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package com.sun.tools.xjc.reader;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;
import com.sun.tools.xjc.ErrorReceiver;
import com.sun.tools.xjc.model.Model;
/**
* Holds all the binding related singleton components in a "ring",
* and let you access those components, creating them as necessary.
*
*
* A {@link Ring} is local to a thread,
* and only one instanceof {@link Ring} can be active at any given time.
*
* Use {@link #begin()} and {@link #end(Ring)} to start/end a ring scope.
* Inside a scope, use {@link #get()} to obtain the instance.
*
*
* When a {@link Model} is built by the reader, an active {@link Ring} scope
* is assumed.
*
*
*
Components in Ring
*
* Depending on the schema language we are dealing with, different
* components are in the model. But at least the following components
* are in the ring.
*
*
* - {@link ErrorReceiver}
*
*
* @author Kohsuke Kawaguchi
*/
public final class Ring {
private final Map components = new HashMap();
private static final ThreadLocal instances = new ThreadLocal() {
public Ring initialValue() {
return new Ring();
}
};
private Ring() {}
public static void add( Class clazz, T instance ) {
assert !get().components.containsKey(clazz);
get().components.put(clazz,instance);
}
public static void add( T o ) {
add((Class)o.getClass(),o);
}
public static T get( Class key ) {
T t = (T)get().components.get(key);
if(t==null) {
try {
Constructor c = key.getDeclaredConstructor();
c.setAccessible(true);
t = c.newInstance();
if(!get().components.containsKey(key))
// many components register themselves.
add(key,t);
} catch (InstantiationException e) {
throw new Error(e);
} catch (IllegalAccessException e) {
throw new Error(e);
} catch (NoSuchMethodException e) {
throw new Error(e);
} catch (InvocationTargetException e) {
throw new Error(e);
}
}
assert t!=null;
return t;
}
/**
* A {@link Ring} instance is associated with a thread.
*/
public static Ring get() {
return instances.get();
}
/**
* Starts a new scope.
*/
public static Ring begin() {
Ring r = instances.get();
instances.set(new Ring());
return r;
}
/**
* Ends a scope.
*/
public static void end(Ring old) {
instances.set(old);
}
}