net.yetamine.lang.collections.MappingStorage Maven / Gradle / Ivy
Show all versions of net.yetamine.lang Show documentation
/*
* Copyright 2016 Yetamine
*
* 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 net.yetamine.lang.collections;
import java.io.Serializable;
import java.util.Map;
import java.util.Objects;
import java.util.function.BiFunction;
import java.util.function.Function;
/**
* A compatibility-retaining child of {@link Mapping}.
*
* @param
* the type of keys
* @param
* the type of values
*
* @deprecated Use {@link Mapping} instead as this interface adds nothing new
* and exists for compatibility in this version.
*/
@Deprecated
public interface MappingStorage extends Mapping {
/**
* Returns an instance that stores nothing and always returns {@code null}.
*
* @param
* the type of keys
* @param
* the type of values
*
* @return the instance of an empty immutable instance
*/
static MappingStorage empty() {
return EmptyMappingStorage.INSTANCE.cast();
}
/**
* Returns a new instance based on the given {@link Map} instance.
*
*
* The result inherits all characteristics (like thread safety) from the
* given map which is used as the underlying storage.
*
* @param
* the type of keys
* @param
* the type of values
* @param map
* the map to use as the underlying storage. It must not be
* {@code null}.
*
* @return the instance using the given map
*/
static MappingStorage adapting(Map map) {
return new MappingStorageAdapter<>(map);
}
}
/**
* A singleton implementing an empty {@link MappingStorage}.
*/
enum EmptyMappingStorage implements MappingStorage {
/** Sole instance of this class. */
INSTANCE;
/**
* Casts this instance to the given type.
*
* @param
* the type of keys
* @param
* the type of values
*
* @return this instance
*/
@SuppressWarnings("unchecked")
public MappingStorage cast() {
return (MappingStorage) this;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#get(java.lang.Object)
*/
public Object get(Object key) {
return null;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#put(java.lang.Object,
* java.lang.Object)
*/
public Object put(Object key, Object value) {
return null;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#putIfAbsent(java.lang.Object,
* java.lang.Object)
*/
public Object putIfAbsent(Object key, Object value) {
return null;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#replace(java.lang.Object,
* java.lang.Object)
*/
public Object replace(Object key, Object value) {
return null;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#replace(java.lang.Object,
* java.lang.Object, java.lang.Object)
*/
public boolean replace(Object key, Object oldValue, Object newValue) {
return (oldValue == null);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#clear()
*/
public void clear() {
// Do nothing
}
/**
* @see net.yetamine.lang.collections.MappingStorage#remove(java.lang.Object)
*/
public Object remove(Object key) {
return null;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#remove(java.lang.Object,
* java.lang.Object)
*/
public boolean remove(Object key, Object value) {
return false;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#merge(java.lang.Object,
* java.lang.Object, java.util.function.BiFunction)
*/
public Object merge(Object key, Object value, BiFunction remapping) {
Objects.requireNonNull(remapping);
return value;
}
/**
* @see net.yetamine.lang.collections.MappingStorage#compute(java.lang.Object,
* java.util.function.BiFunction)
*/
public Object compute(Object key, BiFunction remapping) {
Objects.requireNonNull(remapping);
return remapping.apply(key, null);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#computeIfAbsent(java.lang.Object,
* java.util.function.Function)
*/
public Object computeIfAbsent(Object key, Function mapping) {
Objects.requireNonNull(mapping);
return mapping.apply(key);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#computeIfPresent(java.lang.Object,
* java.util.function.BiFunction)
*/
public Object computeIfPresent(Object key, BiFunction remapping) {
Objects.requireNonNull(remapping);
return null;
}
}
/**
* The default implementation for {@link MappingStorage#adapting(Map)}.
*
* @param
* the type of keys
* @param
* the type of values
*/
final class MappingStorageAdapter implements Serializable, MappingStorage {
/** Serialization version: 1 */
private static final long serialVersionUID = 1L;
/** Underlying storage. */
private final Map map;
/**
* Creates a new instance.
*
* @param storage
* the underlying storage. It must not be {@code null}.
*/
public MappingStorageAdapter(Map storage) {
map = Objects.requireNonNull(storage);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#get(java.lang.Object)
*/
public V get(Object key) {
return map.get(key);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#put(java.lang.Object,
* java.lang.Object)
*/
public V put(K key, V value) {
return map.put(key, value);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#putIfAbsent(java.lang.Object,
* java.lang.Object)
*/
public V putIfAbsent(K key, V value) {
return map.putIfAbsent(key, value);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#replace(java.lang.Object,
* java.lang.Object)
*/
public V replace(K key, V value) {
return map.replace(key, value);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#replace(java.lang.Object,
* java.lang.Object, java.lang.Object)
*/
public boolean replace(K key, V oldValue, V newValue) {
return map.replace(key, oldValue, newValue);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#clear()
*/
public void clear() {
map.clear();
}
/**
* @see net.yetamine.lang.collections.MappingStorage#remove(java.lang.Object)
*/
public V remove(Object key) {
return map.remove(key);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#remove(java.lang.Object,
* java.lang.Object)
*/
public boolean remove(Object key, Object value) {
return map.remove(key, value);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#merge(java.lang.Object,
* java.lang.Object, java.util.function.BiFunction)
*/
public V merge(K key, V value, BiFunction remapping) {
return map.merge(key, value, remapping);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#compute(java.lang.Object,
* java.util.function.BiFunction)
*/
public V compute(K key, BiFunction remapping) {
return map.compute(key, remapping);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#computeIfAbsent(java.lang.Object,
* java.util.function.Function)
*/
public V computeIfAbsent(K key, Function mapping) {
return map.computeIfAbsent(key, mapping);
}
/**
* @see net.yetamine.lang.collections.MappingStorage#computeIfPresent(java.lang.Object,
* java.util.function.BiFunction)
*/
public V computeIfPresent(K key, BiFunction remapping) {
return map.computeIfPresent(key, remapping);
}
}