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/*
 * Copyright (C) 2007 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 io.prestosql.hadoop.$internal.com.google.common.collect;

import static io.prestosql.hadoop.$internal.com.google.common.base.Preconditions.checkNotNull;

import io.prestosql.hadoop.$internal.com.google.common.annotations.Beta;
import io.prestosql.hadoop.$internal.com.google.common.annotations.GwtCompatible;

import java.util.Collection;
import java.util.List;
import java.util.ListIterator;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedSet;

/**
 * Factories and utilities pertaining to the {@link Constraint} interface.
 *
 * @see MapConstraints
 * @author Mike Bostock
 * @author Jared Levy
 * @since 3.0
 */
@Beta
@GwtCompatible
public final class Constraints {
  private Constraints() {}

  // enum singleton pattern
  private enum NotNullConstraint implements Constraint {
    INSTANCE;

    @Override
    public Object checkElement(Object element) {
      return checkNotNull(element);
    }

    @Override public String toString() {
      return "Not null";
    }
  }

  /**
   * Returns a constraint that verifies that the element is not null. If the
   * element is null, a {@link NullPointerException} is thrown.
   */
  // safe to narrow the type since checkElement returns its argument directly
  @SuppressWarnings("unchecked")
  public static  Constraint notNull() {
    return (Constraint) NotNullConstraint.INSTANCE;
  }

  /**
   * Returns a constrained view of the specified collection, using the specified
   * constraint. Any operations that add new elements to the collection will
   * call the provided constraint. However, this method does not verify that
   * existing elements satisfy the constraint.
   *
   * 

The returned collection is not serializable. * * @param collection the collection to constrain * @param constraint the constraint that validates added elements * @return a constrained view of the collection */ public static Collection constrainedCollection( Collection collection, Constraint constraint) { return new ConstrainedCollection(collection, constraint); } /** @see Constraints#constrainedCollection */ static class ConstrainedCollection extends ForwardingCollection { private final Collection delegate; private final Constraint constraint; public ConstrainedCollection( Collection delegate, Constraint constraint) { this.delegate = checkNotNull(delegate); this.constraint = checkNotNull(constraint); } @Override protected Collection delegate() { return delegate; } @Override public boolean add(E element) { constraint.checkElement(element); return delegate.add(element); } @Override public boolean addAll(Collection elements) { return delegate.addAll(checkElements(elements, constraint)); } } /** * Returns a constrained view of the specified set, using the specified * constraint. Any operations that add new elements to the set will call the * provided constraint. However, this method does not verify that existing * elements satisfy the constraint. * *

The returned set is not serializable. * * @param set the set to constrain * @param constraint the constraint that validates added elements * @return a constrained view of the set */ public static Set constrainedSet( Set set, Constraint constraint) { return new ConstrainedSet(set, constraint); } /** @see Constraints#constrainedSet */ static class ConstrainedSet extends ForwardingSet { private final Set delegate; private final Constraint constraint; public ConstrainedSet(Set delegate, Constraint constraint) { this.delegate = checkNotNull(delegate); this.constraint = checkNotNull(constraint); } @Override protected Set delegate() { return delegate; } @Override public boolean add(E element) { constraint.checkElement(element); return delegate.add(element); } @Override public boolean addAll(Collection elements) { return delegate.addAll(checkElements(elements, constraint)); } } /** * Returns a constrained view of the specified sorted set, using the specified * constraint. Any operations that add new elements to the sorted set will * call the provided constraint. However, this method does not verify that * existing elements satisfy the constraint. * *

The returned set is not serializable. * * @param sortedSet the sorted set to constrain * @param constraint the constraint that validates added elements * @return a constrained view of the sorted set */ public static SortedSet constrainedSortedSet( SortedSet sortedSet, Constraint constraint) { return new ConstrainedSortedSet(sortedSet, constraint); } /** @see Constraints#constrainedSortedSet */ private static class ConstrainedSortedSet extends ForwardingSortedSet { final SortedSet delegate; final Constraint constraint; ConstrainedSortedSet( SortedSet delegate, Constraint constraint) { this.delegate = checkNotNull(delegate); this.constraint = checkNotNull(constraint); } @Override protected SortedSet delegate() { return delegate; } @Override public SortedSet headSet(E toElement) { return constrainedSortedSet(delegate.headSet(toElement), constraint); } @Override public SortedSet subSet(E fromElement, E toElement) { return constrainedSortedSet( delegate.subSet(fromElement, toElement), constraint); } @Override public SortedSet tailSet(E fromElement) { return constrainedSortedSet(delegate.tailSet(fromElement), constraint); } @Override public boolean add(E element) { constraint.checkElement(element); return delegate.add(element); } @Override public boolean addAll(Collection elements) { return delegate.addAll(checkElements(elements, constraint)); } } /** * Returns a constrained view of the specified list, using the specified * constraint. Any operations that add new elements to the list will call the * provided constraint. However, this method does not verify that existing * elements satisfy the constraint. * *

If {@code list} implements {@link RandomAccess}, so will the returned * list. The returned list is not serializable. * * @param list the list to constrain * @param constraint the constraint that validates added elements * @return a constrained view of the list */ public static List constrainedList( List list, Constraint constraint) { return (list instanceof RandomAccess) ? new ConstrainedRandomAccessList(list, constraint) : new ConstrainedList(list, constraint); } /** @see Constraints#constrainedList */ @GwtCompatible private static class ConstrainedList extends ForwardingList { final List delegate; final Constraint constraint; ConstrainedList(List delegate, Constraint constraint) { this.delegate = checkNotNull(delegate); this.constraint = checkNotNull(constraint); } @Override protected List delegate() { return delegate; } @Override public boolean add(E element) { constraint.checkElement(element); return delegate.add(element); } @Override public void add(int index, E element) { constraint.checkElement(element); delegate.add(index, element); } @Override public boolean addAll(Collection elements) { return delegate.addAll(checkElements(elements, constraint)); } @Override public boolean addAll(int index, Collection elements) { return delegate.addAll(index, checkElements(elements, constraint)); } @Override public ListIterator listIterator() { return constrainedListIterator(delegate.listIterator(), constraint); } @Override public ListIterator listIterator(int index) { return constrainedListIterator(delegate.listIterator(index), constraint); } @Override public E set(int index, E element) { constraint.checkElement(element); return delegate.set(index, element); } @Override public List subList(int fromIndex, int toIndex) { return constrainedList( delegate.subList(fromIndex, toIndex), constraint); } } /** @see Constraints#constrainedList */ static class ConstrainedRandomAccessList extends ConstrainedList implements RandomAccess { ConstrainedRandomAccessList( List delegate, Constraint constraint) { super(delegate, constraint); } } /** * Returns a constrained view of the specified list iterator, using the * specified constraint. Any operations that would add new elements to the * underlying list will be verified by the constraint. * * @param listIterator the iterator for which to return a constrained view * @param constraint the constraint for elements in the list * @return a constrained view of the specified iterator */ private static ListIterator constrainedListIterator( ListIterator listIterator, Constraint constraint) { return new ConstrainedListIterator(listIterator, constraint); } /** @see Constraints#constrainedListIterator */ static class ConstrainedListIterator extends ForwardingListIterator { private final ListIterator delegate; private final Constraint constraint; public ConstrainedListIterator( ListIterator delegate, Constraint constraint) { this.delegate = delegate; this.constraint = constraint; } @Override protected ListIterator delegate() { return delegate; } @Override public void add(E element) { constraint.checkElement(element); delegate.add(element); } @Override public void set(E element) { constraint.checkElement(element); delegate.set(element); } } static Collection constrainedTypePreservingCollection( Collection collection, Constraint constraint) { if (collection instanceof SortedSet) { return constrainedSortedSet((SortedSet) collection, constraint); } else if (collection instanceof Set) { return constrainedSet((Set) collection, constraint); } else if (collection instanceof List) { return constrainedList((List) collection, constraint); } else { return constrainedCollection(collection, constraint); } } /** * Returns a constrained view of the specified multiset, using the specified * constraint. Any operations that add new elements to the multiset will call * the provided constraint. However, this method does not verify that * existing elements satisfy the constraint. * *

The returned multiset is not serializable. * * @param multiset the multiset to constrain * @param constraint the constraint that validates added elements * @return a constrained view of the multiset */ public static Multiset constrainedMultiset( Multiset multiset, Constraint constraint) { return new ConstrainedMultiset(multiset, constraint); } /** @see Constraints#constrainedMultiset */ static class ConstrainedMultiset extends ForwardingMultiset { private Multiset delegate; private final Constraint constraint; public ConstrainedMultiset( Multiset delegate, Constraint constraint) { this.delegate = checkNotNull(delegate); this.constraint = checkNotNull(constraint); } @Override protected Multiset delegate() { return delegate; } @Override public boolean add(E element) { return standardAdd(element); } @Override public boolean addAll(Collection elements) { return delegate.addAll(checkElements(elements, constraint)); } @Override public int add(E element, int occurrences) { constraint.checkElement(element); return delegate.add(element, occurrences); } @Override public int setCount(E element, int count) { constraint.checkElement(element); return delegate.setCount(element, count); } @Override public boolean setCount(E element, int oldCount, int newCount) { constraint.checkElement(element); return delegate.setCount(element, oldCount, newCount); } } /* * TODO(kevinb): For better performance, avoid making a copy of the elements * by having addAll() call add() repeatedly instead. */ private static Collection checkElements( Collection elements, Constraint constraint) { Collection copy = Lists.newArrayList(elements); for (E element : copy) { constraint.checkElement(element); } return copy; } }