_WARNINGS_KEY_UNCHECKED
public ARRAY_SET KEY_GENERIC clone() {
ARRAY_SET KEY_GENERIC c;
try {
c = (ARRAY_SET KEY_GENERIC)super.clone();
}
catch(CloneNotSupportedException cantHappen) {
throw new InternalError();
}
c.a = a.clone();
return c;
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
s.defaultWriteObject();
for(int i = 0; i < size; i++) s.WRITE_KEY(a[i]);
}
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
a = new KEY_TYPE[size];
for(int i = 0; i < size; i++) a[i] = s.READ_KEY();
}
}