Module org.mule.runtime.extensions.api

Package org.mule.runtime.extension.api.util

Class HierarchyClassMap<V>

java.lang.Object

org.mule.runtime.extension.api.util.HierarchyClassMap<V>

Type Parameters:

V - the generic type of the mapped values

All Implemented Interfaces:

Map<Class<?>,V>

public class HierarchyClassMap<V>
extends Object
implements Map<Class<?>,V>

A utility implementation of Map which keys are instances of Class and values are instances of generic type V.

This classes' value comes from its get(Object) and containsKey(Object) methods being redefined to support hierarchical lookups. For example, consider types Dog and RabidDog, such that RabidDog extends Dog. If the map contains both keys, then the behaviour is the same as in a standard map. However, if get(Object) is invoked the key Dog but only RabidDog is mapped, this implementation will still find a value for Dog, since it will recursively traverse across all entries looking for keys which are assignable from that key. When no value is found, then the search is retried using the key's superclass. Recursion ends when the Object class is reached or when no superclass is available (if you searched for Object in the first place) A consistent behaviour will occur when using the containsKey(Object) method.

This also works when the key is an interface, with the difference that no recursion is performed in that case.

Interfaces

If an interface key is used and no explicit mapping is defined, no special behaviour is used.

Ordering considerations

• Exact matches are always privileged. Meaning that if the Dog key has a specific value mapped, it will be preferred over a RabidDog key
• This implementation works by wrapping an existing map (look at the constructors Javadocs). When performing searches, the iteration order depends on the rules of the underlying match. When multiple entries could match a specific query, no guarantees are offered regarding which value will be returned on each invokation

Performance considerations

When there's an explicit mapping for a given key, the performance is the same as in the backing map. When a deep search occurs, then the performance drops to O(n^n) (worst case).

Other methods

Other than get(Object) and containsKey(Object), no other method has been overridden. Behaviour will be that of the backing map.

Since:

1.0

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
HierarchyClassMap()	Creates a new instance which behaves like a HashMap
HierarchyClassMap(Map<Class<?>,V> delegate)	Creates a new instance which wraps the given delegate, inheriting its rules.

Method Summary

Modifier and Type	Method	Description
void	clear()
V	compute(Class<?> key, BiFunction<? super Class<?>,? super V,? extends V> remappingFunction)
V	computeIfAbsent(Class<?> key, Function<? super Class<?>,? extends V> mappingFunction)
V	computeIfPresent(Class<?> key, BiFunction<? super Class<?>,? super V,? extends V> remappingFunction)
boolean	containsKey(Object key)	Determines if there's a matching mapping by the rules described on the class javadoc.
boolean	containsValue(Object value)
Set<Map.Entry<Class<?>,V>>	entrySet()
boolean	equals(Object o)
void	forEach(BiConsumer<? super Class<?>,? super V> action)
V	get(Object key)	Fetches a value associated to the given key following the rules described on the class javadoc
V	getOrDefault(Object key, V defaultValue)
int	hashCode()
boolean	isEmpty()
Set<Class<?>>	keySet()
V	merge(Class<?> key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)
V	put(Class<?> key, V value)
void	putAll(Map<? extends Class<?>,? extends V> m)
V	putIfAbsent(Class<?> key, V value)
V	remove(Object key)
boolean	remove(Object key, Object value)
V	replace(Class<?> key, V value)
boolean	replace(Class<?> key, V oldValue, V newValue)
void	replaceAll(BiFunction<? super Class<?>,? super V,? extends V> function)
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

HierarchyClassMap

public HierarchyClassMap()

Creates a new instance which behaves like a HashMap

HierarchyClassMap

public HierarchyClassMap(Map<Class<?>,V> delegate)

Creates a new instance which wraps the given delegate, inheriting its rules.

Parameters:

delegate - a backing Map with predictable iteration order

Method Details

get

public V get(Object key)

Fetches a value associated to the given key following the rules described on the class javadoc

Specified by:

get in interface Map<Class<?>,V>

Parameters:

key - the key

Returns:

the associated value or null

size

public int size()

Specified by:

size in interface Map<Class<?>,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<Class<?>,V>

containsKey

public boolean containsKey(Object key)

Determines if there's a matching mapping by the rules described on the class javadoc.

Specified by:

containsKey in interface Map<Class<?>,V>

Parameters:

key - the considered key

Returns:

whether there's a mapping for this key or not

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<Class<?>,V>

put

public V put(Class<?> key,
 V value)

Specified by:

put in interface Map<Class<?>,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<Class<?>,V>

putAll

public void putAll(Map<? extends Class<?>,? extends V> m)

Specified by:

putAll in interface Map<Class<?>,V>

clear

public void clear()

Specified by:

clear in interface Map<Class<?>,V>

keySet

public Set<Class<?>> keySet()

Specified by:

keySet in interface Map<Class<?>,V>

values

public Collection<V> values()

Specified by:

values in interface Map<Class<?>,V>

entrySet

public Set<Map.Entry<Class<?>,V>> entrySet()

Specified by:

entrySet in interface Map<Class<?>,V>

equals

public boolean equals(Object o)

Specified by:

equals in interface Map<Class<?>,V>

Overrides:

equals in class Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<Class<?>,V>

Overrides:

hashCode in class Object

getOrDefault

public V getOrDefault(Object key,
 V defaultValue)

Specified by:

getOrDefault in interface Map<Class<?>,V>

forEach

public void forEach(BiConsumer<? super Class<?>,? super V> action)

Specified by:

forEach in interface Map<Class<?>,V>

replaceAll

public void replaceAll(BiFunction<? super Class<?>,? super V,? extends V> function)

Specified by:

replaceAll in interface Map<Class<?>,V>

putIfAbsent

public V putIfAbsent(Class<?> key,
 V value)

Specified by:

putIfAbsent in interface Map<Class<?>,V>

remove

public boolean remove(Object key,
 Object value)

Specified by:

remove in interface Map<Class<?>,V>

replace

public boolean replace(Class<?> key,
 V oldValue,
 V newValue)

Specified by:

replace in interface Map<Class<?>,V>

replace

public V replace(Class<?> key,
 V value)

Specified by:

replace in interface Map<Class<?>,V>

computeIfAbsent

public V computeIfAbsent(Class<?> key,
 Function<? super Class<?>,? extends V> mappingFunction)

Specified by:

computeIfAbsent in interface Map<Class<?>,V>

computeIfPresent

public V computeIfPresent(Class<?> key,
 BiFunction<? super Class<?>,? super V,? extends V> remappingFunction)

Specified by:

computeIfPresent in interface Map<Class<?>,V>

compute

public V compute(Class<?> key,
 BiFunction<? super Class<?>,? super V,? extends V> remappingFunction)

Specified by:

compute in interface Map<Class<?>,V>

merge

public V merge(Class<?> key,
 V value,
 BiFunction<? super V,? super V,? extends V> remappingFunction)

Specified by:

merge in interface Map<Class<?>,V>