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-// IntHashtable - a Hashtable that uses ints as the keys
-//
-// This is 90% based on JavaSoft's java.util.Hashtable.
-//
-// Visit the ACME Labs Java page for up-to-date versions of this and other
-// fine Java utilities: http://www.acme.com/java/
-
-package imaging.framework;
-
-import java.util.*;
-
-/// A Hashtable that uses ints as the keys.
-// <P>
-// Use just like java.util.Hashtable, except that the keys must be ints.
-// This is much faster than creating a new Integer for each access.
-// <P>
-// <A HREF="/resources/classes/Acme/IntHashtable.java">Fetch the software.</A><BR>
-// <A HREF="/resources/classes/Acme.tar.Z">Fetch the entire Acme package.</A>
-// <P>
-// @see java.util.Hashtable
-
-public class IntHashtable extends Dictionary implements Cloneable
- {
- /// The hash table data.
- private IntHashtableEntry table[];
-
- /// The total number of entries in the hash table.
- private int count;
-
- /// Rehashes the table when count exceeds this threshold.
- private int threshold;
-
- /// The load factor for the hashtable.
- private float loadFactor;
-
- /// Constructs a new, empty hashtable with the specified initial
- // capacity and the specified load factor.
- // @param initialCapacity the initial number of buckets
- // @param loadFactor a number between 0.0 and 1.0, it defines
- // the threshold for rehashing the hashtable into
- // a bigger one.
- // @exception IllegalArgumentException If the initial capacity
- // is less than or equal to zero.
- // @exception IllegalArgumentException If the load factor is
- // less than or equal to zero.
- public IntHashtable( int initialCapacity, float loadFactor )
- {
- if ( initialCapacity <= 0 || loadFactor <= 0.0 )
- throw new IllegalArgumentException();
- this.loadFactor = loadFactor;
- table = new IntHashtableEntry[initialCapacity];
- threshold = (int) ( initialCapacity * loadFactor );
- }
-
- /// Constructs a new, empty hashtable with the specified initial
- // capacity.
- // @param initialCapacity the initial number of buckets
- public IntHashtable( int initialCapacity )
- {
- this( initialCapacity, 0.75f );
- }
-
- /// Constructs a new, empty hashtable. A default capacity and load factor
- // is used. Note that the hashtable will automatically grow when it gets
- // full.
- public IntHashtable()
- {
- this( 101, 0.75f );
- }
-
- /// Returns the number of elements contained in the hashtable.
- public int size()
- {
- return count;
- }
-
- /// Returns true if the hashtable contains no elements.
- public boolean isEmpty()
- {
- return count == 0;
- }
-
- /// Returns an enumeration of the hashtable's keys.
- // @see IntHashtable#elements
- public synchronized Enumeration keys()
- {
- return new IntHashtableEnumerator( table, true );
- }
-
- /// Returns an enumeration of the elements. Use the Enumeration methods
- // on the returned object to fetch the elements sequentially.
- // @see IntHashtable#keys
- public synchronized Enumeration elements()
- {
- return new IntHashtableEnumerator( table, false );
- }
-
- /// Returns true if the specified object is an element of the hashtable.
- // This operation is more expensive than the containsKey() method.
- // @param value the value that we are looking for
- // @exception NullPointerException If the value being searched
- // for is equal to null.
- // @see IntHashtable#containsKey
- public synchronized boolean contains( Object value )
- {
- if ( value == null )
- throw new NullPointerException();
- IntHashtableEntry tab[] = table;
- for ( int i = tab.length ; i-- > 0 ; )
- {
- for ( IntHashtableEntry e = tab[i] ; e != null ; e = e.next )
- {
- if ( e.value.equals( value ) )
- return true;
- }
- }
- return false;
- }
-
- /// Returns true if the collection contains an element for the key.
- // @param key the key that we are looking for
- // @see IntHashtable#contains
- public synchronized boolean containsKey( int key )
- {
- IntHashtableEntry tab[] = table;
- int hash = key;
- int index = ( hash & 0x7FFFFFFF ) % tab.length;
- for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next )
- {
- if ( e.hash == hash && e.key == key )
- return true;
- }
- return false;
- }
-
- /// Gets the object associated with the specified key in the
- // hashtable.
- // @param key the specified key
- // @returns the element for the key or null if the key
- // is not defined in the hash table.
- // @see IntHashtable#put
- public synchronized Object get( int key )
- {
- IntHashtableEntry tab[] = table;
- int hash = key;
- int index = ( hash & 0x7FFFFFFF ) % tab.length;
- for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next )
- {
- if ( e.hash == hash && e.key == key )
- return e.value;
- }
- return null;
- }
-
- /// A get method that takes an Object, for compatibility with
- // java.util.Dictionary. The Object must be an Integer.
- public Object get( Object okey )
- {
- if ( ! ( okey instanceof Integer ) )
- throw new InternalError( "key is not an Integer" );
- Integer ikey = (Integer) okey;
- int key = ikey.intValue();
- return get( key );
- }
-
- /// Rehashes the content of the table into a bigger table.
- // This method is called automatically when the hashtable's
- // size exceeds the threshold.
- protected void rehash()
- {
- int oldCapacity = table.length;
- IntHashtableEntry oldTable[] = table;
-
- int newCapacity = oldCapacity * 2 + 1;
- IntHashtableEntry newTable[] = new IntHashtableEntry[newCapacity];
-
- threshold = (int) ( newCapacity * loadFactor );
- table = newTable;
-
- for ( int i = oldCapacity ; i-- > 0 ; )
- {
- for ( IntHashtableEntry old = oldTable[i] ; old != null ; )
- {
- IntHashtableEntry e = old;
- old = old.next;
-
- int index = ( e.hash & 0x7FFFFFFF ) % newCapacity;
- e.next = newTable[index];
- newTable[index] = e;
- }
- }
- }
-
- /// Puts the specified element into the hashtable, using the specified
- // key. The element may be retrieved by doing a get() with the same key.
- // The key and the element cannot be null.
- // @param key the specified key in the hashtable
- // @param value the specified element
- // @exception NullPointerException If the value of the element
- // is equal to null.
- // @see IntHashtable#get
- // @return the old value of the key, or null if it did not have one.
- public synchronized Object put( int key, Object value )
- {
- // Make sure the value is not null.
- if ( value == null )
- throw new NullPointerException();
-
- // Makes sure the key is not already in the hashtable.
- IntHashtableEntry tab[] = table;
- int hash = key;
- int index = ( hash & 0x7FFFFFFF ) % tab.length;
- for ( IntHashtableEntry e = tab[index] ; e != null ; e = e.next )
- {
- if ( e.hash == hash && e.key == key )
- {
- Object old = e.value;
- e.value = value;
- return old;
- }
- }
-
- if ( count >= threshold )
- {
- // Rehash the table if the threshold is exceeded.
- rehash();
- return put( key, value );
- }
-
- // Creates the new entry.
- IntHashtableEntry e = new IntHashtableEntry();
- e.hash = hash;
- e.key = key;
- e.value = value;
- e.next = tab[index];
- tab[index] = e;
- ++count;
- return null;
- }
-
- /// A put method that takes an Object, for compatibility with
- // java.util.Dictionary. The Object must be an Integer.
- public Object put( Object okey, Object value )
- {
- if ( ! ( okey instanceof Integer ) )
- throw new InternalError( "key is not an Integer" );
- Integer ikey = (Integer) okey;
- int key = ikey.intValue();
- return put( key, value );
- }
-
- /// Removes the element corresponding to the key. Does nothing if the
- // key is not present.
- // @param key the key that needs to be removed
- // @return the value of key, or null if the key was not found.
- public synchronized Object remove( int key )
- {
- IntHashtableEntry tab[] = table;
- int hash = key;
- int index = ( hash & 0x7FFFFFFF ) % tab.length;
- for ( IntHashtableEntry e = tab[index], prev = null ; e != null ; prev = e, e = e.next )
- {
- if ( e.hash == hash && e.key == key )
- {
- if ( prev != null )
- prev.next = e.next;
- else
- tab[index] = e.next;
- --count;
- return e.value;
- }
- }
- return null;
- }
-
- /// A remove method that takes an Object, for compatibility with
- // java.util.Dictionary. The Object must be an Integer.
- public Object remove( Object okey )
- {
- if ( ! ( okey instanceof Integer ) )
- throw new InternalError( "key is not an Integer" );
- Integer ikey = (Integer) okey;
- int key = ikey.intValue();
- return remove( key );
- }
-
- /// Clears the hash table so that it has no more elements in it.
- public synchronized void clear()
- {
- IntHashtableEntry tab[] = table;
- for ( int index = tab.length; --index >= 0; )
- tab[index] = null;
- count = 0;
- }
-
- /// Creates a clone of the hashtable. A shallow copy is made,
- // the keys and elements themselves are NOT cloned. This is a
- // relatively expensive operation.
- public synchronized Object clone()
- {
- try
- {
- IntHashtable t = (IntHashtable) super.clone();
- t.table = new IntHashtableEntry[table.length];
- for ( int i = table.length ; i-- > 0 ; )
- t.table[i] = ( table[i] != null ) ?
- (IntHashtableEntry) table[i].clone() : null;
- return t;
- }
- catch ( CloneNotSupportedException e)
- {
- // This shouldn't happen, since we are Cloneable.
- throw new InternalError();
- }
- }
-
- /// Converts to a rather lengthy String.
- public synchronized String toString()
- {
- int max = size() - 1;
- StringBuffer buf = new StringBuffer();
- Enumeration k = keys();
- Enumeration e = elements();
- buf.append( "{" );
-
- for ( int i = 0; i <= max; ++i )
- {
- String s1 = k.nextElement().toString();
- String s2 = e.nextElement().toString();
- buf.append( s1 + "=" + s2 );
- if ( i < max )
- buf.append( ", " );
- }
- buf.append( "}" );
- return buf.toString();
- }
- }
-
-
-class IntHashtableEntry
- {
- int hash;
- int key;
- Object value;
- IntHashtableEntry next;
-
- protected Object clone()
- {
- IntHashtableEntry entry = new IntHashtableEntry();
- entry.hash = hash;
- entry.key = key;
- entry.value = value;
- entry.next = ( next != null ) ? (IntHashtableEntry) next.clone() : null;
- return entry;
- }
- }
-
-
-class IntHashtableEnumerator implements Enumeration
- {
- boolean keys;
- int index;
- IntHashtableEntry table[];
- IntHashtableEntry entry;
-
- IntHashtableEnumerator( IntHashtableEntry table[], boolean keys )
- {
- this.table = table;
- this.keys = keys;
- this.index = table.length;
- }
-
- public boolean hasMoreElements()
- {
- if ( entry != null )
- return true;
- while ( index-- > 0 )
- if ( ( entry = table[index] ) != null )
- return true;
- return false;
- }
-
- public Object nextElement()
- {
- if ( entry == null )
- while ( ( index-- > 0 ) && ( ( entry = table[index] ) == null ) )
- ;
- if ( entry != null )
- {
- IntHashtableEntry e = entry;
- entry = e.next;
- return keys ? new Integer( e.key ) : e.value;
- }
- throw new NoSuchElementException( "IntHashtableEnumerator" );
- }
- }