/* Soot - a J*va Optimization Framework
 * Copyright (C) 1997-1999 Raja Vallee-Rai
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Modified by the Sable Research Group and others 1997-1999.  
 * See the 'credits' file distributed with Soot for the complete list of
 * contributors.  (Soot is distributed at http://www.sable.mcgill.ca/soot)
 */


package soot.util;

import java.util.*;

/** Implementation of HashMap which guarantees a stable
 * (between executions) order for its elements upon iteration.
 *
 * This is quite useful for maps of Locals, to avoid nondeterministic
 * local-name drift. */
public class DeterministicHashMap extends HashMap
{
    Set<Object> keys = new TrustingMonotonicArraySet();
    
    /** Constructs a DeterministicHashMap with the given initial capacity. */
    public DeterministicHashMap(int initialCapacity)
    {
        super(initialCapacity);
    }

    /** Constructs a DeterministicHashMap with the given initial capacity and load factor. */
    public DeterministicHashMap(int initialCapacity, float loadFactor)
    {
        super(initialCapacity, loadFactor);    
    }
    
    /** Inserts a mapping in this HashMap from <code>key</code> to <code>value</code>. */
    public Object put(Object key, Object value)
    {
        if(!containsKey(key))
            keys.add(key);
    
        return super.put(key, value);    
    }   

    /** Returns a backed list of entries for this HashMap (unsupported). */
    public Collection entries()
    {
        throw new UnsupportedOperationException();
    }    
    
    /** Removes the given object from this HashMap (unsupported). */
    public Object remove(Object obj)
    {
        throw new UnsupportedOperationException();
    }
    
    /** Returns a backed list of keys for this HashMap (unsupported). */
    public Set<Object> keySet()
    {
        return keys;
    }
}

/** ArraySet which doesn't check that the elements that you insert
    are previous uncontained. */

class TrustingMonotonicArraySet extends AbstractSet
{
    private static final int DEFAULT_SIZE = 8;

    private int numElements;
    private int maxElements;
    private Object[] elements;

    public TrustingMonotonicArraySet()
    {
        maxElements = DEFAULT_SIZE;
        elements = new Object[DEFAULT_SIZE];
        numElements = 0;
    }

    /**
     * Create a set which contains the given elements.
     */

    public TrustingMonotonicArraySet(Object[] elements)
    {
        this();

        for (Object element : elements)
			add(element);
    }

    public void clear()
    {
        numElements = 0;
    }

    public boolean contains(Object obj)
    {
        for(int i = 0; i < numElements; i++)
            if(elements[i].equals(obj))
                return true;

        return false;
    }

    public boolean add(Object e)
    {
        // Expand array if necessary
            if(numElements == maxElements)
                doubleCapacity();

        // Add element
            elements[numElements++] = e;
            return true;
    }

    public int size()
    {
        return numElements;
    }

    public Iterator iterator()
    {
        return new ArrayIterator();
    }

    private class ArrayIterator implements Iterator
    {
        int nextIndex;

        ArrayIterator()
        {
            nextIndex = 0;
        }

        public boolean hasNext()
        {
            return nextIndex < numElements;
        }

        public Object next() throws NoSuchElementException
        {
            if(!(nextIndex < numElements))
                throw new NoSuchElementException();

            return elements[nextIndex++];
        }

        public void remove() throws NoSuchElementException
        {
            if(nextIndex == 0)
                throw new NoSuchElementException();
            else
            {
                removeElementAt(nextIndex - 1);
                nextIndex = nextIndex - 1;
            }
        }
    }

    private void removeElementAt(int index)
    {
        throw new UnsupportedOperationException();
        /*
        // Handle simple case
            if(index  == numElements - 1)
            {
                numElements--;
                return;
            }

        // Else, shift over elements
            System.arraycopy(elements, index + 1, elements, index, numElements - (index + 1));
            numElements--; */
    }


    private void doubleCapacity()
    {
        int newSize = maxElements * 2;

        Object[] newElements = new Object[newSize];

        System.arraycopy(elements, 0, newElements, 0, numElements);
        elements = newElements;
        maxElements = newSize;
    }

    public Object[] toArray()
    {
        Object[] array = new Object[numElements];

        System.arraycopy(elements, 0, array, 0, numElements);
        return array;
    }
}