com.bigdata.bop.bindingSet

Class EmptyBindingSet

java.lang.Object

com.bigdata.bop.bindingSet.EmptyBindingSet

All Implemented Interfaces:

IBindingSet, Serializable, Cloneable

public final class EmptyBindingSet
extends Object
implements IBindingSet, Serializable

An immutable empty binding set.

Version:

$Id$

Author:

Bryan Thompson

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static EmptyBindingSet	INSTANCE Immutable singleton.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear(IVariable var) Clear any binding for the variable.
void	clearAll() Clear all bindings.
EmptyBindingSet	clone() Return a shallow copy of the binding set.
boolean	containsErrorValues()
EmptyBindingSet	copy(IVariable[] variablesToDrop) Return a shallow copy of the binding set, eliminating unnecessary variables.
EmptyBindingSet	copyMinusErrors(IVariable[] variablesToDrop) Returns the same object.
boolean	equals(Object t) True iff the variables and their bound values are the same for the two binding sets.
IConstant	get(IVariable var) Return the binding for the variable.
int	hashCode() The hash code of an empty binding set is always zero.
boolean	isBound(IVariable var) Return true iff the variable is bound.
boolean	isEmpty() true iff there are no variable bindings in the binding set.
Iterator<Map.Entry<IVariable,IConstant>>	iterator() Visits the bindings.
void	set(IVariable var, IConstant val) Bind the variable to the value.
int	size() The #of bound variables.
Iterator<IVariable>	vars() Visits the bound variables.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final transient EmptyBindingSet INSTANCE

Immutable singleton.

Method Detail

clone

public EmptyBindingSet clone()

Description copied from interface: IBindingSet

Return a shallow copy of the binding set.

Specified by:

clone in interface IBindingSet

Overrides:

clone in class Object

copy

public EmptyBindingSet copy(IVariable[] variablesToDrop)

Description copied from interface: IBindingSet

Return a shallow copy of the binding set, eliminating unnecessary variables.

Specified by:

copy in interface IBindingSet

Parameters:

variablesToDrop - When non-null, only the listed variables are retained.

copyMinusErrors

public EmptyBindingSet copyMinusErrors(IVariable[] variablesToDrop)

Returns the same object.

Specified by:

copyMinusErrors in interface IBindingSet

Parameters:

variablesToDrop - When non-null, only the listed variables are retained.

containsErrorValues

public final boolean containsErrorValues()

Specified by:

containsErrorValues in interface IBindingSet

Returns:

false, always

clear

public void clear(IVariable var)

Description copied from interface: IBindingSet

Clear any binding for the variable.

Specified by:

clear in interface IBindingSet

Parameters:

var - The variable.

clearAll

public void clearAll()

Description copied from interface: IBindingSet

Clear all bindings.

Specified by:

clearAll in interface IBindingSet

iterator

public Iterator<Map.Entry<IVariable,IConstant>> iterator()

Description copied from interface: IBindingSet

Visits the bindings.

Specified by:

iterator in interface IBindingSet

set

public void set(IVariable var,
       IConstant val)

Description copied from interface: IBindingSet

Bind the variable to the value.

Specified by:

set in interface IBindingSet

Parameters:

var - The variable.

val - The value (MAY NOT be null).

isEmpty

public boolean isEmpty()

Description copied from interface: IBindingSet

true iff there are no variable bindings in the binding set.

Specified by:

isEmpty in interface IBindingSet

size

public int size()

Description copied from interface: IBindingSet

The #of bound variables.

Specified by:

size in interface IBindingSet

equals

public boolean equals(Object t)

Description copied from interface: IBindingSet

True iff the variables and their bound values are the same for the two binding sets.

Specified by:

equals in interface IBindingSet

Overrides:

equals in class Object

Parameters:

t - Another binding set.

hashCode

public int hashCode()

The hash code of an empty binding set is always zero.

Specified by:

hashCode in interface IBindingSet

Overrides:

hashCode in class Object

get

public IConstant get(IVariable var)

Description copied from interface: IBindingSet

Return the binding for the variable.

Specified by:

get in interface IBindingSet

Parameters:

var - The variable.

Returns:

the binding for the variable -or- null iff the variable is not bound.

isBound

public boolean isBound(IVariable var)

Description copied from interface: IBindingSet

Return true iff the variable is bound.

Specified by:

isBound in interface IBindingSet

Parameters:

var - The variable.

Returns:

true if the variable is bound.

vars

public Iterator<IVariable> vars()

Description copied from interface: IBindingSet

Visits the bound variables.

Specified by:

vars in interface IBindingSet