Package com.carrotsearch.hppc

Class CharObjectWormMap<VType>

  • All Implemented Interfaces:
    Accountable, CharObjectAssociativeContainer<VType>, CharObjectMap<VType>, Preallocable, java.lang.Cloneable, java.lang.Iterable<CharObjectCursor<VType>>
    @Generated(date="2020-09-07T17:20:15+0200",
           value="KTypeVTypeWormMap.java")
public class CharObjectWormMap<VType>
extends java.lang.Object
implements CharObjectMap<VType>, Preallocable, java.lang.Cloneable, Accountable
    A hash map of char to Object, implemented using Worm Hashing strategy.

    This strategy is appropriate for a medium sized map (less than 2M entries). It takes more time to put entries in the map because it maintains chains of entries having the same hash. Then the lookup speed is fast even if the map is heavy loaded or hashes are clustered. On average it takes slightly less memory than CharObjectHashMap: slightly heavier but the load factor is higher (it varies around 80%) so it enlarges later.

    See Also:
    HPPC interfaces diagram

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected int iterationSeed
      Seed used to ensure the hash iteration order is different from an iteration to another.
      char[] keys
      The array holding keys.
      byte[] next
      abs(next[i])=offset to next chained entry index.
      protected int size
      Map size (number of entries).
      java.lang.Object[] values
      The array holding values.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clear all keys and values in the container.
      CharObjectWormMap<VType> clone()
      Clones this map.
      boolean containsKey​(char key)
      Returns true if this container has an association to a value for the given key.
      void ensureCapacity​(int expectedElements)
      Ensure this container can hold at least the given number of elements without resizing its buffers.
      boolean equals​(java.lang.Object o)
      Compares the specified object with this set for equality.
      <T extends CharObjectProcedure<? super VType>>
      T      		 forEach​(T procedure)
      Applies a given procedure to all keys-value pairs in this container.
      static <VType> CharObjectWormMap<VType> from​(char[] keys, VType[] values)
      Creates a new instance from two index-aligned arrays of key-value pairs.
      VType get​(char key)  
      VType getOrDefault​(char key, VType defaultValue)  
      int hashCode()  
      protected int hashKey​(char key)
      Returns a hash code for the given key.
      boolean indexExists​(int index)  
      VType indexGet​(int index)
      Returns the value associated with an existing key.
      void indexInsert​(int index, char key, VType value)
      Inserts a key-value pair for a key that is not present in the map.
      int indexOf​(char key)
      Returns a logical "index" of a given key that can be used to speed up follow-up value setters or getters in certain scenarios (conditional logic).
      VType indexReplace​(int index, VType newValue)
      Replaces the value associated with an existing key and returns any previous value stored for that key.
      boolean isEmpty()  
      java.util.Iterator<CharObjectCursor<VType>> iterator()
      Returns a cursor over the entries (key-value pairs) in this map.
      com.carrotsearch.hppc.CharObjectWormMap.KeysContainer keys()
      Returns a collection of keys of this container.
      protected int nextIterationSeed()
      Provides the next iteration seed used to build the iteration starting slot and offset increment.
      VType noValue()
      The value returned when there is no value associated to a key in this map.
      VType put​(char key, VType value)
      Place a given key and value in the container.
      int putAll​(CharObjectAssociativeContainer<? extends VType> 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 CharObjectCursor<? extends VType>> iterable)
      Puts all keys from an iterable cursor to this map, replacing the values of existing keys, if such keys are present.
      boolean putIfAbsent​(char key, VType value)  
      long ramBytesAllocated()
      Allocated memory estimation
      long ramBytesUsed()
      Bytes that is actually been used
      void release()
      Removes all elements from the collection and additionally releases any internal buffers.
      VType remove​(char key)
      Remove all values at the given key.
      int removeAll​(CharContainer other)
      Removes all keys (and associated values) present in a given container.
      int removeAll​(CharObjectPredicate<? super VType> predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      int removeAll​(CharPredicate predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      int size()  
      java.lang.String toString()  
      ObjectCollection<VType> values()
      Returns a container view of all values present in this container.
      java.lang.String visualizeKeyDistribution​(int characters)
      Visually depict the distribution of keys.

      • Methods inherited from class java.lang.Object

        finalize, getClass, notify, notifyAll, wait, wait, wait

      • Methods inherited from interface java.lang.Iterable

        forEach, spliterator

    • Field Detail

      • keys

        public char[] keys
        The array holding keys.

      • values

        public java.lang.Object[] values
        The array holding values.

      • next

        public byte[] next
        abs(next[i])=offset to next chained entry index.

        next[i]=0 for free bucket.

        The offset is always forward, and the array is considered circular, meaning that an entry at the end of the array may point to an entry at the beginning with a positive offset.

        The offset is always forward, but the sign of the offset encodes head/tail of chain. next[i] > 0 for the first head-of-chain entry (within [1,WormUtil.maxOffset(int)]), next[i] < 0 for the subsequent tail-of-chain entries (within [-WormUtil.maxOffset(int),-1]. For the last entry in the chain, abs(next[i])=WormUtil.END_OF_CHAIN.

      • size

        protected int size
        Map size (number of entries).

      • iterationSeed

        protected int iterationSeed
        Seed used to ensure the hash iteration order is different from an iteration to another.

    • Constructor Detail

      • CharObjectWormMap

        public CharObjectWormMap()
        New instance with sane defaults.

      • CharObjectWormMap

        public CharObjectWormMap​(int expectedElements)
        New instance with the provided defaults.

        There is no load factor parameter as this map enlarges automatically. In practice the load factor varies around 80% (between 75% and 90%). The load factor is 100% for tiny maps.

        Parameters:
        expectedElements - The expected number of elements. The capacity of the map is calculated based on it.

      • CharObjectWormMap

        public CharObjectWormMap​(CharObjectAssociativeContainer<? extends VType> container)
        Creates a new instance from all key-value pairs of another container.

    • Method Detail

      • from

        public static <VType> CharObjectWormMap<VType> from​(char[] keys,
                                                    VType[] values)
        Creates a new instance from two index-aligned arrays of key-value pairs.

      • clone

        public CharObjectWormMap<VType> clone()
        Clones this map. The cloning operation is efficient because it copies directly the internal arrays, without having to put entries in the cloned map. The cloned map has the same entries and the same capacity as this map.
        Overrides:
        clone in class java.lang.Object
        Returns:
        A shallow copy of this map.

      • noValue

        public VType noValue()
        The value returned when there is no value associated to a key in this map. This method can be extended to change it.

      • get

        public VType get​(char key)
        Specified by:
        get in interface CharObjectMap<VType>
        Returns:
        Returns the value associated with the given key or the default value for the value type, if the key is not associated with any value. For numeric value types, this default value is 0, for object types it is null.

      • getOrDefault

        public VType getOrDefault​(char key,
                          VType defaultValue)
        Specified by:
        getOrDefault in interface CharObjectMap<VType>
        Returns:
        Returns the value associated with the given key or the provided default value if the key is not associated with any value.

      • put

        public VType put​(char key,
                 VType value)
        Description copied from interface: CharObjectMap
        Place a given key and value in the container.
        Specified by:
        put in interface CharObjectMap<VType>
        Returns:
        The value previously stored under the given key in the map is returned.

      • putAll

        public int putAll​(CharObjectAssociativeContainer<? extends VType> container)
        Description copied from interface: CharObjectMap
        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 CharObjectMap<VType>
        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 int putAll​(java.lang.Iterable<? extends CharObjectCursor<? extends VType>> iterable)
        Description copied from interface: CharObjectMap
        Puts all keys from an iterable cursor to this map, replacing the values of existing keys, if such keys are present.
        Specified by:
        putAll in interface CharObjectMap<VType>
        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 boolean putIfAbsent​(char key,
                           VType 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.

      • remove

        public VType remove​(char key)
        Description copied from interface: CharObjectMap
        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 CharObjectMap<VType>

      • forEach

        public <T extends CharObjectPredicate<? super VType>> T forEach​(T predicate)
        Description copied from interface: CharObjectAssociativeContainer
        Applies a given predicate to all keys-value pairs in this container. Returns the argument (any subclass of CharObjectPredicate. 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. The iteration is continued as long as the predicate returns true.
        Specified by:
        forEach in interface CharObjectAssociativeContainer<VType>

      • keys

        public com.carrotsearch.hppc.CharObjectWormMap.KeysContainer keys()
        Description copied from interface: CharObjectAssociativeContainer
        Returns a collection of keys of 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:
        keys in interface CharObjectAssociativeContainer<VType>

      • iterator

        public java.util.Iterator<CharObjectCursor<VType>> iterator()
        Description copied from interface: CharObjectAssociativeContainer
        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 CharObjectAssociativeContainer<VType>
        Specified by:
        iterator in interface java.lang.Iterable<VType>

      • equals

        public boolean equals​(java.lang.Object o)
        Description copied from interface: CharObjectMap
        Compares the specified object with this set for equality. Returns true if and only if the specified object is also a CharObjectMap and both objects contains exactly the same key-value pairs.
        Specified by:
        equals in interface CharObjectMap<VType>
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Specified by:
        hashCode in interface CharObjectMap<VType>
        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.

      • hashKey

        protected int hashKey​(char key)
        Returns a hash code for the given key.

      • indexExists

        public boolean indexExists​(int index)
        Specified by:
        indexExists in interface CharObjectMap<VType>
        Parameters:
        index - The index of a given key, as returned from CharObjectMap.indexOf(char).
        Returns:
        Returns true if the index corresponds to an existing key or false otherwise. This is equivalent to checking whether the index is a positive value (existing keys) or a negative value (non-existing keys).
        See Also:
        CharObjectMap.indexOf(char)

      • indexGet

        public VType indexGet​(int index)
        Description copied from interface: CharObjectMap
        Returns the value associated with an existing key.
        Specified by:
        indexGet in interface CharObjectMap<VType>
        Parameters:
        index - The index of an existing key.
        Returns:
        Returns the value currently associated with the key.
        See Also:
        CharObjectMap.indexOf(char)

      • indexReplace

        public VType indexReplace​(int index,
                          VType newValue)
        Description copied from interface: CharObjectMap
        Replaces the value associated with an existing key and returns any previous value stored for that key.
        Specified by:
        indexReplace in interface CharObjectMap<VType>
        Parameters:
        index - The index of an existing key.
        Returns:
        Returns the previous value associated with the key.
        See Also:
        CharObjectMap.indexOf(char)

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • ensureCapacity

        public void ensureCapacity​(int expectedElements)
        Description copied from interface: Preallocable
        Ensure this container can hold at least the given number of elements without resizing its buffers.
        Specified by:
        ensureCapacity in interface Preallocable
        Parameters:
        expectedElements - The total number of elements, inclusive.

      • visualizeKeyDistribution

        public java.lang.String visualizeKeyDistribution​(int characters)
        Description copied from interface: CharObjectMap
        Visually depict the distribution of keys.
        Specified by:
        visualizeKeyDistribution in interface CharObjectMap<VType>
        Parameters:
        characters - The number of characters to "squeeze" the entire buffer into.
        Returns:
        Returns a sequence of characters where '.' depicts an empty fragment of the internal buffer and 'X' depicts full or nearly full capacity within the buffer's range and anything between 1 and 9 is between.

      • ramBytesAllocated

        public long ramBytesAllocated()
        Description copied from interface: Accountable
        Allocated memory estimation
        Specified by:
        ramBytesAllocated in interface Accountable
        Returns:
        Ram allocated in bytes

      • ramBytesUsed

        public long ramBytesUsed()
        Description copied from interface: Accountable
        Bytes that is actually been used
        Specified by:
        ramBytesUsed in interface Accountable
        Returns:
        Ram used in bytes

      • nextIterationSeed

        protected int nextIterationSeed()
        Provides the next iteration seed used to build the iteration starting slot and offset increment. This method does not need to be synchronized, what matters is that each thread gets a sequence of varying seeds.