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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.wicket.util.collections;
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
/**
* This is an integer hashmap that has the exact same features and interface as a normal Map except
* that the key is directly an integer. So no hash is calculated or key object is stored.
*
* @author jcompagner
*
* @param
* The value in the map
*/
public class IntHashMap implements Cloneable, Serializable
{
transient volatile Set keySet = null;
transient volatile Collection values = null;
/**
* The default initial capacity - MUST be a power of two.
*/
static final int DEFAULT_INITIAL_CAPACITY = 16;
/**
* The maximum capacity, used if a higher value is implicitly specified by either of the
* constructors with arguments. MUST be a power of two <= 1<<30.
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* The load factor used when none specified in constructor.
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* The table, resized as necessary. Length MUST Always be a power of two.
*/
transient Entry[] table;
/**
* The number of key-value mappings contained in this identity hash map.
*/
transient int size;
/**
* The next size value at which to resize (capacity * load factor).
*
* @serial
*/
int threshold;
/**
* The load factor for the hash table.
*
* @serial
*/
final float loadFactor;
/**
* The number of times this HashMap has been structurally modified Structural modifications are
* those that change the number of mappings in the HashMap or otherwise modify its internal
* structure (e.g., rehash). This field is used to make iterators on Collection-views of the
* HashMap fail-fast. (See ConcurrentModificationException).
*/
transient AtomicInteger modCount = new AtomicInteger(0);
/**
* Constructs an empty HashMap with the specified initial capacity and load factor.
*
* @param initialCapacity
* The initial capacity.
* @param loadFactor
* The load factor.
* @throws IllegalArgumentException
* if the initial capacity is negative or the load factor is nonpositive.
*/
@SuppressWarnings("unchecked")
public IntHashMap(int initialCapacity, final float loadFactor)
{
if (initialCapacity < 0)
{
throw new IllegalArgumentException("Illegal initial capacity: " + //$NON-NLS-1$
initialCapacity);
}
if (initialCapacity > MAXIMUM_CAPACITY)
{
initialCapacity = MAXIMUM_CAPACITY;
}
if ((loadFactor <= 0) || Float.isNaN(loadFactor))
{
throw new IllegalArgumentException("Illegal load factor: " + //$NON-NLS-1$
loadFactor);
}
// Find a power of 2 >= initialCapacity
int capacity = 1;
while (capacity < initialCapacity)
{
capacity <<= 1;
}
this.loadFactor = loadFactor;
threshold = (int)(capacity * loadFactor);
table = new Entry[capacity];
init();
}
/**
* Constructs an empty HashMap with the specified initial capacity and the default load
* factor (0.75).
*
* @param initialCapacity
* the initial capacity.
* @throws IllegalArgumentException
* if the initial capacity is negative.
*/
public IntHashMap(final int initialCapacity)
{
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
/**
* Constructs an empty HashMap with the default initial capacity (16) and the default
* load factor (0.75).
*/
@SuppressWarnings("unchecked")
public IntHashMap()
{
loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int)(DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
table = new Entry[DEFAULT_INITIAL_CAPACITY];
init();
}
// internal utilities
/**
* Initialization hook for subclasses. This method is called in all constructors and
* pseudo-constructors (clone, readObject) after HashMap has been initialized but before any
* entries have been inserted. (In the absence of this method, readObject would require explicit
* knowledge of subclasses.)
*/
void init()
{
}
/**
* Returns index for hash code h.
*
* @param h
* @param length
* @return The index for the hash integer for the given length
*/
static int indexFor(final int h, final int length)
{
return h & (length - 1);
}
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map.
*/
public int size()
{
return size;
}
/**
* Returns true if this map contains no key-value mappings.
*
* @return true if this map contains no key-value mappings.
*/
public boolean isEmpty()
{
return size == 0;
}
/**
* Returns the value to which the specified key is mapped in this identity hash map, or
* null if the map contains no mapping for this key. A return value of null
* does not necessarily indicate that the map contains no mapping for the key; it is also
* possible that the map explicitly maps the key to null. The containsKey
* method may be used to distinguish these two cases.
*
* @param key
* the key whose associated value is to be returned.
* @return the value to which this map maps the specified key, or null if the map
* contains no mapping for this key.
* @see #put(int, Object)
*/
public V get(final int key)
{
int i = indexFor(key, table.length);
Entry e = table[i];
while (true)
{
if (e == null)
{
return null;
}
if (key == e.key)
{
return e.value;
}
e = e.next;
}
}
/**
* Returns true if this map contains a mapping for the specified key.
*
* @param key
* The key whose presence in this map is to be tested
* @return true if this map contains a mapping for the specified key.
*/
public boolean containsKey(final int key)
{
int i = indexFor(key, table.length);
Entry e = table[i];
while (e != null)
{
if (key == e.key)
{
return true;
}
e = e.next;
}
return false;
}
/**
* Returns the entry associated with the specified key in the HashMap. Returns null if the
* HashMap contains no mapping for this key.
*
* @param key
* @return The Entry object for the given hash key
*/
Entry getEntry(final int key)
{
int i = indexFor(key, table.length);
Entry e = table[i];
while ((e != null) && !(key == e.key))
{
e = e.next;
}
return e;
}
/**
* Associates the specified value with the specified key in this map. If the map previously
* contained a mapping for this key, the old value is replaced.
*
* @param key
* key with which the specified value is to be associated.
* @param value
* value to be associated with the specified key.
* @return previous value associated with specified key, or null if there was no
* mapping for key. A null return can also indicate that the HashMap previously
* associated null with the specified key.
*/
public V put(final int key, final V value)
{
int i = indexFor(key, table.length);
for (Entry e = table[i]; e != null; e = e.next)
{
if (key == e.key)
{
V oldValue = e.value;
e.value = value;
return oldValue;
}
}
modCount.incrementAndGet();
addEntry(key, value, i);
return null;
}
/**
* This method is used instead of put by constructors and pseudoconstructors (clone,
* readObject). It does not resize the table, check for comodification, etc. It calls
* createEntry rather than addEntry.
*
* @param key
* @param value
*/
private void putForCreate(final int key, final V value)
{
int i = indexFor(key, table.length);
/**
* Look for preexisting entry for key. This will never happen for clone or deserialize. It
* will only happen for construction if the input Map is a sorted map whose ordering is
* inconsistent w/ equals.
*/
for (Entry e = table[i]; e != null; e = e.next)
{
if (key == e.key)
{
e.value = value;
return;
}
}
createEntry(key, value, i);
}
void putAllForCreate(final IntHashMap m)
{
for (Entry entry : m.entrySet())
{
putForCreate(entry.getKey(), entry.getValue());
}
}
/**
* Rehashes the contents of this map into a new array with a larger capacity. This method is
* called automatically when the number of keys in this map reaches its threshold.
*
* If current capacity is MAXIMUM_CAPACITY, this method does not resize the map, but but sets
* threshold to Integer.MAX_VALUE. This has the effect of preventing future calls.
*
* @param newCapacity
* the new capacity, MUST be a power of two; must be greater than current capacity
* unless current capacity is MAXIMUM_CAPACITY (in which case value is irrelevant).
*/
@SuppressWarnings("unchecked")
void resize(final int newCapacity)
{
Entry[] oldTable = table;
int oldCapacity = oldTable.length;
if (oldCapacity == MAXIMUM_CAPACITY)
{
threshold = Integer.MAX_VALUE;
return;
}
Entry[] newTable = new Entry[newCapacity];
transfer(newTable);
table = newTable;
threshold = (int)(newCapacity * loadFactor);
}
/**
* Transfer all entries from current table to newTable.
*
* @param newTable
*/
void transfer(final Entry[] newTable)
{
Entry[] src = table;
int newCapacity = newTable.length;
for (int j = 0; j < src.length; j++)
{
Entry e = src[j];
if (e != null)
{
src[j] = null;
do
{
Entry next = e.next;
int i = indexFor(e.key, newCapacity);
e.next = newTable[i];
newTable[i] = e;
e = next;
}
while (e != null);
}
}
}
/**
* Copies all of the mappings from the specified map to this map These mappings will replace any
* mappings that this map had for any of the keys currently in the specified map.
*
* @param m
* mappings to be stored in this map.
* @throws NullPointerException
* if the specified map is null.
*/
public void putAll(final IntHashMap m)
{
int numKeysToBeAdded = m.size();
if (numKeysToBeAdded == 0)
{
return;
}
/*
* Expand the map if the map if the number of mappings to be added is greater than or equal
* to threshold. This is conservative; the obvious condition is (m.size() + size) >=
* threshold, but this condition could result in a map with twice the appropriate capacity,
* if the keys to be added overlap with the keys already in this map. By using the
* conservative calculation, we subject ourself to at most one extra resize.
*/
if (numKeysToBeAdded > threshold)
{
int targetCapacity = (int)(numKeysToBeAdded / loadFactor + 1);
if (targetCapacity > MAXIMUM_CAPACITY)
{
targetCapacity = MAXIMUM_CAPACITY;
}
int newCapacity = table.length;
while (newCapacity < targetCapacity)
{
newCapacity <<= 1;
}
if (newCapacity > table.length)
{
resize(newCapacity);
}
}
for (Entry entry : m.entrySet())
{
put(entry.getKey(), entry.getValue());
}
}
/**
* Removes the mapping for this key from this map if present.
*
* @param key
* key whose mapping is to be removed from the map.
* @return previous value associated with specified key, or null if there was no
* mapping for key. A null return can also indicate that the map previously
* associated null with the specified key.
*/
public V remove(final int key)
{
Entry e = removeEntryForKey(key);
return (e == null ? null : e.value);
}
/**
* Removes and returns the entry associated with the specified key in the HashMap. Returns null
* if the HashMap contains no mapping for this key.
*
* @param key
* @return The Entry object that was removed
*/
Entry removeEntryForKey(final int key)
{
int i = indexFor(key, table.length);
Entry prev = table[i];
Entry e = prev;
while (e != null)
{
Entry next = e.next;
if (key == e.key)
{
modCount.incrementAndGet();
size--;
if (prev == e)
{
table[i] = next;
}
else
{
prev.next = next;
}
return e;
}
prev = e;
e = next;
}
return e;
}
/**
* Special version of remove for EntrySet.
*
* @param o
* @return The entry that was removed
*/
@SuppressWarnings("unchecked")
Entry removeMapping(final Object o)
{
if (!(o instanceof Entry))
{
return null;
}
Entry entry = (Entry)o;
int key = entry.getKey();
int i = indexFor(key, table.length);
Entry prev = table[i];
Entry e = prev;
while (e != null)
{
Entry next = e.next;
if ((e.key == key) && e.equals(entry))
{
modCount.incrementAndGet();
size--;
if (prev == e)
{
table[i] = next;
}
else
{
prev.next = next;
}
return e;
}
prev = e;
e = next;
}
return e;
}
/**
* Removes all mappings from this map.
*/
public void clear()
{
modCount.incrementAndGet();
Entry tab[] = table;
for (int i = 0; i < tab.length; i++)
{
tab[i] = null;
}
size = 0;
}
/**
* Returns true if this map maps one or more keys to the specified value.
*
* @param value
* value whose presence in this map is to be tested.
* @return true if this map maps one or more keys to the specified value.
*/
public boolean containsValue(final Object value)
{
if (value == null)
{
return containsNullValue();
}
for (Entry entry : table)
{
for (Entry e = entry; e != null; e = e.next)
{
if (value.equals(e.value))
{
return true;
}
}
}
return false;
}
/**
* Special-case code for containsValue with null argument
*
* @return boolean true if there is a null value in this map
*/
private boolean containsNullValue()
{
Entry tab[] = table;
for (Entry tabEntry : tab)
{
for (Entry e = tabEntry; e != null; e = e.next)
{
if (e.value == null)
{
return true;
}
}
}
return false;
}
/**
* Returns a shallow copy of this HashMap instance: the keys and values themselves are
* not cloned.
*
* @return a shallow copy of this map.
*/
@SuppressWarnings("unchecked")
@Override
public Object clone() throws CloneNotSupportedException
{
IntHashMap result = null;
try
{
result = (IntHashMap)super.clone();
result.table = new Entry[table.length];
result.entrySet = null;
result.modCount.set(0);
result.size = 0;
result.init();
result.putAllForCreate(this);
}
catch (CloneNotSupportedException e)
{
// assert false;
}
return result;
}
/**
* @author jcompagner
* @param
* type of value object
*/
public static class Entry
{
final int key;
V value;
Entry next;
/**
* Create new entry.
*
* @param k
* @param v
* @param n
*/
Entry(final int k, final V v, final Entry n)
{
value = v;
next = n;
key = k;
}
/**
* @return The int key of this entry
*/
public int getKey()
{
return key;
}
/**
* @return Gets the value object of this entry
*/
public V getValue()
{
return value;
}
/**
* @param newValue
* @return The previous value
*/
public V setValue(final V newValue)
{
V oldValue = value;
value = newValue;
return oldValue;
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
@SuppressWarnings("unchecked")
@Override
public boolean equals(final Object o)
{
if (!(o instanceof Entry))
{
return false;
}
Entry e = (Entry)o;
int k1 = getKey();
int k2 = e.getKey();
if (k1 == k2)
{
Object v1 = getValue();
Object v2 = e.getValue();
if ((v1 == v2) || ((v1 != null) && v1.equals(v2)))
{
return true;
}
}
return false;
}
/**
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode()
{
return key ^ (value == null ? 0 : value.hashCode());
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
return getKey() + "=" + getValue(); //$NON-NLS-1$
}
}
/**
* Add a new entry with the specified key, value and hash code to the specified bucket. It is
* the responsibility of this method to resize the table if appropriate.
*
* Subclass overrides this to alter the behavior of put method.
*
* @param key
* @param value
* @param bucketIndex
*/
void addEntry(final int key, final V value, final int bucketIndex)
{
table[bucketIndex] = new Entry<>(key, value, table[bucketIndex]);
if (size++ >= threshold)
{
resize(2 * table.length);
}
}
/**
* Like addEntry except that this version is used when creating entries as part of Map
* construction or "pseudo-construction" (cloning, deserialization). This version needn't worry
* about resizing the table.
*
* Subclass overrides this to alter the behavior of HashMap(Map), clone, and readObject.
*
* @param key
* @param value
* @param bucketIndex
*/
void createEntry(final int key, final V value, final int bucketIndex)
{
table[bucketIndex] = new Entry<>(key, value, table[bucketIndex]);
size++;
}
private abstract class HashIterator implements Iterator
{
Entry next; // next entry to return
int expectedModCount; // For fast-fail
int index; // current slot
Entry current; // current entry
HashIterator()
{
expectedModCount = modCount.get();
Entry[] t = table;
int i = t.length;
Entry n = null;
if (size != 0)
{ // advance to first entry
while ((i > 0) && ((n = t[--i]) == null))
{
/* NoOp */
}
}
next = n;
index = i;
}
/**
* @see java.util.Iterator#hasNext()
*/
@Override
public boolean hasNext()
{
return next != null;
}
Entry nextEntry()
{
if (!modCount.compareAndSet(expectedModCount, expectedModCount))
{
throw new ConcurrentModificationException();
}
Entry e = next;
if (e == null)
{
throw new NoSuchElementException();
}
Entry n = e.next;
Entry[] t = table;
int i = index;
while ((n == null) && (i > 0))
{
n = t[--i];
}
index = i;
next = n;
return current = e;
}
/**
* @see java.util.Iterator#remove()
*/
@Override
public void remove()
{
if (current == null)
{
throw new IllegalStateException();
}
if (!modCount.compareAndSet(expectedModCount, expectedModCount))
{
throw new ConcurrentModificationException();
}
int k = current.key;
current = null;
removeEntryForKey(k);
expectedModCount = modCount.get();
}
}
private class ValueIterator extends HashIterator
{
/**
* @see java.util.Iterator#next()
*/
@Override
public V next()
{
return nextEntry().value;
}
}
private class KeyIterator extends HashIterator
{
/**
* @see java.util.Iterator#next()
*/
@Override
public Integer next()
{
return nextEntry().getKey();
}
}
private class EntryIterator extends HashIterator>
{
/**
* @see java.util.Iterator#next()
*/
@Override
public Entry next()
{
return nextEntry();
}
}
// Subclass overrides these to alter behavior of views' iterator() method
Iterator newKeyIterator()
{
return new KeyIterator();
}
Iterator newValueIterator()
{
return new ValueIterator();
}
Iterator> newEntryIterator()
{
return new EntryIterator();
}
// Views
private transient Set> entrySet = null;
/**
* Returns a set view of the keys contained in this map. The set is backed by the map, so
* changes to the map are reflected in the set, and vice-versa. The set supports element
* removal, which removes the corresponding mapping from this map, via the
* Iterator.remove, Set.remove, removeAll, retainAll, and
* clear operations. It does not support the add or addAll
* operations.
*
* @return a set view of the keys contained in this map.
*/
public Set keySet()
{
Set ks = keySet;
return (ks != null ? ks : (keySet = new KeySet()));
}
private class KeySet extends AbstractSet
{
/**
* @see java.util.AbstractCollection#iterator()
*/
@Override
public Iterator iterator()
{
return newKeyIterator();
}
/**
* @see java.util.AbstractCollection#size()
*/
@Override
public int size()
{
return size;
}
/**
* @see java.util.AbstractCollection#contains(java.lang.Object)
*/
@Override
public boolean contains(final Object o)
{
if (o instanceof Number)
{
return containsKey(((Number)o).intValue());
}
return false;
}
/**
* @see java.util.AbstractCollection#remove(java.lang.Object)
*/
@Override
public boolean remove(final Object o)
{
if (o instanceof Number)
{
return removeEntryForKey(((Number)o).intValue()) != null;
}
return false;
}
/**
* @see java.util.AbstractCollection#clear()
*/
@Override
public void clear()
{
IntHashMap.this.clear();
}
}
/**
* Returns a collection view of the values contained in this map. The collection is backed by
* the map, so changes to the map are reflected in the collection, and vice-versa. The
* collection supports element removal, which removes the corresponding mapping from this map,
* via the Iterator.remove, Collection.remove, removeAll,
* retainAll, and clear operations. It does not support the add or
* addAll operations.
*
* @return a collection view of the values contained in this map.
*/
public Collection values()
{
Collection vs = values;
return (vs != null ? vs : (values = new Values()));
}
private class Values extends AbstractCollection
{
/**
* @see java.util.AbstractCollection#iterator()
*/
@Override
public Iterator iterator()
{
return newValueIterator();
}
/**
* @see java.util.AbstractCollection#size()
*/
@Override
public int size()
{
return size;
}
/**
* @see java.util.AbstractCollection#contains(java.lang.Object)
*/
@Override
public boolean contains(final Object o)
{
return containsValue(o);
}
/**
* @see java.util.AbstractCollection#clear()
*/
@Override
public void clear()
{
IntHashMap.this.clear();
}
}
/**
* Returns a collection view of the mappings contained in this map. Each element in the returned
* collection is a Map.Entry. The collection is backed by the map, so changes to the
* map are reflected in the collection, and vice-versa. The collection supports element removal,
* which removes the corresponding mapping from the map, via the Iterator.remove,
* Collection.remove, removeAll, retainAll, and clear
* operations. It does not support the add or addAll operations.
*
* @return a collection view of the mappings contained in this map.
* @see Map.Entry
*/
public Set> entrySet()
{
Set> es = entrySet;
return (es != null ? es : (entrySet = new EntrySet()));
}
private class EntrySet extends AbstractSet>
{
/**
* @see java.util.AbstractCollection#iterator()
*/
@Override
public Iterator> iterator()
{
return newEntryIterator();
}
/**
* @see java.util.AbstractCollection#contains(java.lang.Object)
*/
@SuppressWarnings("unchecked")
@Override
public boolean contains(final Object o)
{
if (!(o instanceof Entry))
{
return false;
}
Entry e = (Entry)o;
Entry candidate = getEntry(e.getKey());
return (candidate != null) && candidate.equals(e);
}
/**
* @see java.util.AbstractCollection#remove(java.lang.Object)
*/
@Override
public boolean remove(final Object o)
{
return removeMapping(o) != null;
}
/**
* @see java.util.AbstractCollection#size()
*/
@Override
public int size()
{
return size;
}
/**
* @see java.util.AbstractCollection#clear()
*/
@Override
public void clear()
{
IntHashMap.this.clear();
}
}
/**
* Save the state of the HashMap instance to a stream (i.e., serialize it).
*
* @param s
* The ObjectOutputStream
* @throws IOException
*
* @serialData The capacity of the HashMap (the length of the bucket array) is emitted
* (int), followed by the size of the HashMap (the number of key-value
* mappings), followed by the key (Object) and value (Object) for each key-value
* mapping represented by the HashMap The key-value mappings are emitted in the
* order that they are returned by entrySet().iterator().
*
*/
private void writeObject(final java.io.ObjectOutputStream s) throws IOException
{
// Write out the threshold, loadfactor, and any hidden stuff
s.defaultWriteObject();
// Write out number of buckets
s.writeInt(table.length);
// Write out size (number of Mappings)
s.writeInt(size);
// Write out keys and values (alternating)
for (Entry entry : entrySet())
{
s.writeInt(entry.getKey());
s.writeObject(entry.getValue());
}
}
private static final long serialVersionUID = 362498820763181265L;
/**
* Reconstitute the HashMap instance from a stream (i.e., deserialize it).
*
* @param s
* @throws IOException
* @throws ClassNotFoundException
*/
@SuppressWarnings("unchecked")
private void readObject(final java.io.ObjectInputStream s) throws IOException,
ClassNotFoundException
{
modCount = new AtomicInteger(0);
// Read in the threshold, loadfactor, and any hidden stuff
s.defaultReadObject();
// Read in number of buckets and allocate the bucket array;
int numBuckets = s.readInt();
table = new Entry[numBuckets];
init(); // Give subclass a chance to do its thing.
// Read in size (number of Mappings)
int size = s.readInt();
// Read the keys and values, and put the mappings in the HashMap
for (int i = 0; i < size; i++)
{
int key = s.readInt();
V value = (V)s.readObject();
putForCreate(key, value);
}
}
// These methods are used when serializing HashSets
int capacity()
{
return table.length;
}
float loadFactor()
{
return loadFactor;
}
}
