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/*
* 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.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import org.apache.commons.collections4.OrderedMap;
import org.apache.commons.collections4.OrderedMapIterator;
import org.apache.commons.collections4.ResettableIterator;
import org.apache.commons.collections4.iterators.AbstractUntypedIteratorDecorator;
import org.apache.commons.collections4.keyvalue.AbstractMapEntry;
import org.apache.commons.collections4.list.UnmodifiableList;
/**
* Decorates a Map to ensure that the order of addition is retained
* using a List to maintain order.
*
* The order will be used via the iterators and toArray methods on the views.
* The order is also returned by the MapIterator.
* The orderedMapIterator() method accesses an iterator that can
* iterate both forwards and backwards through the map.
* In addition, non-interface methods are provided to access the map by index.
*
* If an object is added to the Map for a second time, it will remain in the
* original position in the iteration.
*
* Note that ListOrderedMap 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.
*
* Note that ListOrderedMap doesn't work with
* {@link java.util.IdentityHashMap IdentityHashMap}, {@link CaseInsensitiveMap},
* or similar maps that violate the general contract of {@link java.util.Map}.
* The ListOrderedMap (or, more precisely, the underlying List)
* is relying on {@link Object#equals(Object) equals()}. This is fine, as long as the
* decorated Map is also based on {@link Object#equals(Object) equals()},
* and {@link Object#hashCode() hashCode()}, which
* {@link java.util.IdentityHashMap IdentityHashMap}, and
* {@link CaseInsensitiveMap} don't: The former uses ==, and
* the latter uses {@link Object#equals(Object) equals()} on a lower-cased
* key.
*
* This class is {@link Serializable} starting with Commons Collections 3.1.
*
* @param the type of the keys in this map
* @param the type of the values in this map
* @since 3.0
*/
public class ListOrderedMap
extends AbstractMapDecorator
implements OrderedMap, Serializable {
/** Serialization version */
private static final long serialVersionUID = 2728177751851003750L;
/** Internal list to hold the sequence of objects */
private final List insertOrder = new ArrayList<>();
/**
* Factory method to create an ordered map.
*
* An ArrayList is used to retain order.
*
* @param the key type
* @param the value type
* @param map the map to decorate, must not be null
* @return a new list ordered map
* @throws NullPointerException if map is null
* @since 4.0
*/
public static ListOrderedMap listOrderedMap(final Map map) {
return new ListOrderedMap<>(map);
}
//-----------------------------------------------------------------------
/**
* Constructs a new empty ListOrderedMap that decorates
* a HashMap.
*
* @since 3.1
*/
public ListOrderedMap() {
this(new HashMap());
}
/**
* Constructor that wraps (not copies).
*
* @param map the map to decorate, must not be null
* @throws NullPointerException if map is null
*/
protected ListOrderedMap(final Map map) {
super(map);
insertOrder.addAll(decorated().keySet());
}
//-----------------------------------------------------------------------
/**
* Write the map out using a custom routine.
*
* @param out the output stream
* @throws IOException if an error occurs while writing to the stream
* @since 3.1
*/
private void writeObject(final ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(map);
}
/**
* Read the map in using a custom routine.
*
* @param in the input stream
* @throws IOException if an error occurs while reading from the stream
* @throws ClassNotFoundException if an object read from the stream can not be loaded
* @since 3.1
*/
@SuppressWarnings("unchecked") // (1) should only fail if input stream is incorrect
private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
map = (Map) in.readObject(); // (1)
}
// Implement OrderedMap
//-----------------------------------------------------------------------
@Override
public OrderedMapIterator mapIterator() {
return new ListOrderedMapIterator<>(this);
}
/**
* Gets the first key in this map by insert order.
*
* @return the first key currently in this map
* @throws NoSuchElementException if this map is empty
*/
@Override
public K firstKey() {
if (size() == 0) {
throw new NoSuchElementException("Map is empty");
}
return insertOrder.get(0);
}
/**
* Gets the last key in this map by insert order.
*
* @return the last key currently in this map
* @throws NoSuchElementException if this map is empty
*/
@Override
public K lastKey() {
if (size() == 0) {
throw new NoSuchElementException("Map is empty");
}
return insertOrder.get(size() - 1);
}
/**
* Gets the next key to the one specified using insert order.
* This method performs a list search to find the key and is O(n).
*
* @param key the key to find previous for
* @return the next key, null if no match or at start
*/
@Override
public K nextKey(final Object key) {
final int index = insertOrder.indexOf(key);
if (index >= 0 && index < size() - 1) {
return insertOrder.get(index + 1);
}
return null;
}
/**
* Gets the previous key to the one specified using insert order.
* This method performs a list search to find the key and is O(n).
*
* @param key the key to find previous for
* @return the previous key, null if no match or at start
*/
@Override
public K previousKey(final Object key) {
final int index = insertOrder.indexOf(key);
if (index > 0) {
return insertOrder.get(index - 1);
}
return null;
}
//-----------------------------------------------------------------------
@Override
public V put(final K key, final V value) {
if (decorated().containsKey(key)) {
// re-adding doesn't change order
return decorated().put(key, value);
}
// first add, so add to both map and list
final V result = decorated().put(key, value);
insertOrder.add(key);
return result;
}
@Override
public void putAll(final Map map) {
for (final Map.Entry entry : map.entrySet()) {
put(entry.getKey(), entry.getValue());
}
}
/**
* Puts the values contained in a supplied Map into the Map starting at
* the specified index.
*
* @param index the index in the Map to start at.
* @param map the Map containing the entries to be added.
* @throws IndexOutOfBoundsException if the index is out of range [0, size]
*/
public void putAll(int index, final Map map) {
if (index < 0 || index > insertOrder.size()) {
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + insertOrder.size());
}
for (final Map.Entry entry : map.entrySet()) {
final K key = entry.getKey();
final boolean contains = containsKey(key);
// The return value of put is null if the key did not exist OR the value was null
// so it cannot be used to determine whether the key was added
put(index, entry.getKey(), entry.getValue());
if (!contains) {
// if no key was replaced, increment the index
index++;
} else {
// otherwise put the next item after the currently inserted key
index = indexOf(entry.getKey()) + 1;
}
}
}
@Override
public V remove(final Object key) {
V result = null;
if (decorated().containsKey(key)) {
result = decorated().remove(key);
insertOrder.remove(key);
}
return result;
}
@Override
public void clear() {
decorated().clear();
insertOrder.clear();
}
//-----------------------------------------------------------------------
/**
* Gets a view over the keys in the map.
*
* The Collection will be ordered by object insertion into the map.
*
* @see #keyList()
* @return the fully modifiable collection view over the keys
*/
@Override
public Set keySet() {
return new KeySetView<>(this);
}
/**
* Gets a view over the keys in the map as a List.
*
* The List will be ordered by object insertion into the map.
* The List is unmodifiable.
*
* @see #keySet()
* @return the unmodifiable list view over the keys
* @since 3.2
*/
public List keyList() {
return UnmodifiableList.unmodifiableList(insertOrder);
}
/**
* Gets a view over the values in the map.
*
* The Collection will be ordered by object insertion into the map.
*
* From Commons Collections 3.2, this Collection can be cast
* to a list, see {@link #valueList()}
*
* @see #valueList()
* @return the fully modifiable collection view over the values
*/
@Override
public Collection values() {
return new ValuesView<>(this);
}
/**
* Gets a view over the values in the map as a List.
*
* The List will be ordered by object insertion into the map.
* The List supports remove and set, but does not support add.
*
* @see #values()
* @return the partially modifiable list view over the values
* @since 3.2
*/
public List valueList() {
return new ValuesView<>(this);
}
/**
* Gets a view over the entries in the map.
*
* The Set will be ordered by object insertion into the map.
*
* @return the fully modifiable set view over the entries
*/
@Override
public Set> entrySet() {
return new EntrySetView<>(this, this.insertOrder);
}
//-----------------------------------------------------------------------
/**
* Returns the Map as a string.
*
* @return the Map as a String
*/
@Override
public String toString() {
if (isEmpty()) {
return "{}";
}
final StringBuilder buf = new StringBuilder();
buf.append('{');
boolean first = true;
for (final Map.Entry entry : entrySet()) {
final K key = entry.getKey();
final V value = entry.getValue();
if (first) {
first = false;
} else {
buf.append(", ");
}
buf.append(key == this ? "(this Map)" : key);
buf.append('=');
buf.append(value == this ? "(this Map)" : value);
}
buf.append('}');
return buf.toString();
}
//-----------------------------------------------------------------------
/**
* Gets the key at the specified index.
*
* @param index the index to retrieve
* @return the key at the specified index
* @throws IndexOutOfBoundsException if the index is invalid
*/
public K get(final int index) {
return insertOrder.get(index);
}
/**
* Gets the value at the specified index.
*
* @param index the index to retrieve
* @return the key at the specified index
* @throws IndexOutOfBoundsException if the index is invalid
*/
public V getValue(final int index) {
return get(insertOrder.get(index));
}
/**
* Gets the index of the specified key.
*
* @param key the key to find the index of
* @return the index, or -1 if not found
*/
public int indexOf(final Object key) {
return insertOrder.indexOf(key);
}
/**
* Sets the value at the specified index.
*
* @param index the index of the value to set
* @param value the new value to set
* @return the previous value at that index
* @throws IndexOutOfBoundsException if the index is invalid
* @since 3.2
*/
public V setValue(final int index, final V value) {
final K key = insertOrder.get(index);
return put(key, value);
}
/**
* Puts a key-value mapping into the map at the specified index.
*
* If the map already contains the key, then the original mapping
* is removed and the new mapping added at the specified index.
* The remove may change the effect of the index. The index is
* always calculated relative to the original state of the map.
*
* Thus the steps are: (1) remove the existing key-value mapping,
* then (2) insert the new key-value mapping at the position it
* would have been inserted had the remove not occurred.
*
* @param index the index at which the mapping should be inserted
* @param key the key
* @param value the value
* @return the value previously mapped to the key
* @throws IndexOutOfBoundsException if the index is out of range [0, size]
* @since 3.2
*/
public V put(int index, final K key, final V value) {
if (index < 0 || index > insertOrder.size()) {
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + insertOrder.size());
}
final Map m = decorated();
if (m.containsKey(key)) {
final V result = m.remove(key);
final int pos = insertOrder.indexOf(key);
insertOrder.remove(pos);
if (pos < index) {
index--;
}
insertOrder.add(index, key);
m.put(key, value);
return result;
}
insertOrder.add(index, key);
m.put(key, value);
return null;
}
/**
* Removes the element at the specified index.
*
* @param index the index of the object to remove
* @return the removed value, or null if none existed
* @throws IndexOutOfBoundsException if the index is invalid
*/
public V remove(final int index) {
return remove(get(index));
}
/**
* Gets an unmodifiable List view of the keys which changes as the map changes.
*
* The returned list is unmodifiable because changes to the values of
* the list (using {@link java.util.ListIterator#set(Object)}) will
* effectively remove the value from the list and reinsert that value at
* the end of the list, which is an unexpected side effect of changing the
* value of a list. This occurs because changing the key, changes when the
* mapping is added to the map and thus where it appears in the list.
*
* An alternative to this method is to use the better named
* {@link #keyList()} or {@link #keySet()}.
*
* @see #keyList()
* @see #keySet()
* @return The ordered list of keys.
*/
public List asList() {
return keyList();
}
//-----------------------------------------------------------------------
static class ValuesView extends AbstractList {
private final ListOrderedMap parent;
@SuppressWarnings("unchecked")
ValuesView(final ListOrderedMap parent) {
super();
this.parent = (ListOrderedMap) parent;
}
@Override
public int size() {
return this.parent.size();
}
@Override
public boolean contains(final Object value) {
return this.parent.containsValue(value);
}
@Override
public void clear() {
this.parent.clear();
}
@Override
public Iterator iterator() {
return new AbstractUntypedIteratorDecorator, V>(parent.entrySet().iterator()) {
@Override
public V next() {
return getIterator().next().getValue();
}
};
}
@Override
public V get(final int index) {
return this.parent.getValue(index);
}
@Override
public V set(final int index, final V value) {
return this.parent.setValue(index, value);
}
@Override
public V remove(final int index) {
return this.parent.remove(index);
}
}
//-----------------------------------------------------------------------
static class KeySetView extends AbstractSet {
private final ListOrderedMap parent;
@SuppressWarnings("unchecked")
KeySetView(final ListOrderedMap parent) {
super();
this.parent = (ListOrderedMap) parent;
}
@Override
public int size() {
return this.parent.size();
}
@Override
public boolean contains(final Object value) {
return this.parent.containsKey(value);
}
@Override
public void clear() {
this.parent.clear();
}
@Override
public Iterator iterator() {
return new AbstractUntypedIteratorDecorator, K>(parent.entrySet().iterator()) {
@Override
public K next() {
return getIterator().next().getKey();
}
};
}
}
//-----------------------------------------------------------------------
static class EntrySetView extends AbstractSet> {
private final ListOrderedMap parent;
private final List insertOrder;
private Set> entrySet;
public EntrySetView(final ListOrderedMap parent, final List insertOrder) {
super();
this.parent = parent;
this.insertOrder = insertOrder;
}
private Set> getEntrySet() {
if (entrySet == null) {
entrySet = parent.decorated().entrySet();
}
return entrySet;
}
@Override
public int size() {
return this.parent.size();
}
@Override
public boolean isEmpty() {
return this.parent.isEmpty();
}
@Override
public boolean contains(final Object obj) {
return getEntrySet().contains(obj);
}
@Override
public boolean containsAll(final Collection coll) {
return getEntrySet().containsAll(coll);
}
@Override
@SuppressWarnings("unchecked")
public boolean remove(final Object obj) {
if (obj instanceof Map.Entry == false) {
return false;
}
if (getEntrySet().contains(obj)) {
final Object key = ((Map.Entry) obj).getKey();
parent.remove(key);
return true;
}
return false;
}
@Override
public void clear() {
this.parent.clear();
}
@Override
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
return getEntrySet().equals(obj);
}
@Override
public int hashCode() {
return getEntrySet().hashCode();
}
@Override
public String toString() {
return getEntrySet().toString();
}
@Override
public Iterator> iterator() {
return new ListOrderedIterator<>(parent, insertOrder);
}
}
//-----------------------------------------------------------------------
static class ListOrderedIterator extends AbstractUntypedIteratorDecorator> {
private final ListOrderedMap parent;
private K last = null;
ListOrderedIterator(final ListOrderedMap parent, final List insertOrder) {
super(insertOrder.iterator());
this.parent = parent;
}
@Override
public Map.Entry next() {
last = getIterator().next();
return new ListOrderedMapEntry<>(parent, last);
}
@Override
public void remove() {
super.remove();
parent.decorated().remove(last);
}
}
//-----------------------------------------------------------------------
static class ListOrderedMapEntry extends AbstractMapEntry {
private final ListOrderedMap parent;
ListOrderedMapEntry(final ListOrderedMap parent, final K key) {
super(key, null);
this.parent = parent;
}
@Override
public V getValue() {
return parent.get(getKey());
}
@Override
public V setValue(final V value) {
return parent.decorated().put(getKey(), value);
}
}
//-----------------------------------------------------------------------
static class ListOrderedMapIterator implements OrderedMapIterator, ResettableIterator {
private final ListOrderedMap parent;
private ListIterator iterator;
private K last = null;
private boolean readable = false;
ListOrderedMapIterator(final ListOrderedMap parent) {
super();
this.parent = parent;
this.iterator = parent.insertOrder.listIterator();
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public K next() {
last = iterator.next();
readable = true;
return last;
}
@Override
public boolean hasPrevious() {
return iterator.hasPrevious();
}
@Override
public K previous() {
last = iterator.previous();
readable = true;
return last;
}
@Override
public void remove() {
if (readable == false) {
throw new IllegalStateException(AbstractHashedMap.REMOVE_INVALID);
}
iterator.remove();
parent.map.remove(last);
readable = false;
}
@Override
public K getKey() {
if (readable == false) {
throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID);
}
return last;
}
@Override
public V getValue() {
if (readable == false) {
throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID);
}
return parent.get(last);
}
@Override
public V setValue(final V value) {
if (readable == false) {
throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID);
}
return parent.map.put(last, value);
}
@Override
public void reset() {
iterator = parent.insertOrder.listIterator();
last = null;
readable = false;
}
@Override
public String toString() {
if (readable == true) {
return "Iterator[" + getKey() + "=" + getValue() + "]";
}
return "Iterator[]";
}
}
}