/*******************************************************************************
* Copyright (c) 2005, 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.internal.filesystem;
import java.net.URI;
import java.util.HashMap;
import org.eclipse.core.filesystem.*;
import org.eclipse.core.filesystem.provider.FileSystem;
import org.eclipse.core.runtime.*;
import org.eclipse.osgi.util.NLS;
/**
* The class manages internal implementation of methods on EFS.
* This includes maintaining a list of file system extensions.
*/
public class InternalFileSystemCore implements IRegistryChangeListener {
private static final InternalFileSystemCore INSTANCE = new InternalFileSystemCore();
/**
* A map (String -> (IConfigurationElement or IFileSystem)) mapping URI
* scheme to the file system for that scheme. If the corresponding file
* system has never been accessed, then the map contains the configuration
* element for the extension. Once the file system has been created, the
* map contains the IFileSystem instance for that scheme.
*/
private HashMap fileSystems;
/**
* Returns the singleton instance of this class.
* @return The singleton instance.
*/
public static InternalFileSystemCore getInstance() {
return INSTANCE;
}
/**
* This class has a singleton instance.
*/
private InternalFileSystemCore() {
super();
RegistryFactory.getRegistry().addRegistryChangeListener(this);
}
/**
* Implements the method EFS#getFileSystem(String)
*
* @param scheme The URI scheme of the file system
* @return The file system
* @throws CoreException
*/
public IFileSystem getFileSystem(String scheme) throws CoreException {
if (scheme == null)
throw new NullPointerException();
final HashMap registry = getFileSystemRegistry();
Object result = registry.get(scheme);
if (result == null)
Policy.error(EFS.ERROR_INTERNAL, NLS.bind(Messages.noFileSystem, scheme));
if (result instanceof IFileSystem)
return (IFileSystem) result;
try {
IConfigurationElement element = (IConfigurationElement) result;
FileSystem fs = (FileSystem) element.createExecutableExtension("run"); //$NON-NLS-1$
fs.initialize(scheme);
//store the file system instance so we don't have to keep recreating it
registry.put(scheme, fs);
return fs;
} catch (CoreException e) {
//remove this invalid file system from the registry
registry.remove(scheme);
throw e;
}
}
/**
* Implements the method EFS#getLocalFileSystem()
*
* @return The local file system
*/
public IFileSystem getLocalFileSystem() {
try {
return getFileSystem(EFS.SCHEME_FILE);
} catch (CoreException e) {
//the local file system is always present
throw new Error(e);
}
}
/**
* Implements the method EFS#getStore(URI)
*
* @param uri The URI of the store to retrieve
* @return The file store corresponding to the given URI
* @throws CoreException
*/
public IFileStore getStore(URI uri) throws CoreException {
final String scheme = uri.getScheme();
if (scheme == null)
Policy.error(EFS.ERROR_INTERNAL, Messages.noScheme + uri);
return getFileSystem(scheme).getStore(uri);
}
/**
* Returns the fully initialized file system registry
* @return The file system registry
*/
private synchronized HashMap getFileSystemRegistry() {
if (fileSystems == null) {
fileSystems = new HashMap();
IExtensionPoint point = RegistryFactory.getRegistry().getExtensionPoint(EFS.PI_FILE_SYSTEM, EFS.PT_FILE_SYSTEMS);
IExtension[] extensions = point.getExtensions();
for (int i = 0; i < extensions.length; i++) {
IConfigurationElement[] elements = extensions[i].getConfigurationElements();
for (int j = 0; j < elements.length; j++) {
if ("filesystem".equals(elements[j].getName())) { //$NON-NLS-1$
String scheme = elements[j].getAttribute("scheme"); //$NON-NLS-1$
if (scheme != null)
fileSystems.put(scheme, elements[j]);
}
}
}
}
return fileSystems;
}
/*
* (non-Javadoc)
* @see org.eclipse.core.runtime.IRegistryChangeListener#registryChanged(org.eclipse.core.runtime.IRegistryChangeEvent)
*/
public void registryChanged(IRegistryChangeEvent event) {
IExtensionDelta[] changes = event.getExtensionDeltas(EFS.PI_FILE_SYSTEM, EFS.PT_FILE_SYSTEMS);
if (changes.length == 0)
return;
synchronized (this) {
//let the registry be rebuilt lazily
fileSystems = null;
}
}
/**
* Implements {@link EFS#getNullFileSystem()}.
* @return The null file system
*/
public IFileSystem getNullFileSystem() {
try {
return getFileSystem(EFS.SCHEME_NULL);
} catch (CoreException e) {
//the local file system is always present
throw new Error(e);
}
}
}