org.freemarker/freemarker/2.3.28 : freemarker/ext/util/IdentityHashMap.java

IdentityHashMap
https://freemarker.apache.org/: FreeMarker is a "template engine"; a generic tool to generate text output based on templates. (Apache Software Foundation)
Apache License, Version 2.0
/*
 * 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 freemarker.ext.util;

import java.util.AbstractCollection;
import java.util.AbstractMap;
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;

Was used instead of IdentityHashMap before that was added to Java itself in Java 1.4. 
Deprecated: Use IdentityHashMap instead./**
 * Was used instead of {@link java.util.IdentityHashMap} before that was added to Java itself in Java 1.4. 
 * 
 * @deprecated Use {@link java.util.IdentityHashMap} instead.
 */
@SuppressWarnings("rawtypes")
@Deprecated
public class IdentityHashMap
    extends AbstractMap
    implements Map, Cloneable, java.io.Serializable {

    public static final long serialVersionUID = 362498820763181265L;
    The hash table data.
/**
     * The hash table data.
     */
    private transient Entry table[];

    The total number of mappings in the hash table.
/**
     * The total number of mappings in the hash table.
     */
    private transient int count;

    The table is rehashed when its size exceeds this threshold.  (The
value of this field is (int)(capacity * loadFactor).)
/**
     * The table is rehashed when its size exceeds this threshold.  (The
     * value of this field is (int)(capacity * loadFactor).)
     */
    private int threshold;

    The load factor for the hashtable.
/**
     * The load factor for the hashtable.
     */
    private float loadFactor;

    The number of times this IdentityHashMap has been structurally modified
Structural modifications are those that change the number of mappings in
the IdentityHashMap or otherwise modify its internal structure (e.g.,
rehash).  This field is used to make iterators on Collection-views of
the IdentityHashMap fail-fast.  (See ConcurrentModificationException).
/**
     * The number of times this IdentityHashMap has been structurally modified
     * Structural modifications are those that change the number of mappings in
     * the IdentityHashMap or otherwise modify its internal structure (e.g.,
     * rehash).  This field is used to make iterators on Collection-views of
     * the IdentityHashMap fail-fast.  (See ConcurrentModificationException).
     */
    private transient int modCount = 0;

    Constructs a new, empty map with the specified initial
capacity and the specified load factor.
Params: initialCapacity –   the initial capacity of the IdentityHashMap.
loadFactor –        the load factor of the IdentityHashMap
Throws: IllegalArgumentException –  if the initial capacity is less
              than zero, or if the load factor is nonpositive./**
     * Constructs a new, empty map with the specified initial
     * capacity and the specified load factor.
     *
     * @param      initialCapacity   the initial capacity of the IdentityHashMap.
     * @param      loadFactor        the load factor of the IdentityHashMap
     * @throws     IllegalArgumentException  if the initial capacity is less
     *               than zero, or if the load factor is nonpositive.
     */
    public IdentityHashMap(int initialCapacity, float loadFactor) {
        if (initialCapacity < 0)
            throw new IllegalArgumentException(
                "Illegal Initial Capacity: " + initialCapacity);
        if (loadFactor <= 0 || Float.isNaN(loadFactor))
            throw new IllegalArgumentException(
                "Illegal Load factor: " + loadFactor);
        if (initialCapacity == 0)
            initialCapacity = 1;
        this.loadFactor = loadFactor;
        table = new Entry[initialCapacity];
        threshold = (int) (initialCapacity * loadFactor);
    }

    Constructs a new, empty map with the specified initial capacity
and default load factor, which is 0.75.
Params: initialCapacity –   the initial capacity of the IdentityHashMap.
Throws: IllegalArgumentException – if the initial capacity is less
             than zero./**
     * Constructs a new, empty map with the specified initial capacity
     * and default load factor, which is <tt>0.75</tt>.
     *
     * @param   initialCapacity   the initial capacity of the IdentityHashMap.
     * @throws    IllegalArgumentException if the initial capacity is less
     *              than zero.
     */
    public IdentityHashMap(int initialCapacity) {
        this(initialCapacity, 0.75f);
    }

    Constructs a new, empty map with a default capacity and load
factor, which is 0.75.
/**
     * Constructs a new, empty map with a default capacity and load
     * factor, which is <tt>0.75</tt>.
     */
    public IdentityHashMap() {
        this(11, 0.75f);
    }

    Constructs a new map with the same mappings as the given map.  The
map is created with a capacity of twice the number of mappings in
the given map or 11 (whichever is greater), and a default load factor,
which is 0.75.
Params: t – the map whose mappings are to be placed in this map./**
     * Constructs a new map with the same mappings as the given map.  The
     * map is created with a capacity of twice the number of mappings in
     * the given map or 11 (whichever is greater), and a default load factor,
     * which is <tt>0.75</tt>.
     *
     * @param t the map whose mappings are to be placed in this map.
     */
    public IdentityHashMap(Map t) {
        this(Math.max(2 * t.size(), 11), 0.75f);
        putAll(t);
    }

    Returns the number of key-value mappings in this map.
Returns: the number of key-value mappings in this map./**
     * 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 count;
    }

    Returns true if this map contains no key-value mappings.
Returns: true if this map contains no key-value mappings./**
     * Returns <tt>true</tt> if this map contains no key-value mappings.
     *
     * @return <tt>true</tt> if this map contains no key-value mappings.
     */
    @Override
    public boolean isEmpty() {
        return count == 0;
    }

    Returns true if this map maps one or more keys to the
specified value.
Params: value – value whose presence in this map is to be tested.
Returns: true if this map maps one or more keys to the
        specified value./**
     * Returns <tt>true</tt> 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 <tt>true</tt> if this map maps one or more keys to the
     *         specified value.
     */
    @Override
    public boolean containsValue(Object value) {
        Entry tab[] = table;

        if (value == null) {
            for (int i = tab.length; i-- > 0; )
                for (Entry e = tab[i]; e != null; e = e.next)
                    if (e.value == null)
                        return true;
        } else {
            for (int i = tab.length; i-- > 0; )
                for (Entry e = tab[i]; e != null; e = e.next)
                    if (value.equals(e.value))
                        return true;
        }

        return false;
    }

    Returns true if this map contains a mapping for the specified
key.
Params: key – key whose presence in this Map is to be tested.
Returns: true if this map contains a mapping for the specified
key./**
     * Returns <tt>true</tt> if this map contains a mapping for the specified
     * key.
     *
     * @return <tt>true</tt> if this map contains a mapping for the specified
     * key.
     * @param key key whose presence in this Map is to be tested.
     */
    @Override
    public boolean containsKey(Object key) {
        Entry tab[] = table;
        if (key != null) {
            int hash = System.identityHashCode(key);
            int index = (hash & 0x7FFFFFFF) % tab.length;
            for (Entry e = tab[index]; e != null; e = e.next)
                if (e.hash == hash && key == e.key)
                    return true;
        } else {
            for (Entry e = tab[0]; e != null; e = e.next)
                if (e.key == null)
                    return true;
        }

        return false;
    }

    Returns the value to which this map maps the specified key.  Returns
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's also possible that the map
explicitly maps the key to null.  The containsKey
operation may be used to distinguish these two cases.
Params: key – key whose associated value is to be returned.
Returns: the value to which this map maps the specified key./**
     * Returns the value to which this map maps the specified key.  Returns
     * <tt>null</tt> if the map contains no mapping for this key.  A return
     * value of <tt>null</tt> does not <i>necessarily</i> indicate that the
     * map contains no mapping for the key; it's also possible that the map
     * explicitly maps the key to <tt>null</tt>.  The <tt>containsKey</tt>
     * operation may be used to distinguish these two cases.
     *
     * @return the value to which this map maps the specified key.
     * @param key key whose associated value is to be returned.
     */
    @Override
    public Object get(Object key) {
        Entry tab[] = table;

        if (key != null) {
            int hash = System.identityHashCode(key);
            int index = (hash & 0x7FFFFFFF) % tab.length;
            for (Entry e = tab[index]; e != null; e = e.next)
                if ((e.hash == hash) && key == e.key)
                    return e.value;
        } else {
            for (Entry e = tab[0]; e != null; e = e.next)
                if (e.key == null)
                    return e.value;
        }

        return null;
    }

    Rehashes the contents of this map into a new IdentityHashMap instance
with a larger capacity. This method is called automatically when the
number of keys in this map exceeds its capacity and load factor.
/**
     * Rehashes the contents of this map into a new <tt>IdentityHashMap</tt> instance
     * with a larger capacity. This method is called automatically when the
     * number of keys in this map exceeds its capacity and load factor.
     */
    private void rehash() {
        int oldCapacity = table.length;
        Entry oldMap[] = table;

        int newCapacity = oldCapacity * 2 + 1;
        Entry newMap[] = new Entry[newCapacity];

        modCount++;
        threshold = (int) (newCapacity * loadFactor);
        table = newMap;

        for (int i = oldCapacity; i-- > 0; ) {
            for (Entry old = oldMap[i]; old != null; ) {
                Entry e = old;
                old = old.next;

                int index = (e.hash & 0x7FFFFFFF) % newCapacity;
                e.next = newMap[index];
                newMap[index] = 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.
Params: key – key with which the specified value is to be associated.
value – value to be associated with the specified key.
Returns: previous value associated with specified key, or null
       if there was no mapping for key.  A null return can
       also indicate that the IdentityHashMap previously associated
       null with the specified key./**
     * 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 <tt>null</tt>
     *	       if there was no mapping for key.  A <tt>null</tt> return can
     *	       also indicate that the IdentityHashMap previously associated
     *	       <tt>null</tt> with the specified key.
     */
    @Override
    public Object put(Object key, Object value) {
        // Makes sure the key is not already in the IdentityHashMap.
        Entry tab[] = table;
        int hash = 0;
        int index = 0;

        if (key != null) {
            hash = System.identityHashCode(key);
            index = (hash & 0x7FFFFFFF) % tab.length;
            for (Entry e = tab[index]; e != null; e = e.next) {
                if ((e.hash == hash) && key == e.key) {
                    Object old = e.value;
                    e.value = value;
                    return old;
                }
            }
        } else {
            for (Entry e = tab[0]; e != null; e = e.next) {
                if (e.key == null) {
                    Object old = e.value;
                    e.value = value;
                    return old;
                }
            }
        }

        modCount++;
        if (count >= threshold) {
            // Rehash the table if the threshold is exceeded
            rehash();

            tab = table;
            index = (hash & 0x7FFFFFFF) % tab.length;
        }

        // Creates the new entry.
        Entry e = new Entry(hash, key, value, tab[index]);
        tab[index] = e;
        count++;
        return null;
    }

    Removes the mapping for this key from this map if present.
Params: key – key whose mapping is to be removed from the map.
Returns: 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./**
     * 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 <tt>null</tt>
     *	       if there was no mapping for key.  A <tt>null</tt> return can
     *	       also indicate that the map previously associated <tt>null</tt>
     *	       with the specified key.
     */
    @Override
    public Object remove(Object key) {
        Entry tab[] = table;

        if (key != null) {
            int hash = System.identityHashCode(key);
            int index = (hash & 0x7FFFFFFF) % tab.length;

            for (Entry e = tab[index], prev = null;
                e != null;
                prev = e, e = e.next) {
                if ((e.hash == hash) && key == e.key) {
                    modCount++;
                    if (prev != null)
                        prev.next = e.next;
                    else
                        tab[index] = e.next;

                    count--;
                    Object oldValue = e.value;
                    e.value = null;
                    return oldValue;
                }
            }
        } else {
            for (Entry e = tab[0], prev = null;
                e != null;
                prev = e, e = e.next) {
                if (e.key == null) {
                    modCount++;
                    if (prev != null)
                        prev.next = e.next;
                    else
                        tab[0] = e.next;

                    count--;
                    Object oldValue = e.value;
                    e.value = null;
                    return oldValue;
                }
            }
        }

        return null;
    }

    Copies all of the mappings from the specified map to this one.
These mappings replace any mappings that this map had for any of the
keys currently in the specified Map.
Params: t – Mappings to be stored in this map./**
     * Copies all of the mappings from the specified map to this one.
     *
     * These mappings replace any mappings that this map had for any of the
     * keys currently in the specified Map.
     *
     * @param t Mappings to be stored in this map.
     */
    @Override
    public void putAll(Map t) {
        Iterator i = t.entrySet().iterator();
        while (i.hasNext()) {
            Map.Entry e = (Map.Entry) i.next();
            put(e.getKey(), e.getValue());
        }
    }

    Removes all mappings from this map.
/**
     * Removes all mappings from this map.
     */
    @Override
    public void clear() {
        Entry tab[] = table;
        modCount++;
        for (int index = tab.length; --index >= 0; )
            tab[index] = null;
        count = 0;
    }

    Returns a shallow copy of this IdentityHashMap instance: the keys and
values themselves are not cloned.
Returns: a shallow copy of this map./**
     * Returns a shallow copy of this <tt>IdentityHashMap</tt> instance: the keys and
     * values themselves are not cloned.
     *
     * @return a shallow copy of this map.
     */
    @Override
    public Object clone() {
        try {
            IdentityHashMap t = (IdentityHashMap) super.clone();
            t.table = new Entry[table.length];
            for (int i = table.length; i-- > 0; ) {
                t.table[i] =
                    (table[i] != null) ? (Entry) table[i].clone() : null;
            }
            t.keySet = null;
            t.entrySet = null;
            t.values = null;
            t.modCount = 0;
            return t;
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError();
        }
    }

    // Views

    private transient Set keySet = null;
    private transient Set entrySet = null;
    private transient Collection values = 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.
Returns: a set view of the keys contained in this map./**
     * 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 <tt>Iterator.remove</tt>,
     * <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and
     * <tt>clear</tt> operations.  It does not support the <tt>add</tt> or
     * <tt>addAll</tt> operations.
     *
     * @return a set view of the keys contained in this map.
     */
    @Override
    public Set keySet() {
        if (keySet == null) {
            keySet = new AbstractSet()
            {
                @Override
                public Iterator iterator() {
                    return getHashIterator(KEYS);
                }
                @Override
                public int size() {
                    return count;
                }
                @Override
                public boolean contains(Object o) {
                    return containsKey(o);
                }
                @Override
                public boolean remove(Object o) {
                    int oldSize = count;
                    IdentityHashMap.this.remove(o);
                    return count != oldSize;
                }
                @Override
                public void clear() {
                    IdentityHashMap.this.clear();
                }
            };
        }
        return keySet;
    }

    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.
Returns: a collection view of the values contained in this map./**
     * 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
     * <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
     * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
     * It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
     *
     * @return a collection view of the values contained in this map.
     */
    @Override
    public Collection values() {
        if (values == null) {
            values = new AbstractCollection()
            {
                @Override
                public Iterator iterator() {
                    return getHashIterator(VALUES);
                }
                @Override
                public int size() {
                    return count;
                }
                @Override
                public boolean contains(Object o) {
                    return containsValue(o);
                }
                @Override
                public void clear() {
                    IdentityHashMap.this.clear();
                }
            };
        }
        return values;
    }

    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.
See Also: Entry
Returns: a collection view of the mappings contained in this map./**
     * Returns a collection view of the mappings contained in this map.  Each
     * element in the returned collection is a <tt>Map.Entry</tt>.  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
     * <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>,
     * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations.
     * It does not support the <tt>add</tt> or <tt>addAll</tt> operations.
     *
     * @return a collection view of the mappings contained in this map.
     * @see java.util.Map.Entry
     */
    @Override
    public Set entrySet() {
        if (entrySet == null) {
            entrySet = new AbstractSet()
            {
                @Override
                public Iterator iterator() {
                    return getHashIterator(ENTRIES);
                }

                @Override
                public boolean contains(Object o) {
                    if (!(o instanceof Map.Entry))
                        return false;
                    Map.Entry entry = (Map.Entry) o;
                    Object key = entry.getKey();
                    Entry tab[] = table;
                    int hash = (key == null ? 0 : System.identityHashCode(key));
                    int index = (hash & 0x7FFFFFFF) % tab.length;

                    for (Entry e = tab[index]; e != null; e = e.next)
                        if (e.hash == hash && e.equals(entry))
                            return true;
                    return false;
                }

                @Override
                public boolean remove(Object o) {
                    if (!(o instanceof Map.Entry))
                        return false;
                    Map.Entry entry = (Map.Entry) o;
                    Object key = entry.getKey();
                    Entry tab[] = table;
                    int hash = (key == null ? 0 : System.identityHashCode(key));
                    int index = (hash & 0x7FFFFFFF) % tab.length;

                    for (Entry e = tab[index], prev = null;
                        e != null;
                        prev = e, e = e.next) {
                        if (e.hash == hash && e.equals(entry)) {
                            modCount++;
                            if (prev != null)
                                prev.next = e.next;
                            else
                                tab[index] = e.next;

                            count--;
                            e.value = null;
                            return true;
                        }
                    }
                    return false;
                }

                @Override
                public int size() {
                    return count;
                }

                @Override
                public void clear() {
                    IdentityHashMap.this.clear();
                }
            };
        }

        return entrySet;
    }

    private Iterator getHashIterator(int type) {
        if (count == 0) {
            return emptyHashIterator;
        } else {
            return new HashIterator(type);
        }
    }

    IdentityHashMap collision list entry.
/**
     * IdentityHashMap collision list entry.
     */
    private static class Entry implements Map.Entry {
        int hash;
        Object key;
        Object value;
        Entry next;

        Entry(int hash, Object key, Object value, Entry next) {
            this.hash = hash;
            this.key = key;
            this.value = value;
            this.next = next;
        }

        @Override
        protected Object clone() {
            return new Entry(
                hash,
                key,
                value,
                (next == null ? null : (Entry) next.clone()));
        }

        // Map.Entry Ops

        public Object getKey() {
            return key;
        }

        public Object getValue() {
            return value;
        }

        public Object setValue(Object value) {
            Object oldValue = this.value;
            this.value = value;
            return oldValue;
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof Map.Entry))
                return false;
            Map.Entry e = (Map.Entry) o;

            return (key == e.getKey())
                && (value == null
                    ? e.getValue() == null
                    : value.equals(e.getValue()));
        }

        @Override
        public int hashCode() {
            return hash ^ (value == null ? 0 : value.hashCode());
        }

        @Override
        public String toString() {
            return key + "=" + value;
        }
    }

    // Types of Iterators
    private static final int KEYS = 0;
    private static final int VALUES = 1;
    private static final int ENTRIES = 2;

    private static EmptyHashIterator emptyHashIterator =
        new EmptyHashIterator();

    private static class EmptyHashIterator implements Iterator {

        EmptyHashIterator() {

        }

        public boolean hasNext() {
            return false;
        }

        public Object next() {
            throw new NoSuchElementException();
        }

        public void remove() {
            throw new IllegalStateException();
        }

    }

    private class HashIterator implements Iterator {
        Entry[] table = IdentityHashMap.this.table;
        int index = table.length;
        Entry entry = null;
        Entry lastReturned = null;
        int type;

        The modCount value that the iterator believes that the backing
List should have.  If this expectation is violated, the iterator
has detected concurrent modification.
/**
         * The modCount value that the iterator believes that the backing
         * List should have.  If this expectation is violated, the iterator
         * has detected concurrent modification.
         */
        private int expectedModCount = modCount;

        HashIterator(int type) {
            this.type = type;
        }

        public boolean hasNext() {
            Entry e = entry;
            int i = index;
            Entry t[] = table;
            /* Use locals for faster loop iteration */
            while (e == null && i > 0)
                e = t[--i];
            entry = e;
            index = i;
            return e != null;
        }

        public Object next() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();

            Entry et = entry;
            int i = index;
            Entry t[] = table;

            /* Use locals for faster loop iteration */
            while (et == null && i > 0)
                et = t[--i];

            entry = et;
            index = i;
            if (et != null) {
                Entry e = lastReturned = entry;
                entry = e.next;
                return type == KEYS ? e.key : (type == VALUES ? e.value : e);
            }
            throw new NoSuchElementException();
        }

        public void remove() {
            if (lastReturned == null)
                throw new IllegalStateException();
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();

            Entry[] tab = IdentityHashMap.this.table;
            int index = (lastReturned.hash & 0x7FFFFFFF) % tab.length;

            for (Entry e = tab[index], prev = null;
                e != null;
                prev = e, e = e.next) {
                if (e == lastReturned) {
                    modCount++;
                    expectedModCount++;
                    if (prev == null)
                        tab[index] = e.next;
                    else
                        prev.next = e.next;
                    count--;
                    lastReturned = null;
                    return;
                }
            }
            throw new ConcurrentModificationException();
        }
    }

    Save the state of the IdentityHashMap instance to a stream (i.e.,
serialize it).
@serialData The capacity of the IdentityHashMap (the length of the
	   bucket array) is emitted (int), followed  by the
	   size of the IdentityHashMap (the number of key-value
	   mappings), followed by the key (Object) and value (Object)
	   for each key-value mapping represented by the IdentityHashMap
The key-value mappings are emitted in no particular order./**
     * Save the state of the <tt>IdentityHashMap</tt> instance to a stream (i.e.,
     * serialize it).
     *
     * @serialData The <i>capacity</i> of the IdentityHashMap (the length of the
     *		   bucket array) is emitted (int), followed  by the
     *		   <i>size</i> of the IdentityHashMap (the number of key-value
     *		   mappings), followed by the key (Object) and value (Object)
     *		   for each key-value mapping represented by the IdentityHashMap
     * The key-value mappings are emitted in no particular order.
     */
    private void writeObject(java.io.ObjectOutputStream s)
        throws java.io.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(count);

        // Write out keys and values (alternating)
        for (int index = table.length - 1; index >= 0; index--) {
            Entry entry = table[index];

            while (entry != null) {
                s.writeObject(entry.key);
                s.writeObject(entry.value);
                entry = entry.next;
            }
        }
    }

    Reconstitute the IdentityHashMap instance from a stream (i.e.,
deserialize it).
/**
     * Reconstitute the <tt>IdentityHashMap</tt> instance from a stream (i.e.,
     * deserialize it).
     */
    private void readObject(java.io.ObjectInputStream s)
        throws java.io.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];

        // Read in size (number of Mappings)
        int size = s.readInt();

        // Read the keys and values, and put the mappings in the IdentityHashMap
        for (int i = 0; i < size; i++) {
            Object key = s.readObject();
            Object value = s.readObject();
            put(key, value);
        }
    }

    int capacity() {
        return table.length;
    }

    float loadFactor() {
        return loadFactor;
    }
}
Params:	initialCapacity – the initial capacity of the IdentityHashMap. loadFactor – the load factor of the IdentityHashMap
Throws:	IllegalArgumentException – if the initial capacity is less than zero, or if the load factor is nonpositive.
Params:	value – value whose presence in this map is to be tested.
Returns:	`true` if this map maps one or more keys to the specified value.
Params:	key – key whose presence in this Map is to be tested.
Returns:	`true` if this map contains a mapping for the specified key.
Params:	key – key whose associated value is to be returned.
Returns:	the value to which this map maps the specified key.
Params:	key – key with which the specified value is to be associated. value – value to be associated with the specified key.
Returns:	previous value associated with specified key, or `null` if there was no mapping for key. A `null` return can also indicate that the IdentityHashMap previously associated `null` with the specified key.
Params:	key – key whose mapping is to be removed from the map.
Returns:	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.
See Also:	Entry
Returns:	a collection view of the mappings contained in this map.
/

org.freemarker/ freemarker/ 2.3.28/ freemarker/ext/util/IdentityHashMap.java
