org.checkerframework.framework.util.typeinference

Interface TypeArgumentInference

All Known Implementing Classes:

DefaultTypeArgumentInference

public interface TypeArgumentInference

Instances of TypeArgumentInference are used to infer the types of method type arguments when no explicit arguments are provided.

e.g. If we have a method declaration:

 <A,B> B method(A a, B b) {...}
 

And an invocation of that method:

 method("some Str", 35);
 

TypeArgumentInference will determine what the type arguments to type parameters A and B are. In Java, if T(A) = the type argument for a, in the above example T(A) == String and T(B) == Integer

For the Checker Framework we also need to infer reasonable annotations for these type arguments. For information on inferring type arguments see the documentation in JLS7 and JLS8: http://docs.oracle.com/javase/specs/jls/se8/html/jls-18.html http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2.7

Note: It appears that Java 8 greatly improved the type argument inference and related error messaging but I have found it useful to consult the JLS 7 as well.

Method Summary

Modifier and Type	Method and Description
Map<TypeVariable,AnnotatedTypeMirror>	inferTypeArgs(AnnotatedTypeFactory typeFactory, ExpressionTree invocation, ExecutableElement methodElem, AnnotatedTypeMirror.AnnotatedExecutableType methodType) Infer the type arguments for the method or constructor invocation given by invocation.

Method Detail

inferTypeArgs

Map<TypeVariable,AnnotatedTypeMirror> inferTypeArgs(AnnotatedTypeFactory typeFactory,
                                                    ExpressionTree invocation,
                                                    ExecutableElement methodElem,
                                                    AnnotatedTypeMirror.AnnotatedExecutableType methodType)

Infer the type arguments for the method or constructor invocation given by invocation.

Parameters:

typeFactory - the type factory used to create methodType

invocation - a tree representing the method or constructor invocation for which we are inferring type arguments

methodElem - the element for the declaration of the method being invoked

methodType - the declaration type of method elem

Returns:

a mapping between the Java type parameter and the annotated type that was inferred for it

Note: We use the Java TypeVariable type because this uniquely identifies a declaration where as two uses of an AnnotatedTypeVariable may be uses of the same declaration but are not .equals to each other.