Package ptolemy.data.type

Class ObjectType

java.lang.Object

ptolemy.data.type.StructuredType

ptolemy.data.type.ObjectType

All Implemented Interfaces:

java.lang.Cloneable, Type

public class ObjectType
extends StructuredType
implements java.lang.Cloneable

A type of tokens that contain arbitrary Java objects. An instance of this class specifies the Java class that the contents of the ObjectTokens of that type must be instances of.

A special type lattice is defined for variants of ObjectType. The top element of the elements in the type lattice is an ObjectType that does not specify any Java class as the class for the contents of its tokens. In the expression language, that element can be referred to with "object" or "object()". Any ObjectToken conforms to this type. A subtype of this type specifies a Java class. In the expression language, such a subtype can be defined with "object(string)", where string is a string (starting and ending with a quote). For example, the following expression refers to a variant of ObjectType to which only ObjectTokens containing atomic actors as their contents conform:

object("ptolemy.actor.AtomicActor")

This ObjectType is a subtype of the most general ObjectType, "object". Furthermore, it is also a subtype of "object(\"ptolemy.kernel.Entity\")", and at the same time a supertype of "object(\"ptolemy.actor.lib.Const\")".

The bottom element of the type lattice is an artificial ObjectType with ObjectType.BottomClass as its specified Java class. In Java, the class hierarchy does not form a lattice, so this artificial type is needed to be the greatest lower bound for any two classes if one is not a subclass of the other.

Since:

Ptolemy II 8.0

Version:

$Id$

Author:

Thomas Huining Feng

See Also:

ObjectToken

Pt.AcceptedRating:

Red (tfeng)

Pt.ProposedRating:

Red (tfeng)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ObjectType.BottomClass	An artificial Java class that serves as the bottom element.

Field Summary

Fields

Modifier and Type	Field	Description
static ObjectType	BOTTOM	The bottom element among all ObjectTypes.
static ObjectType	TOP	The top element among all ObjectTypes.

Fields inherited from class ptolemy.data.type.StructuredType

MAXDEPTHBOUND

Fields inherited from interface ptolemy.data.type.Type

HASH_INVALID

Constructor Summary

Constructors

Constructor	Description
ObjectType()	Construct an ObjectType with null as the Java class specified in it.
ObjectType(java.lang.Class<?> valueClass)	Construct an ObjectType with the given Java class as the class specified in it.
ObjectType(java.lang.Object value, java.lang.Class<?> valueClass)	Construct an ObjectType with the given Java class as the class specified in it.

Method Summary

Modifier and Type	Method	Description
protected int	_compare(StructuredType type)	Compare this type with the specified type.
protected StructuredType	_getRepresentative()	Return a static instance of this object type.
protected StructuredType	_greatestLowerBound(StructuredType type)	Return the greatest lower bound of this type with the specified type.
protected StructuredType	_leastUpperBound(StructuredType type)	Return the least upper bound of this type with the specified type.
java.lang.Object	clone()	Return a deep clone of this type.
Token	convert(Token token)	Convert the specified token into a token having the type represented by this object.
boolean	equals(java.lang.Object object)	Determine if the argument represents the same type as this object.
java.lang.Class<?>	getTokenClass()	Return the class for tokens that this type represents.
java.lang.Object	getValue()	Get the actual value.
java.lang.Class<?>	getValueClass()	Get the Java class specified in this type, of which the contents of ObjectTokens conforming to this type must be instances.
int	hashCode()	Return the hash code for this object.
void	initialize(Type type)	Ignore, as this type does not have elements.
boolean	isAbstract()	Return true if this type does not correspond to a single token class.
boolean	isCompatible(Type type)	Return true if the specified type is less than or equal to this type.
boolean	isConstant()	Test if the argument type is compatible with this type.
boolean	isInstantiable()	Determine if this Type corresponds to an instantiable token class.
boolean	isSubstitutionInstance(Type type)	Return true if the specified type is a substitution instance of this type.
java.lang.String	toString()	Return a string describing this object.

Methods inherited from class ptolemy.data.type.StructuredType

add, depth, divide, getTypeHash, modulo, multiply, one, subtract, updateType, zero

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

BOTTOM

public static final ObjectType BOTTOM

The bottom element among all ObjectTypes.

TOP

public static final ObjectType TOP

The top element among all ObjectTypes. The value of this variable is == to the BaseType.OBJECT so that code generation can use "xxx == BaseType.OBJECT".

Constructor Detail

ObjectType

public ObjectType()

Construct an ObjectType with null as the Java class specified in it. This type is the most general type (top element) among all the ObjectTypes.

ObjectType

public ObjectType(java.lang.Class<?> valueClass)

Construct an ObjectType with the given Java class as the class specified in it.

Parameters:

valueClass - The Java class.

ObjectType

public ObjectType(java.lang.Object value,
                  java.lang.Class<?> valueClass)
           throws IllegalActionException

Construct an ObjectType with the given Java class as the class specified in it.

Parameters:

value - The actual object value, or null if the value is unknown.

valueClass - The Java class.

Throws:

IllegalActionException - If the value is not an instance of valueClass.

Method Detail

clone

public java.lang.Object clone()

Return a deep clone of this type.

Specified by:

clone in interface Type

Specified by:

clone in class StructuredType

Returns:

A Type.

convert

public Token convert(Token token)
              throws IllegalActionException

Convert the specified token into a token having the type represented by this object.

Specified by:

convert in interface Type

Parameters:

token - a token.

Returns:

a token.

Throws:

IllegalActionException - If lossless conversion cannot be done.

equals

public boolean equals(java.lang.Object object)

Determine if the argument represents the same type as this object.

Specified by:

equals in interface Type

Overrides:

equals in class java.lang.Object

Parameters:

object - A Type.

Returns:

True if the argument represents the same type as this object; false otherwise.

getTokenClass

public java.lang.Class<?> getTokenClass()

Return the class for tokens that this type represents. The returned class is always ObjectToken.

Specified by:

getTokenClass in interface Type

Returns:

The class for tokens that this type represents.

getValue

public java.lang.Object getValue()

Get the actual value.

Returns:

The actual value, or null if it is unknown.

getValueClass

public java.lang.Class<?> getValueClass()

Get the Java class specified in this type, of which the contents of ObjectTokens conforming to this type must be instances.

Returns:

The Java class specified in this type.

hashCode

public int hashCode()

Return the hash code for this object.

Overrides:

hashCode in class java.lang.Object

Returns:

The hash code.

initialize

public void initialize(Type type)

Ignore, as this type does not have elements.

Specified by:

initialize in class StructuredType

Parameters:

type - The type to initialize unknown elements to.

isAbstract

public boolean isAbstract()

Return true if this type does not correspond to a single token class. This occurs if the type is not instantiable, or it represents either an abstract base class or an interface.

Specified by:

isAbstract in interface Type

Overrides:

isAbstract in class StructuredType

Returns:

True if this type does not correspond to a single token class.

isCompatible

public boolean isCompatible(Type type)

Return true if the specified type is less than or equal to this type.

Specified by:

isCompatible in interface Type

Parameters:

type - The type to be checked

Returns:

True if the specified type is less than or equal to this type.

isConstant

public boolean isConstant()

Test if the argument type is compatible with this type. Compatible is defined as follows: If this type is a constant, the argument is compatible if it is the same or less than this type in the type lattice; If this type is a variable, the argument is compatible if it is a substitution instance of this type.

Specified by:

isConstant in interface Type

Returns:

True if the argument is compatible with this type.

isInstantiable

public boolean isInstantiable()

Determine if this Type corresponds to an instantiable token class.

Specified by:

isInstantiable in interface Type

Returns:

True if this type corresponds to an instantiable token class.

isSubstitutionInstance

public boolean isSubstitutionInstance(Type type)

Return true if the specified type is a substitution instance of this type. For the argument to be a substitution instance, it must be either the same as this type, or it must be a type that can be obtained by replacing the BaseType.UNKNOWN component of this type by another type.

Specified by:

isSubstitutionInstance in interface Type

Parameters:

type - A Type.

Returns:

True if the argument is a substitution instance of this type.

toString

public java.lang.String toString()

Return a string describing this object.

Specified by:

toString in interface Type

Overrides:

toString in class java.lang.Object

Returns:

A string of form 'object("classname")'.

_compare

protected int _compare(StructuredType type)

Compare this type with the specified type. The specified type must be of the same structured type, otherwise an exception will be thrown. This method returns one of ptolemy.graph.CPO.LOWER, ptolemy.graph.CPO.SAME, ptolemy.graph.CPO.HIGHER, ptolemy.graph.CPO.INCOMPARABLE, indicating this type is lower than, equal to, higher than, or incomparable with the specified type in the type hierarchy, respectively.

Specified by:

_compare in class StructuredType

Parameters:

type - a StructuredType.

Returns:

An integer.

Throws:

java.lang.IllegalArgumentException - If the specified type is not the same structured type as this one.

_getRepresentative

protected StructuredType _getRepresentative()

Return a static instance of this object type. The return value is used by TypeLattice to represent this type.

Specified by:

_getRepresentative in class StructuredType

Returns:

The bottom object type.

_greatestLowerBound

protected StructuredType _greatestLowerBound(StructuredType type)

Return the greatest lower bound of this type with the specified type. The specified type must be of the same structured type, otherwise an exception will be thrown.

Specified by:

_greatestLowerBound in class StructuredType

Parameters:

type - a StructuredType.

Returns:

a StructuredType.

Throws:

java.lang.IllegalArgumentException - If the specified type is not the same structured type as this one.

_leastUpperBound

protected StructuredType _leastUpperBound(StructuredType type)

Return the least upper bound of this type with the specified type. The specified type must be of the same structured type, otherwise an exception will be thrown.

Specified by:

_leastUpperBound in class StructuredType

Parameters:

type - a StructuredType.

Returns:

a StructuredType.

Throws:

java.lang.IllegalArgumentException - If the specified type is not the same structured type as this one.