/*
 * 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.
 */
package org.apache.commons.collections4.map;

import java.io.Serializable;

import java.util.Collection;
import java.util.Map;
import java.util.Set;

import org.apache.commons.collections4.set.CompositeSet;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.collections4.collection.CompositeCollection;

Decorates a map of other maps to provide a single unified view.

Changes made to this map will actually be made on the decorated map.
Add and remove operations require the use of a pluggable strategy. If no
strategy is provided then add and remove are unsupported.


Note that CompositeMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map<Object,Object>). This class may throw exceptions when accessed by concurrent threads without synchronization. 
Type parameters:
<K> – the type of the keys in this map
<V> – the type of the values in this map
Since:
3.0/**
 * Decorates a map of other maps to provide a single unified view.
 * <p>
 * Changes made to this map will actually be made on the decorated map.
 * Add and remove operations require the use of a pluggable strategy. If no
 * strategy is provided then add and remove are unsupported.
 * </p>
 * <p>
 * <strong>Note that CompositeMap is not synchronized and is not thread-safe.</strong>
 * If you wish to use this map from multiple threads concurrently, you must use
 * appropriate synchronization. The simplest approach is to wrap this map
 * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
 * exceptions when accessed by concurrent threads without synchronization.
 * </p>
 *
 * @param <K> the type of the keys in this map
 * @param <V> the type of the values in this map
 * @since 3.0
 */
public class CompositeMap<K, V> extends AbstractIterableMap<K, V> implements Serializable {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = -6096931280583808322L;

    
Array of all maps in the composite /** Array of all maps in the composite */
    private Map<K, V>[] composite;

    
Handle mutation operations /** Handle mutation operations */
    private MapMutator<K, V> mutator;

    
Create a new, empty, CompositeMap.
/**
     * Create a new, empty, CompositeMap.
     */
    @SuppressWarnings("unchecked")
    public CompositeMap() {
        this(new Map[] {}, null);
    }

    
Create a new CompositeMap with two composited Map instances.
Params:
one –  the first Map to be composited
two –  the second Map to be composited
Throws:
IllegalArgumentException – if there is a key collision/**
     * Create a new CompositeMap with two composited Map instances.
     *
     * @param one  the first Map to be composited
     * @param two  the second Map to be composited
     * @throws IllegalArgumentException if there is a key collision
     */
    @SuppressWarnings("unchecked")
    public CompositeMap(final Map<K, V> one, final Map<K, V> two) {
        this(new Map[] { one, two }, null);
    }

    
Create a new CompositeMap with two composited Map instances.
Params:
one –  the first Map to be composited
two –  the second Map to be composited
mutator –  MapMutator to be used for mutation operations/**
     * Create a new CompositeMap with two composited Map instances.
     *
     * @param one  the first Map to be composited
     * @param two  the second Map to be composited
     * @param mutator  MapMutator to be used for mutation operations
     */
    @SuppressWarnings("unchecked")
    public CompositeMap(final Map<K, V> one, final Map<K, V> two, final MapMutator<K, V> mutator) {
        this(new Map[] { one, two }, mutator);
    }

    
Create a new CompositeMap which composites all of the Map instances in the
argument. It copies the argument array, it does not use it directly.
Params:
composite –  the Maps to be composited
Throws:
IllegalArgumentException – if there is a key collision/**
     * Create a new CompositeMap which composites all of the Map instances in the
     * argument. It copies the argument array, it does not use it directly.
     *
     * @param composite  the Maps to be composited
     * @throws IllegalArgumentException if there is a key collision
     */
    public CompositeMap(final Map<K, V>... composite) {
        this(composite, null);
    }

    
Create a new CompositeMap which composites all of the Map instances in the
argument. It copies the argument array, it does not use it directly.
Params:
composite –  Maps to be composited
mutator –  MapMutator to be used for mutation operations/**
     * Create a new CompositeMap which composites all of the Map instances in the
     * argument. It copies the argument array, it does not use it directly.
     *
     * @param composite  Maps to be composited
     * @param mutator  MapMutator to be used for mutation operations
     */
    @SuppressWarnings("unchecked")
    public CompositeMap(final Map<K, V>[] composite, final MapMutator<K, V> mutator) {
        this.mutator = mutator;
        this.composite = new Map[0];
        for (int i = composite.length - 1; i >= 0; --i) {
            this.addComposited(composite[i]);
        }
    }

    //-----------------------------------------------------------------------
    
Specify the MapMutator to be used by mutation operations.
Params:
mutator –  the MapMutator to be used for mutation delegation/**
     * Specify the MapMutator to be used by mutation operations.
     *
     * @param mutator  the MapMutator to be used for mutation delegation
     */
    public void setMutator(final MapMutator<K, V> mutator) {
        this.mutator = mutator;
    }

    
Add an additional Map to the composite.
Params:
map –  the Map to be added to the composite
Throws:
IllegalArgumentException – if there is a key collision and there is no
        MapMutator set to handle it./**
     * Add an additional Map to the composite.
     *
     * @param map  the Map to be added to the composite
     * @throws IllegalArgumentException if there is a key collision and there is no
     *         MapMutator set to handle it.
     */
    @SuppressWarnings("unchecked")
    public synchronized void addComposited(final Map<K, V> map) throws IllegalArgumentException {
        if (map != null) {
            for (int i = composite.length - 1; i >= 0; --i) {
                final Collection<K> intersect = CollectionUtils.intersection(this.composite[i].keySet(), map.keySet());
                if (intersect.size() != 0) {
                    if (this.mutator == null) {
                        throw new IllegalArgumentException("Key collision adding Map to CompositeMap");
                    }
                    this.mutator.resolveCollision(this, this.composite[i], map, intersect);
                }
            }
            final Map<K, V>[] temp = new Map[this.composite.length + 1];
            System.arraycopy(this.composite, 0, temp, 0, this.composite.length);
            temp[temp.length - 1] = map;
            this.composite = temp;
        }
    }

    
Remove a Map from the composite.
Params:
map –  the Map to be removed from the composite
Returns:
The removed Map or null if map is not in the composite/**
     * Remove a Map from the composite.
     *
     * @param map  the Map to be removed from the composite
     * @return The removed Map or <code>null</code> if map is not in the composite
     */
    @SuppressWarnings("unchecked")
    public synchronized Map<K, V> removeComposited(final Map<K, V> map) {
        final int size = this.composite.length;
        for (int i = 0; i < size; ++i) {
            if (this.composite[i].equals(map)) {
                final Map<K, V>[] temp = new Map[size - 1];
                System.arraycopy(this.composite, 0, temp, 0, i);
                System.arraycopy(this.composite, i + 1, temp, i, size - i - 1);
                this.composite = temp;
                return map;
            }
        }
        return null;
    }

    //-----------------------------------------------------------------------
    
Calls clear() on all composited Maps.
Throws:
UnsupportedOperationException – if any of the composited Maps do not support clear()/**
     * Calls <code>clear()</code> on all composited Maps.
     *
     * @throws UnsupportedOperationException if any of the composited Maps do not support clear()
     */
    @Override
    public void clear() {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            this.composite[i].clear();
        }
    }

    
Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains at a mapping for a key k such that (key==null ? k==null : key.equals(k)). (There can be at most one such mapping.) 
Params:
key –  key whose presence in this map is to be tested.
Throws:
ClassCastException – if the key is of an inappropriate type for
        this map (optional).
NullPointerException – if the key is null and this map does not not permit null keys (optional).
Returns:
true if this map contains a mapping for the specified key./**
     * Returns {@code true} if this map contains a mapping for the specified
     * key.  More formally, returns {@code true} if and only if
     * this map contains at a mapping for a key {@code k} such that
     * {@code (key==null ? k==null : key.equals(k))}.  (There can be
     * at most one such mapping.)
     *
     * @param key  key whose presence in this map is to be tested.
     * @return {@code true} if this map contains a mapping for the specified
     *         key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     *         this map (optional).
     * @throws NullPointerException if the key is {@code null} and this map
     *            does not not permit {@code null} keys (optional).
     */
    @Override
    public boolean containsKey(final Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return true;
            }
        }
        return false;
    }

    
Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that (value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations of the Map interface. 
Params:
value – value whose presence in this map is to be tested.
Throws:
ClassCastException – if the value is of an inappropriate type for
        this map (optional).
NullPointerException – if the value is null and this map does not not permit null values (optional).
Returns:
true if this map maps one or more keys to the specified value./**
     * Returns {@code true} if this map maps one or more keys to the
     * specified value.  More formally, returns {@code true} if and only if
     * this map contains at least one mapping to a value {@code v} such that
     * {@code (value==null ? v==null : value.equals(v))}.  This operation
     * will probably require time linear in the map size for most
     * implementations of the {@code Map} interface.
     *
     * @param value value whose presence in this map is to be tested.
     * @return {@code true} if this map maps one or more keys to the
     *         specified value.
     * @throws ClassCastException if the value is of an inappropriate type for
     *         this map (optional).
     * @throws NullPointerException if the value is {@code null} and this map
     *            does not not permit {@code null} values (optional).
     */
    @Override
    public boolean containsValue(final Object value) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsValue(value)) {
                return true;
            }
        }
        return false;
    }

    
Returns a set view of the mappings contained in this map.  Each element
in the returned set is a Map.Entry. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations. 

This implementation returns a CompositeSet which
composites the entry sets from all of the composited maps.
See Also:
CompositeSet
Returns:
a set view of the mappings contained in this map./**
     * Returns a set view of the mappings contained in this map.  Each element
     * in the returned set is a <code>Map.Entry</code>.  The set is backed by the
     * map, so changes to the map are reflected in the set, and vice-versa.
     * If the map is modified while an iteration over the set is in progress,
     * the results of the iteration are undefined.  The set supports element
     * removal, which removes the corresponding mapping from the map, via the
     * {@code Iterator.remove}, {@code Set.remove}, {@code removeAll},
     * {@code retainAll} and {@code clear} operations.  It does not support
     * the {@code add} or {@code addAll} operations.
     * <p>
     * This implementation returns a <code>CompositeSet</code> which
     * composites the entry sets from all of the composited maps.
     *
     * @see CompositeSet
     * @return a set view of the mappings contained in this map.
     */
    @Override
    public Set<Map.Entry<K, V>> entrySet() {
        final CompositeSet<Map.Entry<K, V>> entries = new CompositeSet<>();
        for (int i = composite.length - 1; i >= 0; --i) {
            entries.addComposited(composite[i].entrySet());
        }
        return entries;
    }

    
Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases. 
More formally, if this map contains a mapping from a key k to a value v such that (key==null ? k==null :
key.equals(k)), then this method returns v; otherwise it returns null. (There can be at most one such mapping.) 
Params:
key – key whose associated value is to be returned.
Throws:
ClassCastException – if the key is of an inappropriate type for
        this map (optional).
NullPointerException – key is null and this map does not not permit null keys (optional).
See Also:
containsKey(Object)
Returns:
the value to which this map maps the specified key, or null if the map contains no mapping for this key./**
     * Returns the value to which this map maps the specified key.  Returns
     * {@code null} if the map contains no mapping for this key.  A return
     * value of {@code null} does not <i>necessarily</i> indicate that the
     * map contains no mapping for the key; it's also possible that the map
     * explicitly maps the key to {@code null}.  The {@code containsKey}
     * operation may be used to distinguish these two cases.
     *
     * <p>More formally, if this map contains a mapping from a key
     * {@code k} to a value {@code v} such that <code>(key==null ? k==null :
     * key.equals(k))</code>, then this method returns {@code v}; otherwise
     * it returns {@code null}.  (There can be at most one such mapping.)
     *
     * @param key key whose associated value is to be returned.
     * @return the value to which this map maps the specified key, or
     *         {@code null} if the map contains no mapping for this key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     *         this map (optional).
     * @throws NullPointerException key is {@code null} and this map does not
     *         not permit {@code null} keys (optional).
     *
     * @see #containsKey(Object)
     */
    @Override
    public V get(final Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return this.composite[i].get(key);
            }
        }
        return null;
    }

    
Returns true if this map contains no key-value mappings. 
Returns:
true if this map contains no key-value mappings./**
     * Returns {@code true} if this map contains no key-value mappings.
     *
     * @return {@code true} if this map contains no key-value mappings.
     */
    @Override
    public boolean isEmpty() {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (!this.composite[i].isEmpty()) {
                return false;
            }
        }
        return true;
    }

    
Returns a set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll retainAll, and clear operations. It does not support the add or addAll operations. 

This implementation returns a CompositeSet which
composites the key sets from all of the composited maps.
Returns:
a set view of the keys contained in this map./**
     * Returns a set view of the keys contained in this map.  The set is
     * backed by the map, so changes to the map are reflected in the set, and
     * vice-versa.  If the map is modified while an iteration over the set is
     * in progress, the results of the iteration are undefined.  The set
     * supports element removal, which removes the corresponding mapping from
     * the map, via the {@code Iterator.remove}, {@code Set.remove},
     * {@code removeAll} {@code retainAll}, and {@code clear} operations.
     * It does not support the add or {@code addAll} operations.
     * <p>
     * This implementation returns a <code>CompositeSet</code> which
     * composites the key sets from all of the composited maps.
     *
     * @return a set view of the keys contained in this map.
     */
    @Override
    public Set<K> keySet() {
        final CompositeSet<K> keys = new CompositeSet<>();
        for (int i = this.composite.length - 1; i >= 0; --i) {
            keys.addComposited(this.composite[i].keySet());
        }
        return keys;
    }

    
Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for this key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)) 
Params:
key – key with which the specified value is to be associated.
value – value to be associated with the specified key.
Throws:
UnsupportedOperationException – if no MapMutator has been specified
ClassCastException – if the class of the specified key or value
           prevents it from being stored in this map.
IllegalArgumentException – if some aspect of this key or value
           prevents it from being stored in this map.
NullPointerException – this map does not permit null keys or values, and the specified key or value is null.
Returns:
previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values./**
     * Associates the specified value with the specified key in this map
     * (optional operation).  If the map previously contained a mapping for
     * this key, the old value is replaced by the specified value.  (A map
     * {@code m} is said to contain a mapping for a key {@code k} if and only
     * if {@link #containsKey(Object) m.containsKey(k)} would return
     * {@code true}.))
     *
     * @param key key with which the specified value is to be associated.
     * @param value value to be associated with the specified key.
     * @return previous value associated with specified key, or {@code null}
     *         if there was no mapping for key.  A {@code null} return can
     *         also indicate that the map previously associated {@code null}
     *         with the specified key, if the implementation supports
     *         {@code null} values.
     *
     * @throws UnsupportedOperationException if no MapMutator has been specified
     * @throws ClassCastException if the class of the specified key or value
     *            prevents it from being stored in this map.
     * @throws IllegalArgumentException if some aspect of this key or value
     *            prevents it from being stored in this map.
     * @throws NullPointerException this map does not permit {@code null}
     *            keys or values, and the specified key or value is
     *            {@code null}.
     */
    @Override
    public V put(final K key, final V value) {
        if (this.mutator == null) {
            throw new UnsupportedOperationException("No mutator specified");
        }
        return this.mutator.put(this, this.composite, key, value);
    }

    
Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is unspecified if the specified map is modified while the operation is in progress. 
Params:
map – Mappings to be stored in this map.
Throws:
UnsupportedOperationException – if the putAll method is not supported by this map.
ClassCastException – if the class of a key or value in the
        specified map prevents it from being stored in this map.
IllegalArgumentException – some aspect of a key or value in the
        specified map prevents it from being stored in this map.
NullPointerException – the specified map is null, or if this map does not permit null keys or values, and the specified map contains null keys or values./**
     * Copies all of the mappings from the specified map to this map
     * (optional operation).  The effect of this call is equivalent to that
     * of calling {@link #put(Object,Object) put(k, v)} on this map once
     * for each mapping from key {@code k} to value {@code v} in the
     * specified map.  The behavior of this operation is unspecified if the
     * specified map is modified while the operation is in progress.
     *
     * @param map Mappings to be stored in this map.
     *
     * @throws UnsupportedOperationException if the {@code putAll} method is
     *         not supported by this map.
     *
     * @throws ClassCastException if the class of a key or value in the
     *         specified map prevents it from being stored in this map.
     *
     * @throws IllegalArgumentException some aspect of a key or value in the
     *         specified map prevents it from being stored in this map.
     * @throws NullPointerException the specified map is {@code null}, or if
     *         this map does not permit {@code null} keys or values, and the
     *         specified map contains {@code null} keys or values.
     */
    @Override
    public void putAll(final Map<? extends K, ? extends V> map) {
        if (this.mutator == null) {
            throw new UnsupportedOperationException("No mutator specified");
        }
        this.mutator.putAll(this, this.composite, map);
    }

    
Removes the mapping for this key from this map if it is present (optional operation). More formally, if this map contains a mapping from key k to value v such that (key==null ?  k==null : key.equals(k)), that mapping
is removed.  (The map can contain at most one such mapping.)
Returns the value to which the map previously associated the key, or null if the map contained no mapping for this key. (A null return can also indicate that the map previously associated null with the specified key if the implementation supports null values.) The map will not contain a mapping for the specified key once the call returns. 
Params:
key – key whose mapping is to be removed from the map.
Throws:
ClassCastException – if the key is of an inappropriate type for
        the composited map (optional).
NullPointerException – if the key is null and the composited map does not not permit null keys (optional).
UnsupportedOperationException – if the remove method is not supported by the composited map containing the key
Returns:
previous value associated with specified key, or null if there was no mapping for key./**
     * Removes the mapping for this key from this map if it is present
     * (optional operation).   More formally, if this map contains a mapping
     * from key {@code k} to value {@code v} such that
     * <code>(key==null ?  k==null : key.equals(k))</code>, that mapping
     * is removed.  (The map can contain at most one such mapping.)
     *
     * <p>Returns the value to which the map previously associated the key, or
     * {@code null} if the map contained no mapping for this key.  (A
     * {@code null} return can also indicate that the map previously
     * associated {@code null} with the specified key if the implementation
     * supports {@code null} values.)  The map will not contain a mapping for
     * the specified  key once the call returns.
     *
     * @param key key whose mapping is to be removed from the map.
     * @return previous value associated with specified key, or {@code null}
     *         if there was no mapping for key.
     *
     * @throws ClassCastException if the key is of an inappropriate type for
     *         the composited map (optional).
     * @throws NullPointerException if the key is {@code null} and the composited map
     *            does not not permit {@code null} keys (optional).
     * @throws UnsupportedOperationException if the {@code remove} method is
     *         not supported by the composited map containing the key
     */
    @Override
    public V remove(final Object key) {
        for (int i = this.composite.length - 1; i >= 0; --i) {
            if (this.composite[i].containsKey(key)) {
                return this.composite[i].remove(key);
            }
        }
        return null;
    }

    
Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE. 
Returns:
the number of key-value mappings in this map./**
     * Returns the number of key-value mappings in this map.  If the
     * map contains more than {@code Integer.MAX_VALUE} elements, returns
     * {@code Integer.MAX_VALUE}.
     *
     * @return the number of key-value mappings in this map.
     */
    @Override
    public int size() {
        int size = 0;
        for (int i = this.composite.length - 1; i >= 0; --i) {
            size += this.composite[i].size();
        }
        return size;
    }

    
Returns a collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress, the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations. 
Returns:
a collection view of the values contained in this map./**
     * Returns a collection view of the values contained in this map.  The
     * collection is backed by the map, so changes to the map are reflected in
     * the collection, and vice-versa.  If the map is modified while an
     * iteration over the collection is in progress, the results of the
     * iteration are undefined.  The collection supports element removal,
     * which removes the corresponding mapping from the map, via the
     * {@code Iterator.remove}, {@code Collection.remove},
     * {@code removeAll}, {@code retainAll} and {@code clear} operations.
     * It does not support the add or {@code addAll} operations.
     *
     * @return a collection view of the values contained in this map.
     */
    @Override
    public Collection<V> values() {
        final CompositeCollection<V> values = new CompositeCollection<>();
        for (int i = composite.length - 1; i >= 0; --i) {
            values.addComposited(composite[i].values());
        }
        return values;
    }

    
Checks if this Map equals another as per the Map specification.
Params:
obj –  the object to compare to
Returns:
true if the maps are equal/**
     * Checks if this Map equals another as per the Map specification.
     *
     * @param obj  the object to compare to
     * @return true if the maps are equal
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj instanceof Map) {
            final Map<?, ?> map = (Map<?, ?>) obj;
            return this.entrySet().equals(map.entrySet());
        }
        return false;
    }

    
Gets a hash code for the Map as per the Map specification.
{@inheritDoc}
/**
     * Gets a hash code for the Map as per the Map specification.
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        int code = 0;
        for (final Map.Entry<K, V> entry : entrySet()) {
            code += entry.hashCode();
        }
        return code;
    }

    
This interface allows definition for all of the indeterminate
mutators in a CompositeMap, as well as providing a hook for
callbacks on key collisions.
Type parameters:
<K> – the type of the keys in the map
<V> – the type of the values in the map/**
     * This interface allows definition for all of the indeterminate
     * mutators in a CompositeMap, as well as providing a hook for
     * callbacks on key collisions.
     *
     * @param <K> the type of the keys in the map
     * @param <V> the type of the values in the map
     */
    public interface MapMutator<K, V> extends Serializable {
        
Called when adding a new Composited Map results in a
key collision.
Params:
composite –  the CompositeMap with the collision
existing –  the Map already in the composite which contains the
       offending key
added –  the Map being added
intersect –  the intersection of the keysets of the existing and added maps/**
         * Called when adding a new Composited Map results in a
         * key collision.
         *
         * @param composite  the CompositeMap with the collision
         * @param existing  the Map already in the composite which contains the
         *        offending key
         * @param added  the Map being added
         * @param intersect  the intersection of the keysets of the existing and added maps
         */
        void resolveCollision(CompositeMap<K, V> composite, Map<K, V> existing,
                Map<K, V> added, Collection<K> intersect);

        
Called when the CompositeMap.put() method is invoked.
Params:
map –  the CompositeMap which is being modified
composited –  array of Maps in the CompositeMap being modified
key –  key with which the specified value is to be associated.
value –  value to be associated with the specified key.
Throws:
UnsupportedOperationException – if not defined
ClassCastException – if the class of the specified key or value
           prevents it from being stored in this map.
IllegalArgumentException – if some aspect of this key or value
           prevents it from being stored in this map.
NullPointerException – this map does not permit null keys or values, and the specified key or value is null.
Returns:
previous value associated with specified key, or null if there was no mapping for key. A null return can also indicate that the map previously associated null with the specified key, if the implementation supports null values./**
         * Called when the CompositeMap.put() method is invoked.
         *
         * @param map  the CompositeMap which is being modified
         * @param composited  array of Maps in the CompositeMap being modified
         * @param key  key with which the specified value is to be associated.
         * @param value  value to be associated with the specified key.
         * @return previous value associated with specified key, or {@code null}
         *         if there was no mapping for key.  A {@code null} return can
         *         also indicate that the map previously associated {@code null}
         *         with the specified key, if the implementation supports
         *         {@code null} values.
         *
         * @throws UnsupportedOperationException if not defined
         * @throws ClassCastException if the class of the specified key or value
         *            prevents it from being stored in this map.
         * @throws IllegalArgumentException if some aspect of this key or value
         *            prevents it from being stored in this map.
         * @throws NullPointerException this map does not permit {@code null}
         *            keys or values, and the specified key or value is
         *            {@code null}.
         */
        V put(CompositeMap<K, V> map, Map<K, V>[] composited, K key, V value);

        
Called when the CompositeMap.putAll() method is invoked.
Params:
map –  the CompositeMap which is being modified
composited –  array of Maps in the CompositeMap being modified
mapToAdd –  Mappings to be stored in this CompositeMap
Throws:
UnsupportedOperationException – if not defined
ClassCastException – if the class of the specified key or value
           prevents it from being stored in this map.
IllegalArgumentException – if some aspect of this key or value
           prevents it from being stored in this map.
NullPointerException – this map does not permit null keys or values, and the specified key or value is null./**
         * Called when the CompositeMap.putAll() method is invoked.
         *
         * @param map  the CompositeMap which is being modified
         * @param composited  array of Maps in the CompositeMap being modified
         * @param mapToAdd  Mappings to be stored in this CompositeMap
         *
         * @throws UnsupportedOperationException if not defined
         * @throws ClassCastException if the class of the specified key or value
         *            prevents it from being stored in this map.
         * @throws IllegalArgumentException if some aspect of this key or value
         *            prevents it from being stored in this map.
         * @throws NullPointerException this map does not permit {@code null}
         *            keys or values, and the specified key or value is
         *            {@code null}.
         */
        void putAll(CompositeMap<K, V> map, Map<K, V>[] composited,
                Map<? extends K, ? extends V> mapToAdd);
    }
}