com.sun.jersey.core.util.KeyComparatorHashMap Maven / Gradle / Ivy
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package com.sun.jersey.core.util;
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import com.sun.jersey.impl.ImplMessages;
/**
* A implementation similar to {@link java.util.HashMap} but supports the
* comparison of keys using a {@link KeyComparator}.
*
* @author [email protected]
*/
@SuppressWarnings("unchecked")
public class KeyComparatorHashMap
extends AbstractMap
implements Map, Cloneable, Serializable
{
/**
* 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 volatile int modCount;
public int getDEFAULT_INITIAL_CAPACITY() {
return DEFAULT_INITIAL_CAPACITY;
}
final KeyComparator keyComparator;
/**
* 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.
*/
public KeyComparatorHashMap(int initialCapacity, float loadFactor, KeyComparator keyComparator) {
if (initialCapacity < 0)
throw new IllegalArgumentException(ImplMessages.ILLEGAL_INITIAL_CAPACITY(initialCapacity));
if (initialCapacity > MAXIMUM_CAPACITY)
initialCapacity = MAXIMUM_CAPACITY;
if (loadFactor <= 0 || Float.isNaN(loadFactor))
throw new IllegalArgumentException(ImplMessages.ILLEGAL_LOAD_FACTOR(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();
this.keyComparator = keyComparator;
}
/**
* 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 KeyComparatorHashMap(int initialCapacity, KeyComparator keyComparator) {
this(initialCapacity, DEFAULT_LOAD_FACTOR, keyComparator);
}
/**
* Constructs an empty HashMap with the default initial capacity
* (16) and the default load factor (0.75).
*/
public KeyComparatorHashMap(KeyComparator keyComparator) {
this.loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int)(DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
table = new Entry[DEFAULT_INITIAL_CAPACITY];
init();
this.keyComparator = keyComparator;
}
/**
* Constructs a new HashMap with the same mappings as the
* specified Map. The HashMap is created with
* default load factor (0.75) and an initial capacity sufficient to
* hold the mappings in the specified Map.
*
* @param m the map whose mappings are to be placed in this map.
* @throws NullPointerException if the specified map is null.
*/
public KeyComparatorHashMap(Map m,
KeyComparator keyComparator) {
this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR, keyComparator);
putAllForCreate(m);
}
//
/**
* Get 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).
*
* @return return the modification count.
*/
public int getModCount() {
return modCount;
}
// 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() {
}
/**
* Value representing null keys inside tables.
*/
static final Object NULL_KEY = new Object();
/**
* Returns internal representation for key. Use NULL_KEY if key is null.
*/
static T maskNull(T key) {
return key == null ? (T)NULL_KEY : key;
}
static boolean isNull(T key) {
return key == NULL_KEY;
}
/**
* Returns key represented by specified internal representation.
*/
static T unmaskNull(T key) {
return key == NULL_KEY ? null : key;
}
/**
* Returns a hash value for the specified object. In addition to
* the object's own hashCode, this method applies a "supplemental
* hash function," which defends against poor quality hash functions.
* This is critical because HashMap uses power-of two length
* hash tables.
*
* The shift distances in this function were chosen as the result
* of an automated search over the entire four-dimensional search space.
*/
static int hash(Object x) {
int h = x.hashCode();
h += ~(h << 9);
h ^= (h >>> 14);
h += (h << 4);
h ^= (h >>> 10);
return h;
}
/**
* Check for equality of non-null reference x and possibly-null y.
*/
static boolean eq(Object x, Object y) {
return x == y || x.equals(y);
}
/**
* Returns index for hash code h.
*/
static int indexFor(int h, 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.
*/
@Override
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.
*/
@Override
public boolean isEmpty() {
return size == 0;
}
int keyComparatorHash(K k) {
return isNull(k)
? hash(k.hashCode())
: hash(keyComparator.hash(k));
}
int hash(int h) {
h += ~(h << 9);
h ^= (h >>> 14);
h += (h << 4);
h ^= (h >>> 10);
return h;
}
/**
* Check for equality of non-null reference x and possibly-null y.
*/
boolean keyComparatorEq(K x, K y) {
if (isNull(x)) {
return x == y;
} else if (isNull(y)) {
return x == y;
} else {
return x == y || keyComparator.equals(x, y);
}
}
/**
* 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(Object, Object)
*/
@Override
public V get(Object key) {
K k = (K)maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
Entry e = table[i];
while (true) {
if (e == null)
return null;
if (e.hash == hash && keyComparatorEq(k, 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.
*/
@Override
public boolean containsKey(Object key) {
K k = (K)maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
Entry e = table[i];
while (e != null) {
if (e.hash == hash && keyComparatorEq(k, 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.
*/
Entry getEntry(K key) {
K k = maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
Entry e = table[i];
while (e != null && !(e.hash == hash && keyComparatorEq(k, 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.
*/
@Override
public V put(K key, V value) {
K k = maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
for (Entry e = table[i]; e != null; e = e.next) {
if (e.hash == hash && keyComparatorEq(k, e.key)) {
V oldValue = e.value;
e.value = value;
e.recordAccess(this);
return oldValue;
}
}
modCount++;
addEntry(hash, k, 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.
*/
private void putForCreate(K key, V value) {
K k = maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, 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 (e.hash == hash && keyComparatorEq(k, e.key)) {
e.value = value;
return;
}
}
createEntry(hash, k, value, i);
}
void putAllForCreate(Map m) {
for (Iterator> i = m.entrySet().iterator(); i.hasNext(); ) {
Map.Entry e = i.next();
putForCreate(e.getKey(), e.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 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).
*/
void resize(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.
*/
void transfer(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.hash, 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.
*/
@Override
public void putAll(Map 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 (Iterator> i = m.entrySet().iterator(); i.hasNext(); ) {
Map.Entry e = i.next();
put(e.getKey(), e.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.
*/
@Override
public V remove(Object 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.
*/
Entry removeEntryForKey(Object key) {
K k = (K)maskNull(key);
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
Entry prev = table[i];
Entry e = prev;
while (e != null) {
Entry next = e.next;
if (e.hash == hash && keyComparatorEq(k, e.key)) {
modCount++;
size--;
if (prev == e)
table[i] = next;
else
prev.next = next;
e.recordRemoval(this);
return e;
}
prev = e;
e = next;
}
return e;
}
/**
* Special version of remove for EntrySet.
*/
Entry removeMapping(Object o) {
if (!(o instanceof Map.Entry))
return null;
Map.Entry entry = (Map.Entry) o;
K k = (K)maskNull(entry.getKey());
int hash = keyComparatorHash(k);
int i = indexFor(hash, table.length);
Entry prev = table[i];
Entry e = prev;
while (e != null) {
Entry next = e.next;
if (e.hash == hash && e.equals(entry)) {
modCount++;
size--;
if (prev == e)
table[i] = next;
else
prev.next = next;
e.recordRemoval(this);
return e;
}
prev = e;
e = next;
}
return e;
}
/**
* Removes all mappings from this map.
*/
@Override
public void clear() {
modCount++;
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.
*/
@Override
public boolean containsValue(Object value) {
if (value == null)
return containsNullValue();
Entry[] tab = table;
for (int i = 0; i < tab.length ; i++)
for (Entry e = tab[i] ; e != null ; e = e.next)
if (value.equals(e.value))
return true;
return false;
}
/**
* Special-case code for containsValue with null argument
**/
private boolean containsNullValue() {
Entry[] tab = table;
for (int i = 0; i < tab.length ; i++)
for (Entry e = tab[i] ; 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.
*/
@Override
public Object clone() {
KeyComparatorHashMap result = null;
try {
result = (KeyComparatorHashMap)super.clone();
} catch (CloneNotSupportedException e) {
// assert false;
}
result.table = new Entry[table.length];
result.entrySet = null;
result.modCount = 0;
result.size = 0;
result.init();
result.putAllForCreate(this);
return result;
}
static class Entry implements Map.Entry {
final K key;
V value;
final int hash;
Entry next;
/**
* Create new entry.
*/
Entry(int h, K k, V v, Entry n) {
value = v;
next = n;
key = k;
hash = h;
}
public K getKey() {
return KeyComparatorHashMap.unmaskNull(key);
}
public V getValue() {
return value;
}
public V setValue(V newValue) {
V oldValue = value;
value = newValue;
return oldValue;
}
@Override
public boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry e = (Map.Entry)o;
Object k1 = getKey();
Object k2 = e.getKey();
if (k1 == k2 || (k1 != null && k1.equals(k2))) {
Object v1 = getValue();
Object v2 = e.getValue();
if (v1 == v2 || (v1 != null && v1.equals(v2)))
return true;
}
return false;
}
@Override
public int hashCode() {
return (key==NULL_KEY ? 0 : key.hashCode()) ^
(value==null ? 0 : value.hashCode());
}
@Override
public String toString() {
return getKey() + "=" + getValue();
}
/**
* This method is invoked whenever the value in an entry is
* overwritten by an invocation of put(k,v) for a key k that's already
* in the HashMap.
*/
void recordAccess(KeyComparatorHashMap m) {
}
/**
* This method is invoked whenever the entry is
* removed from the table.
*/
void recordRemoval(KeyComparatorHashMap m) {
}
}
/**
* 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.
*/
void addEntry(int hash, K key, V value, int bucketIndex) {
Entry e = table[bucketIndex];
table[bucketIndex] = new Entry(hash, key, value, e);
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.
*/
void createEntry(int hash, K key, V value, int bucketIndex) {
Entry e = table[bucketIndex];
table[bucketIndex] = new Entry(hash, key, value, e);
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;
Entry[] t = table;
int i = t.length;
Entry n = null;
if (size != 0) { // advance to first entry
while (i > 0 && (n = t[--i]) == null)
;
}
next = n;
index = i;
}
public boolean hasNext() {
return next != null;
}
Entry nextEntry() {
if (modCount != 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;
}
public void remove() {
if (current == null)
throw new IllegalStateException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
K k = current.key;
current = null;
KeyComparatorHashMap.this.removeEntryForKey(k);
expectedModCount = modCount;
}
}
private class ValueIterator extends HashIterator {
public V next() {
return nextEntry().value;
}
}
private class KeyIterator extends HashIterator {
public K next() {
return nextEntry().getKey();
}
}
private class EntryIterator extends HashIterator> {
public Map.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 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.
*/
public Set> entrySet() {
Set> es = entrySet;
return (es != null ? es : (entrySet = (Set>) (Set) new EntrySet()));
}
private class EntrySet extends AbstractSet/*>*/ {
public Iterator/*>*/ iterator() {
return newEntryIterator();
}
@Override
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry e = (Map.Entry) o;
Entry candidate = getEntry(e.getKey());
return candidate != null && candidate.equals(e);
}
@Override
public boolean remove(Object o) {
return removeMapping(o) != null;
}
public int size() {
return size;
}
@Override
public void clear() {
KeyComparatorHashMap.this.clear();
}
}
/**
* Save the state of the HashMap instance to a stream (i.e.,
* serialize it).
*
* @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(java.io.ObjectOutputStream s)
throws IOException
{
Iterator> i = entrySet().iterator();
// 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)
while (i.hasNext()) {
Map.Entry e = i.next();
s.writeObject(e.getKey());
s.writeObject(e.getValue());
}
}
/**
* Reconstitute the HashMap instance from a stream (i.e.,
* deserialize it).
*/
private void readObject(java.io.ObjectInputStream s)
throws IOException, ClassNotFoundException
{
// 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