code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.runtime;
  
  import java.util.Enumeration;
  
  /**
   * IMPORTANT NOTE:
   * This code was taken from Sun's Java1.1 JDK java.util.HashTable.java
   * All "synchronized" keywords and some methods we do not need have been 
   * all been removed.
   */
  
  /**
   * Object that wraps entries in the hash-table
   * @author Morten Jorgensen
   */
  class HashtableEntry {
      int hash;
      Object key;
      Object value;
      HashtableEntry next;
  
      protected Object clone() {
  	HashtableEntry entry = new HashtableEntry();
  	entry.hash = hash;
  	entry.key = key;
  	entry.value = value;
  	entry.next = (next != null) ? (HashtableEntry)next.clone() : null;
  	return entry;
      }
  }
  
  /**
   * The main hash-table implementation
   */
  public class Hashtable {
  
      private transient HashtableEntry table[]; // hash-table entries
      private transient int count;              // number of entries
      private int threshold;                    // current size of hash-tabke
      private float loadFactor;                 // load factor
  
      /**
       * Constructs a new, empty hashtable with the specified initial 
       * capacity and the specified load factor. 
       */
      public Hashtable(int initialCapacity, float loadFactor) {
  	if (initialCapacity <= 0) initialCapacity = 11;
  	if (loadFactor <= 0.0) loadFactor = 0.75f;
  	this.loadFactor = loadFactor;
  	table = new HashtableEntry[initialCapacity];
  	threshold = (int)(initialCapacity * loadFactor);
      }
  
      /**
       * Constructs a new, empty hashtable with the specified initial capacity
       * and default load factor.
       */
      public Hashtable(int initialCapacity) {
  	this(initialCapacity, 0.75f);
      }
  
      /**
       * Constructs a new, empty hashtable with a default capacity and load
       * factor. 
       */
      public Hashtable() {
  	this(101, 0.75f);
      }
  
      /**
       * Returns the number of keys in this hashtable.
       */
      public int size() {
  	return count;
      }
  
      /**
       * Tests if this hashtable maps no keys to values.
       */
      public boolean isEmpty() {
  	return count == 0;
      }
  
      /**
       * Returns an enumeration of the keys in this hashtable.
       */
      public Enumeration keys() {
  	return new HashtableEnumerator(table, true);
      }
  
      /**
       * Returns an enumeration of the values in this hashtable.
       * Use the Enumeration methods on the returned object to fetch the elements
       * sequentially.
       */
      public Enumeration elements() {
  	return new HashtableEnumerator(table, false);
      }
  
      /**
       * Tests if some key maps into the specified value in this hashtable.
       * This operation is more expensive than the <code>containsKey</code>
       * method.
       */
      public boolean contains(Object value) {
  
  	if (value == null) throw new NullPointerException();
  
  	int i;
  	HashtableEntry e;
  	HashtableEntry tab[] = table;
  
  	for (i = tab.length ; i-- > 0 ;) {
  	    for (e = tab[i] ; e != null ; e = e.next) {
  		if (e.value.equals(value)) {
  		    return true;
  		}
  	    }
  	}
  	return false;
      }
  
      /**
       * Tests if the specified object is a key in this hashtable.
       */
      public boolean containsKey(Object key) {
  	HashtableEntry e;
  	HashtableEntry tab[] = table;
  	int hash = key.hashCode();
  	int index = (hash & 0x7FFFFFFF) % tab.length;
  
  	for (e = tab[index] ; e != null ; e = e.next)
  	    if ((e.hash == hash) && e.key.equals(key))
  		return true;
  
  	return false;
      }
  
      /**
       * Returns the value to which the specified key is mapped in this hashtable.
       */
      public Object get(Object key) {
  	HashtableEntry e;
  	HashtableEntry tab[] = table;
  	int hash = key.hashCode();
  	int index = (hash & 0x7FFFFFFF) % tab.length;
  
  	for (e = tab[index] ; e != null ; e = e.next) 
  	    if ((e.hash == hash) && e.key.equals(key)) 
  		return e.value;
  
  	return null;
      }
  
      /**
       * Rehashes the contents of the hashtable into a hashtable with a 
       * larger capacity. This method is called automatically when the 
       * number of keys in the hashtable exceeds this hashtable's capacity 
       * and load factor. 
       */
      protected void rehash() {
  	HashtableEntry e, old;
  	int i, index;
  	int oldCapacity = table.length;
  	HashtableEntry oldTable[] = table;
  
  	int newCapacity = oldCapacity * 2 + 1;
  	HashtableEntry newTable[] = new HashtableEntry[newCapacity];
  
  	threshold = (int)(newCapacity * loadFactor);
  	table = newTable;
  
  	for (i = oldCapacity ; i-- > 0 ;) {
  	    for (old = oldTable[i] ; old != null ; ) {
  		e = old;
  		old = old.next;
  		index = (e.hash & 0x7FFFFFFF) % newCapacity;
  		e.next = newTable[index];
  		newTable[index] = e;
  	    }
  	}
      }
  
      /**
       * Maps the specified <code>key</code> to the specified 
       * <code>value</code> in this hashtable. Neither the key nor the 
       * value can be <code>null</code>. 
       * <p>
       * The value can be retrieved by calling the <code>get</code> method 
       * with a key that is equal to the original key. 
       */
      public Object put(Object 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.
  	HashtableEntry e;
  	HashtableEntry tab[] = table;
  	int hash = key.hashCode();
  	int index = (hash & 0x7FFFFFFF) % tab.length;
  
  	for (e = tab[index] ; e != null ; e = e.next) {
  	    if ((e.hash == hash) && e.key.equals(key)) {
  		Object old = e.value;
  		e.value = value;
  		return old;
  	    }
  	}
  
  	// Rehash the table if the threshold is exceeded
  	if (count >= threshold) {
  	    rehash();
  	    return put(key, value);
  	} 
  
  	// Creates the new entry.
  	e = new HashtableEntry();
  	e.hash = hash;
  	e.key = key;
  	e.value = value;
  	e.next = tab[index];
  	tab[index] = e;
  	count++;
  	return null;
      }
  
      /**
       * Removes the key (and its corresponding value) from this 
       * hashtable. This method does nothing if the key is not in the hashtable.
       */
      public Object remove(Object key) {
  	HashtableEntry e, prev;
  	HashtableEntry tab[] = table;
  	int hash = key.hashCode();
  	int index = (hash & 0x7FFFFFFF) % tab.length;
  	for (e = tab[index], prev = null ; e != null ; prev = e, e = e.next) {
  	    if ((e.hash == hash) && e.key.equals(key)) {
  		if (prev != null)
  		    prev.next = e.next;
  		else
  		    tab[index] = e.next;
  		count--;
  		return e.value;
  	    }
  	}
  	return null;
      }
  
      /**
       * Clears this hashtable so that it contains no keys. 
       */
      public void clear() {
  	HashtableEntry tab[] = table;
  	for (int index = tab.length; --index >= 0; )
  	    tab[index] = null;
  	count = 0;
      }
  
      /**
       * Returns a rather long string representation of this hashtable.
       * Handy for debugging - leave it here!!!
       */
      public String toString() {
  	int i;
  	int max = size() - 1;
  	StringBuffer buf = new StringBuffer();
  	Enumeration k = keys();
  	Enumeration e = elements();
  	buf.append("{");
  
  	for (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();
      }
  
      /**
       * A hashtable enumerator class.  This class should remain opaque 
       * to the client. It will use the Enumeration interface.
       */
      static class HashtableEnumerator implements Enumeration {
  	boolean keys;
  	int index;
  	HashtableEntry table[];
  	HashtableEntry entry;
  
  	HashtableEnumerator(HashtableEntry 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) {
  		HashtableEntry e = entry;
  		entry = e.next;
  		return keys ? e.key : e.value;
  	    }
  	    return null;
  	}
      }
  
  }
  