de.uni_tuebingen.sfb.lichtenstein.formulas
Class FirstOrderEquality

java.lang.Object
  de.uni_tuebingen.sfb.lichtenstein.formulas.FormulaImpl
      de.uni_tuebingen.sfb.lichtenstein.formulas.AtomicFormula
          de.uni_tuebingen.sfb.lichtenstein.formulas.FirstOrderEquality

All Implemented Interfaces:

Formula, Visitable, Serializable

public final class FirstOrderEquality
extends AtomicFormula

A class representing the atomic formula that says two first order variables are equal.

Author:

Hendrik Maryns

See Also:

Serialized Form

Constructor Summary

FirstOrderEquality(FirstOrderVariable first, FirstOrderVariable second)
Initialize a new first order equality, involving two first order variables.

Method Summary

void	accept(FormulaVisitor visitor) Accept a formula visitor.
protected Set<Predicate>	computePredicates() Return all predicates in this formula.
protected Set<Variable>	computeVariables() Simply return the two variables.
boolean	containsVariable(Variable var) Returns whether this formula contains the given variable.
boolean	equals(Object other) Indicates whether some other object is “equal to” this one.
FirstOrderVariable	getFirstVariable() Returns the first variable.
FirstOrderVariable	getSecondVariable() Returns the second variable.
int	hashCode() Returns a hash code value for the object.
String	toString() Returns a string representation of the object.

Methods inherited from class de.uni_tuebingen.sfb.lichtenstein.formulas.AtomicFormula

getNormalForm, isFree

Methods inherited from class de.uni_tuebingen.sfb.lichtenstein.formulas.FormulaImpl

and, exists, exists, forAll, forAll, getFreeVariables, getPredicates, getVariables, iff, implies, isClosed, not, or

Methods inherited from class java.lang.Object

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

Constructor Detail

FirstOrderEquality

public FirstOrderEquality(FirstOrderVariable first,
                          FirstOrderVariable second)

Initialize a new first order equality, involving two first order variables.

Parameters:

first - The first variable.

second - The second variable.

Precondition:

Both variables have to be effective. | first != null && second != null

Postconditions:

The first variable is given to the first given variable. | new.getFirstVariable() == first

The second variable is given to the second given variable. | new.getSecondVariable() == second

Method Detail

getFirstVariable

public FirstOrderVariable getFirstVariable()

Returns the first variable.

Returns:

This is the first first order variable. | result == getVariableAt(0)

getSecondVariable

public FirstOrderVariable getSecondVariable()

Returns the second variable.

Returns:

This is the second first order variable. | result == getVariableAt(1)

computeVariables

protected Set<Variable> computeVariables()

Simply return the two variables.

Specified by:

computeVariables in class FormulaImpl

Returns:

The two variables in the right order. | result.size() == 2 && | result.contains(getFirstVariable()) && | result.contains(getSecondVariable())

containsVariable

public boolean containsVariable(Variable var)

Returns whether this formula contains the given variable.

Parameters:

var - The variable to check.

computePredicates

protected Set<Predicate> computePredicates()

Return all predicates in this formula.

Specified by:

computePredicates in class FormulaImpl

Returns:

A first order equality cannot contain predicates. | result.isEmpty()

equals

public boolean equals(Object other)

Indicates whether some other object is “equal to” this one.

Overrides:

equals in class FormulaImpl

Returns:

Two equalities are equal if they compare the same variables. | let otherEquals = (FirstOrderEquality) other in | if ( otherEquals.getFirstVariable() != getFirstVariable() ) | then result == false | else if ( otherEquals.getSecondVariable() != getSecondVariable() ) | then result == false | else result == true

hashCode

public int hashCode()

Returns a hash code value for the object.

Specified by:

hashCode in class FormulaImpl

Returns:

The hash code is based on the hash codes of the variables and of the characteristic symbol. | result == getFirstVariable().hashCode() + "=".hashCode() + getSecondVariable().hashCode()

toString

public String toString()

Returns a string representation of the object.

Specified by:

toString in class FormulaImpl

Returns:

The string representations of the variables are given, with the equal sign: = in between them. | result == getFirstVariable().toString() + "=" + getSecondVariable().toString()

accept

public void accept(FormulaVisitor visitor)
            throws VisitorException

Accept a formula visitor. The iteration is done by the visitor, not by the composed formulas.

Parameters:

visitor - The visitor that is to be accepted to do its work.

Throws:

VisitorException - [CAN] A visitor can throw an exception.