http://labs.carrotsearch.com/hppc.html/hppc: High Performance Primitive Collections. Fundamental data structures (maps, sets, lists, stacks, queues) generated for combinations of object and primitive types to conserve JVM memory and speed up execution. (Carrot Search s.c.)
  • Dawid Weiss
  • Stanisław Osiński 
  
package com.carrotsearch.hppc;

import java.util.*;

import com.carrotsearch.hppc.cursors.*;
import com.carrotsearch.hppc.predicates.*;
import com.carrotsearch.hppc.procedures.*;

import static com.carrotsearch.hppc.HashContainers.*;
import static com.carrotsearch.hppc.Containers.*;


A hash map of short to byte, implemented using open
addressing with linear probing for collision resolution.

Note: read about important differences 
between hash and scatter sets.


See Also:
/**
 * A hash map of <code>short</code> to <code>byte</code>, implemented using open
 * addressing with linear probing for collision resolution.
 * 
 * <p><strong>Note:</strong> read about <a href="{@docRoot}/overview-summary.html#scattervshash">important differences 
 * between hash and scatter sets</a>.</p>
 * 
 * @see ShortByteScatterMap
 * @see <a href="{@docRoot}/overview-summary.html#interfaces">HPPC interfaces diagram</a> 
 */
  
 @com.carrotsearch.hppc.Generated(
    date = "2018-05-21T12:24:06+0200",
    value = "KTypeVTypeHashMap.java") 
public class ShortByteHashMap
  implements   
               
             ShortByteMap,
             Preallocable,
             Cloneable
{
  
The array holding keys.

/** 
   * The array holding keys.
   */
  public   short []   
         keys;

  
The array holding values. 

/**
   * The array holding values. 
   */
  public   byte []   
         values;

  
We perturb hash values with a container-unique
seed to avoid problems with nearly-sorted-by-hash 
values on iterations.

See Also:
  • hashKey
  • http://issues.carrot2.org/browse/HPPC-80
  • http://issues.carrot2.org/browse/HPPC-103
/**
   * We perturb hash values with a container-unique
   * seed to avoid problems with nearly-sorted-by-hash 
   * values on iterations.
   * 
   * @see #hashKey
   * @see "http://issues.carrot2.org/browse/HPPC-80"
   * @see "http://issues.carrot2.org/browse/HPPC-103"
   */
  protected int keyMixer;

  
The number of stored keys (assigned key slots), excluding the special "empty" key, if any (use size() instead). 
See Also:
/**
   * The number of stored keys (assigned key slots), excluding the special 
   * "empty" key, if any (use {@link #size()} instead).
   * 
   * @see #size()
   */
  protected int assigned;

  
Mask for slot scans in keys. 
/**
   * Mask for slot scans in {@link #keys}.
   */
  protected int mask;

  
Expand (rehash) keys when assigned hits this value. 
/**
   * Expand (rehash) {@link #keys} when {@link #assigned} hits this value. 
   */
  protected int resizeAt;

  
Special treatment for the "empty slot" key marker.

/**
   * Special treatment for the "empty slot" key marker.
   */
  protected boolean hasEmptyKey;
  
  
The load factor for keys. 
/**
   * The load factor for {@link #keys}.
   */
  protected double loadFactor;

  
Per-instance hash order mixing strategy.

See Also:
  • keyMixer
/**
   * Per-instance hash order mixing strategy.
   * @see #keyMixer
   */
  protected HashOrderMixingStrategy orderMixer;

  
New instance with sane defaults.

/**
   * New instance with sane defaults.
   */
  public ShortByteHashMap() {
    this(DEFAULT_EXPECTED_ELEMENTS);
  }

  
New instance with sane defaults.

Params:
  • expectedElements – 
         The expected number of elements guaranteed not to cause buffer
         expansion (inclusive).
/**
   * New instance with sane defaults.
   * 
   * @param expectedElements
   *          The expected number of elements guaranteed not to cause buffer
   *          expansion (inclusive).
   */
  public ShortByteHashMap(int expectedElements) {
    this(expectedElements, DEFAULT_LOAD_FACTOR);
  }

  
New instance with sane defaults.

Params:
  • expectedElements – 
         The expected number of elements guaranteed not to cause buffer
         expansion (inclusive).
  • loadFactor –  The load factor for internal buffers. Insane load factors (zero, full capacity) are rejected by verifyLoadFactor(double).
/**
   * New instance with sane defaults.
   * 
   * @param expectedElements
   *          The expected number of elements guaranteed not to cause buffer
   *          expansion (inclusive).
   * @param loadFactor
   *          The load factor for internal buffers. Insane load factors (zero, full capacity)
   *          are rejected by {@link #verifyLoadFactor(double)}.
   */
  public ShortByteHashMap(int expectedElements, double loadFactor) {
    this(expectedElements, loadFactor, HashOrderMixing.defaultStrategy());
  }

  
New instance with the provided defaults.

Params:
  • expectedElements – 
         The expected number of elements guaranteed not to cause a rehash (inclusive).
  • loadFactor –  The load factor for internal buffers. Insane load factors (zero, full capacity) are rejected by verifyLoadFactor(double).
  • orderMixer –  Hash key order mixing strategy. See HashOrderMixing for predefined implementations. Use constant mixers only if you understand the potential consequences.
/**
   * New instance with the provided defaults.
   * 
   * @param expectedElements
   *          The expected number of elements guaranteed not to cause a rehash (inclusive).
   * @param loadFactor
   *          The load factor for internal buffers. Insane load factors (zero, full capacity)
   *          are rejected by {@link #verifyLoadFactor(double)}.
   * @param orderMixer
   *          Hash key order mixing strategy. See {@link HashOrderMixing} for predefined
   *          implementations. Use constant mixers only if you understand the potential
   *          consequences.
   */
  public ShortByteHashMap(int expectedElements, double loadFactor, HashOrderMixingStrategy orderMixer) {
    this.orderMixer = orderMixer;
    this.loadFactor = verifyLoadFactor(loadFactor);
    ensureCapacity(expectedElements);
  }

  
Create a hash map from all key-value pairs of another container.

/**
   * Create a hash map from all key-value pairs of another container.
   */
  public ShortByteHashMap(ShortByteAssociativeContainer container) {
    this(container.size());
    putAll(container);
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte put(short key, byte value) {
    assert assigned < mask + 1;

    final int mask = this.mask;
    if (((key) == 0)) {
      hasEmptyKey = true;
      byte previousValue =  values[mask + 1];
      values[mask + 1] = value;
      return previousValue;
    } else {
      final short[] keys =  this.keys;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          final byte previousValue =  values[slot];
          values[slot] = value;
          return previousValue;
        }
        slot = (slot + 1) & mask;
      }

      if (assigned == resizeAt) {
        allocateThenInsertThenRehash(slot, key, value);
      } else {
        keys[slot] = key;
        values[slot] = value;
      }

      assigned++;
      return ((byte) 0);
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int putAll(ShortByteAssociativeContainer container) {
    final int count = size();
    for (ShortByteCursor c : container) {
      put(c.key, c.value);
    }
    return size() - count;
  }

  
Puts all key/value pairs from a given iterable into this map.

/**
   * Puts all key/value pairs from a given iterable into this map.
   */
  @Override
  public int putAll(Iterable<? extends ShortByteCursor> iterable){
    final int count = size();
    for (ShortByteCursor c : iterable) {
      put(c.key, c.value);
    }
    return size() - count;
  }

  
Trove-inspired API method. An equivalent
of the following code:

if (!map.containsKey(key)) map.put(value);



Params:
  • key – The key of the value to check.
  • value – The value to put if key does not exist.
Returns:true if key did not exist and value
was placed in the map.
/**
   * <a href="http://trove4j.sourceforge.net">Trove</a>-inspired API method. An equivalent
   * of the following code:
   * <pre>
   * if (!map.containsKey(key)) map.put(value);
   * </pre>
   * 
   * @param key The key of the value to check.
   * @param value The value to put if <code>key</code> does not exist.
   * @return <code>true</code> if <code>key</code> did not exist and <code>value</code>
   * was placed in the map.
   */
  public boolean putIfAbsent(short key, byte value) {
    int keyIndex = indexOf(key);
    if (!indexExists(keyIndex)) {
      indexInsert(keyIndex, key, value);
      return true;
    } else {
      return false;
    }
  }

    
  
If key exists, putValue is inserted into the map,
otherwise any existing value is incremented by additionValue.

Params:
  • key – 
         The key of the value to adjust.
  • putValue – 
         The value to put if key does not exist.
  • incrementValue – 
         The value to add to the existing value if key exists.
Returns:Returns the current value associated with key (after
        changes).
/**
   * If <code>key</code> exists, <code>putValue</code> is inserted into the map,
   * otherwise any existing value is incremented by <code>additionValue</code>.
   * 
   * @param key
   *          The key of the value to adjust.
   * @param putValue
   *          The value to put if <code>key</code> does not exist.
   * @param incrementValue
   *          The value to add to the existing value if <code>key</code> exists.
   * @return Returns the current value associated with <code>key</code> (after
   *         changes).
   */
  @Override
  public byte putOrAdd(short key, byte putValue, byte incrementValue) {
    assert assigned < mask + 1;

    int keyIndex = indexOf(key);
    if (indexExists(keyIndex)) {
      putValue = ((byte) (( values[keyIndex]) + (incrementValue)));
      indexReplace(keyIndex, putValue);
    } else {
      indexInsert(keyIndex, key, putValue);
    }
    return putValue;
  }
    

     
  
Adds incrementValue to any existing value for the given key
or inserts incrementValue if key did not previously exist.

Params:
  • key – The key of the value to adjust.
  • incrementValue – The value to put or add to the existing value if key exists.
Returns:Returns the current value associated with key (after changes).
/**
   * Adds <code>incrementValue</code> to any existing value for the given <code>key</code>
   * or inserts <code>incrementValue</code> if <code>key</code> did not previously exist.
   * 
   * @param key The key of the value to adjust.
   * @param incrementValue The value to put or add to the existing value if <code>key</code> exists.
   * @return Returns the current value associated with <code>key</code> (after changes).
   */
  @Override
  public byte addTo(short key, byte incrementValue)
  {
    return putOrAdd(key, incrementValue, incrementValue);
  }
    

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte remove(short key) {
    final int mask = this.mask;
    if (((key) == 0)) {
      hasEmptyKey = false;
      byte previousValue =  values[mask + 1];
      values[mask + 1] = ((byte) 0);
      return previousValue;
    } else {
      final short[] keys =  this.keys;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          final byte previousValue =  values[slot];
          shiftConflictingKeys(slot);
          return previousValue;
        }
        slot = (slot + 1) & mask;
      }

      return ((byte) 0);
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int removeAll(ShortContainer other) {
    final int before = size();

    // Try to iterate over the smaller set of values or
    // over the container that isn't implementing 
    // efficient contains() lookup.

    if (other.size() >= size() &&
        other instanceof ShortLookupContainer) {
      if (hasEmptyKey) {
        if (other.contains(((short) 0))) {
          hasEmptyKey = false;
          values[mask + 1] = ((byte) 0);
        }
      }

      final short[] keys =  this.keys;
      for (int slot = 0, max = this.mask; slot <= max;) {
        short existing;
        if (!((existing = keys[slot]) == 0) && other.contains(existing)) {
          // Shift, do not increment slot.
          shiftConflictingKeys(slot);
        } else {
          slot++;
        }
      }
    } else {
      for (ShortCursor c : other) {
        this.remove( c.value);
      }
    }

    return before - size();
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int removeAll(ShortBytePredicate predicate) {
    final int before = size();

    final int mask = this.mask;

    if (hasEmptyKey) {
      if (predicate.apply(((short) 0),  values[mask + 1])) {
        hasEmptyKey = false;
        values[mask + 1] = ((byte) 0);
      }
    }

    final short[] keys =  this.keys;
    final byte[] values =  this.values;
    for (int slot = 0; slot <= mask;) {
      short existing;
      if (!((existing = keys[slot]) == 0) && 
          predicate.apply(existing, values[slot])) {
        // Shift, do not increment slot.
        shiftConflictingKeys(slot);
      } else {
        slot++;
      }
    }

    return before - size();    
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int removeAll(ShortPredicate predicate) {
    final int before = size();

    if (hasEmptyKey) {
      if (predicate.apply(((short) 0))) {
        hasEmptyKey = false;
        values[mask + 1] = ((byte) 0);
      }
    }

    final short[] keys =  this.keys;
    for (int slot = 0, max = this.mask; slot <= max;) {
      short existing;
      if (!((existing = keys[slot]) == 0) &&
          predicate.apply(existing)) {
        // Shift, do not increment slot.
        shiftConflictingKeys(slot);
      } else {
        slot++;
      }
    }

    return before - size();
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte get(short key) {
    if (((key) == 0)) {
      return hasEmptyKey ?  values[mask + 1] : ((byte) 0);
    } else {
      final short[] keys =  this.keys;
      final int mask = this.mask;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          return  values[slot];
        }
        slot = (slot + 1) & mask;
      }

      return ((byte) 0);
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte getOrDefault(short key, byte defaultValue) {
    if (((key) == 0)) {
      return hasEmptyKey ?  values[mask + 1] : defaultValue;
    } else {
      final short[] keys =  this.keys;
      final int mask = this.mask;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          return  values[slot];
        }
        slot = (slot + 1) & mask;
      }

      return defaultValue;
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public boolean containsKey(short key) {
    if (((key) == 0)) {
      return hasEmptyKey;
    } else {
      final short[] keys =  this.keys;
      final int mask = this.mask;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          return true;
        }
        slot = (slot + 1) & mask;
      }    

      return false;
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int indexOf(short key) {
    final int mask = this.mask;
    if (((key) == 0)) {
      return hasEmptyKey ? mask + 1 : ~(mask + 1);
    } else {
      final short[] keys =  this.keys;
      int slot = hashKey(key) & mask;

      short existing;
      while (!((existing = keys[slot]) == 0)) {
        if (((existing) == ( key))) {
          return slot;
        }
        slot = (slot + 1) & mask;
      }

      return ~slot;
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public boolean indexExists(int index) {
    assert index < 0 || 
           (index >= 0 && index <= mask) ||
           (index == mask + 1 && hasEmptyKey);

    return index >= 0; 
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte indexGet(int index) {
    assert index >= 0 : "The index must point at an existing key.";
    assert index <= mask ||
           (index == mask + 1 && hasEmptyKey);

    return  values[index];
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public byte indexReplace(int index, byte newValue) {
    assert index >= 0 : "The index must point at an existing key.";
    assert index <= mask ||
           (index == mask + 1 && hasEmptyKey);

    byte previousValue =  values[index];
    values[index] = newValue;
    return previousValue;
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public void indexInsert(int index, short key, byte value) {
    assert index < 0 : "The index must not point at an existing key.";

    index = ~index;
    if (((key) == 0)) {
      assert index == mask + 1;
      values[index] = value;
      hasEmptyKey = true;
    } else {
      assert ((keys[index]) == 0);

      if (assigned == resizeAt) {
        allocateThenInsertThenRehash(index, key, value);
      } else {
        keys[index] = key;
        values[index] = value;
      }

      assigned++;
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public void clear() {
    assigned = 0;
    hasEmptyKey = false;

    Arrays.fill(keys, ((short) 0));

    /*  */
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public void release() {
    assigned = 0;
    hasEmptyKey = false;

    keys = null;
    values = null;
    ensureCapacity(Containers.DEFAULT_EXPECTED_ELEMENTS);
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int size() {
    return assigned + (hasEmptyKey ? 1 : 0);
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  public boolean isEmpty() {
    return size() == 0;
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public int hashCode() {
    int h = hasEmptyKey ? 0xDEADBEEF : 0;
    for (ShortByteCursor c : this) {
      h += BitMixer.mix(c.key) +
           BitMixer.mix(c.value);
    }
    return h;
  }

  
{@inheritDoc} 

/**
   * {@inheritDoc} 
   */
  @Override
  public boolean equals(Object obj) {
    return obj != null &&
           getClass() == obj.getClass() &&
           equalElements(getClass().cast(obj));
  }

  
Return true if all keys of some other container exist in this container.

/**
   * Return true if all keys of some other container exist in this container.
   */
  protected boolean equalElements(ShortByteHashMap other) {
    if (other.size() != size()) {
      return false;
    }

    for (ShortByteCursor c : other) {
      short key =  c.key;
      if (!containsKey(key) ||
          !((get(key)) == (c.value))) {
        return false;
      }
    }

    return true;
  }

  
Ensure this container can hold at least the
given number of keys (entries) without resizing its buffers.

Params:
  • expectedElements – The total number of keys, inclusive.
/**
   * Ensure this container can hold at least the
   * given number of keys (entries) without resizing its buffers.
   * 
   * @param expectedElements The total number of keys, inclusive.
   */
  @Override
  public void ensureCapacity(int expectedElements) {
    if (expectedElements > resizeAt || keys == null) {
      final short[] prevKeys =  this.keys;
      final byte[] prevValues =  this.values;
      allocateBuffers(minBufferSize(expectedElements, loadFactor));
      if (prevKeys != null && !isEmpty()) {
        rehash(prevKeys, prevValues);
      }
    }
  }

  
An iterator implementation for ShortByteHashMap.iterator. 
/**
   * An iterator implementation for {@link #iterator}.
   */
  private final class EntryIterator extends AbstractIterator<ShortByteCursor> {
    private final ShortByteCursor cursor;
    private final int max = mask + 1;
    private int slot = -1;

    public EntryIterator() {
      cursor = new ShortByteCursor();
    }

    @Override
    protected ShortByteCursor fetch() {
      if (slot < max) {
        short existing;
        for (slot++; slot < max; slot++) {
          if (!((existing =  keys[slot]) == 0)) {
            cursor.index = slot;
            cursor.key = existing;
            cursor.value =  values[slot];
            return cursor;
          }
        }
      }

      if (slot == max && hasEmptyKey) {
        cursor.index = slot;
        cursor.key = ((short) 0);
        cursor.value =  values[max];
        slot++;
        return cursor;
      }

      return done();
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public Iterator<ShortByteCursor> iterator() {
      return new EntryIterator();
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public <T extends ShortByteProcedure> T forEach(T procedure) {
    final short[] keys =  this.keys;
    final byte[] values =  this.values;

    if (hasEmptyKey) {
      procedure.apply(((short) 0),  values[mask + 1]);
    }

    for (int slot = 0, max = this.mask; slot <= max; slot++) {
      if (!((keys[slot]) == 0)) {
        procedure.apply(keys[slot], values[slot]);
      }
    }

    return procedure;
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public <T extends ShortBytePredicate> T forEach(T predicate) {
    final short[] keys =  this.keys;
    final byte[] values =  this.values;

    if (hasEmptyKey) {
      if (!predicate.apply(((short) 0),  values[mask + 1])) {
        return predicate;
      }
    }

    for (int slot = 0, max = this.mask; slot <= max; slot++) {
      if (!((keys[slot]) == 0)) {
        if (!predicate.apply(keys[slot], values[slot])) {
          break;
        }
      }
    }

    return predicate;
  }

  
Returns a specialized view of the keys of this associated container. The view additionally implements ObjectLookupContainer. 
/**
   * Returns a specialized view of the keys of this associated container. The
   * view additionally implements {@link ObjectLookupContainer}.
   */
  public KeysContainer keys() {
    return new KeysContainer();
  }

  
A view of the keys inside this hash map.

/**
   * A view of the keys inside this hash map.
   */
  public final class KeysContainer extends AbstractShortCollection 
                                   implements ShortLookupContainer {
    private final ShortByteHashMap owner = ShortByteHashMap.this;

    @Override
    public boolean contains(short e) {
      return owner.containsKey(e);
    }

    @Override
    public <T extends ShortProcedure> T forEach(final T procedure) {
      owner.forEach(new ShortByteProcedure() {
        @Override
        public void apply(short key, byte value) {
          procedure.apply(key);
        }
      });

      return procedure;
    }

    @Override
    public <T extends ShortPredicate> T forEach(final T predicate) {
      owner.forEach(new ShortBytePredicate() {
        @Override
        public boolean apply(short key, byte value) {
          return predicate.apply(key);
        }
      });

      return predicate;
    }

    @Override
    public boolean isEmpty() {
      return owner.isEmpty();
    }

    @Override
    public Iterator<ShortCursor> iterator() {
      return new KeysIterator();
    }

    @Override
    public int size() {
      return owner.size();
    }

    @Override
    public void clear() {
      owner.clear();
    }
    
    @Override
    public void release() {
      owner.release();
    }

    @Override
    public int removeAll(ShortPredicate predicate) {
      return owner.removeAll(predicate);
    }

    @Override
    public int removeAll(final short e) {
      final boolean hasKey = owner.containsKey(e);
      if (hasKey) {
        owner.remove(e);
        return 1;
      } else {
        return 0;
      }
    }
  };

  
An iterator over the set of assigned keys.

/**
   * An iterator over the set of assigned keys.
   */
  private final class KeysIterator extends AbstractIterator<ShortCursor> {
    private final ShortCursor cursor;
    private final int max = mask + 1;
    private int slot = -1;

    public KeysIterator() {
      cursor = new ShortCursor();
    }

    @Override
    protected ShortCursor fetch() {
      if (slot < max) {
        short existing;
        for (slot++; slot < max; slot++) {
          if (!((existing =  keys[slot]) == 0)) {
            cursor.index = slot;
            cursor.value = existing;
            return cursor;
          }
        }
      }

      if (slot == max && hasEmptyKey) {
        cursor.index = slot;
        cursor.value = ((short) 0);
        slot++;
        return cursor;
      }

      return done();
    }
  }

  
Returns:Returns a container with all values stored in this map.
/**
   * @return Returns a container with all values stored in this map.
   */
  @Override
  public ByteCollection values() {
    return new ValuesContainer();
  }

  
A view over the set of values of this map.

/**
   * A view over the set of values of this map.
   */
  private final class ValuesContainer extends AbstractByteCollection {
    private final ShortByteHashMap owner = ShortByteHashMap.this;

    @Override
    public int size() {
      return owner.size();
    }

    @Override
    public boolean isEmpty() {
      return owner.isEmpty();
    }

    @Override
    public boolean contains(byte value) {
      for (ShortByteCursor c : owner) {
        if (((c.value) == (value))) {
          return true;
        }
      }
      return false;
    }

    @Override
    public <T extends ByteProcedure> T forEach(T procedure) {
      for (ShortByteCursor c : owner) {
        procedure.apply(c.value);
      }
      return procedure;
    }

    @Override
    public <T extends BytePredicate> T forEach(T predicate) {
      for (ShortByteCursor c : owner) {
        if (!predicate.apply(c.value)) {
          break;
        }
      }
      return predicate;
    }

    @Override
    public Iterator<ByteCursor> iterator() {
      return new ValuesIterator();
    }

    @Override
    public int removeAll(final byte e) {
      return owner.removeAll(new ShortBytePredicate() {
        @Override
        public boolean apply(short key, byte value) {
          return ((value) == (e));
        }
      });
    }

    @Override
    public int removeAll(final BytePredicate predicate) {
      return owner.removeAll(new ShortBytePredicate() {
        @Override
        public boolean apply(short key, byte value) {
          return predicate.apply(value);
        }
      });
    }

    @Override
    public void clear() {
      owner.clear();
    }
    
    @Override
    public void release() {
      owner.release();
    }
  }
  
  
An iterator over the set of assigned values.

/**
   * An iterator over the set of assigned values.
   */
  private final class ValuesIterator extends AbstractIterator<ByteCursor> {
    private final ByteCursor cursor;
    private final int max = mask + 1;
    private int slot = -1;

    public ValuesIterator() {
      cursor = new ByteCursor();
    }

    @Override
    protected ByteCursor fetch() {
      if (slot < max) {
        for (slot++; slot < max; slot++) {
          if (!(( keys[slot]) == 0)) {
            cursor.index = slot;
            cursor.value =  values[slot];
            return cursor;
          }
        }
      }

      if (slot == max && hasEmptyKey) {
        cursor.index = slot;
        cursor.value =  values[max];
        slot++;
        return cursor;
      }

      return done();
    }
  }

  
{@inheritDoc}

/**
   * {@inheritDoc}
   */
  @Override
  public ShortByteHashMap clone() {
    try {
      /*  */
      ShortByteHashMap cloned = (ShortByteHashMap) super.clone();
      cloned.keys = keys.clone();
      cloned.values = values.clone();
      cloned.hasEmptyKey = cloned.hasEmptyKey;
      cloned.orderMixer = orderMixer.clone();
      return cloned;
    } catch (CloneNotSupportedException e) {
      throw new RuntimeException(e);
    }
  }

  
Convert the contents of this map to a human-friendly string.

/**
   * Convert the contents of this map to a human-friendly string.
   */
  @Override
  public String toString() {
    final StringBuilder buffer = new StringBuilder();
    buffer.append("[");

    boolean first = true;
    for (ShortByteCursor cursor : this) {
      if (!first) {
        buffer.append(", ");
      }
      buffer.append(cursor.key);
      buffer.append("=>");
      buffer.append(cursor.value);
      first = false;
    }
    buffer.append("]");
    return buffer.toString();
  }

  @Override
  public String visualizeKeyDistribution(int characters) {
    return ShortBufferVisualizer.visualizeKeyDistribution(keys, mask, characters);
  }

  
Creates a hash map from two index-aligned arrays of key-value pairs.

/**
   * Creates a hash map from two index-aligned arrays of key-value pairs.
   */
  public static  ShortByteHashMap from(short[] keys, byte[] values) {
    if (keys.length != values.length) {
      throw new IllegalArgumentException("Arrays of keys and values must have an identical length.");
    }

    ShortByteHashMap map = new ShortByteHashMap(keys.length);
    for (int i = 0; i < keys.length; i++) {
      map.put(keys[i], values[i]);
    }

    return map;
  }
    
  
Returns a hash code for the given key.

The default implementation mixes the hash of the key with keyMixer to differentiate hash order of keys between hash containers. Helps alleviate problems resulting from linear conflict resolution in open addressing.


The output from this function should evenly distribute keys across the
entire integer range.


/**
   * Returns a hash code for the given key.
   * 
   * <p>The default implementation mixes the hash of the key with {@link #keyMixer}
   * to differentiate hash order of keys between hash containers. Helps
   * alleviate problems resulting from linear conflict resolution in open
   * addressing.</p>
   * 
   * <p>The output from this function should evenly distribute keys across the
   * entire integer range.</p>
   */
    protected  
  int hashKey(short key) {
    assert !((key) == 0); // Handled as a special case (empty slot marker).
    return BitMixer.mix(key, this.keyMixer);
  }

  
Validate load factor range and return it. Override and suppress if you need
insane load factors.

/**
   * Validate load factor range and return it. Override and suppress if you need
   * insane load factors.
   */
  protected double verifyLoadFactor(double loadFactor) {
    checkLoadFactor(loadFactor, MIN_LOAD_FACTOR, MAX_LOAD_FACTOR);
    return loadFactor;
  }

  
Rehash from old buffers to new buffers. 

/**
   * Rehash from old buffers to new buffers. 
   */
  protected void rehash(short[] fromKeys, byte[] fromValues) {
    assert fromKeys.length == fromValues.length &&
           HashContainers.checkPowerOfTwo(fromKeys.length - 1);
    
    // Rehash all stored key/value pairs into the new buffers.
    final short[] keys =  this.keys;
    final byte[] values =  this.values;
    final int mask = this.mask;
    short existing;

    // Copy the zero element's slot, then rehash everything else.
    int from = fromKeys.length - 1;
    keys[keys.length - 1] = fromKeys[from];
    values[values.length - 1] = fromValues[from];
    while (--from >= 0) {
      if (!((existing = fromKeys[from]) == 0)) {
        int slot = hashKey(existing) & mask;
        while (!((keys[slot]) == 0)) {
          slot = (slot + 1) & mask;
        }
        keys[slot] = existing;
        values[slot] = fromValues[from];
      }
    }
  }

  
Allocate new internal buffers. This method attempts to allocate
and assign internal buffers atomically (either allocations succeed or not).

/**
   * Allocate new internal buffers. This method attempts to allocate
   * and assign internal buffers atomically (either allocations succeed or not).
   */
  protected void allocateBuffers(int arraySize) {
    assert Integer.bitCount(arraySize) == 1;

    // Compute new hash mixer candidate before expanding.
    final int newKeyMixer = this.orderMixer.newKeyMixer(arraySize);

    // Ensure no change is done if we hit an OOM.
    short[] prevKeys =  this.keys;
    byte[] prevValues =  this.values;
    try {
      int emptyElementSlot = 1;
      this.keys = (new short [arraySize + emptyElementSlot]);
      this.values = (new byte [arraySize + emptyElementSlot]);
    } catch (OutOfMemoryError e) {
      this.keys = prevKeys;
      this.values = prevValues;
      throw new BufferAllocationException(
          "Not enough memory to allocate buffers for rehashing: %,d -> %,d", 
          e,
          this.mask + 1, 
          arraySize);
    }

    this.resizeAt = expandAtCount(arraySize, loadFactor);
    this.keyMixer = newKeyMixer;
    this.mask = arraySize - 1;
  }

  
This method is invoked when there is a new key/ value pair to be inserted into
the buffers but there is not enough empty slots to do so.
New buffers are allocated. If this succeeds, we know we can proceed
with rehashing so we assign the pending element to the previous buffer
(possibly violating the invariant of having at least one empty slot)
and rehash all keys, substituting new buffers at the end.  

/**
   * This method is invoked when there is a new key/ value pair to be inserted into
   * the buffers but there is not enough empty slots to do so.
   * 
   * New buffers are allocated. If this succeeds, we know we can proceed
   * with rehashing so we assign the pending element to the previous buffer
   * (possibly violating the invariant of having at least one empty slot)
   * and rehash all keys, substituting new buffers at the end.  
   */
  protected void allocateThenInsertThenRehash(int slot, short pendingKey, byte pendingValue) {
    assert assigned == resizeAt
           && (( keys[slot]) == 0)
           && !((pendingKey) == 0);

    // Try to allocate new buffers first. If we OOM, we leave in a consistent state.
    final short[] prevKeys =  this.keys;
    final byte[] prevValues =  this.values;
    allocateBuffers(nextBufferSize(mask + 1, size(), loadFactor));
    assert this.keys.length > prevKeys.length;

    // We have succeeded at allocating new data so insert the pending key/value at
    // the free slot in the old arrays before rehashing.
    prevKeys[slot] = pendingKey;
    prevValues[slot] = pendingValue;

    // Rehash old keys, including the pending key.
    rehash(prevKeys, prevValues);
  }
  
  
Shift all the slot-conflicting keys and values allocated to 
(and including) slot.

/**
   * Shift all the slot-conflicting keys and values allocated to 
   * (and including) <code>slot</code>.
   */
  protected void shiftConflictingKeys(int gapSlot) {
    final short[] keys =  this.keys;
    final byte[] values =  this.values;
    final int mask = this.mask;

    // Perform shifts of conflicting keys to fill in the gap.
    int distance = 0;
    while (true) {
      final int slot = (gapSlot + (++distance)) & mask;
      final short existing = keys[slot];
      if (((existing) == 0)) {
        break;
      }

      final int idealSlot = hashKey(existing);
      final int shift = (slot - idealSlot) & mask;
      if (shift >= distance) {
        // Entry at this position was originally at or before the gap slot.
        // Move the conflict-shifted entry to the gap's position and repeat the procedure
        // for any entries to the right of the current position, treating it
        // as the new gap.
        keys[gapSlot] = existing;
        values[gapSlot] = values[slot]; 
        gapSlot = slot;
        distance = 0;
      }
    }

    // Mark the last found gap slot without a conflict as empty.
    keys[gapSlot] = ((short) 0);
    values[gapSlot] = ((byte) 0);
    assigned--;
  }

        
}