/*  A parametric class for sets,
 *  based on java.util.Hashtable
 *  @author  Martin Odersky
 *  @version 1.0alpha8 96/11/22
 *  @java-version 1.33, 95/12/15
 *  @java-author Arthur van Hoff
 */

/*
 * Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

package pepa.process;

import pizza.util.*;


/**
 * Hashtable collision list.
 */
class CSetEntry<A> {

  A elem;
  int hash;
  CSetEntry<A> next;
  
  CSetEntry(A elem, int hash, CSetEntry<A> next) {
    this.elem = elem;
    this.hash = hash;
    this.next = next;
  }
  
  public A element() {
    return this.elem;
  }

  protected CSetEntry<A> copy() {
    return new CSetEntry(elem, hash,
			 (next != null) ? next.copy() : null);
  }
}


/* To sucessfully store and retrieve objects from a set, the
 * object used as the elem must implement the hashCode() and equals()
 * methods.<p>
 *
 */
public
class CSet<A implements EqAndHash<A>> implements Cloneable {
    /**
     * The hash table data.
     */
    private CSetEntry<A> 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 CSet(int initialCapacity, float loadFactor) {
	if ((initialCapacity <= 0) || (loadFactor <= 0.0)) {
	    throw new IllegalArgumentException();
	}
	this.loadFactor = loadFactor;
	table = new CSetEntry[initialCapacity];
	threshold = (int)(initialCapacity * loadFactor);
    }

    /**
     * Constructs a new, empty set with the specified initial
     * capacity.
     * @param initialCapacity the initial number of buckets
     */
    public CSet(int initialCapacity) {
	this(initialCapacity, 0.75f);
    }

    /**
     * Constructs a new, empty set. A default capacity and load factor
     * is used. Note that the set will automatically grow when it gets
     * full.
     */
    public CSet() {
	this(101, 0.75f);
    }

    /**
     * Returns the number of elements contained in the set.
     */
    public int size() {
	return count;
    }

    /**
     * Returns true if the set contains no elements.
     */
    public boolean isEmpty() {
	return count == 0;
    }

    /**
     * Returns an enumeration of the elements. Use the Enumeration methods
     * on the returned object to fetch the elements sequentially.
     * @see Hashtable#keys
     * @see Enumeration
     */
    public synchronized Enumeration<A> elements() {
	return new CSetEnumerator(table);
    }

   /**
     * Returns true if the collection contains an element for the elem.
     * @param elem the elem that we are looking for
     * @see Hashtable#contains
     */
    public synchronized boolean contains(A elem) {
	CSetEntry<A> tab[] = table;
	int hash = elem.hashCode();
	//int hash = ((Object)elem).hashCode();
	int index = (hash & 0x7FFFFFFF) % tab.length;
	// it hashes the element to find a hash table location. Dowh.
	// I need to override the hash function I guess, do it on the String
	// which is the name
	//System.out.println("parameter hash is " + hash);
	//System.out.println("this hash is " + hash);
	//System.out.println("testing membership...");
	for (CSetEntry<A> e = tab[index] ; e != null ; e = e.next) {
	    //System.out.println("really now...");
	  if (e.element().equals(elem)) {
	      //System.out.println("contains is true");
	    return true;
	  }
	}
	return false;
    }

    /**
     * Rehashes the content of the table into a bigger table.
     * This method is called automatically when the set's
     * size exceeds the threshold.
     */
    protected void rehash() {
	int oldCapacity = table.length;
	CSetEntry<A> oldTable[] = table;

	int newCapacity = oldCapacity * 2 + 1;
	CSetEntry<A> newTable[] = new CSetEntry[newCapacity];

	threshold = (int)(newCapacity * loadFactor);
	table = newTable;

	//System.out.println("rehash old=" + oldCapacity + ", new=" + newCapacity + ", thresh=" + threshold + ", count=" + count);

	for (int i = oldCapacity ; i-- > 0 ;) {
	    for (CSetEntry<A> old = oldTable[i] ; old != null ; ) {
		CSetEntry<A> e = old;
		old = old.next;

		int index = (e.hash & 0x7FFFFFFF) % newCapacity;
		e.next = newTable[index];
		newTable[index] = e;
	    }
	}
    }

  public boolean equals(CSet<A> l) {
    Enumeration<A> el = l.elements();
    while (el.hasMoreElements()) {
      if (! this.contains(el.nextElement())) {
	return false;
      }
    }
    Enumeration<A> tl = this.elements();
    while (tl.hasMoreElements()) {
      if (! l.contains(tl.nextElement())) {
	return false;
      }
    }
    return true;
  }

  
    /**
     * Puts the specified element into the set
     */
    public synchronized void put(A elem) {
	// Makes sure the elem is not already in the set.
	CSetEntry<A> tab[] = table;
	int hash = elem.hashCode();
	//int hash = ((Object)elem).hashCode();
	int index = (hash & 0x7FFFFFFF) % tab.length;
	for (CSetEntry<A> e = tab[index] ; e != null ; e = e.next) {
	    if ((e.hash == hash) && ((Object)e.elem).equals((Object)elem)) {
		return;
	    }
	}

	if (count >= threshold) {
	    // Rehash the table if the threshold is exceeded
	    rehash();
	    put(elem);
	}

	// Creates the new entry.
	tab[index] = new CSetEntry(elem, hash, tab[index]);
	count++;
    }

    /**
     * Removes the element corresponding to the elem. Does nothing if the
     * elem is not present.
     * return true iff `elem' was in set.
     * @param elem the elem that needs to be removed
     */
    public synchronized boolean remove(A elem) {
	CSetEntry<A> tab[] = table;
	int hash = elem.hashCode();
	//int hash = ((Object)elem).hashCode();
	int index = (hash & 0x7FFFFFFF) % tab.length;
	for (CSetEntry<A> e = tab[index], prev = null ; e != null ; prev = e, e = e.next) {
	    if ((e.hash == hash) && ((Object)e.elem).equals((Object)elem)) {
		if (prev != null) {
		    prev.next = e.next;
		} else {
		    tab[index] = e.next;
		}
		count--;
		return true;
	    }
	}
	return false;
    }

    /**
     * Clears the set so that it has no more elements in it.
     */
    public synchronized void clear() {
	CSetEntry<A> tab[] = table;
	for (int index = tab.length; --index >= 0; )
	    tab[index] = null;
	count = 0;
    }

    /**
     * Creates a clone of the set. A shallow copy is made,
     * the keys and elements themselves are NOT cloned. This is a
     * relatively expensive operation.
     */
    public synchronized Object clone() {
	CSet<A> t = new CSet(table.length, loadFactor);
	for (int i = table.length ; i-- > 0 ; ) {
	    t.table[i] = (table[i] != null) ? table[i].copy() : null;
	}
	return t;
    }

    /**
     * Converts to a rather lengthy String.
     */
    public synchronized String toString() {
	int max = size() - 1;
	StringBuffer buf = new StringBuffer();
	Enumeration<A> e = elements();
	buf.append("{");

	for (int i = 0; i <= max; i++) {
	    String s2 = ((Object)e.nextElement()).toString();
	    buf.append(s2);
	    if (i < max) {
		buf.append(", ");
	    }
	}
	buf.append("}");
	return buf.toString();
    }
}

/**
 * A set enumerator class.  This class should remain opaque
 * to the client. It will use the Enumeration interface.
 */
class CSetEnumerator<A> implements Enumeration<A> {
    int index;
    CSetEntry<A> table[];
    CSetEntry<A> entry;

    CSetEnumerator(CSetEntry<A> table[]) {
	this.table = table;
	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 A nextElement() {
	if (entry == null) {
	    while ((index-- > 0) && ((entry = table[index]) == null));
	}
	if (entry != null) {
	    CSetEntry<A> e = entry;
	    entry = e.next;
	    return e.elem;
	}
	throw new NoSuchElementException("CSetEnumerator");
    }
}