org.checkerframework.checker.nullness

Class CollectionToArrayHeuristics

java.lang.Object

org.checkerframework.checker.nullness.CollectionToArrayHeuristics

public class CollectionToArrayHeuristics
extends Object

Determines the nullness type of calls to Collection.toArray().

The semantics of Collection.toArray(T[]) cannot be captured by the nullness type system syntax. The nullness type of the returned array depends on the size of the passed parameter. In particular, the returned array component is of type @NonNull if the following conditions hold:

1. The receiver collection type argument is NonNull, and
2. The passed array size is less than the collection size. Here are heuristics to handle the most common cases:
   1. an empty array initializer, e.g. c.toArray(new String[] {}),
   2. array creation tree of size 0, e.g. c.toArray(new String[0]), or
   3. array creation tree of the collection size method invocation c.toArray(new String[c.size()])

Note: The nullness of the returned array doesn't depend on the passed array nullness.

Constructor Summary

Constructors

Constructor and Description
CollectionToArrayHeuristics(ProcessingEnvironment env, NullnessAnnotatedTypeFactory factory)

Method Summary

Modifier and Type	Method and Description
void	handle(MethodInvocationTree tree, AnnotatedTypeMirror.AnnotatedExecutableType method) If the method invocation is a call to toArray, then it manipulates the returned type of method arg to contain the appropriate nullness.

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionToArrayHeuristics

public CollectionToArrayHeuristics(ProcessingEnvironment env,
                                   NullnessAnnotatedTypeFactory factory)

Method Detail

handle

public void handle(MethodInvocationTree tree,
                   AnnotatedTypeMirror.AnnotatedExecutableType method)

If the method invocation is a call to toArray, then it manipulates the returned type of method arg to contain the appropriate nullness. Otherwise, it does nothing.

Parameters:

tree - method invocation tree

method - invoked method type