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/*
* Copyright (C) 2008 The Guava Authors
*
* 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 org.glassfish.jersey.internal.guava;
import java.util.AbstractCollection;
import java.util.Collection;
import java.util.Iterator;
import java.util.function.Function;
import static org.glassfish.jersey.internal.guava.Preconditions.checkArgument;
import static org.glassfish.jersey.internal.guava.Preconditions.checkNotNull;
/**
* Provides static methods for working with {@code Collection} instances.
*
* @author Chris Povirk
* @author Mike Bostock
* @author Jared Levy
* @since 2.0 (imported from Google Collections Library)
*/
final class Collections2 {
static final Joiner STANDARD_JOINER = Joiner.on();
private Collections2() {
}
/**
* Delegates to {@link Collection#contains}. Returns {@code false} if the
* {@code contains} method throws a {@code ClassCastException} or
* {@code NullPointerException}.
*/
static boolean safeContains(
Collection collection, Object object) {
checkNotNull(collection);
try {
return collection.contains(object);
} catch (ClassCastException e) {
return false;
} catch (NullPointerException e) {
return false;
}
}
/**
* Delegates to {@link Collection#remove}. Returns {@code false} if the
* {@code remove} method throws a {@code ClassCastException} or
* {@code NullPointerException}.
*/
static boolean safeRemove(Collection collection, Object object) {
checkNotNull(collection);
try {
return collection.remove(object);
} catch (ClassCastException e) {
return false;
} catch (NullPointerException e) {
return false;
}
}
/**
* Returns a collection that applies {@code function} to each element of
* {@code fromCollection}. The returned collection is a live view of {@code
* fromCollection}; changes to one affect the other.
*
*
The returned collection's {@code add()} and {@code addAll()} methods
* throw an {@link UnsupportedOperationException}. All other collection
* methods are supported, as long as {@code fromCollection} supports them.
*
*
The returned collection isn't threadsafe or serializable, even if
* {@code fromCollection} is.
*
*
When a live view is not needed, it may be faster to copy the
* transformed collection and use the copy.
*
*
If the input {@code Collection} is known to be a {@code List}, consider
* {@link Lists#transform}. If only an {@code Iterable} is available, use
* {@link Iterables#transform}.
*/
public static Collection transform(Collection fromCollection,
Function function) {
return new TransformedCollection(fromCollection, function);
}
/**
* Returns best-effort-sized StringBuilder based on the given collection size.
*/
static StringBuilder newStringBuilderForCollection(int size) {
CollectPreconditions.checkNonnegative(size, "size");
return new StringBuilder((int) Math.min(size * 8L, Ints.MAX_POWER_OF_TWO));
}
/**
* Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557
*/
static Collection cast(Iterable iterable) {
return (Collection) iterable;
}
static class TransformedCollection extends AbstractCollection {
final Collection fromCollection;
final Function function;
TransformedCollection(Collection fromCollection,
Function function) {
this.fromCollection = checkNotNull(fromCollection);
this.function = checkNotNull(function);
}
@Override
public void clear() {
fromCollection.clear();
}
@Override
public boolean isEmpty() {
return fromCollection.isEmpty();
}
@Override
public Iterator iterator() {
return Iterators.transform(fromCollection.iterator(), function);
}
@Override
public int size() {
return fromCollection.size();
}
}
}