org.objectweb.fractal.julia.loader
Class BasicLoader

java.lang.Object
  org.objectweb.fractal.julia.loader.BasicLoader

All Implemented Interfaces:

Loader

Direct Known Subclasses:

DynamicLoader

public class BasicLoader
extends Object
implements Loader

Provides a basic implementation of the Loader interface. This implementation loads the required classes from the class path.

Requirements

• none.

Constructor Summary

BasicLoader()

Method Summary

Tree	evalTree(Tree tree, Map context) Evaluates the given tree in the given context.
protected Class	generateClass(String name, Tree classDescriptor, Object loader) Generates the class whose descriptor is given, with the given name.
void	init(Map context) Initializes this loader.
Class	loadClass(String name, Object loader) Loads the class whose name is given.
Class	loadClass(Tree classDescriptor, Object loader) Loads or generates the class whose descriptor is given.
Tree	loadTree(String name) Loads the tree whose name is given.
Object	newObject(Tree objectDescriptor, Object loader) Creates and returns the object whose description is given.

Methods inherited from class java.lang.Object

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

Constructor Detail

BasicLoader

public BasicLoader()

Method Detail

init

public void init(Map context)
          throws Exception

Description copied from interface: Loader

Initializes this loader.

Specified by:

init in interface Loader

Parameters:

context - the initialization arguments.

Throws:

Exception - if the initialization fails.

loadTree

public Tree loadTree(String name)
              throws Exception

Description copied from interface: Loader

Loads the tree whose name is given.

Specified by:

loadTree in interface Loader

Parameters:

name - a tree name.

Returns:

the tree whose name is given.

Throws:

Exception - if the tree is not found or cannot be loaded.

evalTree

public Tree evalTree(Tree tree,
                     Map context)
              throws Exception

Description copied from interface: Loader

Evaluates the given tree in the given context. Each leaf node of the given tree whose name begins with ' is replaced by the evaluation of the tree associated to this name in the given context (except if the result of this evaluation is "QUOTE"). For example the evaluation of "('x d)" in a context where x is associated to "(a 'y)", y is associated to "(b 'z)", and z is associated to "QUOTE" gives "((a (b 'z)) d)".

Specified by:

evalTree in interface Loader

Parameters:

tree - the tree to be evaluated.

context - a map associating names to trees.

Returns:

the evaluated tree.

Throws:

Exception - if a name is not found in the given context. The exception's detail is equal to this name.

newObject

public Object newObject(Tree objectDescriptor,
                        Object loader)
                 throws Exception

Description copied from interface: Loader

Creates and returns the object whose description is given.

Specified by:

newObject in interface Loader

Parameters:

objectDescriptor - the descriptor of the object to be created. This descriptor must be either of the form "className", or of the form "(classDescriptor arg1 ... argN)". In the first case, "className" must be the fully qualified name of a class. In the second case, "classDescriptor" must be a valid class descriptor (see loadClass). "arg1" ... "argN" can be arbitrary trees.

loader - an optional class loader to load auxiliary classes.

Returns:

an object created according to the given description. If this description is of the form "className", this method returns a new instance of the "className" class (which must have a default public constructor). If the description is of the form "(classDescriptor arg1 ... argN)", the class described by "classDescriptor" is loaded or generated with the loadClass method, and a new instance of this class is created (this class must have a default public constructor). Then, if the arguments "arg1 ... argN" are not empty, the initialize method is used to initialize the previous instance (in this case, the "classDescriptor" class must implement the Initializable interface; the initialize method is called with (arg1 ... argN) as parameter). Finally the previously created object is returned.

Throws:

Exception - if the specified object cannot be created.

loadClass

public Class loadClass(String name,
                       Object loader)
                throws ClassNotFoundException

Description copied from interface: Loader

Loads the class whose name is given.

Specified by:

loadClass in interface Loader

Parameters:

name - the fully qualified name of the class to be returned.

loader - an optional class loader to load auxiliary classes.

Returns:

the class whose name is given.

Throws:

ClassNotFoundException - if the specified class is not found.

loadClass

public Class loadClass(Tree classDescriptor,
                       Object loader)
                throws ClassNotFoundException

Description copied from interface: Loader

Loads or generates the class whose descriptor is given.

Specified by:

loadClass in interface Loader

Parameters:

classDescriptor - the descriptor of the class to be loaded or dynamically generated. This descriptor must be either of the form "className", or of the form "(objectDescriptor arg1 ... argN)". In the first case, "className" must be the fully qualified name of a class. In the second case, "objectDescriptor" must be a valid object descriptor (see newObject), describing an object that implements the ClassGenerator interface. "arg1" ... "argN" can be arbitrary trees.

loader - an optional class loader to load auxiliary classes.

Returns:

the class whose description is given. If this description is of the form "className", this method returns the "className" class. If the description is of the form "(objectDescriptor arg1 ... argN)", the class generator described by "objectDescriptor" is instantiated with the newObject method, and its generateClass method is used to generate a class (this method is called with classDescriptor as second argument), which is finally returned.

Throws:

ClassNotFoundException - is the specified class cannot be loaded or dynamically generated.

generateClass

protected Class generateClass(String name,
                              Tree classDescriptor,
                              Object loader)
                       throws ClassNotFoundException

Generates the class whose descriptor is given, with the given name. The generated class must implement the Generated interface, and its getFcGeneratorParameters method must return classDescriptor.toString(). The default implementation of this method throws an exception.

Parameters:

name - the name of the class to be generated.

classDescriptor - the descriptor of the class to be generated. This descriptor must be of the form "(objectDescriptor arg1 ... argN)" (see loadClass).

loader - an optional class loader to load auxiliary classes.

Returns:

a class named name and whose content is described by the given class descriptor.

Throws:

ClassNotFoundException - if a problem occurs during the generation of the class.