de.unkrig.commons.lang.protocol

Class Mappings

java.lang.Object

de.unkrig.commons.lang.protocol.Mappings

public final class Mappings
extends java.lang.Object

Utility methods related to Mapping.

Method Summary

Modifier and Type	Method and Description
static <K,V> Mapping<K,V>	augment(Mapping<K,V> in, java.lang.Object... keysAndValues) Equivalent with union(Mapping, Mapping), where the first argument is in and the second is constructed from the given keyValuePairs.
static <K,V> Mapping<K,V>	constant(V constantValue)
static <K,V> Mapping<K,V>	fromMap(java.util.Map<K,V> map) Returns a proxy Mapping for a Map.
static <K,T> T	get(Mapping<? extends K,?> mapping, java.lang.Object key, java.lang.Class<T> targetType) Invokes Mapping.get(Object) on the mapping and, if the result is not null, converts it to the given targetType.
static <K> java.lang.Object	getNonNull(Mapping<K,?> mapping, java.lang.String key)
static <K,T> T	getNonNull(Mapping<K,?> mapping, java.lang.String key, java.lang.Class<T> targetType)
static <K,V> Mapping<K,V>	mapping(java.lang.Object... keysAndValues)
static <K,V> Mapping<K,V>	none()
static <K,V> Mapping<K,V>	override(Mapping<K,V> in, java.lang.Object... keysAndValues) Equivalent with union(Mapping, Mapping), where the first argument is constructed from the given keyValuePairs and the second argument is in.
static Mapping<java.lang.String,java.lang.Object>	propertiesOf(java.lang.Object subject) Returns a mapping of property names to property values for the given subject object.
static <K,V> Mapping<K,V>	union(Mapping<K,V> op1, Mapping<K,V> op2) Returns a mapping that implements the "union" of two mappings.

Methods inherited from class java.lang.Object

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

Method Detail

fromMap

public static <K,V> Mapping<K,V> fromMap(java.util.Map<K,V> map)

Returns a proxy Mapping for a Map. This is very straightforward because the Map declares all methods that the Mapping requires. (Actually the Map should extend Mapping, but doesn't.)

mapping

public static <K,V> Mapping<K,V> mapping(java.lang.Object... keysAndValues)

Parameters:

keysAndValues - An alternating sequence of keys and values; even elements must have type K, odd elements must have type V

Returns:

A mapping of the keys and values

none

public static <K,V> Mapping<K,V> none()

Returns:

A Mapping with no mappings

propertiesOf

public static Mapping<java.lang.String,java.lang.Object> propertiesOf(java.lang.Object subject)

Returns a mapping of property names to property values for the given subject object.

The existence of a property "propertyName" is determined by the existence of one of the following, in this order:

• A public method "getPropertyName()"
• A public method "isPropertyName()"
• A public method "hasPropertyName()"
• A public method "propertyName()"
• A public field named "propertyName"

Returns:

A mapping of property name to property value

get

@Nullable
public static <K,T> T get(Mapping<? extends K,?> mapping,
                                     java.lang.Object key,
                                     java.lang.Class<T> targetType)

Invokes Mapping.get(Object) on the mapping and, if the result is not null, converts it to the given targetType.

Throws:

java.lang.IllegalArgumentException - The type of the value of the property is not assignable to T

getNonNull

public static <K> java.lang.Object getNonNull(Mapping<K,?> mapping,
                                              java.lang.String key)

Returns:

The value to which the mapping maps the key

Throws:

java.lang.IllegalArgumentException - The mapping does not contain the given key

java.lang.IllegalArgumentException - The mapping contains the key, but the mapped value is null

getNonNull

public static <K,T> T getNonNull(Mapping<K,?> mapping,
                                 java.lang.String key,
                                 java.lang.Class<T> targetType)

Returns:

The value to which the mapping maps the key

Throws:

java.lang.IllegalArgumentException - The mapping does not contain the given key

java.lang.IllegalArgumentException - The mapping contains the key, but the mapped value is null

java.lang.IllegalArgumentException - The mapping contains the key, but the mapped value is not assignable to T

union

public static <K,V> Mapping<K,V> union(Mapping<K,V> op1,
                                       Mapping<K,V> op2)

Returns a mapping that implements the "union" of two mappings.

For the returned Mapping, the following conditions apply:

• A key is contained in the result iff it is contained in (at least) one of the operands.
• The value mapped to a key is the value mapped to the key in the first of the operands which contains the key, or null iff none of the operands contain the key.

augment

public static <K,V> Mapping<K,V> augment(Mapping<K,V> in,
                                         java.lang.Object... keysAndValues)

Equivalent with union(Mapping, Mapping), where the first argument is in and the second is constructed from the given keyValuePairs.

Parameters:

keysAndValues - An alternating sequence of keys and values; even elements must have type K, odd elements must have type V

override

public static <K,V> Mapping<K,V> override(Mapping<K,V> in,
                                          java.lang.Object... keysAndValues)

Equivalent with union(Mapping, Mapping), where the first argument is constructed from the given keyValuePairs and the second argument is in.

Parameters:

keysAndValues - An alternating sequence of keys and values; even elements must have type K, odd elements must have type V

constant

public static <K,V> Mapping<K,V> constant(V constantValue)

Returns:

A mapping which always returns value, independent from the keyvalue