vfs.java

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/*
 * VFS.java - Virtual filesystem implementation
 * :tabSize=8:indentSize=8:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 2000, 2002 Slava Pestov
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package org.gjt.sp.jedit.io;

//{{{ Imports
import gnu.regexp.*;
import java.awt.Color;
import java.awt.Component;
import java.io.*;
import java.util.*;
import org.gjt.sp.jedit.buffer.BufferIORequest;
import org.gjt.sp.jedit.msg.PropertiesChanged;
import org.gjt.sp.jedit.*;
import org.gjt.sp.util.Log;
//}}}

/**
 * A virtual filesystem implementation.<p>
 *
 * <b>Session objects:</b><p>
 *
 * A session is used to persist things like login information, any network
 * sockets, etc. File system implementations that do not need this kind of
 * persistence return a dummy object as a session.<p>
 *
 * Methods whose names are prefixed with "_" expect to be given a
 * previously-obtained session object. A session must be obtained from the AWT
 * thread in one of two ways:
 *
 * <ul>
 * <li>{@link #createVFSSession(String,Component)}</li>
 * <li>{@link #showBrowseDialog(Object[],Component)}</li>
 * </ul>
 *
 * When done, the session must be disposed of using
 * {@link #_endVFSSession(Object,Component)}.<p>
 *
 * <b>Thread safety:</b><p>
 *
 * The following methods cannot be called from an I/O thread:
 *
 * <ul>
 * <li>{@link #createVFSSession(String,Component)}</li>
 * <li>{@link #insert(View,Buffer,String)}</li>
 * <li>{@link #load(View,Buffer,String)}</li>
 * <li>{@link #save(View,Buffer,String)}</li>
 * <li>{@link #showBrowseDialog(Object[],Component)}</li>
 * </ul>
 *
 * All remaining methods are (required to be) thread-safe.
 *
 * @see VFSManager#registerVFS(String,VFS)
 * @see VFSManager#getVFSByName(String)
 * @see VFSManager#getVFSForPath(String)
 * @see VFSManager#getVFSForProtocol(String)
 *
 * @author Slava Pestov
 * @author $Id: VFS.java,v 1.25 2003/02/11 02:31:06 spestov Exp $
 */
public abstract class VFS
{
	//{{{ Capabilities

	/**
	 * Read capability.
	 * @since jEdit 2.6pre2
	 */
	public static final int READ_CAP = 1 << 0;

	/**
	 * Write capability.
	 * @since jEdit 2.6pre2
	 */
	public static final int WRITE_CAP = 1 << 1;

	/**
	 * If set, a menu item for this VFS will appear in the browser's
	 * <b>Plugins</b> menu. The property <code>vfs.<i>name</i>.label</code>
	 * is used as a menu item label.<p>
	 *
	 * When invoked, the menu item calls the
	 * {@link #showBrowseDialog(Object[],Component)} method of the VFS,
	 * and then lists the directory returned by that method.<p>
	 *
	 * If this capability is not set, it will still be possible to type in
	 * URLs for this VFS in the browser, but there won't be a user-visible
	 * way of doing this.
	 *
	 * @since jEdit 2.6pre2
	 */
	public static final int BROWSE_CAP = 1 << 2;

	/**
	 * Delete file capability.
	 * @since jEdit 2.6pre2
	 */
	public static final int DELETE_CAP = 1 << 3;

	/**
	 * Rename file capability.
	 * @since jEdit 2.6pre2
	 */
	public static final int RENAME_CAP = 1 << 4;

	/**
	 * Make directory capability.
	 * @since jEdit 2.6pre2
	 */
	public static final int MKDIR_CAP = 1 << 5;

	/**
	 * Low latency capability. If this is not set, then a confirm dialog
	 * will be shown before doing a directory search in this VFS.
	 * @since jEdit 4.1pre1
	 */
	public static final int LOW_LATENCY_CAP = 1 << 6;

	//}}}

	//{{{ VFS constructor
	/**
	 * Creates a new virtual filesystem.
	 * @param name The name
	 */
	public VFS(String name)
	{
		this.name = name;
	} //}}}

	//{{{ VFS constructor
	/**
	 * Creates a new virtual filesystem.
	 * @param name The name
	 * @param caps The capabilities
	 */
	public VFS(String name, int caps)
	{
		this.name = name;
		this.caps = caps;
	} //}}}

	//{{{ getName() method
	/**
	 * Returns this VFS's name. The name is used to obtain the
	 * label stored in the <code>vfs.<i>name</i>.label</code>
	 * property.
	 */
	public String getName()
	{
		return name;
	} //}}}

	//{{{ getCapabilities() method
	/**
	 * Returns the capabilities of this VFS.
	 * @since jEdit 2.6pre2
	 */
	public int getCapabilities()
	{
		return caps;
	} //}}}

	//{{{ showBrowseDialog() method
	/**
	 * Displays a dialog box that should set up a session and return
	 * the initial URL to browse.
	 * @param session Where the VFS session will be stored
	 * @param comp The component that will parent error dialog boxes
	 * @return The URL
	 * @since jEdit 2.7pre1
	 */
	public String showBrowseDialog(Object[] session, Component comp)
	{
		return null;
	} //}}}

	//{{{ getFileName() method
	/**
	 * Returns the file name component of the specified path.
	 * @param path The path
	 * @since jEdit 3.1pre4
	 */
	public String getFileName(String path)
	{
		if(path.equals("/"))
			return path;

		int count = Math.max(0,path.length() - 2);
		int index = Math.max(path.lastIndexOf('/',count),
			path.lastIndexOf(File.separatorChar,count));
		if(index == -1)
			index = path.indexOf(':');

		// don't want getFileName("roots:") to return ""
		if(index == -1 || index == path.length() - 1)
			return path;

		return path.substring(index + 1);
	} //}}}

	//{{{ getParentOfPath() method
	/**
	 * Returns the parent of the specified path. This must be
	 * overridden to return a non-null value for browsing of this
	 * filesystem to work.
	 * @param path The path
	 * @since jEdit 2.6pre5
	 */
	public String getParentOfPath(String path)
	{
		// ignore last character of path to properly handle
		// paths like /foo/bar/
		int count = Math.max(0,path.length() - 2);
		int index = path.lastIndexOf(File.separatorChar,count);
		if(index == -1)
			index = path.lastIndexOf('/',count);
		if(index == -1)
		{
			// this ensures that getFileParent("protocol:"), for
			// example, is "protocol:" and not "".
			index = path.lastIndexOf(':');
		}

		return path.substring(0,index + 1);
	} //}}}

	//{{{ constructPath() method
	/**
	 * Constructs a path from the specified directory and
	 * file name component. This must be overridden to return a
	 * non-null value, otherwise browsing this filesystem will
	 * not work.<p>
	 *
	 * Unless you are writing a VFS, this method should not be called
	 * directly. To ensure correct behavior, you <b>must</b> call
	 * {@link org.gjt.sp.jedit.MiscUtilities#constructPath(String,String)}
	 * instead.
	 *
	 * @param parent The parent directory
	 * @param path The path
	 * @since jEdit 2.6pre2
	 */
	public String constructPath(String parent, String path)
	{
		return parent + path;
	} //}}}

	//{{{ getFileSeparator() method
	/**
	 * Returns the file separator used by this VFS.
	 * @since jEdit 2.6pre9
	 */
	public char getFileSeparator()
	{
		return '/';
	} //}}}

	//{{{ getTwoStageSaveName() method
	/**
	 * Returns a temporary file name based on the given path.
	 *
	 * By default jEdit first saves a file to <code>#<i>name</i>#save#</code>
	 * and then renames it to the original file. However some virtual file
	 * systems might not support the <code>#</code> character in filenames,
	 * so this method permits the VFS to override this behavior.
	 *
	 * @param path The path name
	 * @since jEdit 4.1pre7
	 */
	public String getTwoStageSaveName(String path)
	{
		return MiscUtilities.constructPath(getParentOfPath(path),
			'#' + getFileName(path) + "#save#");
	} //}}}

	//{{{ reloadDirectory() method
	/**
	 * Called before a directory is reloaded by the file system browser.
	 * Can be used to flush a cache, etc.
	 * @since jEdit 4.0pre3
	 */
	public void reloadDirectory(String path) {} //}}}

	//{{{ createVFSSession() method
	/**
	 * Creates a VFS session. This method is called from the AWT thread,
	 * so it should not do any I/O. It could, however, prompt for
	 * a login name and password, for example.
	 * @param path The path in question
	 * @param comp The component that will parent any dialog boxes shown
	 * @return The session
	 * @since jEdit 2.6pre3
	 */
	public Object createVFSSession(String path, Component comp)
	{
		return new Object();
	} //}}}

	//{{{ load() method
	/**
	 * Loads the specified buffer. The default implementation posts
	 * an I/O request to the I/O thread.
	 * @param view The view
	 * @param buffer The buffer
	 * @param path The path
	 */
	public boolean load(View view, Buffer buffer, String path)
	{
		if((getCapabilities() & READ_CAP) == 0)
		{
			VFSManager.error(view,path,"vfs.not-supported.load",new String[] { name });
			return false;
		}

		Object session = createVFSSession(path,view);
		if(session == null)
			return false;

		if((getCapabilities() & WRITE_CAP) == 0)
			buffer.setReadOnly(true);

		BufferIORequest request = new BufferIORequest(
			BufferIORequest.LOAD,view,buffer,session,this,path);
		if(buffer.isTemporary())
			// this makes HyperSearch much faster
			request.run();
		else
			VFSManager.runInWorkThread(request);

		return true;
	} //}}}

	//{{{ save() method
	/**
	 * Saves the specifies buffer. The default implementation posts
	 * an I/O request to the I/O thread.
	 * @param view The view
	 * @param buffer The buffer
	 * @param path The path
	 */
	public boolean save(View view, Buffer buffer, String path)
	{
		if((getCapabilities() & WRITE_CAP) == 0)
		{
			VFSManager.error(view,path,"vfs.not-supported.save",new String[] { name });
			return false;
		}

		Object session = createVFSSession(path,view);
		if(session == null)
			return false;

		/* When doing a 'save as', the path to save to (path)
		 * will not be the same as the buffer's previous path
		 * (buffer.getPath()). In that case, we want to create
		 * a backup of the new path, even if the old path was
		 * backed up as well (BACKED_UP property set) */
		if(!path.equals(buffer.getPath()))
			buffer.unsetProperty(Buffer.BACKED_UP);

		VFSManager.runInWorkThread(new BufferIORequest(
			BufferIORequest.SAVE,view,buffer,session,this,path));
		return true;
	} //}}}

	//{{{ insert() method
	/**
	 * Inserts a file into the specified buffer. The default implementation
	 * posts an I/O request to the I/O thread.
	 * @param view The view
	 * @param buffer The buffer
	 * @param path The path
	 */
	public boolean insert(View view, Buffer buffer, String path)
	{
		if((getCapabilities() & READ_CAP) == 0)
		{
			VFSManager.error(view,path,"vfs.not-supported.load",new String[] { name });
			return false;
		}

		Object session = createVFSSession(path,view);
		if(session == null)
			return false;

		VFSManager.runInWorkThread(new BufferIORequest(
			BufferIORequest.INSERT,view,buffer,session,this,path));
		return true;
	} //}}}

	// the remaining methods are called from the I/O thread

	//{{{ _canonPath() method
	/**
	 * Returns the canonical form of the specified path name. For example,
	 * <code>~</code> might be expanded to the user's home directory.
	 * @param session The session
	 * @param path The path
	 * @param comp The component that will parent error dialog boxes
	 * @exception IOException if an I/O error occurred
	 * @since jEdit 4.0pre2