Package org.checkerframework.framework.util.typeinference.constraint

Class TUConstraint

java.lang.Object

org.checkerframework.framework.util.typeinference.constraint.TUConstraint

Direct Known Subclasses:

TIsU, TSubU, TSuperU

public abstract class TUConstraint
extends Object

Subclasses of TUConstraint represent constraints between a type parameter, whose type arguments are being inferred, and the types used to do that inference. These constraints are used by the TASolver to infer arguments.

TU constraints come in the classic form of subtype, supertype, and equality constraints.

• T <: U -- implies T is a subtype of U, it is represented by TSubU
  
• T >: U -- implies T is a supertype of U, it is represented by TSuperU
  
• T = U -- implies T is equal to U, it is represented by TIsU
  

Note, it is important that the type parameter is represented by an AnnotatedTypeVariable because if a use of the type parameter has a primary annotation, then the two types represented in by a TUConstraint are NOT constrained in the hierarchy of that annotation. e.g.

 <T> void method(List<@NonNull T> t1, T t2)
 method(new ArrayList<@NonNull String>(), null);
 

The above method call would eventually be reduced to constraints: [@NonNull String == @NonNull T, @Nullable null <: T]

In this example, if we did not ignore the first constraint then the type argument would be exactly @NonNull String and the second argument would be invalid. However, the correct inference would be @Nullable String and both arguments would be valid.

Field Summary

Fields

Modifier and Type	Field	Description
final AnnotatedTypeMirror	relatedType	A type used to infer an argument for the typeVariable T.
final AnnotatedTypeMirror.AnnotatedTypeVariable	typeVariable	An AnnotatedTypeVariable representing a target type parameter for which we are inferring a type argument.
final boolean	uIsArg	Whether or not U is a type from an argument to the method.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	TUConstraint(AnnotatedTypeMirror.AnnotatedTypeVariable typeVariable, AnnotatedTypeMirror relatedType, boolean uIsArg)

Method Summary

Modifier and Type	Method	Description
boolean	equals(@Nullable Object thatObject)
int	hashCode()

Methods inherited from class java.lang.Object

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

Field Details

typeVariable

public final AnnotatedTypeMirror.AnnotatedTypeVariable typeVariable

An AnnotatedTypeVariable representing a target type parameter for which we are inferring a type argument. This is the T in the TUConstraints.

relatedType

public final AnnotatedTypeMirror relatedType

A type used to infer an argument for the typeVariable T. This would be the U in the TUConstraints.

uIsArg

public final boolean uIsArg

Whether or not U is a type from an argument to the method.

Constructor Details

TUConstraint

protected TUConstraint(AnnotatedTypeMirror.AnnotatedTypeVariable typeVariable,
 AnnotatedTypeMirror relatedType,
 boolean uIsArg)

Method Details

equals

public boolean equals(@Nullable Object thatObject)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object