Package org.checkerframework.framework.type

Class SubtypeVisitHistory

java.lang.Object

org.checkerframework.framework.type.SubtypeVisitHistory

public class SubtypeVisitHistory
extends Object

THIS CLASS IS DESIGNED FOR USE WITH DefaultTypeHierarchy, DefaultRawnessComparer, and StructuralEqualityComparer ONLY.

VisitHistory tracks triples of (type1, type2, top), where type1 is a subtype of type2. It does not track when type1 is not a subtype of type2; such entries are missing from the history. Clients of this class can check whether or not they have visited an equivalent pair of AnnotatedTypeMirrors already. This is necessary in order to halt visiting on recursive bounds.

This class is primarily used to implement isSubtype(ATM, ATM). The pair of types corresponds to the subtype and the supertype being checked. A single subtype may be visited more than once, but with a different supertype. For example, if the two types are @A T extends @B Serializable<T> and @C Serializable<?>, then isSubtype is first called on those types and then on @B Serializable<T> and @C Serializable<?>.

Callers should call clear() once an outermost (non-nested) isSubtype call completes, so that the history does not accumulate entries across unrelated isSubtype calls. Entries only need to persist for the duration of a single such call, to guard against infinite recursion within it; letting the map grow for the whole compilation unit only makes every subsequent lookup slower, for no benefit, since unrelated calls do not repeat the same (type1, type2) pair.

Constructor Summary

Constructors

Constructor	Description
SubtypeVisitHistory()	Creates a new SubtypeVisitHistory.

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all entries from the history.
boolean	contains(AnnotatedTypeMirror type1, AnnotatedTypeMirror type2, AnnotationMirror currentTop)	Returns true if type1 and type2 (or an equivalent pair) have been passed to the put method previously.
void	put(AnnotatedTypeMirror type1, AnnotatedTypeMirror type2, AnnotationMirror currentTop, boolean isSubtype)	Put a visit for type1, type2, and top in the history.
void	remove(AnnotatedTypeMirror type1, AnnotatedTypeMirror type2, AnnotationMirror currentTop)	Remove type1 and type2.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

SubtypeVisitHistory

public SubtypeVisitHistory()

Creates a new SubtypeVisitHistory.

Method Details

put

public void put(AnnotatedTypeMirror type1,
 AnnotatedTypeMirror type2,
 AnnotationMirror currentTop,
 boolean isSubtype)

Put a visit for type1, type2, and top in the history. Has no effect if isSubtype is false.

Parameters:

type1 - the first type

type2 - the second type

currentTop - the top of the relevant type hierarchy; only annotations from that hierarchy are considered

isSubtype - true if type1 is a subtype of type2; if false, this method does nothing

remove

public void remove(AnnotatedTypeMirror type1,
 AnnotatedTypeMirror type2,
 AnnotationMirror currentTop)

Remove type1 and type2.

contains

public boolean contains(AnnotatedTypeMirror type1,
 AnnotatedTypeMirror type2,
 AnnotationMirror currentTop)

Returns true if type1 and type2 (or an equivalent pair) have been passed to the put method previously.

Returns:

true if an equivalent pair has already been added to the history

clear

public void clear()

Removes all entries from the history.

toString

public String toString()

Overrides:

toString in class Object