it.unimi.dsi.fastutil.bytes.Byte2ReferenceArrayMap Maven / Gradle / Ivy
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/*
* Copyright (C) 2007-2017 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 it.unimi.dsi.fastutil.bytes;
import java.util.Map;
import java.util.NoSuchElementException;
import it.unimi.dsi.fastutil.objects.AbstractObjectSet;
import it.unimi.dsi.fastutil.objects.ObjectIterator;
import it.unimi.dsi.fastutil.objects.ReferenceCollection;
import it.unimi.dsi.fastutil.objects.AbstractReferenceCollection;
import it.unimi.dsi.fastutil.objects.ObjectArrays;
/**
* A simple, brute-force implementation of a map based on two parallel backing
* arrays.
*
*
* The main purpose of this implementation is that of wrapping cleanly the
* brute-force approach to the storage of a very small number of pairs: just put
* them into two parallel arrays and scan linearly to find an item.
*/
public class Byte2ReferenceArrayMap extends AbstractByte2ReferenceMap implements java.io.Serializable, Cloneable {
private static final long serialVersionUID = 1L;
/** The keys (valid up to {@link #size}, excluded). */
private transient byte[] key;
/** The values (parallel to {@link #key}). */
private transient Object[] value;
/** The number of valid entries in {@link #key} and {@link #value}. */
private int size;
/**
* Creates a new empty array map with given key and value backing arrays. The
* resulting map will have as many entries as the given arrays.
*
*
* It is responsibility of the caller that the elements of {@code key} are
* distinct.
*
* @param key
* the key array.
* @param value
* the value array (it must have the same length as
* {@code key}).
*/
public Byte2ReferenceArrayMap(final byte[] key, final Object[] value) {
this.key = key;
this.value = value;
size = key.length;
if (key.length != value.length)
throw new IllegalArgumentException(
"Keys and values have different lengths (" + key.length + ", " + value.length + ")");
}
/**
* Creates a new empty array map.
*/
public Byte2ReferenceArrayMap() {
this.key = ByteArrays.EMPTY_ARRAY;
this.value = ObjectArrays.EMPTY_ARRAY;
}
/**
* Creates a new empty array map of given capacity.
*
* @param capacity
* the initial capacity.
*/
public Byte2ReferenceArrayMap(final int capacity) {
this.key = new byte[capacity];
this.value = new Object[capacity];
}
/**
* Creates a new empty array map copying the entries of a given map.
*
* @param m
* a map.
*/
public Byte2ReferenceArrayMap(final Byte2ReferenceMap m) {
this(m.size());
putAll(m);
}
/**
* Creates a new empty array map copying the entries of a given map.
*
* @param m
* a map.
*/
public Byte2ReferenceArrayMap(final Map m) {
this(m.size());
putAll(m);
}
/**
* Creates a new array map with given key and value backing arrays, using the
* given number of elements.
*
*
* It is responsibility of the caller that the first {@code size} elements of
* {@code key} are distinct.
*
* @param key
* the key array.
* @param value
* the value array (it must have the same length as
* {@code key}).
* @param size
* the number of valid elements in {@code key} and {@code value}.
*/
public Byte2ReferenceArrayMap(final byte[] key, final Object[] value, final int size) {
this.key = key;
this.value = value;
this.size = size;
if (key.length != value.length)
throw new IllegalArgumentException(
"Keys and values have different lengths (" + key.length + ", " + value.length + ")");
if (size > key.length)
throw new IllegalArgumentException("The provided size (" + size
+ ") is larger than or equal to the backing-arrays size (" + key.length + ")");
}
private final class EntrySet extends AbstractObjectSet> implements FastEntrySet {
@Override
public ObjectIterator> iterator() {
return new ObjectIterator>() {
int curr = -1, next = 0;
@Override
public boolean hasNext() {
return next < size;
}
@Override
@SuppressWarnings("unchecked")
public Entry next() {
if (!hasNext())
throw new NoSuchElementException();
return new AbstractByte2ReferenceMap.BasicEntry<>(key[curr = next], (V) value[next++]);
}
@Override
public void remove() {
if (curr == -1)
throw new IllegalStateException();
curr = -1;
final int tail = size-- - next--;
System.arraycopy(key, next + 1, key, next, tail);
System.arraycopy(value, next + 1, value, next, tail);
value[size] = null;
}
};
}
@Override
public ObjectIterator> fastIterator() {
return new ObjectIterator>() {
int next = 0, curr = -1;
final BasicEntry entry = new BasicEntry<>();
@Override
public boolean hasNext() {
return next < size;
}
@Override
@SuppressWarnings("unchecked")
public Entry next() {
if (!hasNext())
throw new NoSuchElementException();
entry.key = key[curr = next];
entry.value = (V) value[next++];
return entry;
}
@Override
public void remove() {
if (curr == -1)
throw new IllegalStateException();
curr = -1;
final int tail = size-- - next--;
System.arraycopy(key, next + 1, key, next, tail);
System.arraycopy(value, next + 1, value, next, tail);
value[size] = null;
}
};
}
@Override
public int size() {
return size;
}
@Override
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
final Map.Entry e = (Map.Entry) o;
if (e.getKey() == null || !(e.getKey() instanceof Byte))
return false;
final byte k = ((Byte) (e.getKey())).byteValue();
return Byte2ReferenceArrayMap.this.containsKey(k)
&& ((Byte2ReferenceArrayMap.this.get(k)) == ((e.getValue())));
}
@Override
@SuppressWarnings("unchecked")
public boolean remove(final Object o) {
if (!(o instanceof Map.Entry))
return false;
final Map.Entry e = (Map.Entry) o;
if (e.getKey() == null || !(e.getKey() instanceof Byte))
return false;
final byte k = ((Byte) (e.getKey())).byteValue();
final V v = ((V) e.getValue());
final int oldPos = Byte2ReferenceArrayMap.this.findKey(k);
if (oldPos == -1 || !((v) == (Byte2ReferenceArrayMap.this.value[oldPos])))
return false;
final int tail = size - oldPos - 1;
System.arraycopy(Byte2ReferenceArrayMap.this.key, oldPos + 1, Byte2ReferenceArrayMap.this.key, oldPos,
tail);
System.arraycopy(Byte2ReferenceArrayMap.this.value, oldPos + 1, Byte2ReferenceArrayMap.this.value, oldPos,
tail);
Byte2ReferenceArrayMap.this.size--;
Byte2ReferenceArrayMap.this.value[size] = null;
return true;
}
}
@Override
public FastEntrySet byte2ReferenceEntrySet() {
return new EntrySet();
}
private int findKey(final byte k) {
final byte[] key = this.key;
for (int i = size; i-- != 0;)
if (((key[i]) == (k)))
return i;
return -1;
}
@Override
@SuppressWarnings("unchecked")
public V get(final byte k) {
final byte[] key = this.key;
for (int i = size; i-- != 0;)
if (((key[i]) == (k)))
return (V) value[i];
return defRetValue;
}
@Override
public int size() {
return size;
}
@Override
public void clear() {
for (int i = size; i-- != 0;) {
value[i] = null;
}
size = 0;
}
@Override
public boolean containsKey(final byte k) {
return findKey(k) != -1;
}
@Override
public boolean containsValue(Object v) {
for (int i = size; i-- != 0;)
if (((value[i]) == (v)))
return true;
return false;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
@SuppressWarnings("unchecked")
public V put(byte k, V v) {
final int oldKey = findKey(k);
if (oldKey != -1) {
final V oldValue = (V) value[oldKey];
value[oldKey] = v;
return oldValue;
}
if (size == key.length) {
final byte[] newKey = new byte[size == 0 ? 2 : size * 2];
final Object[] newValue = new Object[size == 0 ? 2 : size * 2];
for (int i = size; i-- != 0;) {
newKey[i] = key[i];
newValue[i] = value[i];
}
key = newKey;
value = newValue;
}
key[size] = k;
value[size] = v;
size++;
return defRetValue;
}
@Override
@SuppressWarnings("unchecked")
public V remove(final byte k) {
final int oldPos = findKey(k);
if (oldPos == -1)
return defRetValue;
final V oldValue = (V) value[oldPos];
final int tail = size - oldPos - 1;
System.arraycopy(key, oldPos + 1, key, oldPos, tail);
System.arraycopy(value, oldPos + 1, value, oldPos, tail);
size--;
value[size] = null;
return oldValue;
}
@Override
public ByteSet keySet() {
return new AbstractByteSet() {
@Override
public boolean contains(final byte k) {
return findKey(k) != -1;
}
@Override
public boolean remove(final byte k) {
final int oldPos = findKey(k);
if (oldPos == -1)
return false;
final int tail = size - oldPos - 1;
System.arraycopy(key, oldPos + 1, key, oldPos, tail);
System.arraycopy(value, oldPos + 1, value, oldPos, tail);
size--;
return true;
}
@Override
public ByteIterator iterator() {
return new ByteIterator() {
int pos = 0;
@Override
public boolean hasNext() {
return pos < size;
}
@Override
public byte nextByte() {
if (!hasNext())
throw new NoSuchElementException();
return key[pos++];
}
@Override
public void remove() {
if (pos == 0)
throw new IllegalStateException();
final int tail = size - pos;
System.arraycopy(key, pos, key, pos - 1, tail);
System.arraycopy(value, pos, value, pos - 1, tail);
size--;
}
};
}
@Override
public int size() {
return size;
}
@Override
public void clear() {
Byte2ReferenceArrayMap.this.clear();
}
};
}
@Override
public ReferenceCollection values() {
return new AbstractReferenceCollection() {
@Override
public boolean contains(final Object v) {
return containsValue(v);
}
@Override
public it.unimi.dsi.fastutil.objects.ObjectIterator iterator() {
return new it.unimi.dsi.fastutil.objects.ObjectIterator() {
int pos = 0;
@Override
public boolean hasNext() {
return pos < size;
}
@Override
@SuppressWarnings("unchecked")
public V next() {
if (!hasNext())
throw new NoSuchElementException();
return (V) value[pos++];
}
@Override
public void remove() {
if (pos == 0)
throw new IllegalStateException();
final int tail = size - pos;
System.arraycopy(key, pos, key, pos - 1, tail);
System.arraycopy(value, pos, value, pos - 1, tail);
size--;
}
};
}
@Override
public int size() {
return size;
}
@Override
public void clear() {
Byte2ReferenceArrayMap.this.clear();
}
};
}
/**
* Returns a deep copy of this map.
*
*
* This method performs a deep copy of this hash map; the data stored in the
* map, however, is not cloned. Note that this makes a difference only for
* object keys.
*
* @return a deep copy of this map.
*/
@Override
@SuppressWarnings("unchecked")
public Byte2ReferenceArrayMap clone() {
Byte2ReferenceArrayMap c;
try {
c = (Byte2ReferenceArrayMap) super.clone();
} catch (CloneNotSupportedException cantHappen) {
throw new InternalError();
}
c.key = key.clone();
c.value = value.clone();
return c;
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
s.defaultWriteObject();
for (int i = 0; i < size; i++) {
s.writeByte(key[i]);
s.writeObject(value[i]);
}
}
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
key = new byte[size];
value = new Object[size];
for (int i = 0; i < size; i++) {
key[i] = s.readByte();
value[i] = s.readObject();
}
}
}