org.renjin.appengine.AppEngineLocalFilesSystemProvider.java Source code

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Here is the source code for org.renjin.appengine.AppEngineLocalFilesSystemProvider.java

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/*
 * R : A Computer Language for Statistical Data Analysis
 * Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 * Copyright (C) 1997--2008  The R Development Core Team
 * Copyright (C) 2003, 2004  The R Foundation
 * Copyright (C) 2010 bedatadriven
 *
 * 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 3 of the License, or
 * (at your option) 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, see <http://www.gnu.org/licenses/>.
 */

package org.renjin.appengine;

import java.io.File;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;

import org.apache.commons.vfs2.Capability;
import org.apache.commons.vfs2.FileName;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystem;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.FileType;
import org.apache.commons.vfs2.provider.AbstractFileProvider;
import org.apache.commons.vfs2.provider.LocalFileProvider;
import org.apache.commons.vfs2.provider.UriParser;

/**
 * Provides read-only access to the application context
 * on the local file system.
 *
 * <p>We have to be careful because trying to read or
 * touch parent folders (e.g. /base) will throw a SecurityException
 *
 */
public class AppEngineLocalFilesSystemProvider extends AbstractFileProvider
        implements LocalFileProvider, Comparable<AppEngineLocalFilesSystemProvider> {

    private File rootFile;

    public final static Collection CAPABILITIES = Collections.unmodifiableCollection(Arrays
            .asList(new Capability[] { Capability.GET_TYPE, Capability.GET_LAST_MODIFIED, Capability.LIST_CHILDREN,
                    Capability.READ_CONTENT, Capability.URI, Capability.RANDOM_ACCESS_READ }));

    public AppEngineLocalFilesSystemProvider(File rootFile) {
        this.rootFile = rootFile;
    }

    @Override
    public FileObject findLocalFile(String name) throws FileSystemException {
        return findFile(null, name, null);
    }

    @Override
    public FileObject findLocalFile(File file) throws FileSystemException {
        return findFile(null, file.getPath(), null);
    }

    @Override
    public FileObject findFile(FileObject baseFile, String uri, FileSystemOptions properties)
            throws FileSystemException {

        // Parse the name
        final StringBuilder buffer = new StringBuilder(uri);
        String scheme = UriParser.extractScheme(uri, buffer);
        if (scheme == null) {
            scheme = "file";
        }

        UriParser.fixSeparators(buffer);

        FileType fileType = UriParser.normalisePath(buffer);
        final String path = buffer.toString();

        // Create the temp file system if it does not exist
        // FileSystem filesystem = findFileSystem( this, (Properties) null);
        FileSystem filesystem = findFileSystem(this, properties);
        if (filesystem == null) {
            final FileName rootName = getContext().parseURI(scheme + ":" + FileName.ROOT_PATH);

            filesystem = new AppEngineLocalFileSystem(rootName, rootFile.getAbsolutePath(), properties);
            addFileSystem(this, filesystem);
        }

        // Find the file
        return filesystem.resolveFile(path);
    }

    @Override
    public Collection getCapabilities() {
        return CAPABILITIES;
    }

    @Override
    public int compareTo(AppEngineLocalFilesSystemProvider o) {
        return hashCode() - o.hashCode();
    }

    @Override
    public boolean isAbsoluteLocalName(String name) {
        return name.startsWith("/");
    }
}