135 lines
4.1 KiB
Java
135 lines
4.1 KiB
Java
/*
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* Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package com.sun.tools.internal.xjc.reader;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.InvocationTargetException;
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import java.util.HashMap;
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import java.util.Map;
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import com.sun.tools.internal.xjc.ErrorReceiver;
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import com.sun.tools.internal.xjc.model.Model;
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/**
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* Holds all the binding related singleton components in a "ring",
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* and let you access those components, creating them as necessary.
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*
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* <p>
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* A {@link Ring} is local to a thread,
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* and only one instanceof {@link Ring} can be active at any given time.
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*
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* Use {@link #begin()} and {@link #end(Ring)} to start/end a ring scope.
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* Inside a scope, use {@link #get()} to obtain the instance.
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*
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* <p>
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* When a {@link Model} is built by the reader, an active {@link Ring} scope
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* is assumed.
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*
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*
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* <h2>Components in Ring</h2>
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* <p>
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* Depending on the schema language we are dealing with, different
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* components are in the model. But at least the following components
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* are in the ring.
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*
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* <ul>
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* <li>{@link ErrorReceiver}
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* </ul>
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*
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* @author Kohsuke Kawaguchi
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*/
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public final class Ring {
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private final Map<Class,Object> components = new HashMap<Class,Object>();
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private static final ThreadLocal<Ring> instances = new ThreadLocal<Ring>();
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private Ring() {}
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public static <T> void add( Class<T> clazz, T instance ) {
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assert !get().components.containsKey(clazz);
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get().components.put(clazz,instance);
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}
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public static <T> void add( T o ) {
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add((Class<T>)o.getClass(),o);
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}
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public static <T> T get( Class<T> key ) {
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T t = (T)get().components.get(key);
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if(t==null) {
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try {
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Constructor<T> c = key.getDeclaredConstructor();
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c.setAccessible(true);
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t = c.newInstance();
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if(!get().components.containsKey(key))
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// many components register themselves.
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add(key,t);
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} catch (InstantiationException e) {
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throw new Error(e);
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} catch (IllegalAccessException e) {
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throw new Error(e);
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} catch (NoSuchMethodException e) {
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throw new Error(e);
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} catch (InvocationTargetException e) {
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throw new Error(e);
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}
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}
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assert t!=null;
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return t;
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}
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/**
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* A {@link Ring} instance is associated with a thread.
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*/
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public static Ring get() {
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return instances.get();
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}
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/**
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* Starts a new scope.
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*/
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public static Ring begin() {
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Ring r = null;
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synchronized (instances) {
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r = instances.get();
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instances.set(new Ring());
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}
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return r;
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}
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/**
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* Ends a scope.
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*/
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public static void end(Ring old) {
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synchronized (instances) {
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instances.remove();
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instances.set(old);
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}
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}
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}
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