Package gnu.mapping

Class Location<T>

java.lang.Object

gnu.mapping.Location<T>

Direct Known Subclasses:

ClassMemberLocation, ConstrainedLocation, IndirectableLocation, ProcLocation, PropertyLocation

public abstract class Location<T>
extends Object

A Location is an abstract cell/location/variable with a value of type T.

Field Summary

Fields

Modifier and Type	Field	Description
static String	UNBOUND	Magic value used to indicate there is no property binding.

Constructor Summary

Constructors

Constructor	Description
Location()

Method Summary

Modifier and Type	Method	Description
static Location	define(Symbol name)	Implement top-level 'define' for Scheme in interactive mode.
boolean	entered()	True if directly entered in an Environment.
abstract T	get()	Get the current value of this location.
T	get(T defaultValue)
Location	getBase()
Object	getKeyProperty()
Symbol	getKeySymbol()
T	getValue()
abstract boolean	isBound()
boolean	isConstant()
static IndirectableLocation	make(Symbol name)
static Location	make(Object init, String name)
static IndirectableLocation	make(String name)
void	print(PrintWriter ps)
abstract void	set(T value)
void	setRestore(Object oldValue)	Restore an old value.
T	setValue(T newValue)
Object	setWithSave(T newValue)	Set a value, but return cookie so old value can be restored.
String	toString()
void	undefine()

Methods inherited from class java.lang.Object

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

Field Detail

UNBOUND

public static final String UNBOUND

Magic value used to indicate there is no property binding.

Constructor Detail

Location

public Location()

Method Detail

getKeySymbol

public Symbol getKeySymbol()

getKeyProperty

public Object getKeyProperty()

toString

public String toString()

Overrides:

toString in class Object

get

public T get(T defaultValue)

get

public abstract T get()

Get the current value of this location.

Throws:

UnboundLocationException - the location does not have a value.

set

public abstract void set(T value)

undefine

public void undefine()

setWithSave

public Object setWithSave(T newValue)

Set a value, but return cookie so old value can be restored. This is intended for fluid-let where (in the case of multiple threads) a simple save-restore isn't always the right thing.

setRestore

public void setRestore(Object oldValue)

Restore an old value.

Parameters:

oldValue - the return value from a prior setWithSave.

isBound

public abstract boolean isBound()

isConstant

public boolean isConstant()

getBase

public Location getBase()

getValue

public final T getValue()

setValue

public final T setValue(T newValue)

entered

public boolean entered()

True if directly entered in an Environment. (Only if NamedLocation.)

print

public void print(PrintWriter ps)

make

public static Location make(Object init,
                            String name)

make

public static IndirectableLocation make(String name)

make

public static IndirectableLocation make(Symbol name)

define

public static Location define(Symbol name)

Implement top-level 'define' for Scheme in interactive mode. I.e. if there is no binding, create it; if the existing binding is non-constant, set its value; if it is constant, create a new binding initialized to the old value (though we actually change the binding to non-constant).