Direct Known Subclasses:
A2F, F2A, FIsA

public abstract class AFConstraint extends Object
AFConstraint represent the initial constraints used to infer type arguments for method invocations and new class invocations. These constraints are simplified then converted to TUConstraints during type argument inference.

Subclasses of AFConstraint represent the following types of constraints:

A 《 F and F 》 A both imply that A is convertible to F. F 《 A and A 》 F both imply that F is convertible to A (this may happen due to wildcard/typevar bounds and recursive types) A = F implies that A is exactly F

In the Checker Framework a type, A will be convertible to another type F, if AnnotatedTypes.asSuper will return a non-null value when A is passed as a subtype and F the supertype to the method.

In Java type A will be convertible to another type F if there exists a conversion context/method that transforms the one type into the other.

A 《 F and F 》 A are represented by class A2F F 《 A and A 》 F are represented by class F2A F = A is represented by class FIsA

  • Field Details

  • Constructor Details

    • AFConstraint

      protected AFConstraint(AnnotatedTypeMirror argument, AnnotatedTypeMirror formalParameter)
      Create a constraint for type arguments for a methodd invocation or new class invocation.
  • Method Details

    • isIrreducible

      public boolean isIrreducible(Set<TypeVariable> targets)
      Returns true if this constraint can't be broken up into other constraints or further simplified. In general, if either argument or formal parameter is a use of the type parameters we are inferring over then the constraint cannot be reduced further.
      targets - the type parameters whose arguments we are trying to solve for
      true if this constraint can't be broken up into other constraints or further simplified
    • equals

      public boolean equals(@Nullable Object thatObject)
      equals in class Object
    • hashCode

      public int hashCode()
      hashCode in class Object
    • toTUConstraint

      public abstract TUConstraint toTUConstraint()
      Once AFConstraints are irreducible it can be converted to a TU constraint, constraints between individual type parameters for which we are inferring an argument (T) and Java types (U).
      a TUConstraint that represents this AFConstraint
    • substitute

      public AFConstraint substitute(Map<TypeVariable,AnnotatedTypeMirror> substitutions)
      Given a partial solution to our type argument inference, replace any uses of type parameters that have been solved with their arguments.

      That is: Let S be a partial solution to our inference (i.e. we have inferred type arguments for some types) Let S be a map (T0 => A0, T1 => A1, ..., TN => AN) where Ti is a type parameter and Ai is its solved argument. For all uses of Ti in this constraint, replace them with Ai.

      For the mapping (T0 => A0), the following constraint: ArrayList<T0> << List<T1>

      Becomes: ArrayList<A0> << List<T1>

      A constraint: T0 << T1

      Becomes: A0 << T1

      substitutions - a mapping of target type parameter to the type argument to
      a new constraint that contains no use of the keys in substitutions
    • construct

      protected abstract AFConstraint construct(AnnotatedTypeMirror newArgument, AnnotatedTypeMirror newFormalParameter)
      Used to create a new constraint of the same subclass of AFConstraint.