Package org.apache.xerces.util

Class SymbolHash

  • public class SymbolHash
extends java.lang.Object
    This class is an unsynchronized hash table primarily used for String to Object mapping.

    The hash code uses the same algorithm as SymbolTable class.

    Version:
    $Id: SymbolHash.java 1867092 2019-09-18 03:54:53Z mukulg $
    Author:
    Elena Litani

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      protected static class  SymbolHash.Entry
      This class is a key table entry.

    • Constructor Summary

      Constructors 
      Constructor Description
      SymbolHash()
      Constructs a key table with the default size.
      SymbolHash​(int size)
      Constructs a key table with a given size.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Remove all key/value association.
      java.lang.Object get​(java.lang.Object key)
      Get the value associated with the given key.
      java.lang.Object[] getEntries()
      Return key/value pairs of all entries in the map
      int getLength()
      Get the number of key/value pairs stored in this table.
      int getValues​(java.lang.Object[] elements, int from)
      Add all values to the given array.
      protected int hash​(java.lang.Object key)
      Returns a hashcode value for the specified key.
      SymbolHash makeClone()
      Make a clone of this object.
      void put​(java.lang.Object key, java.lang.Object value)
      Adds the key/value mapping to the key table.
      protected void rebalance()
      Randomly selects a new hash function and reorganizes this SymbolHash in order to more evenly distribute its entries across the table.
      protected void rehash()
      Increases the capacity of and internally reorganizes this SymbolHash, in order to accommodate and access its entries more efficiently.
      protected SymbolHash.Entry search​(java.lang.Object key, int bucket)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • MAX_HASH_COLLISIONS

        protected static final int MAX_HASH_COLLISIONS
        Maximum hash collisions per bucket.
        See Also:
        Constant Field Values

      • fTableSize

        protected int fTableSize
        Actual table size

      • fNum

        protected int fNum
        Number of elements.

      • fHashMultipliers

        protected int[] fHashMultipliers
        Array of randomly selected hash function multipliers or null if the default String.hashCode() function should be used.

    • Constructor Detail

      • SymbolHash

        public SymbolHash()
        Constructs a key table with the default size.

      • SymbolHash

        public SymbolHash​(int size)
        Constructs a key table with a given size.
        Parameters:
        size - the size of the key table.

    • Method Detail

      • put

        public void put​(java.lang.Object key,
                java.lang.Object value)
        Adds the key/value mapping to the key table. If the key already exists, the previous value associated with this key is overwritten by the new value.
        Parameters:
        key -
        value -

      • get

        public java.lang.Object get​(java.lang.Object key)
        Get the value associated with the given key.
        Parameters:
        key -
        Returns:
        the value associated with the given key.

      • getLength

        public int getLength()
        Get the number of key/value pairs stored in this table.
        Returns:
        the number of key/value pairs stored in this table.

      • getValues

        public int getValues​(java.lang.Object[] elements,
                     int from)
        Add all values to the given array. The array must have enough entry.
        Parameters:
        elements - the array to store the elements
        from - where to start store element in the array
        Returns:
        number of elements copied to the array

      • getEntries

        public java.lang.Object[] getEntries()
        Return key/value pairs of all entries in the map

      • makeClone

        public SymbolHash makeClone()
        Make a clone of this object.

      • clear

        public void clear()
        Remove all key/value association. This tries to save a bit of GC'ing by at least keeping the fBuckets array around.

      • search

        protected SymbolHash.Entry search​(java.lang.Object key,
                                  int bucket)

      • hash

        protected int hash​(java.lang.Object key)
        Returns a hashcode value for the specified key.
        Parameters:
        key - The key to hash.

      • rehash

        protected void rehash()
        Increases the capacity of and internally reorganizes this SymbolHash, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the SymbolHash exceeds its number of buckets.

      • rebalance

        protected void rebalance()
        Randomly selects a new hash function and reorganizes this SymbolHash in order to more evenly distribute its entries across the table. This method is called automatically when the number keys in one of the SymbolHash's buckets exceeds MAX_HASH_COLLISIONS.