flat3map.java

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    /**
     * Create an instance of the map used for storage when in delegation mode.
     * <p>
     * This can be overridden by subclasses to provide a different map implementation.
     * Not every AbstractHashedMap is suitable, identity and reference based maps
     * would be poor choices.
     *
     * @return a new AbstractHashedMap or subclass
     * @since Commons Collections 3.1
     */
    protected AbstractHashedMap createDelegateMap() {
        return new HashedMap();
    }

    /**
     * Removes the specified mapping from this map.
     * 
     * @param key  the mapping to remove
     * @return the value mapped to the removed key, null if key not in map
     */
    public Object remove(Object key) {
        if (delegateMap != null) {
            return delegateMap.remove(key);
        }
        if (size == 0) {
            return null;
        }
        if (key == null) {
            switch (size) {  // drop through
                case 3:
                    if (key3 == null) {
                        Object old = value3;
                        hash3 = 0;
                        key3 = null;
                        value3 = null;
                        size = 2;
                        return old;
                    }
                    if (key2 == null) {
                        Object old = value3;
                        hash2 = hash3;
                        key2 = key3;
                        value2 = value3;
                        hash3 = 0;
                        key3 = null;
                        value3 = null;
                        size = 2;
                        return old;
                    }
                    if (key1 == null) {
                        Object old = value3;
                        hash1 = hash3;
                        key1 = key3;
                        value1 = value3;
                        hash3 = 0;
                        key3 = null;
                        value3 = null;
                        size = 2;
                        return old;
                    }
                    return null;
                case 2:
                    if (key2 == null) {
                        Object old = value2;
                        hash2 = 0;
                        key2 = null;
                        value2 = null;
                        size = 1;
                        return old;
                    }
                    if (key1 == null) {
                        Object old = value2;
                        hash1 = hash2;
                        key1 = key2;
                        value1 = value2;
                        hash2 = 0;
                        key2 = null;
                        value2 = null;
                        size = 1;
                        return old;
                    }
                    return null;
                case 1:
                    if (key1 == null) {
                        Object old = value1;
                        hash1 = 0;
                        key1 = null;
                        value1 = null;
                        size = 0;
                        return old;
                    }
            }
        } else {
            if (size > 0) {
                int hashCode = key.hashCode();
                switch (size) {  // drop through
                    case 3:
                        if (hash3 == hashCode && key.equals(key3)) {
                            Object old = value3;
                            hash3 = 0;
                            key3 = null;
                            value3 = null;
                            size = 2;
                            return old;
                        }
                        if (hash2 == hashCode && key.equals(key2)) {
                            Object old = value3;
                            hash2 = hash3;
                            key2 = key3;
                            value2 = value3;
                            hash3 = 0;
                            key3 = null;
                            value3 = null;
                            size = 2;
                            return old;
                        }
                        if (hash1 == hashCode && key.equals(key1)) {
                            Object old = value3;
                            hash1 = hash3;
                            key1 = key3;
                            value1 = value3;
                            hash3 = 0;
                            key3 = null;
                            value3 = null;
                            size = 2;
                            return old;
                        }
                        return null;
                    case 2:
                        if (hash2 == hashCode && key.equals(key2)) {
                            Object old = value2;
                            hash2 = 0;
                            key2 = null;
                            value2 = null;
                            size = 1;
                            return old;
                        }
                        if (hash1 == hashCode && key.equals(key1)) {
                            Object old = value2;
                            hash1 = hash2;
                            key1 = key2;
                            value1 = value2;
                            hash2 = 0;
                            key2 = null;
                            value2 = null;
                            size = 1;
                            return old;
                        }
                        return null;
                    case 1:
                        if (hash1 == hashCode && key.equals(key1)) {
                            Object old = value1;
                            hash1 = 0;
                            key1 = null;
                            value1 = null;
                            size = 0;
                            return old;
                        }
                }
            }
        }
        return null;
    }

    /**
     * Clears the map, resetting the size to zero and nullifying references
     * to avoid garbage collection issues.
     */
    public void clear() {
        if (delegateMap != null) {
            delegateMap.clear();  // should aid gc
            delegateMap = null;  // switch back to flat mode
        } else {
            size = 0;
            hash1 = hash2 = hash3 = 0;
            key1 = key2 = key3 = null;
            value1 = value2 = value3 = null;
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Gets an iterator over the map.
     * Changes made to the iterator affect this map.
     * <p>
     * A MapIterator returns the keys in the map. It also provides convenient
     * methods to get the key and value, and set the value.
     * It avoids the need to create an entrySet/keySet/values object.
     * It also avoids creating the Map Entry object.
     * 
     * @return the map iterator
     */
    public MapIterator mapIterator() {
        if (delegateMap != null) {
            return delegateMap.mapIterator();
        }
        if (size == 0) {
            return EmptyMapIterator.INSTANCE;
        }
        return new FlatMapIterator(this);
    }

    /**
     * FlatMapIterator
     */
    static class FlatMapIterator implements MapIterator, ResettableIterator {
        private final Flat3Map parent;
        private int nextIndex = 0;
        private boolean canRemove = false;
        
        FlatMapIterator(Flat3Map parent) {
            super();
            this.parent = parent;
        }

        public boolean hasNext() {
            return (nextIndex < parent.size);
        }

        public Object next() {
            if (hasNext() == false) {
                throw new NoSuchElementException(AbstractHashedMap.NO_NEXT_ENTRY);
            }
            canRemove = true;
            nextIndex++;
            return getKey();
        }

        public void remove() {
            if (canRemove == false) {
                throw new IllegalStateException(AbstractHashedMap.REMOVE_INVALID);
            }
            parent.remove(getKey());
            nextIndex--;
            canRemove = false;
        }

        public Object getKey() {
            if (canRemove == false) {
                throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID);
            }
            switch (nextIndex) {
                case 3:
                    return parent.key3;
                case 2:
                    return parent.key2;
                case 1:
                    return parent.key1;
            }
            throw new IllegalStateException("Invalid map index");
        }

        public Object getValue() {
            if (canRemove == false) {
                throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID);
            }
            switch (nextIndex) {
                case 3:
                    return parent.value3;
                case 2:
                    return parent.value2;
                case 1:
                    return parent.value1;
            }
            throw new IllegalStateException("Invalid map index");
        }

        public Object setValue(Object value) {
            if (canRemove == false) {
                throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID);
            }
            Object old = getValue();
            switch (nextIndex) {
                case 3: 
                    parent.value3 = value;
                case 2:
                    parent.value2 = value;
                case 1:
                    parent.value1 = value;
            }
            return old;
        }
        
        public void reset() {
            nextIndex = 0;
            canRemove = false;
        }
        
        public String toString() {
            if (canRemove) {
                return "Iterator[" + getKey() + "=" + getValue() + "]";
            } else {
                return "Iterator[]";
            }
        }
    }
    
    /**
     * Gets the entrySet view of the map.
     * Changes made to the view affect this map.
     * The Map Entry is not an independent object and changes as the 
     * iterator progresses.
     * To simply iterate through the entries, use {@link #mapIterator()}.
     * 
     * @return the entrySet view
     */
    public Set entrySet() {
        if (delegateMap != null) {
            return delegateMap.entrySet();
        }
        return new EntrySet(this);
    }
    
    /**
     * EntrySet
     */
    static class EntrySet extends AbstractSet {
        private final Flat3Map parent;
        
        EntrySet(Flat3Map parent) {
            super();
            this.parent = parent;
        }

        public int size() {
            return parent.size();
        }
        
        public void clear() {
            parent.clear();
        }
        
        public boolean remove(Object obj) {
            if (obj instanceof Map.Entry == false) {
                return false;
            }
            Map.Entry entry = (Map.Entry) obj;
            Object key = entry.getKey();
            boolean result = parent.containsKey(key);
            parent.remove(key);
            return result;
        }

        public Iterator iterator() {
            if (parent.delegateMap != null) {
                return parent.delegateMap.entrySet().iterator();
            }
            if (parent.size() == 0) {
                return EmptyIterator.INSTANCE;
            }
            return new EntrySetIterator(parent);
        }
    }

    /**
     * EntrySetIterator and MapEntry
     */
    static class EntrySetIterator implements Iterator, Map.Entry {
        private final Flat3Map parent;
        private int nextIndex = 0;
        private boolean canRemove = false;
        
        EntrySetIterator(Flat3Map parent) {
            super();
            this.parent = parent;
        }

        public boolean hasNext() {
            return (nextIndex < parent.size);
        }

        public Object next() {
            if (hasNext() == false) {
                throw new NoSuchElementException(AbstractHashedMap.NO_NEXT_ENTRY);
            }
            canRemove = true;
            nextIndex++;
            return this;