org.apache.reef.tang.implementation.java

Class ClassHierarchyImpl

java.lang.Object

org.apache.reef.tang.implementation.java.ClassHierarchyImpl

All Implemented Interfaces:

ClassHierarchy, JavaClassHierarchy

public class ClassHierarchyImpl
extends Object
implements JavaClassHierarchy

Constructor Summary

Constructors

Constructor and Description
ClassHierarchyImpl()
ClassHierarchyImpl(URL... jars)
ClassHierarchyImpl(URL[] jars, Class<? extends ExternalConstructor<?>>[] parameterParsers)

Method Summary

Methods

Modifier and Type	Method and Description
Class<?>	classForName(String name) Helper method that converts a String to a Class using this ClassHierarchy's classloader.
PackageNode	getNamespace() Return a reference to the root of the ClassHierarchy.
Node	getNode(Class<?> clazz) Look up a class object in this ClassHierarchy.
Node	getNode(String name) Lookup a node in this class hierarchy.
ParameterParser	getParameterParser()
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.
<T> T	parse(NamedParameterNode<T> np, String value) Parse a string, assuming that it is of the type expected by a given NamedParameter.
<T> T	parseDefaultValue(NamedParameterNode<T> name) A helper method that returns the parsed default value of a given NamedParameter.

Methods inherited from class java.lang.Object

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

Constructor Detail

ClassHierarchyImpl

public ClassHierarchyImpl()

ClassHierarchyImpl

public ClassHierarchyImpl(URL... jars)

ClassHierarchyImpl

public ClassHierarchyImpl(URL[] jars,
                  Class<? extends ExternalConstructor<?>>[] parameterParsers)

Method Detail

parseDefaultValue

public <T> T parseDefaultValue(NamedParameterNode<T> name)

A helper method that returns the parsed default value of a given NamedParameter.

Specified by:

parseDefaultValue in interface JavaClassHierarchy

Type Parameters:

T - A type

Parameters:

name - The named parameter that should be checked for a default instance.

Returns:

null or an empty set if there is no default value, the default value (or set of values) otherwise.

Throws:

ClassHierarchyException - if a default value was specified, but could not be parsed, or if a set of values were specified for a non-set parameter.

parse

public <T> T parse(NamedParameterNode<T> np,
          String value)
        throws ParseException

Parse a string, assuming that it is of the type expected by a given NamedParameter.

This method does not deal with sets; if the NamedParameter is set valued, then the provided string should correspond to a single member of the set. It is up to the caller to call parse once for each value that should be parsed as a member of the set.

Specified by:

parse in interface JavaClassHierarchy

Type Parameters:

T - A type

Parameters:

np - The named parameter that will receive the value.

value - A string value to be validated and parsed.

Returns:

a non-null reference to the parsed value.

Throws:

ParseException - if the value failed to parse, or parsed to the wrong type (such as when it specifies a class that does not implement or extend T).

classForName

public Class<?> classForName(String name)
                      throws ClassNotFoundException

Helper method that converts a String to a Class using this ClassHierarchy's classloader.

Specified by:

classForName in interface JavaClassHierarchy

Throws:

ClassNotFoundException

getNode

public Node getNode(Class<?> clazz)

Description copied from interface: JavaClassHierarchy

Look up a class object in this ClassHierarchy. Unlike the version that takes a string in ClassHierarchy, this version does not throw NameResolutionException.

The behavior of this method is undefined if the provided Class object is not from the ClassLoader (or an ancestor of the ClassLoader) associated with this JavaClassHierarchy. By default, Tang uses the default runtime ClassLoader as its root ClassLoader, so static references (expressions like getNode(Foo.class)) are safe.

Specified by:

getNode in interface JavaClassHierarchy

Parameters:

clazz - The class to be looked up in the class hierarchy.

Returns:

The associated NamedParameterNode or ClassNode.

getNode

public Node getNode(String name)
             throws NameResolutionException

Description copied from interface: ClassHierarchy

Lookup a node in this class hierarchy.

Specified by:

getNode in interface ClassHierarchy

Parameters:

name - 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.

getNamespace

public PackageNode getNamespace()

Description copied from interface: ClassHierarchy

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.

Specified by:

getNamespace in interface ClassHierarchy

Returns:

a reference to the root node of this ClassHierarchy.

getParameterParser

public ParameterParser getParameterParser()

isImplementation

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

Description copied from interface: ClassHierarchy

Return whether the impl is a subclass of inter.

Specified by:

isImplementation in interface ClassHierarchy

Parameters:

inter - a interface class

impl - a implementation class

Returns:

true if impl is a subclass of inter.

merge

public ClassHierarchy merge(ClassHierarchy ch)

Description copied from interface: ClassHierarchy

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.

Specified by:

merge in interface ClassHierarchy

Parameters:

ch - a class hierarchy to be merged

Returns:

the merged class hierarchy