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/*
* 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 static com.google.common.base.Preconditions.checkNotNull;
import static java.nio.file.StandardCopyOption.ATOMIC_MOVE;
import static java.nio.file.StandardOpenOption.APPEND;
import static java.nio.file.StandardOpenOption.CREATE;
import static java.nio.file.StandardOpenOption.READ;
import static java.nio.file.StandardOpenOption.TRUNCATE_EXISTING;
import static java.nio.file.StandardOpenOption.WRITE;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import java.nio.file.CopyOption;
import java.nio.file.LinkOption;
import java.nio.file.OpenOption;
import java.util.Arrays;
import java.util.Collection;
import java.util.Set;
/**
* Utility methods for normalizing user-provided options arrays and sets to canonical immutable sets
* of options.
*
* @author Colin Decker
*/
final class Options {
private Options() {}
/** Immutable set containing LinkOption.NOFOLLOW_LINKS. */
public static final ImmutableSet<LinkOption> NOFOLLOW_LINKS =
ImmutableSet.of(LinkOption.NOFOLLOW_LINKS);
/** Immutable empty LinkOption set. */
public static final ImmutableSet<LinkOption> FOLLOW_LINKS = ImmutableSet.of();
private static final ImmutableSet<OpenOption> DEFAULT_READ = ImmutableSet.<OpenOption>of(READ);
private static final ImmutableSet<OpenOption> DEFAULT_READ_NOFOLLOW_LINKS =
ImmutableSet.<OpenOption>of(READ, LinkOption.NOFOLLOW_LINKS);
private static final ImmutableSet<OpenOption> DEFAULT_WRITE =
ImmutableSet.<OpenOption>of(WRITE, CREATE, TRUNCATE_EXISTING);
/** Returns an immutable set of link options. */
public static ImmutableSet<LinkOption> getLinkOptions(LinkOption... options) {
return options.length == 0 ? FOLLOW_LINKS : NOFOLLOW_LINKS;
}
/** Returns an immutable set of open options for opening a new file channel. */
public static ImmutableSet<OpenOption> getOptionsForChannel(Set<? extends OpenOption> options) {
if (options.isEmpty()) {
return DEFAULT_READ;
}
boolean append = options.contains(APPEND);
boolean write = append || options.contains(WRITE);
boolean read = !write || options.contains(READ);
if (read) {
if (append) {
throw new UnsupportedOperationException("'READ' + 'APPEND' not allowed");
}
if (!write) {
// ignore all write related options
return options.contains(LinkOption.NOFOLLOW_LINKS)
? DEFAULT_READ_NOFOLLOW_LINKS
: DEFAULT_READ;
}
}
// options contains write or append and may also contain read
// it does not contain both read and append
return addWrite(options);
}
/** Returns an immutable set of open options for opening a new input stream. */
@SuppressWarnings("unchecked") // safe covariant cast
public static ImmutableSet<OpenOption> getOptionsForInputStream(OpenOption... options) {
boolean nofollowLinks = false;
for (OpenOption option : options) {
if (checkNotNull(option) != READ) {
if (option == LinkOption.NOFOLLOW_LINKS) {
nofollowLinks = true;
} else {
throw new UnsupportedOperationException("'" + option + "' not allowed");
}
}
}
// just return the link options for finding the file, nothing else is needed
return (ImmutableSet<OpenOption>)
(ImmutableSet<?>) (nofollowLinks ? NOFOLLOW_LINKS : FOLLOW_LINKS);
}
/** Returns an immutable set of open options for opening a new output stream. */
public static ImmutableSet<OpenOption> getOptionsForOutputStream(OpenOption... options) {
if (options.length == 0) {
return DEFAULT_WRITE;
}
ImmutableSet<OpenOption> result = addWrite(Arrays.asList(options));
if (result.contains(READ)) {
throw new UnsupportedOperationException("'READ' not allowed");
}
return result;
}
/**
* Returns an {@link ImmutableSet} copy of the given {@code options}, adding {@link
* StandardOpenOption#WRITE} if it isn't already present.
*/
private static ImmutableSet<OpenOption> addWrite(Collection<? extends OpenOption> options) {
return options.contains(WRITE)
? ImmutableSet.copyOf(options)
: ImmutableSet.<OpenOption>builder().add(WRITE).addAll(options).build();
}
/** Returns an immutable set of the given options for a move. */
public static ImmutableSet<CopyOption> getMoveOptions(CopyOption... options) {
return ImmutableSet.copyOf(Lists.asList(LinkOption.NOFOLLOW_LINKS, options));
}
/** Returns an immutable set of the given options for a copy. */
public static ImmutableSet<CopyOption> getCopyOptions(CopyOption... options) {
ImmutableSet<CopyOption> result = ImmutableSet.copyOf(options);
if (result.contains(ATOMIC_MOVE)) {
throw new UnsupportedOperationException("'ATOMIC_MOVE' not allowed");
}
return result;
}
}
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