jimfs/src/main/java/com/google/common/jimfs/StandardAttributeProviders.java

/*
 * Copyright 2013 Google Inc.
 *
 * 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.common.jimfs;

import com.google.common.collect.ImmutableMap;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;

/**
 * Static registry of {@link AttributeProvider} implementations for the standard set of file
 * attribute views Jimfs supports.
 *
 * @author Colin Decker
 */
final class StandardAttributeProviders {

  private StandardAttributeProviders() {}

  private static final ImmutableMap<String, AttributeProvider> PROVIDERS =
      new ImmutableMap.Builder<String, AttributeProvider>()
          .put("basic", new BasicAttributeProvider())
          .put("owner", new OwnerAttributeProvider())
          .put("posix", new PosixAttributeProvider())
          .put("dos", new DosAttributeProvider())
          .put("acl", new AclAttributeProvider())
          .put("user", new UserDefinedAttributeProvider())
          .build();

  /**
   * Returns the attribute provider for the given view, or {@code null} if the given view is not one
   * of the attribute views this supports.
   */
  @NullableDecl
  public static AttributeProvider get(String view) {
    AttributeProvider provider = PROVIDERS.get(view);

    if (provider == null && view.equals("unix")) {
      // create a new UnixAttributeProvider per file system, as it does some caching that should be
      // cleaned up when the file system is garbage collected
      return new UnixAttributeProvider();
    }

    return provider;
  }
}