org.apache.reef.tang

Interface ClassHierarchy

All Known Subinterfaces:

JavaClassHierarchy

All Known Implementing Classes:

ClassHierarchyImpl, ProtocolBufferClassHierarchy

public interface ClassHierarchy

ClassHierarchy objects store information about the interfaces and implementations that are available in a particular runtime environment.

When Tang is running inside the same environment as the injected objects, ClassHierarchy is simply a read-only representation of information that is made available via language reflection.

If Tang is set up to perform remote injection, then the ClassHierarchy it runs against is backed by a flat file, or other summary of the libraries that will be available during injection.

Method Summary

Methods

Modifier and Type	Method and Description
Node	getNamespace() Return a reference to the root of the ClassHierarchy.
Node	getNode(String fullName) Lookup a node in this class hierarchy.
boolean	isImplementation(ClassNode<?> inter, ClassNode<?> impl) Return whether the impl is a subclass of inter.
ClassHierarchy	merge(ClassHierarchy ch) Merge the contents of this ClassHierarchy and the provided one into a new class hierarchy.

Method Detail

getNode

Node getNode(String fullName)
             throws NameResolutionException

Lookup a node in this class hierarchy.

Parameters:

fullName - The full name of the class that will be looked up.

Returns:

A non-null reference to a ClassNode or a NamedParameterNode.

Throws:

NameResolutionException - If the class is not found.

ClassHierarchyException - If the class does not pass Tang's static analysis.

isImplementation

boolean isImplementation(ClassNode<?> inter,
                       ClassNode<?> impl)

Return whether the impl is a subclass of inter.

Parameters:

inter - a interface class

impl - a implementation class

Returns:

true if impl is a subclass of inter.

merge

ClassHierarchy merge(ClassHierarchy ch)

Merge the contents of this ClassHierarchy and the provided one into a new class hierarchy. This allows reflection information from multiple jars to be incorporated into a single ClassHierarchy object. Typical applications do not call this method, and instead provide classpath (or C# assembly) information to Tang when they create ConfigurationBuilder and Configuration objects. The Configuration API transparently invokes merge as necessary, allowing applications to combine configurations that were built against differing classpaths.

ClassHierarchies derived from applications written in different languages cannot be merged.

Parameters:

ch - a class hierarchy to be merged

Returns:

the merged class hierarchy

getNamespace

Node getNamespace()

Return a reference to the root of the ClassHierarchy. This is needed by serialization routines (which have to iterate over the ClassHierarchy's state). Unfortunately, due to limitations of Java, JavaClassHierarchy objects need to be built lazily as callers request classes by name. There is no way to provide an interface that enumerates known claases without exposing this fact; therefore, the Node returned by this method can change over time.

Normal callers (all use cases except ClassHierarchy serialization) should use getNode(String) to lookup classes, since getNamespace() can not support lazy loading of unknown classes.

Returns:

a reference to the root node of this ClassHierarchy.