wytp.proof.rules.type

Class TypeTestNormalisation

java.lang.Object

wytp.proof.util.AbstractProofRule

wytp.proof.util.AbstractClosureRule

wytp.proof.rules.type.TypeTestNormalisation

All Implemented Interfaces:

Proof.LinearRule, Proof.Rule

public class TypeTestNormalisation
extends AbstractClosureRule
implements Proof.LinearRule

Responsible for normalising type tests involving record accesses. For example, consider the following assertion:

 type Point is {null|int x, null|int y}

 assert:
    forall(Point p):
       if:
          p.x is !null
       then:
          p.x is int
 

In solving this, we end up with truths p.x is !null and p.x is int. These are then refined by this rule to be p is {!null x, ...} and p is {int x, ...}. Doing this allows the variable to be exposed which, in turn, enables a retyping of that variable to give the contradiction.

Author:

David J. Pearce

Field Summary

Fields inherited from class wytp.proof.util.AbstractProofRule

simp, types

Constructor Summary

Constructors

Constructor and Description
TypeTestNormalisation(Simplification simplify, TypeSystem types)

Method Summary

Modifier and Type	Method and Description
Proof.State	apply(Proof.Delta.Set existingTruths, Proof.State head, Formula newTruth)
String	getName() Get the name of this rule

Methods inherited from class wytp.proof.util.AbstractClosureRule

apply, apply, getExistingTruths

Methods inherited from class wytp.proof.util.AbstractProofRule

extractDefinedTerms, findAllInstances, substitute

Methods inherited from class java.lang.Object

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

Methods inherited from interface wytp.proof.Proof.LinearRule

apply

Constructor Detail

TypeTestNormalisation

public TypeTestNormalisation(Simplification simplify,
                             TypeSystem types)

Method Detail

getName

public String getName()

Description copied from interface: Proof.Rule

Get the name of this rule

Specified by:

getName in interface Proof.Rule

Returns:

apply

public Proof.State apply(Proof.Delta.Set existingTruths,
                         Proof.State head,
                         Formula newTruth)
                  throws wybs.lang.NameResolver.ResolutionError

Specified by:

apply in class AbstractClosureRule

Throws:

wybs.lang.NameResolver.ResolutionError