org.checkerframework.framework.type

Interface TypeHierarchy

All Known Implementing Classes:

DefaultTypeHierarchy, KeyForAnnotatedTypeFactory.KeyForTypeHierarchy

public interface TypeHierarchy

Compares AnnotatedTypeMirrors for subtype relationships. See also QualifierHierarchy.

Method Summary

Modifier and Type	Method and Description
boolean	isSubtype(AnnotatedTypeMirror subtype, AnnotatedTypeMirror supertype) Returns true if subtype is a subtype of or convertible to supertype for all hierarchies present.

Method Detail

isSubtype

boolean isSubtype(AnnotatedTypeMirror subtype,
                  AnnotatedTypeMirror supertype)

Returns true if subtype is a subtype of or convertible to supertype for all hierarchies present. If the underlying Java type of subtype is not a subtype of or convertible to the underlying Java type of supertype, then the behavior of this method is undefined.

Ideally, types that require conversions would be converted before isSubtype is called, but instead, isSubtype performs some of these conversions.

JLS 5.1 specifies 13 categories of conversions.

4 categories are converted in isSubtype:

• Boxing conversions: isSubtype calls AnnotatedTypes.asSuper( AnnotatedTypeFactory, AnnotatedTypeMirror, AnnotatedTypeMirror) which calls AnnotatedTypeFactory.getBoxedType(org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedPrimitiveType)
• Unboxing conversions: isSubtype calls AnnotatedTypes.asSuper( AnnotatedTypeFactory, AnnotatedTypeMirror, AnnotatedTypeMirror) which calls AnnotatedTypeFactory.getUnboxedType(org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedDeclaredType)
• Capture conversions: Wildcards are treated as though they were converted to type variables
• String conversions: Any type to String. isSubtype calls AnnotatedTypes.asSuper(org.checkerframework.framework.type.AnnotatedTypeFactory, org.checkerframework.framework.type.AnnotatedTypeMirror, T) which calls AnnotatedTypeFactory.getStringType(AnnotatedTypeMirror)

1 happens elsewhere:

• Unchecked conversions: Generic type to raw type. Raw types are instantiated with bounds in AnnotatedTypeFactory#fromTypeTree before is subtype is called

7 are not explicitly converted and are treated as though the types are actually subtypes.

• Identity conversions: type to same type
• Widening primitive conversions: primitive to primitive (no loss of information, byte to short for example)
• Narrowing primitive conversions: primitive to primitive (possibly loss of information, short to byte for example)
• Widening and Narrowing Primitive Conversion: byte to char
• Widening reference conversions: Upcast
• Narrowing reference conversions: Downcast
• Value set conversions: floating-point value from one value set to another without changing its type.

Parameters:

subtype - possible subtype

supertype - possible supertype

Returns:

true if subtype is a subtype of supertype for all hierarchies present.