content: package com.alibaba.fastjson.util;
  
  import java.io.IOException;
  import java.io.Serializable;
  import java.util.*;
  
  /**
   * @deprecated
   */
  public class AntiCollisionHashMap<K, V> extends AbstractMap<K, V> implements
          Map<K, V>, Cloneable, Serializable {
  
      transient volatile Set<K> keySet = null;
      transient volatile Collection<V> 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<K, V>[] table;
  
      /**
       * The number of key-value mappings contained in this 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 SafelyHashMap has been structurally modified
       * Structural modifications are those that change the number of mappings in
       * the SafelyHashMap or otherwise modify its internal structure (e.g.,
       * rehash). This field is used to make iterators on Collection-views of the
       * SafelyHashMap fail-fast. (See ConcurrentModificationException).
       */
      transient volatile int modCount;
  
      /**
       * Constructs an empty <tt>SafelyHashMap</tt> 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
       */
  
      final static int M_MASK = 0x8765fed3;
      final static int SEED = -2128831035;
      final static int KEY = 16777619;
  
      final int random = new Random().nextInt(99999); // a fixed value in an instance
      private int hashString(String key) {
  
          int hash = SEED * random;
          for (int i = 0; i < key.length(); i++)
              hash = (hash * KEY) ^ key.charAt(i);
          return (hash ^ (hash >> 1)) & M_MASK;
      }
  
      public AntiCollisionHashMap(int initialCapacity, float loadFactor) {
          if (initialCapacity < 0)
              throw new IllegalArgumentException("Illegal initial capacity: "
                      + initialCapacity);
          if (initialCapacity > MAXIMUM_CAPACITY)
              initialCapacity = MAXIMUM_CAPACITY;
          if (loadFactor <= 0 || Float.isNaN(loadFactor))
              throw new IllegalArgumentException("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();
      }
  
      /**
       * Constructs an empty <tt>SafelyHashMap</tt> 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 AntiCollisionHashMap(int initialCapacity) {
          this(initialCapacity, DEFAULT_LOAD_FACTOR);
      }
  
      /**
       * Constructs an empty <tt>SafelyHashMap</tt> with the default initial
       * capacity (16) and the default load factor (0.75).
       */
      public AntiCollisionHashMap() {
          this.loadFactor = DEFAULT_LOAD_FACTOR;
          threshold = (int) (DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
          table = new Entry[DEFAULT_INITIAL_CAPACITY];
          init();
      }
  
      /**
       * Constructs a new <tt>SafelyHashMap</tt> with the same mappings as the
       * specified <tt>Map</tt>. The <tt>SafelyHashMap</tt> is created with
       * default load factor (0.75) and an initial capacity sufficient to hold the
       * mappings in the specified <tt>Map</tt>.
       *
       * @param m
       *            the map whose mappings are to be placed in this map
       * @throws NullPointerException
       *             if the specified map is null
       */
      public AntiCollisionHashMap(Map<? extends K, ? extends V> m) {
          this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
                  DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR);
          putAllForCreate(m);
      }
  
      // internal utilities
  
      /**
       * Initialization hook for subclasses. This method is called in all
       * constructors and pseudo-constructors (clone, readObject) after
       * SafelyHashMap 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() {
      }
  
      /**
       * Applies a supplemental hash function to a given hashCode, which defends
       * against poor quality hash functions. This is critical because
       * SafelyHashMap uses power-of-two length hash tables, that otherwise
       * encounter collisions for hashCodes that do not differ in lower bits.
       * Note: Null keys always map to hash 0, thus index 0.
       */
      static int hash(int h) {
          // This function ensures that hashCodes that differ only by
          // constant multiples at each bit position have a bounded
          // number of collisions (approximately 8 at default load factor).
          h = h * h;
          h ^= (h >>> 20) ^ (h >>> 12);
          return h ^ (h >>> 7) ^ (h >>> 4);
      }
  
      /**
       * 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
       */
      public int size() {
          return size;
      }
  
      /**
       * Returns <tt>true</tt> if this map contains no key-value mappings.
       *
       * @return <tt>true</tt> if this map contains no key-value mappings
       */
      public boolean isEmpty() {
          return size == 0;
      }
  
      /**
       * Returns the value to which the specified key is mapped, or {@code null}
       * if this map contains no mapping for the key.
       *
       * <p>
       * More formally, if this map contains a mapping from a key {@code k} to a
       * value {@code v} such that {@code (key==null ? k==null :
       * key.equals(k))}, then this method returns {@code v}; otherwise it returns
       * {@code null}. (There can be at most one such mapping.)
       *
       * <p>
       * A return value of {@code null} 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 {@code null}. The {@link #containsKey
       * containsKey} operation may be used to distinguish these two cases.
       *
       * @see #put(Object, Object)
       */
      public V get(Object key) {
          if (key == null)
              return getForNullKey();
          int hash = 0;
          if (key instanceof String)
              hash = hash(hashString((String) key));
          else
              hash = hash(key.hashCode());
          for (Entry<K, V> e = table[indexFor(hash, table.length)]; e != null; e = e.next) {
              Object k;
              if (e.hash == hash && ((k = e.key) == key || key.equals(k)))
                  return e.value;
          }
          return null;
      }
  
      /**
       * Offloaded version of get() to look up null keys. Null keys map to index
       * 0. This null case is split out into separate methods for the sake of
       * performance in the two most commonly used operations (get and put), but
       * incorporated with conditionals in others.
       */
      private V getForNullKey() {
          for (Entry<K, V> e = table[0]; e != null; e = e.next) {
              if (e.key == null)
                  return e.value;
          }
          return null;
      }
  
      /**
       * Returns <tt>true</tt> if this map contains a mapping for the specified
       * key.
       *
       * @param key
       *            The key whose presence in this map is to be tested
       * @return <tt>true</tt> if this map contains a mapping for the specified
       *         key.
       */
      public boolean containsKey(Object key) {
          return getEntry(key) != null;
      }
  
      /**
       * Returns the entry associated with the specified key in the SafelyHashMap.
       * Returns null if the SafelyHashMap contains no mapping for the key.
       */
      final Entry<K, V> getEntry(Object key) {
          int hash = (key == null) ? 0
                  : (key instanceof String) ? hash(hashString((String) key))
                  : hash(key.hashCode());
          for (Entry<K, V> e = table[indexFor(hash, table.length)]; e != null; e = e.next) {
              Object k;
              if (e.hash == hash
                      && ((k = e.key) == key || (key != null && key.equals(k))))
                  return e;
          }
          return null;
      }
  
      /**
       * Associates the specified value with the specified key in this map. If the
       * map previously contained a mapping for the 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 the previous value associated with <tt>key</tt>, or <tt>null</tt>
       *         if there was no mapping for <tt>key</tt>. (A <tt>null</tt> return
       *         can also indicate that the map previously associated
       *         <tt>null</tt> with <tt>key</tt>.)
       */
      public V put(K key, V value) {
          if (key == null)
              return putForNullKey(value);
          int hash = 0;
          if (key instanceof String)
              hash = hash(hashString((String) key));
          else
              hash = hash(key.hashCode());
          int i = indexFor(hash, table.length);
          for (Entry<K, V> e = table[i]; e != null; e = e.next) {
              Object k;
              if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
                  V oldValue = e.value;
                  e.value = value;
                  return oldValue;
              }
          }
  
          modCount++;
          addEntry(hash, key, value, i);
          return null;
      }
  
      /**
       * Offloaded version of put for null keys
       */
      private V putForNullKey(V value) {
          for (Entry<K, V> e = table[0]; e != null; e = e.next) {
              if (e.key == null) {
                  V oldValue = e.value;
                  e.value = value;
                  return oldValue;
              }
          }
          modCount++;
          addEntry(0, null, value, 0);
          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) {
          int hash = (key == null) ? 0
                  : (key instanceof String) ? hash(hashString((String) key))
                  : hash(key.hashCode());
          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<K, V> e = table[i]; e != null; e = e.next) {
              Object k;
              if (e.hash == hash
                      && ((k = e.key) == key || (key != null && key.equals(k)))) {
                  e.value = value;
                  return;
              }
          }
  
          createEntry(hash, key, value, i);
      }
  
      private void putAllForCreate(Map<? extends K, ? extends V> m) {
          for (Iterator<? extends Map.Entry<? extends K, ? extends V>> i = m
                  .entrySet().iterator(); i.hasNext();) {
              Map.Entry<? extends K, ? extends V> 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<K, V>[] oldTable = table;
          int oldCapacity = oldTable.length;
          if (oldCapacity == MAXIMUM_CAPACITY) {
              threshold = Integer.MAX_VALUE;
              return;
          }
  
          Entry<K, V>[] newTable = new Entry[newCapacity];
          transfer(newTable);
          table = newTable;
          threshold = (int) (newCapacity * loadFactor);
      }
  
      /**
       * Transfers 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<K, V> e = src[j];
              if (e != null) {
                  src[j] = null;
                  do {
                      Entry<K, V> 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
       */
      public void putAll(Map<? extends K, ? extends V> 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<? extends Map.Entry<? extends K, ? extends V>> i = m
                  .entrySet().iterator(); i.hasNext();) {
              Map.Entry<? extends K, ? extends V> e = i.next();
              put(e.getKey(), e.getValue());
          }
      }
  
      /**
       * Removes the mapping for the specified key from this map if present.
       *
       * @param key
       *            key whose mapping is to be removed from the map
       * @return the previous value associated with <tt>key</tt>, or <tt>null</tt>
       *         if there was no mapping for <tt>key</tt>. (A <tt>null</tt> return
       *         can also indicate that the map previously associated
       *         <tt>null</tt> with <tt>key</tt>.)
       */
      public V remove(Object key) {
          Entry<K, V> e = removeEntryForKey(key);
          return (e == null ? null : e.value);
      }
  
      /**
       * Removes and returns the entry associated with the specified key in the
       * SafelyHashMap. Returns null if the SafelyHashMap contains no mapping for
       * this key.
       */
      final Entry<K, V> removeEntryForKey(Object key) {
          int hash = (key == null) ? 0
                  : (key instanceof String) ? hash(hashString((String) key))
                  : hash(key.hashCode());
          int i = indexFor(hash, table.length);
          Entry<K, V> prev = table[i];
          Entry<K, V> e = prev;
  
          while (e != null) {
              Entry<K, V> next = e.next;
              Object k;
              if (e.hash == hash
                      && ((k = e.key) == key || (key != null && key.equals(k)))) {
                  modCount++;
                  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.
       */
      final Entry<K, V> removeMapping(Object o) {
          if (!(o instanceof Map.Entry))
              return null;
  
          Map.Entry<K, V> entry = (Map.Entry<K, V>) o;
          Object key = entry.getKey();
          int hash = (key == null) ? 0
                  : (key instanceof String) ? hash(hashString((String) key))
                  : hash(key.hashCode());
          int i = indexFor(hash, table.length);
          Entry<K, V> prev = table[i];
          Entry<K, V> e = prev;
  
          while (e != null) {
              Entry<K, V> next = e.next;
              if (e.hash == hash && e.equals(entry)) {
                  modCount++;
                  size--;
                  if (prev == e)
                      table[i] = next;
                  else
                      prev.next = next;
                  return e;
              }
              prev = e;
              e = next;
          }
  
          return e;
      }
  
      /**
       * Removes all of the mappings from this map. The map will be empty after
       * this call returns.
       */
      public void clear() {
          modCount++;
          Entry[] tab = table;
          for (int i = 0; i < tab.length; i++)
              tab[i] = null;
          size = 0;
      }
  
      /**
       * 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
       */
      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 <tt>SafelyHashMap</tt> instance: the keys
       * and values themselves are not cloned.
       *
       * @return a shallow copy of this map
       */
      public Object clone() {
          AntiCollisionHashMap<K, V> result = null;
          try {
              result = (AntiCollisionHashMap<K, V>) 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<K, V> implements Map.Entry<K, V> {
          final K key;
          V value;
          Entry<K, V> next;
          final int hash;
  
          /**
           * Creates new entry.
           */
          Entry(int h, K k, V v, Entry<K, V> n) {
              value = v;
              next = n;
              key = k;
              hash = h;
          }
  
          public final K getKey() {
              return key;
          }
  
          public final V getValue() {
              return value;
          }
  
          public final V setValue(V newValue) {
              V oldValue = value;
              value = newValue;
              return oldValue;
          }
  
          public final 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();
                  return (v1 == v2 || (v1 != null && v1.equals(v2)));
              }
              return false;
          }
  
          public final int hashCode() {
              return (key == null ? 0 : key.hashCode())
                      ^ (value == null ? 0 : value.hashCode());
          }
  
          public final String toString() {
              return getKey() + "=" + getValue();
          }
  
      }
  
      /**
       * Adds 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<K, V> e = table[bucketIndex];
          table[bucketIndex] = new Entry<K, V>(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 SafelyHashMap(Map),
       * clone, and readObject.
       */
      void createEntry(int hash, K key, V value, int bucketIndex) {
          Entry<K, V> e = table[bucketIndex];
          table[bucketIndex] = new Entry<K, V>(hash, key, value, e);
          size++;
      }
  
      private abstract class HashIterator<E> implements Iterator<E> {
          Entry<K, V> next; // next entry to return
          int expectedModCount; // For fast-fail
          int index; // current slot
          Entry<K, V> current; // current entry
  
          HashIterator() {
              expectedModCount = modCount;
              if (size > 0) { // advance to first entry
                  Entry[] t = table;
                  while (index < t.length && (next = t[index++]) == null)
                      ;
              }
          }
  
          public final boolean hasNext() {
              return next != null;
          }
  
          final Entry<K, V> nextEntry() {
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
              Entry<K, V> e = next;
              if (e == null)
                  throw new NoSuchElementException();
  
              if ((next = e.next) == null) {
                  Entry[] t = table;
                  while (index < t.length && (next = t[index++]) == null)
                      ;
              }
              current = e;
              return e;
          }
  
          public void remove() {
              if (current == null)
                  throw new IllegalStateException();
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
              Object k = current.key;
              current = null;
              AntiCollisionHashMap.this.removeEntryForKey(k);
              expectedModCount = modCount;
          }
  
      }
  
      private final class ValueIterator extends HashIterator<V> {
          public V next() {
              return nextEntry().value;
          }
      }
  
      private final class KeyIterator extends HashIterator<K> {
          public K next() {
              return nextEntry().getKey();
          }
      }
  
      private final class EntryIterator extends HashIterator<Map.Entry<K, V>> {
          public Map.Entry<K, V> next() {
              return nextEntry();
          }
      }
  
      // Subclass overrides these to alter behavior of views' iterator() method
      Iterator<K> newKeyIterator() {
          return new KeyIterator();
      }
  
      Iterator<V> newValueIterator() {
          return new ValueIterator();
      }
  
      Iterator<Map.Entry<K, V>> newEntryIterator() {
          return new EntryIterator();
      }
  
      // Views
  
      private transient Set<Map.Entry<K, V>> entrySet = null;
  
      /**
       * Returns a {@link 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. If the map is modified while an iteration over the set is in
       * progress (except through the iterator's own <tt>remove</tt> operation),
       * the results of the iteration are undefined. The set supports element
       * removal, which removes the corresponding mapping from the 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.
       */
      public Set<K> keySet() {
  
          Set<K> ks = keySet;
          return (ks != null ? ks : (keySet = new KeySet()));
      }
  
      private final class KeySet extends AbstractSet<K> {
          public Iterator<K> iterator() {
              return newKeyIterator();
          }
  
          public int size() {
              return size;
          }
  
          public boolean contains(Object o) {
              return containsKey(o);
          }
  
          public boolean remove(Object o) {
              return AntiCollisionHashMap.this.removeEntryForKey(o) != null;
          }
  
          public void clear() {
              AntiCollisionHashMap.this.clear();
          }
      }
  
      /**
       * Returns a {@link 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. If the map is modified while an
       * iteration over the collection is in progress (except through the
       * iterator's own <tt>remove</tt> operation), the results of the iteration
       * are undefined. 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.
       */
      public Collection<V> values() {
          Collection<V> vs = values;
          return (vs != null ? vs : (values = new Values()));
      }
  
      private final class Values extends AbstractCollection<V> {
          public Iterator<V> iterator() {
              return newValueIterator();
          }
  
          public int size() {
              return size;
          }
  
          public boolean contains(Object o) {
              return containsValue(o);
          }
  
          public void clear() {
              AntiCollisionHashMap.this.clear();
          }
      }
  
      /**
       * Returns a {@link Set} view of the mappings contained in this map. The set
       * is backed by the map, so changes to the map are reflected in the set, and
       * vice-versa. If the map is modified while an iteration over the set is in
       * progress (except through the iterator's own <tt>remove</tt> operation, or
       * through the <tt>setValue</tt> operation on a map entry returned by the
       * iterator) the results of the iteration are undefined. The set supports
       * element removal, which removes the corresponding mapping from the 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 mappings contained in this map
       */
      public Set<Map.Entry<K, V>> entrySet() {
          return entrySet0();
      }
  
      private Set<Map.Entry<K, V>> entrySet0() {
          Set<Map.Entry<K, V>> es = entrySet;
          return es != null ? es : (entrySet = new EntrySet());
      }
  
      private final class EntrySet extends AbstractSet<Map.Entry<K, V>> {
          public Iterator<Map.Entry<K, V>> iterator() {
              return newEntryIterator();
          }
  
          public boolean contains(Object o) {
              if (!(o instanceof Map.Entry))
                  return false;
              Map.Entry<K, V> e = (Map.Entry<K, V>) o;
              Entry<K, V> candidate = getEntry(e.getKey());
              return candidate != null && candidate.equals(e);
          }
  
          public boolean remove(Object o) {
              return removeMapping(o) != null;
          }
  
          public int size() {
              return size;
          }
  
          public void clear() {
              AntiCollisionHashMap.this.clear();
          }
      }
  
      /**
       * Save the state of the <tt>SafelyHashMap</tt> instance to a stream (i.e.,
       * serialize it).
       *
       * @serialData The <i>capacity</i> of the SafelyHashMap (the length of the
       *             bucket array) is emitted (int), followed by the <i>size</i>
       *             (an int, the number of key-value mappings), followed by the
       *             key (Object) and value (Object) for each key-value mapping.
       *             The key-value mappings are emitted in no particular order.
       */
      private void writeObject(java.io.ObjectOutputStream s) throws IOException {
          Iterator<Map.Entry<K, V>> i = (size > 0) ? entrySet0().iterator()
                  : null;
  
          // 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)
          if (i != null) {
              while (i.hasNext()) {
                  Map.Entry<K, V> e = i.next();
                  s.writeObject(e.getKey());
                  s.writeObject(e.getValue());
              }
          }
      }
  
      private static final long serialVersionUID = 362498820763181265L;
  
      /**
       * Reconstitute the <tt>SafelyHashMap</tt> 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 SafelyHashMap
          for (int i = 0; i < size; i++) {
              K key = (K) s.readObject();
              V value = (V) s.readObject();
              putForCreate(key, value);
          }
      }
  
  }