com.carrotsearch.hppc
Class ByteIntOpenHashMap

java.lang.Object
  extended by com.carrotsearch.hppc.ByteIntOpenHashMap
All Implemented Interfaces:
ByteIntAssociativeContainer, ByteIntMap, java.lang.Cloneable, java.lang.Iterable<ByteIntCursor>

@Generated(date="2011-07-12T16:58:49+0200",
           value="HPPC generated from: ByteIntOpenHashMap.java")
public class ByteIntOpenHashMap
extends java.lang.Object
implements ByteIntMap, java.lang.Cloneable

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

The internal buffers of this implementation (keys, values, allocated) are always allocated to the nearest size that is a power of two. When the capacity exceeds the given load factor, the buffer size is doubled.

See ObjectObjectOpenHashMap class for API similarities and differences against Java Collections.

Important node. The implementation uses power-of-two tables and linear probing, which may cause poor performance (many collisions) if hash values are not properly distributed. This implementation uses rehashing using MurmurHash3.

Author:
This code is inspired by the collaboration and implementation in the fastutil project.

Nested Class Summary
 class ByteIntOpenHashMap.KeysContainer
          A view of the keys inside this hash map.
 
Field Summary
 boolean[] allocated
          Information if an entry (slot) in the values table is allocated or empty.
 int assigned
          Cached number of assigned slots in allocated.
static int DEFAULT_CAPACITY
          Default capacity.
static float DEFAULT_LOAD_FACTOR
          Default load factor.
 byte[] keys
          Hash-indexed array holding all keys.
 float loadFactor
          The load factor for this map (fraction of allocated slots before the buffers must be rehashed or reallocated).
static int MIN_CAPACITY
          Minimum capacity for the map.
 int[] values
          Hash-indexed array holding all values associated to the keys stored in keys.
 
Constructor Summary
ByteIntOpenHashMap()
          Creates a hash map with the default capacity of 16, load factor of 0.75f.
ByteIntOpenHashMap(ByteIntAssociativeContainer container)
          Create a hash map from all key-value pairs of another container.
ByteIntOpenHashMap(int initialCapacity)
          Creates a hash map with the given initial capacity, default load factor of 0.75f.
ByteIntOpenHashMap(int initialCapacity, float loadFactor)
          Creates a hash map with the given initial capacity, load factor.
 
Method Summary
 void clear()
          Clear all keys and values in the container.
 ByteIntOpenHashMap clone()
          
 boolean containsKey(byte key)
          Returns true if this container has an association to a value for the given key.
 boolean equals(java.lang.Object obj)
          Compares the specified object with this set for equality.
<T extends ByteIntProcedure>
T
forEach(T procedure)
          Applies a given procedure to all keys-value pairs in this container.
static ByteIntOpenHashMap from(byte[] keys, int[] values)
          Creates a hash map from two index-aligned arrays of key-value pairs.
static ByteIntOpenHashMap from(ByteIntAssociativeContainer container)
          Create a hash map from another associative container.
 int get(byte key)
          
 int hashCode()
          
 boolean isEmpty()
          
 java.util.Iterator<ByteIntCursor> iterator()
          Returns a cursor over the entries (key-value pairs) in this map.
 ByteIntOpenHashMap.KeysContainer keys()
          Returns a specialized view of the keys of this associated container.
 int lget()
          Returns the last value saved in a call to containsKey(byte).
 int lset(int key)
          Sets the value corresponding to the key saved in the last call to containsKey(byte), if and only if the key exists in the map already.
static ByteIntOpenHashMap newInstance()
          Create a new hash map without providing the full generic signature (constructor shortcut).
static ByteIntOpenHashMap newInstance(int initialCapacity, float loadFactor)
          Create a new hash map without providing the full generic signature (constructor shortcut).
protected  int nextCapacity(int current)
          Return the next possible capacity, counting from the current buffers' size.
 int put(byte key, int value)
          Place a given key and value in the container.
 int putAll(ByteIntAssociativeContainer container)
          Puts all keys from another container to this map, replacing the values of existing keys, if such keys are present.
 int putAll(java.lang.Iterable<? extends ByteIntCursor> iterable)
          Puts all key/value pairs from a given iterable into this map.
 boolean putIfAbsent(byte key, int value)
          Trove-inspired API method.
 int putOrAdd(byte key, int putValue, int additionValue)
          Trove-inspired API method.
 int remove(byte key)
          Remove all values at the given key.
 int removeAll(ByteContainer container)
          Removes all keys (and associated values) present in a given container.
 int removeAll(BytePredicate predicate)
          Removes all keys (and associated values) for which the predicate returns true.
protected  int roundCapacity(int requestedCapacity)
          Round the capacity to the next allowed value.
protected  void shiftConflictingKeys(int slotCurr)
          Shift all the slot-conflicting keys allocated to (and including) slot.
 int size()
          
 java.lang.String toString()
          Convert the contents of this map to a human-friendly string.
 IntContainer values()
          Returns a container view of all values present in this container.
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

DEFAULT_CAPACITY

public static final int DEFAULT_CAPACITY
Default capacity.

See Also:
Constant Field Values

MIN_CAPACITY

public static final int MIN_CAPACITY
Minimum capacity for the map.

See Also:
Constant Field Values

DEFAULT_LOAD_FACTOR

public static final float DEFAULT_LOAD_FACTOR
Default load factor.

See Also:
Constant Field Values

keys

public byte[] keys
Hash-indexed array holding all keys.

See Also:
values

values

public int[] values
Hash-indexed array holding all values associated to the keys stored in keys.

See Also:
keys

allocated

public boolean[] allocated
Information if an entry (slot) in the values table is allocated or empty.

See Also:
assigned

assigned

public int assigned
Cached number of assigned slots in allocated.


loadFactor

public final float loadFactor
The load factor for this map (fraction of allocated slots before the buffers must be rehashed or reallocated).

Constructor Detail

ByteIntOpenHashMap

public ByteIntOpenHashMap()
Creates a hash map with the default capacity of 16, load factor of 0.75f.

See class notes about hash distribution importance.


ByteIntOpenHashMap

public ByteIntOpenHashMap(int initialCapacity)
Creates a hash map with the given initial capacity, default load factor of 0.75f.

See class notes about hash distribution importance.

Parameters:
initialCapacity - Initial capacity (greater than zero and automatically rounded to the next power of two).

ByteIntOpenHashMap

public ByteIntOpenHashMap(int initialCapacity,
                          float loadFactor)
Creates a hash map with the given initial capacity, load factor.

See class notes about hash distribution importance.

Parameters:
initialCapacity - Initial capacity (greater than zero and automatically rounded to the next power of two).
loadFactor - The load factor (greater than zero and smaller than 1).

ByteIntOpenHashMap

public ByteIntOpenHashMap(ByteIntAssociativeContainer container)
Create a hash map from all key-value pairs of another container.

Method Detail

put

public int put(byte key,
               int value)
Place a given key and value in the container.

Specified by:
put in interface ByteIntMap
Returns:
The value previously stored under the given key in the map is returned.

putAll

public final int putAll(ByteIntAssociativeContainer container)
Puts all keys from another container to this map, replacing the values of existing keys, if such keys are present.

Specified by:
putAll in interface ByteIntMap
Returns:
Returns the number of keys added to the map as a result of this call (not previously present in the map). Values of existing keys are overwritten.

putAll

public final int putAll(java.lang.Iterable<? extends ByteIntCursor> iterable)
Puts all key/value pairs from a given iterable into this map.

Specified by:
putAll in interface ByteIntMap
Returns:
Returns the number of keys added to the map as a result of this call (not previously present in the map). Values of existing keys are overwritten.

putIfAbsent

public final boolean putIfAbsent(byte key,
                                 int value)
Trove-inspired API method. An equivalent of the following code:
 if (!map.containsKey(key)) map.put(value);
 

Parameters:
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.

putOrAdd

public final int putOrAdd(byte key,
                          int putValue,
                          int additionValue)
Trove-inspired API method. An equivalent of the following code:
 if (map.containsKey(key)) 
    map.lset(map.lget() + additionValue);
 else
    map.put(key, putValue);
 

Parameters:
key - The key of the value to adjust.
putValue - The value to put if key does not exist.
additionValue - The value to add to the existing value if key exists.
Returns:
Returns the current value associated with key (after changes).

remove

public int remove(byte key)
Remove all values at the given key. The default value for the key type is returned if the value does not exist in the map.

Specified by:
remove in interface ByteIntMap

shiftConflictingKeys

protected final void shiftConflictingKeys(int slotCurr)
Shift all the slot-conflicting keys allocated to (and including) slot.


removeAll

public final int removeAll(ByteContainer container)
Removes all keys (and associated values) present in a given container. An alias to:
 keys().removeAll(container)
 
but with no additional overhead.

Specified by:
removeAll in interface ByteIntAssociativeContainer
Returns:
Returns the number of elements actually removed as a result of this call.

removeAll

public final int removeAll(BytePredicate predicate)
Removes all keys (and associated values) for which the predicate returns true. An alias to:
 keys().removeAll(container)
 
but with no additional overhead.

Specified by:
removeAll in interface ByteIntAssociativeContainer
Returns:
Returns the number of elements actually removed as a result of this call.

get

public int get(byte key)

Use the following snippet of code to check for key existence first and then retrieve the value if it exists.

 if (map.containsKey(key))
   value = map.lget(); 
 

Specified by:
get in interface ByteIntMap
Returns:
Returns the value associated with the given key or the default value for the key type, if the key is not associated with any value. Important note: For primitive type values, the value returned for a non-existing key may not be the default value of the primitive type (it may be any value previously assigned to that slot).

lget

public int lget()
Returns the last value saved in a call to containsKey(byte).

See Also:
containsKey(byte)

lset

public int lset(int key)
Sets the value corresponding to the key saved in the last call to containsKey(byte), if and only if the key exists in the map already.

Returns:
Returns the previous value stored under the given key.
See Also:
containsKey(byte)

containsKey

public boolean containsKey(byte key)
Returns true if this container has an association to a value for the given key.

Saves the associated value for fast access using lget() or lset(int).

 if (map.containsKey(key))
   value = map.lget();
 
or, for example to modify the value at the given key without looking up its slot twice:
 if (map.containsKey(key))
   map.lset(map.lget() + 1);
 

Specified by:
containsKey in interface ByteIntAssociativeContainer

roundCapacity

protected int roundCapacity(int requestedCapacity)
Round the capacity to the next allowed value.


nextCapacity

protected int nextCapacity(int current)
Return the next possible capacity, counting from the current buffers' size.


clear

public void clear()
Clear all keys and values in the container.

Does not release internal buffers.

Specified by:
clear in interface ByteIntAssociativeContainer

size

public int size()

Specified by:
size in interface ByteIntAssociativeContainer
Returns:
Returns the current size (number of assigned keys) in the container.

isEmpty

public boolean isEmpty()

Note that an empty container may still contain many deleted keys (that occupy buffer space). Adding even a single element to such a container may cause rehashing.

Specified by:
isEmpty in interface ByteIntAssociativeContainer
Returns:
Return true if this hash map contains no assigned keys.

hashCode

public int hashCode()

Specified by:
hashCode in interface ByteIntMap
Overrides:
hashCode in class java.lang.Object
Returns:
A hash code of elements stored in the map. The hash code is defined as a sum of hash codes of keys and values stored within the set). Because sum is commutative, this ensures that different order of elements in a set does not affect the hash code.

equals

public boolean equals(java.lang.Object obj)
Compares the specified object with this set for equality. Returns true if and only if the specified object is also a ByteIntMap and both objects contains exactly the same key-value pairs.

Specified by:
equals in interface ByteIntMap
Overrides:
equals in class java.lang.Object

iterator

public java.util.Iterator<ByteIntCursor> iterator()
Returns a cursor over the entries (key-value pairs) in this map. The iterator is implemented as a cursor and it returns the same cursor instance on every call to Iterator.next(). To read the current key and value use the cursor's public fields. An example is shown below.
 for (IntShortCursor c : intShortMap)
 {
     System.out.println("index=" + c.index 
       + " key=" + c.key
       + " value=" + c.value);
 }
 

The index field inside the cursor gives the internal index inside the container's implementation. The interpretation of this index depends on to the container.

Specified by:
iterator in interface ByteIntAssociativeContainer
Specified by:
iterator in interface java.lang.Iterable<ByteIntCursor>

forEach

public <T extends ByteIntProcedure> T forEach(T procedure)
Applies a given procedure to all keys-value pairs in this container. Returns the argument (any subclass of ByteIntProcedure. This lets the caller to call methods of the argument by chaining the call (even if the argument is an anonymous type) to retrieve computed values, for example.

Specified by:
forEach in interface ByteIntAssociativeContainer

keys

public ByteIntOpenHashMap.KeysContainer keys()
Returns a specialized view of the keys of this associated container. The view additionally implements ObjectLookupContainer.

Specified by:
keys in interface ByteIntAssociativeContainer

values

public IntContainer values()
Description copied from interface: ByteIntAssociativeContainer
Returns a container view of all values present in this container. The returned collection is a view over the key set and any modifications (if allowed) introduced to the collection will propagate to the associative container immediately.

Specified by:
values in interface ByteIntAssociativeContainer
Returns:
Returns a container with all values stored in this map.

clone

public ByteIntOpenHashMap clone()

Overrides:
clone in class java.lang.Object

toString

public java.lang.String toString()
Convert the contents of this map to a human-friendly string.

Overrides:
toString in class java.lang.Object

from

public static ByteIntOpenHashMap from(byte[] keys,
                                      int[] values)
Creates a hash map from two index-aligned arrays of key-value pairs.


from

public static ByteIntOpenHashMap from(ByteIntAssociativeContainer container)
Create a hash map from another associative container.


newInstance

public static ByteIntOpenHashMap newInstance()
Create a new hash map without providing the full generic signature (constructor shortcut).


newInstance

public static ByteIntOpenHashMap newInstance(int initialCapacity,
                                             float loadFactor)
Create a new hash map without providing the full generic signature (constructor shortcut).



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