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// Copyright 2014 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.vfs.util;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.vfs.FileSystem;
import com.google.devtools.build.lib.vfs.JavaIoFileSystem;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import com.google.devtools.build.lib.vfs.UnionFileSystem;
import com.google.devtools.build.lib.vfs.UnixFileSystem;
import com.google.devtools.build.lib.vfs.ZipFileSystem;
import java.io.IOException;
import java.util.Map;
/**
* This static file system singleton manages access to a single default
* {@link FileSystem} instance created within the methods of this class.
*/
@ThreadSafe
public final class FileSystems {
private FileSystems() {}
private static FileSystem defaultFileSystem;
/**
* Initializes the default {@link FileSystem} instance as a platform native
* (Unix) file system, creating one iff needed, and returns the instance.
*
* <p>This method is idempotent as long as the initialization is of the same
* type (Native/JavaIo/Union).
*/
public static synchronized FileSystem initDefaultAsNative() {
if (!(defaultFileSystem instanceof UnixFileSystem)) {
defaultFileSystem = new UnixFileSystem();
}
return defaultFileSystem;
}
/**
* Initializes the default {@link FileSystem} instance as a java.io.File
* file system, creating one iff needed, and returns the instance.
*
* <p>This method is idempotent as long as the initialization is of the same
* type (Native/JavaIo/Union).
*/
public static synchronized FileSystem initDefaultAsJavaIo() {
if (!(defaultFileSystem instanceof JavaIoFileSystem)) {
defaultFileSystem = new JavaIoFileSystem();
}
return defaultFileSystem;
}
/**
* Initializes the default {@link FileSystem} instance as a
* {@link UnionFileSystem}, creating one iff needed,
* and returns the instance.
*
* <p>This method is idempotent as long as the initialization is of the same
* type (Native/JavaIo/Union).
*
* @param prefixMapping the desired mapping of path prefixes to delegate file systems
* @param rootFileSystem the default file system for paths that don't match any prefix map
*/
public static synchronized FileSystem initDefaultAsUnion(
Map<PathFragment, FileSystem> prefixMapping, FileSystem rootFileSystem) {
if (!(defaultFileSystem instanceof UnionFileSystem)) {
defaultFileSystem = new UnionFileSystem(prefixMapping, rootFileSystem);
}
return defaultFileSystem;
}
/**
* Returns a new instance of a simple {@link FileSystem} implementation that
* presents the contents of a zip file as a read-only file system view.
*/
public static FileSystem newZipFileSystem(Path zipFile) throws IOException {
return new ZipFileSystem(zipFile);
}
}
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