/*
	* Copyright (C) 2002-2019 Sebastiano Vigna
	*
	* Licensed 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 it.unimi.dsi.fastutil.objects;
import it.unimi.dsi.fastutil.objects.ObjectIterator;
import it.unimi.dsi.fastutil.objects.ObjectIterable;
import it.unimi.dsi.fastutil.objects.ObjectSet;
import it.unimi.dsi.fastutil.objects.ObjectSets;
import it.unimi.dsi.fastutil.objects.ObjectCollection;
import it.unimi.dsi.fastutil.objects.ObjectCollections;
import java.util.Map;
import java.util.function.Consumer;
import it.unimi.dsi.fastutil.objects.Reference2ObjectMap.FastEntrySet;
A class providing static methods and objects that do useful things with
type-specific maps.
See Also:
Collections/**
 * A class providing static methods and objects that do useful things with
 * type-specific maps.
 *
 * @see java.util.Collections
 */
public final class Reference2ObjectMaps {
	private Reference2ObjectMaps() {
	}
	
Returns an iterator that will be fast, if possible, on the entry set of the provided map. 
Params:
map – 
           a map from which we will try to extract a (fast) iterator on the
           entry set.
Returns:
an iterator on the entry set of the given map that will be fast, if
        possible.
Since:
8.0.0/**
	 * Returns an iterator that will be {@linkplain FastEntrySet fast}, if possible,
	 * on the {@linkplain Map#entrySet() entry set} of the provided {@code map}.
	 * 
	 * @param map
	 *            a map from which we will try to extract a (fast) iterator on the
	 *            entry set.
	 * @return an iterator on the entry set of the given map that will be fast, if
	 *         possible.
	 * @since 8.0.0
	 */
	@SuppressWarnings("unchecked")
	public static <K, V> ObjectIterator<Reference2ObjectMap.Entry<K, V>> fastIterator(Reference2ObjectMap<K, V> map) {
		final ObjectSet<Reference2ObjectMap.Entry<K, V>> entries = map.reference2ObjectEntrySet();
		return entries instanceof Reference2ObjectMap.FastEntrySet
				? ((Reference2ObjectMap.FastEntrySet<K, V>) entries).fastIterator()
				: entries.iterator();
	}
	
Iterates quickly, if possible, on the entry set of the provided map. 
Params:
map –  a map on which we will try to iterate quickly.
consumer –  the consumer that will be passed to FastEntrySet.fastForEach(Consumer), if possible, or to Iterable.forEach(Consumer).
Since:
8.1.0/**
	 * Iterates {@linkplain FastEntrySet#fastForEach(Consumer) quickly}, if
	 * possible, on the {@linkplain Map#entrySet() entry set} of the provided
	 * {@code map}.
	 * 
	 * @param map
	 *            a map on which we will try to iterate
	 *            {@linkplain FastEntrySet#fastForEach(Consumer) quickly}.
	 * @param consumer
	 *            the consumer that will be passed to
	 *            {@link FastEntrySet#fastForEach(Consumer)}, if possible, or to
	 *            {@link Iterable#forEach(Consumer)}.
	 * @since 8.1.0
	 */
	@SuppressWarnings("unchecked")
	public static <K, V> void fastForEach(Reference2ObjectMap<K, V> map,
			final Consumer<? super Reference2ObjectMap.Entry<K, V>> consumer) {
		final ObjectSet<Reference2ObjectMap.Entry<K, V>> entries = map.reference2ObjectEntrySet();
		if (entries instanceof Reference2ObjectMap.FastEntrySet)
			((Reference2ObjectMap.FastEntrySet<K, V>) entries).fastForEach(consumer);
		else
			entries.forEach(consumer);
	}
	
Returns an iterable yielding an iterator that will be fast, if possible, on the entry set of the provided map. 
Params:
map – 
           a map from which we will try to extract an iterable yielding a
           (fast) iterator on the entry set.
Returns:
an iterable yielding an iterator on the entry set of the given map
        that will be fast, if possible.
Since:
8.0.0/**
	 * Returns an iterable yielding an iterator that will be
	 * {@linkplain FastEntrySet fast}, if possible, on the
	 * {@linkplain Map#entrySet() entry set} of the provided {@code map}.
	 * 
	 * @param map
	 *            a map from which we will try to extract an iterable yielding a
	 *            (fast) iterator on the entry set.
	 * @return an iterable yielding an iterator on the entry set of the given map
	 *         that will be fast, if possible.
	 * @since 8.0.0
	 */
	@SuppressWarnings("unchecked")
	public static <K, V> ObjectIterable<Reference2ObjectMap.Entry<K, V>> fastIterable(Reference2ObjectMap<K, V> map) {
		final ObjectSet<Reference2ObjectMap.Entry<K, V>> entries = map.reference2ObjectEntrySet();
		return entries instanceof Reference2ObjectMap.FastEntrySet
				? new ObjectIterable<Reference2ObjectMap.Entry<K, V>>() {
					public ObjectIterator<Reference2ObjectMap.Entry<K, V>> iterator() {
						return ((Reference2ObjectMap.FastEntrySet<K, V>) entries).fastIterator();
					}
					public void forEach(final Consumer<? super Reference2ObjectMap.Entry<K, V>> consumer) {
						((Reference2ObjectMap.FastEntrySet<K, V>) entries).fastForEach(consumer);
					}
				}
				: entries;
	}
	
An immutable class representing an empty type-specific map.

This class may be useful to implement your own in case you subclass a
type-specific map.
/**
	 * An immutable class representing an empty type-specific map.
	 *
	 * <p>
	 * This class may be useful to implement your own in case you subclass a
	 * type-specific map.
	 */
	public static class EmptyMap<K, V> extends Reference2ObjectFunctions.EmptyFunction<K, V>
			implements
				Reference2ObjectMap<K, V>,
				java.io.Serializable,
				Cloneable {
		private static final long serialVersionUID = -7046029254386353129L;
		protected EmptyMap() {
		}
		@Override
		public boolean containsValue(final Object v) {
			return false;
		}
		@Override
		public void putAll(final Map<? extends K, ? extends V> m) {
			throw new UnsupportedOperationException();
		}
		@SuppressWarnings("unchecked")
		@Override
		public ObjectSet<Reference2ObjectMap.Entry<K, V>> reference2ObjectEntrySet() {
			return ObjectSets.EMPTY_SET;
		}
		@SuppressWarnings("unchecked")
		@Override
		public ReferenceSet<K> keySet() {
			return ReferenceSets.EMPTY_SET;
		}
		@SuppressWarnings("unchecked")
		@Override
		public ObjectCollection<V> values() {
			return ObjectSets.EMPTY_SET;
		}
		@Override
		public Object clone() {
			return EMPTY_MAP;
		}
		@Override
		public boolean isEmpty() {
			return true;
		}
		@Override
		public int hashCode() {
			return 0;
		}
		@Override
		public boolean equals(final Object o) {
			if (!(o instanceof Map))
				return false;
			return ((Map<?, ?>) o).isEmpty();
		}
		@Override
		public String toString() {
			return "{}";
		}
	}
	
An empty type-specific map (immutable). It is serializable and cloneable.
/**
	 * An empty type-specific map (immutable). It is serializable and cloneable.
	 */
	@SuppressWarnings("rawtypes")
	public static final EmptyMap EMPTY_MAP = new EmptyMap();
	
Returns an empty map (immutable). It is serializable and cloneable.
 This method provides a typesafe access to EMPTY_MAP. 
Returns:
an empty map (immutable)./**
	 * Returns an empty map (immutable). It is serializable and cloneable.
	 *
	 * <p>
	 * This method provides a typesafe access to {@link #EMPTY_MAP}.
	 * 
	 * @return an empty map (immutable).
	 */
	@SuppressWarnings("unchecked")
	public static <K, V> Reference2ObjectMap<K, V> emptyMap() {
		return EMPTY_MAP;
	}
	
An immutable class representing a type-specific singleton map.

This class may be useful to implement your own in case you subclass a
type-specific map.
/**
	 * An immutable class representing a type-specific singleton map.
	 *
	 * <p>
	 * This class may be useful to implement your own in case you subclass a
	 * type-specific map.
	 */
	public static class Singleton<K, V> extends Reference2ObjectFunctions.Singleton<K, V>
			implements
				Reference2ObjectMap<K, V>,
				java.io.Serializable,
				Cloneable {
		private static final long serialVersionUID = -7046029254386353129L;
		protected transient ObjectSet<Reference2ObjectMap.Entry<K, V>> entries;
		protected transient ReferenceSet<K> keys;
		protected transient ObjectCollection<V> values;
		protected Singleton(final K key, final V value) {
			super(key, value);
		}
		@Override
		public boolean containsValue(final Object v) {
			return java.util.Objects.equals(value, v);
		}
		@Override
		public void putAll(final Map<? extends K, ? extends V> m) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ObjectSet<Reference2ObjectMap.Entry<K, V>> reference2ObjectEntrySet() {
			if (entries == null)
				entries = ObjectSets.singleton(new AbstractReference2ObjectMap.BasicEntry<>(key, value));
			return entries;
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		@SuppressWarnings({"rawtypes", "unchecked"})
		public ObjectSet<Map.Entry<K, V>> entrySet() {
			return (ObjectSet) reference2ObjectEntrySet();
		}
		@Override
		public ReferenceSet<K> keySet() {
			if (keys == null)
				keys = ReferenceSets.singleton(key);
			return keys;
		}
		@Override
		public ObjectCollection<V> values() {
			if (values == null)
				values = ObjectSets.singleton(value);
			return values;
		}
		@Override
		public boolean isEmpty() {
			return false;
		}
		@Override
		public int hashCode() {
			return (System.identityHashCode(key)) ^ ((value) == null ? 0 : (value).hashCode());
		}
		@Override
		public boolean equals(final Object o) {
			if (o == this)
				return true;
			if (!(o instanceof Map))
				return false;
			Map<?, ?> m = (Map<?, ?>) o;
			if (m.size() != 1)
				return false;
			return m.entrySet().iterator().next().equals(entrySet().iterator().next());
		}
		@Override
		public String toString() {
			return "{" + key + "=>" + value + "}";
		}
	}
	
Returns a type-specific immutable map containing only the specified pair. The
returned map is serializable and cloneable.

Note that albeit the returned map is immutable, its default return value may
be changed.
Params:
key – 
           the only key of the returned map.
value – 
           the only value of the returned map.
Returns:
a type-specific immutable map containing just the pair &lt;key,value&gt;./**
	 * Returns a type-specific immutable map containing only the specified pair. The
	 * returned map is serializable and cloneable.
	 *
	 * <p>
	 * Note that albeit the returned map is immutable, its default return value may
	 * be changed.
	 *
	 * @param key
	 *            the only key of the returned map.
	 * @param value
	 *            the only value of the returned map.
	 * @return a type-specific immutable map containing just the pair
	 *         {@code &lt;key,value&gt;}.
	 */
	public static <K, V> Reference2ObjectMap<K, V> singleton(final K key, V value) {
		return new Singleton<>(key, value);
	}
	
A synchronized wrapper class for maps. /** A synchronized wrapper class for maps. */
	public static class SynchronizedMap<K, V> extends Reference2ObjectFunctions.SynchronizedFunction<K, V>
			implements
				Reference2ObjectMap<K, V>,
				java.io.Serializable {
		private static final long serialVersionUID = -7046029254386353129L;
		protected final Reference2ObjectMap<K, V> map;
		protected transient ObjectSet<Reference2ObjectMap.Entry<K, V>> entries;
		protected transient ReferenceSet<K> keys;
		protected transient ObjectCollection<V> values;
		protected SynchronizedMap(final Reference2ObjectMap<K, V> m, final Object sync) {
			super(m, sync);
			this.map = m;
		}
		protected SynchronizedMap(final Reference2ObjectMap<K, V> m) {
			super(m);
			this.map = m;
		}
		@Override
		public boolean containsValue(final Object v) {
			synchronized (sync) {
				return map.containsValue(v);
			}
		}
		@Override
		public void putAll(final Map<? extends K, ? extends V> m) {
			synchronized (sync) {
				map.putAll(m);
			}
		}
		@Override
		public ObjectSet<Reference2ObjectMap.Entry<K, V>> reference2ObjectEntrySet() {
			synchronized (sync) {
				if (entries == null)
					entries = ObjectSets.synchronize(map.reference2ObjectEntrySet(), sync);
				return entries;
			}
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		@SuppressWarnings({"unchecked", "rawtypes"})
		public ObjectSet<Map.Entry<K, V>> entrySet() {
			return (ObjectSet) reference2ObjectEntrySet();
		}
		@Override
		public ReferenceSet<K> keySet() {
			synchronized (sync) {
				if (keys == null)
					keys = ReferenceSets.synchronize(map.keySet(), sync);
				return keys;
			}
		}
		@Override
		public ObjectCollection<V> values() {
			synchronized (sync) {
				if (values == null)
					return ObjectCollections.synchronize(map.values(), sync);
				return values;
			}
		}
		@Override
		public boolean isEmpty() {
			synchronized (sync) {
				return map.isEmpty();
			}
		}
		@Override
		public int hashCode() {
			synchronized (sync) {
				return map.hashCode();
			}
		}
		@Override
		public boolean equals(final Object o) {
			if (o == this)
				return true;
			synchronized (sync) {
				return map.equals(o);
			}
		}
		private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
			synchronized (sync) {
				s.defaultWriteObject();
			}
		}
		// Defaultable methods
		@Override
		public V getOrDefault(final Object key, final V defaultValue) {
			synchronized (sync) {
				return map.getOrDefault(key, defaultValue);
			}
		}
		@Override
		public void forEach(final java.util.function.BiConsumer<? super K, ? super V> action) {
			synchronized (sync) {
				map.forEach(action);
			}
		}
		@Override
		public void replaceAll(final java.util.function.BiFunction<? super K, ? super V, ? extends V> function) {
			synchronized (sync) {
				map.replaceAll(function);
			}
		}
		@Override
		public V putIfAbsent(final K key, final V value) {
			synchronized (sync) {
				return map.putIfAbsent(key, value);
			}
		}
		@Override
		public boolean remove(final Object key, final Object value) {
			synchronized (sync) {
				return map.remove(key, value);
			}
		}
		@Override
		public V replace(final K key, final V value) {
			synchronized (sync) {
				return map.replace(key, value);
			}
		}
		@Override
		public boolean replace(final K key, final V oldValue, final V newValue) {
			synchronized (sync) {
				return map.replace(key, oldValue, newValue);
			}
		}
		@Override
		public V computeIfPresent(final K key,
				final java.util.function.BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
			synchronized (sync) {
				return map.computeIfPresent(key, remappingFunction);
			}
		}
		@Override
		public V compute(final K key,
				final java.util.function.BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
			synchronized (sync) {
				return map.compute(key, remappingFunction);
			}
		}
		@Override
		public V merge(final K key, final V value,
				final java.util.function.BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
			synchronized (sync) {
				return map.merge(key, value, remappingFunction);
			}
		}
	}
	
Returns a synchronized type-specific map backed by the given type-specific
map.
Params:
m – 
           the map to be wrapped in a synchronized map.
See Also:
Collections.synchronizedMap(Map<Object,Object>)
Returns:
a synchronized view of the specified map./**
	 * Returns a synchronized type-specific map backed by the given type-specific
	 * map.
	 *
	 * @param m
	 *            the map to be wrapped in a synchronized map.
	 * @return a synchronized view of the specified map.
	 * @see java.util.Collections#synchronizedMap(Map)
	 */
	public static <K, V> Reference2ObjectMap<K, V> synchronize(final Reference2ObjectMap<K, V> m) {
		return new SynchronizedMap<>(m);
	}
	
Returns a synchronized type-specific map backed by the given type-specific
map, using an assigned object to synchronize.
Params:
m – 
           the map to be wrapped in a synchronized map.
sync – 
           an object that will be used to synchronize the access to the map.
See Also:
Collections.synchronizedMap(Map<Object,Object>)
Returns:
a synchronized view of the specified map./**
	 * Returns a synchronized type-specific map backed by the given type-specific
	 * map, using an assigned object to synchronize.
	 *
	 * @param m
	 *            the map to be wrapped in a synchronized map.
	 * @param sync
	 *            an object that will be used to synchronize the access to the map.
	 * @return a synchronized view of the specified map.
	 * @see java.util.Collections#synchronizedMap(Map)
	 */
	public static <K, V> Reference2ObjectMap<K, V> synchronize(final Reference2ObjectMap<K, V> m, final Object sync) {
		return new SynchronizedMap<>(m, sync);
	}
	
An unmodifiable wrapper class for maps. /** An unmodifiable wrapper class for maps. */
	public static class UnmodifiableMap<K, V> extends Reference2ObjectFunctions.UnmodifiableFunction<K, V>
			implements
				Reference2ObjectMap<K, V>,
				java.io.Serializable {
		private static final long serialVersionUID = -7046029254386353129L;
		protected final Reference2ObjectMap<K, V> map;
		protected transient ObjectSet<Reference2ObjectMap.Entry<K, V>> entries;
		protected transient ReferenceSet<K> keys;
		protected transient ObjectCollection<V> values;
		protected UnmodifiableMap(final Reference2ObjectMap<K, V> m) {
			super(m);
			this.map = m;
		}
		@Override
		public boolean containsValue(final Object v) {
			return map.containsValue(v);
		}
		@Override
		public void putAll(final Map<? extends K, ? extends V> m) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ObjectSet<Reference2ObjectMap.Entry<K, V>> reference2ObjectEntrySet() {
			if (entries == null)
				entries = ObjectSets.unmodifiable(map.reference2ObjectEntrySet());
			return entries;
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		@SuppressWarnings({"unchecked", "rawtypes"})
		public ObjectSet<Map.Entry<K, V>> entrySet() {
			return (ObjectSet) reference2ObjectEntrySet();
		}
		@Override
		public ReferenceSet<K> keySet() {
			if (keys == null)
				keys = ReferenceSets.unmodifiable(map.keySet());
			return keys;
		}
		@Override
		public ObjectCollection<V> values() {
			if (values == null)
				return ObjectCollections.unmodifiable(map.values());
			return values;
		}
		@Override
		public boolean isEmpty() {
			return map.isEmpty();
		}
		@Override
		public int hashCode() {
			return map.hashCode();
		}
		@Override
		public boolean equals(final Object o) {
			if (o == this)
				return true;
			return map.equals(o);
		}
		// Defaultable methods
		@Override
		public V getOrDefault(final Object key, final V defaultValue) {
			return map.getOrDefault(key, defaultValue);
		}
		@Override
		public void forEach(final java.util.function.BiConsumer<? super K, ? super V> action) {
			map.forEach(action);
		}
		@Override
		public void replaceAll(final java.util.function.BiFunction<? super K, ? super V, ? extends V> function) {
			throw new UnsupportedOperationException();
		}
		@Override
		public V putIfAbsent(final K key, final V value) {
			throw new UnsupportedOperationException();
		}
		@Override
		public boolean remove(final Object key, final Object value) {
			throw new UnsupportedOperationException();
		}
		@Override
		public V replace(final K key, final V value) {
			throw new UnsupportedOperationException();
		}
		@Override
		public boolean replace(final K key, final V oldValue, final V newValue) {
			throw new UnsupportedOperationException();
		}
		@Override
		public V computeIfPresent(final K key,
				final java.util.function.BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
			throw new UnsupportedOperationException();
		}
		@Override
		public V compute(final K key,
				final java.util.function.BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
			throw new UnsupportedOperationException();
		}
		@Override
		public V merge(final K key, final V value,
				final java.util.function.BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
			throw new UnsupportedOperationException();
		}
	}
	
Returns an unmodifiable type-specific map backed by the given type-specific
map.
Params:
m – 
           the map to be wrapped in an unmodifiable map.
See Also:
Collections.unmodifiableMap(Map<? extends Object,? extends Object>)
Returns:
an unmodifiable view of the specified map./**
	 * Returns an unmodifiable type-specific map backed by the given type-specific
	 * map.
	 *
	 * @param m
	 *            the map to be wrapped in an unmodifiable map.
	 * @return an unmodifiable view of the specified map.
	 * @see java.util.Collections#unmodifiableMap(Map)
	 */
	public static <K, V> Reference2ObjectMap<K, V> unmodifiable(final Reference2ObjectMap<K, V> m) {
		return new UnmodifiableMap<>(m);
	}
}