org.dynalang.mop.collections

Class MapMetaobjectProtocol

java.lang.Object

org.dynalang.mop.impl.MetaobjectProtocolBase

org.dynalang.mop.collections.MapMetaobjectProtocol

All Implemented Interfaces:

BaseMetaobjectProtocol, CallProtocol, ClassBasedMetaobjectProtocol, MetaobjectProtocol

public class MapMetaobjectProtocol
extends MetaobjectProtocolBase
implements ClassBasedMetaobjectProtocol

A metaobject protocol that knows how to manipulate Java maps. Operates on all keys present in the map, and returns BaseMetaobjectProtocol.Result#noAuthority for keys not present (thus allowing fallback to other navigators below it).

Version:

$Id: $

Author:

Attila Szegedi

Nested Class Summary

Nested classes/interfaces inherited from interface org.dynalang.mop.BaseMetaobjectProtocol

BaseMetaobjectProtocol.Result

Constructor Summary

Constructors

Constructor and Description
MapMetaobjectProtocol()

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	call(java.lang.Object callable, CallProtocol callProtocol, java.util.Map args) Calls a callable object with named arguments.
java.lang.Object	call(java.lang.Object callable, CallProtocol callProtocol, java.lang.Object... args) Calls a callable object with positional arguments.
BaseMetaobjectProtocol.Result	delete(java.lang.Object target, java.lang.Object propertyId) Removes a key-value mapping from the map.
java.lang.Object	get(java.lang.Object target, java.lang.Object propertyId) Retrieves a value from the map.
java.lang.Boolean	has(java.lang.Object target, java.lang.Object propertyId) Determines whether a key is present in the map.
boolean	isAuthoritativeForClass(java.lang.Class clazz) Returns whether this metaobject protocol has authority over objects of the specified class.
java.util.Iterator<java.util.Map.Entry>	properties(java.lang.Object target) Retrieves the mappings in the map.
BaseMetaobjectProtocol.Result	put(java.lang.Object target, java.lang.Object propertyId, java.lang.Object value, CallProtocol callProtocol) Binds a key-value pair into the map.
java.lang.Object	representAs(java.lang.Object object, java.lang.Class targetClass) Returns a representation of the specified target object as an object of the specified target class.

Methods inherited from class org.dynalang.mop.impl.MetaobjectProtocolBase

call, call, delete, get, has, propertyIds, put

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.dynalang.mop.MetaobjectProtocol

call, call, delete, get, has, propertyIds, put

Constructor Detail

MapMetaobjectProtocol

public MapMetaobjectProtocol()

Method Detail

isAuthoritativeForClass

public boolean isAuthoritativeForClass(java.lang.Class clazz)

Description copied from interface: ClassBasedMetaobjectProtocol

Returns whether this metaobject protocol has authority over objects of the specified class. Note that if a MOP claims that it has authority over objects of a certain class, it can still return BaseMetaobjectProtocol.Result.noAuthority for certain objects. In that case - when used in CompositeClassBasedMetaobjectProtocol - the other participating MOPs will also be given the chance to handle the object after this MOP was given the chance first.

Specified by:

isAuthoritativeForClass in interface ClassBasedMetaobjectProtocol

Parameters:

clazz - the class of the handled object

Returns:

true if this metaobject protocol has authority over objects of the specified class, false otherwise.

call

public java.lang.Object call(java.lang.Object callable,
                    CallProtocol callProtocol,
                    java.util.Map args)

Description copied from interface: CallProtocol

Calls a callable object with named arguments.

Specified by:

call in interface CallProtocol

Parameters:

callable - the callable object

callProtocol - a marshaller that should be used by this metaobject protocol to convert the arguments to conform to expected argument types for the call.

args - the named arguments for the callable object. null must be treated as empty map. Usually, the map keys are strings, but it is possible that some protocols support non-string keys.

Returns:

BaseMetaobjectProtocol.Result#noAuthority as this MOP has no concept of callables

call

public java.lang.Object call(java.lang.Object callable,
                    CallProtocol callProtocol,
                    java.lang.Object... args)

Description copied from interface: CallProtocol

Calls a callable object with positional arguments.

Specified by:

call in interface CallProtocol

Parameters:

callable - the callable object

callProtocol - a marshaller that should be used by this metaobject protocol to convert the arguments to conform to expected argument types for the call.

args - the positional arguments for the callable object. null must be treated as empty array.

Returns:

BaseMetaobjectProtocol.Result#noAuthority as this MOP has no concept of callables

delete

public BaseMetaobjectProtocol.Result delete(java.lang.Object target,
                                   java.lang.Object propertyId)

Removes a key-value mapping from the map.

Specified by:

delete in interface BaseMetaobjectProtocol

Parameters:

target - the map to remove element from

propertyId - the map key

Returns:

BaseMetaobjectProtocol.Result#ok if the removal was successful. If the map is read-only (throws a UnsupportedOperationException on removal attempt), BaseMetaobjectProtocol.Result#notDeleteable is returned. If the map does not contain the key, or it throws a NullPointerException for a null key, or the target is not a map, BaseMetaobjectProtocol.Result#noAuthority is returned.

get

public java.lang.Object get(java.lang.Object target,
                   java.lang.Object propertyId)

Retrieves a value from the map.

Specified by:

get in interface CallProtocol

Parameters:

target - the map to retrieve from

propertyId - the key for retrieval

Returns:

If the map contains the key, returns the associated value. If the map does not contain the key, or it throws a NullPointerException for a null key, or the target is not a map, BaseMetaobjectProtocol.Result#noAuthority is returned.

has

public java.lang.Boolean has(java.lang.Object target,
                    java.lang.Object propertyId)

Determines whether a key is present in the map.

Specified by:

has in interface BaseMetaobjectProtocol

Parameters:

target - the map to test

propertyId - the key to test for

Returns:

If the map contains the key, returns Boolean.TRUE. If the map does not contain the key, or it throws a NullPointerException for a null key, or the target is not a map, BaseMetaobjectProtocol.Result#noAuthority is returned.

properties

public java.util.Iterator<java.util.Map.Entry> properties(java.lang.Object target)

Retrieves the mappings in the map.

Specified by:

properties in interface BaseMetaobjectProtocol

Parameters:

target - the map whose mappings are retrieved

Returns:

the iterator over the entry set of the map, or empty iterator if the target is not a map.

put

public BaseMetaobjectProtocol.Result put(java.lang.Object target,
                                java.lang.Object propertyId,
                                java.lang.Object value,
                                CallProtocol callProtocol)

Binds a key-value pair into the map.

Specified by:

put in interface BaseMetaobjectProtocol

Parameters:

target - the map where to bind the new mapping

propertyId - the mapping key

value - the mapped value

callProtocol - not used

Returns:

BaseMetaobjectProtocol.Result#ok if the binding was successful. If the map is read-only (throws a UnsupportedOperationException on put attempt), BaseMetaobjectProtocol.Result#notWritable is returned. If the map does not contain the key, or it throws a NullPointerException for a null key or null value, or the target is not a map, BaseMetaobjectProtocol.Result#noAuthority is returned. If the map throws ClassCastException (because it is limited in types of values it can accept), BaseMetaobjectProtocol.Result#noRepresentation is returned.

representAs

public java.lang.Object representAs(java.lang.Object object,
                           java.lang.Class targetClass)

Description copied from interface: CallProtocol

Returns a representation of the specified target object as an object of the specified target class. Typical supported target classes would be wrappers for Java primitive types that map to native types of the higher level languages. I.e. if an object is used as a boolean expression, then the language would ask the protocol to interpret it as boolean by calling representAs(Boolean.TYPE).

Specified by:

representAs in interface CallProtocol

Parameters:

object - the object to represent

targetClass - the target class for representation.

Returns:

BaseMetaobjectProtocol.Result#noAuthority as this MOP has no concept of type conversion