HashedRefs.java

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package jpl.util;


class HashedRefsEntry {
    int hash;
    Object obj;
    public int iref;
    public HashedRefsEntry next;
}


public
class HashedRefs {
    public transient HashedRefsEntry table[];

    private transient int count;

    private int threshold;

    private float loadFactor;

    public HashedRefs(int initialCapacity, float loadFactor) {
        if ((initialCapacity <= 0) || (loadFactor <= 0.0)) {
            throw new IllegalArgumentException();
        }
        this.loadFactor = loadFactor;
        table = new HashedRefsEntry[initialCapacity];
        threshold = (int)(initialCapacity * loadFactor);
    }

    public HashedRefs(int initialCapacity) {
        this(initialCapacity, 0.75f);
    }

    public HashedRefs() {
        this(101, 0.75f);
    }

    public int size() {
        return count;
    }

    protected void rehash() {
        int oldCapacity = table.length;
        HashedRefsEntry oldTable[] = table;

        int newCapacity = oldCapacity * 2 + 1;
        HashedRefsEntry newTable[] = new HashedRefsEntry[newCapacity];

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

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

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

    public synchronized int add(Object obj, int iref) {
        // Make sure the object reference is not null
        if (obj == null) {
            throw new NullPointerException();
        }

        // check whether object is already in the hashtable...
        HashedRefsEntry tab[] = table;
        int hash = java.lang.System.identityHashCode(obj);
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (HashedRefsEntry e = tab[index] ; e != null ; e = e.next) {
            if ((e.hash == hash) && (e.obj == obj)) {
                return e.iref;          // existing global reference to this object
            }
        }

        if (count >= threshold) {
            // Rehash the table if the threshold is exceeded
            rehash();
            return add(obj, iref);
        } 

        // create a new entry...
        HashedRefsEntry e = new HashedRefsEntry();
        e.hash = hash;
        e.obj = obj;
        e.iref = iref;
        e.next = tab[index];
        tab[index] = e;
        count++;
        return 0;                       // indicates this reference has been added
    }

    public synchronized boolean del(Object obj) {
        HashedRefsEntry tab[] = table;
        int hash = java.lang.System.identityHashCode(obj);
        int index = (hash & 0x7FFFFFFF) % tab.length;
        for (HashedRefsEntry e = tab[index], prev = null ; e != null ; prev = e, e = e.next) {
            if ((e.hash == hash) && (e.obj == obj)) {
                if (prev != null) {
                    prev.next = e.next;
                } else {
                    tab[index] = e.next;
                }
                count--;
                return true;
            }
        }
        return false;
    }

    public synchronized void clear() {
        HashedRefsEntry tab[] = table;
        for (int index = tab.length; --index >= 0; )
            tab[index] = null;
        count = 0;
    }

}

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jpl
Author(s): Lorenz Moesenlechner
autogenerated on Fri Jan 11 09:40:29 2013