org.apache.commons.collections4.map.CompositeMap Maven / Gradle / Ivy
/*
* 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 {@link java.util.Collections#synchronizedMap(Map)}. This class may throw
* exceptions when accessed by concurrent threads without synchronization.
*
*
* @param the type of the keys in this map
* @param the type of the values in this map
* @since 3.0
*/
public class CompositeMap extends AbstractIterableMap implements Serializable {
/** Serialization version */
private static final long serialVersionUID = -6096931280583808322L;
/** Array of all maps in the composite */
private Map[] composite;
/** Handle mutation operations */
private MapMutator mutator;
/**
* Create a new, empty, CompositeMap.
*/
@SuppressWarnings("unchecked")
public CompositeMap() {
this(new Map[] {}, null);
}
/**
* 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 one, final Map two) {
this(new Map[] { one, two }, null);
}
/**
* 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 one, final Map two, final MapMutator 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.
*
* @param composite the Maps to be composited
* @throws IllegalArgumentException if there is a key collision
*/
public CompositeMap(final Map... 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.
*
* @param composite Maps to be composited
* @param mutator MapMutator to be used for mutation operations
*/
@SuppressWarnings("unchecked")
public CompositeMap(final Map[] composite, final MapMutator 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.
*
* @param mutator the MapMutator to be used for mutation delegation
*/
public void setMutator(final MapMutator mutator) {
this.mutator = mutator;
}
/**
* 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 map) throws IllegalArgumentException {
if (map != null) {
for (int i = composite.length - 1; i >= 0; --i) {
final Collection 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[] 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.
*
* @param map the Map to be removed from the composite
* @return The removed Map or null if map is not in the composite
*/
@SuppressWarnings("unchecked")
public synchronized Map removeComposited(final Map map) {
final int size = this.composite.length;
for (int i = 0; i < size; ++i) {
if (this.composite[i].equals(map)) {
final Map[] 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()
*/
@Override
public void clear() {
for (int i = this.composite.length - 1; i >= 0; --i) {
this.composite[i].clear();
}
}
/**
* 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 {@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
* {@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.
*
* This implementation returns a CompositeSet 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> entrySet() {
final CompositeSet> 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
* {@code null} if the map contains no mapping for this key. A return
* value of {@code 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 {@code null}. The {@code containsKey}
* operation may be used to distinguish these two cases.
*
* More formally, if this map contains a mapping from a key
* {@code k} to a value {@code v} such that (key==null ? k==null :
* key.equals(k)), 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 {@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 {@code Iterator.remove}, {@code Set.remove},
* {@code removeAll} {@code retainAll}, and {@code clear} operations.
* It does not support the add or {@code addAll} operations.
*
* This implementation returns a CompositeSet 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 keySet() {
final CompositeSet 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
* {@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 {@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 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 {@code k} to value {@code 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
* {@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 {@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
* {@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 values() {
final CompositeCollection 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.
*
* @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}
*/
@Override
public int hashCode() {
int code = 0;
for (final Map.Entry 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.
*
* @param the type of the keys in the map
* @param the type of the values in the map
*/
public interface MapMutator extends Serializable {
/**
* 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 composite, Map existing,
Map added, Collection intersect);
/**
* 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 map, Map[] composited, K key, V value);
/**
* 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 map, Map[] composited,
Map mapToAdd);
}
}