model

Class Constant

java.lang.Object

model.Constant

All Implemented Interfaces:

PCExpression, Unifiable

public class Constant
extends Object
implements Unifiable

This class represents constants or values. It implements Unifiable. The class has a static attribute to differentiate constants of the same names, even if they will be unified if they have the same name.

Author:

Alexandre Camus

Field Summary

Fields

Modifier and Type	Field and Description
private int	id
private static int	nextId
private String	printName

Constructor Summary

Constructors

Constructor and Description
Constant() Constructor of the class.
Constant(String printName) Constructor of the class.

Method Summary

Methods

Modifier and Type	Method and Description
String	getName() Gets the name of the constant.
Constant	replaceVariables(SubstitutionSet s) Replaces all the variables in the constant according to the specified bindings.
Constant	standardizeVariablesApart(Hashtable<Variable,Variable> newVars) Standardizes the variables in order to be sure that there won't be any variable clashes.
String	toString() Returns the constant under the form of: "constantName_id".
SubstitutionSet	unify(Unifiable expr, SubstitutionSet s) Unifies the constant with the specified expr expression given the bindings s.

Methods inherited from class java.lang.Object

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

Field Detail

printName

private String printName

nextId

private static int nextId

id

private int id

Constructor Detail

Constant

public Constant()

Constructor of the class.

Constant

public Constant(String printName)

Constructor of the class.

Parameters:

printName - the name of the constant.

Method Detail

getName

public String getName()

Gets the name of the constant.

Specified by:

getName in interface Unifiable

Returns:

the name of the constant. It will return null if there is no one.

See Also:

Unifiable.getName()

replaceVariables

public Constant replaceVariables(SubstitutionSet s)

Replaces all the variables in the constant according to the specified bindings. This returns the constant itself as it is not a variable and contains no variable.

This method is recursive over all PCExpression implementations. This is a terminal case.

Specified by:

replaceVariables in interface PCExpression

Parameters:

s - the SubstitutionSet that contains the bindings of the variables so far.

Returns:

a Constant object representing the constant.

See Also:

PCExpression.replaceVariables(model.SubstitutionSet)

standardizeVariablesApart

public Constant standardizeVariablesApart(Hashtable<Variable,Variable> newVars)

Standardizes the variables in order to be sure that there won't be any variable clashes. This returns the constant itself as it is not a variable and contains no variable.

This method is recursive over all PCExpression implementations. This is a terminal case.

Specified by:

standardizeVariablesApart in interface PCExpression

Parameters:

newVars - is a parameter to save over the recursion all the variable replacements done so far.

Returns:

a Constant object representing the standardized constant.

See Also:

PCExpression.standardizeVariablesApart(java.util.Hashtable)

unify

public SubstitutionSet unify(Unifiable expr,
                    SubstitutionSet s)

Unifies the constant with the specified expr expression given the bindings s. This tries to get or add bindings in order to make logically equivalent the constant and the specified expression.

This method is recursive over all Unifiable implementations.

Specified by:

unify in interface Unifiable

Parameters:

expr - an expression to unify with the constant.

s - the SubstitutionSet object representing the bindings so far and/or the constraints applied.

Returns:

a SubstitutionSet object that contains all the bindings needed to unify the constant to the specified expression.

See Also:

Unifiable.unify(Unifiable, SubstitutionSet)

toString

public String toString()

Returns the constant under the form of: "constantName_id".

Overrides:

toString in class Object

See Also:

Object.toString()