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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 com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.collect.Ordering;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;
/**
* Immutable representation of a file name. Used both for the name components of paths and as the
* keys for directory entries.
*
* <p>A name has both a display string (used in the {@code toString()} form of a {@code Path} as
* well as for {@code Path} equality and sort ordering) and a canonical string, which is used for
* determining equality of the name during file lookup.
*
* <p>Note: all factory methods return a constant name instance when given the original string "."
* or "..", ensuring that those names can be accessed statically elsewhere in the code while still
* being equal to any names created for those values, regardless of normalization settings.
*
* @author Colin Decker
*/
final class Name {
/** The empty name. */
static final Name EMPTY = new Name("", "");
/** The name to use for a link from a directory to itself. */
public static final Name SELF = new Name(".", ".");
/** The name to use for a link from a directory to its parent directory. */
public static final Name PARENT = new Name("..", "..");
/** Creates a new name with no normalization done on the given string. */
@VisibleForTesting
static Name simple(String name) {
switch (name) {
case ".":
return SELF;
case "..":
return PARENT;
default:
return new Name(name, name);
}
}
/**
* Creates a name with the given display representation and the given canonical representation.
*/
public static Name create(String display, String canonical) {
return new Name(display, canonical);
}
private final String display;
private final String canonical;
private Name(String display, String canonical) {
this.display = checkNotNull(display);
this.canonical = checkNotNull(canonical);
}
@Override
public boolean equals(@NullableDecl Object obj) {
if (obj instanceof Name) {
Name other = (Name) obj;
return canonical.equals(other.canonical);
}
return false;
}
@Override
public int hashCode() {
return Util.smearHash(canonical.hashCode());
}
@Override
public String toString() {
return display;
}
/** Returns an ordering that orders names by their display representation. */
public static Ordering<Name> displayOrdering() {
return DISPLAY_ORDERING;
}
/** Returns an ordering that orders names by their canonical representation. */
public static Ordering<Name> canonicalOrdering() {
return CANONICAL_ORDERING;
}
private static final Ordering<Name> DISPLAY_ORDERING =
Ordering.natural()
.onResultOf(
new Function<Name, String>() {
@Override
public String apply(Name name) {
return name.display;
}
});
private static final Ordering<Name> CANONICAL_ORDERING =
Ordering.natural()
.onResultOf(
new Function<Name, String>() {
@Override
public String apply(Name name) {
return name.canonical;
}
});
}
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