gt:       Object[] array = new Object[valueCount];
context: /*
   * Copyright (C) 2009 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 com.google.common.collect;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.annotations.Beta;
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.annotations.GwtIncompatible;
  import com.google.common.base.Function;
  
  import java.io.IOException;
  import java.io.InvalidObjectException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.TreeMap;
  
  import javax.annotation.Nullable;
  
  /**
   * An immutable {@link SetMultimap} with reliable user-specified key and value
   * iteration order. Does not permit null keys or values.
   *
   * <p>Unlike {@link Multimaps#unmodifiableSetMultimap(SetMultimap)}, which is
   * a <i>view</i> of a separate multimap which can still change, an instance of
   * {@code ImmutableSetMultimap} contains its own data and will <i>never</i>
   * change. {@code ImmutableSetMultimap} is convenient for
   * {@code public static final} multimaps ("constant multimaps") and also lets
   * you easily make a "defensive copy" of a multimap provided to your class by
   * a caller.
   *
   * <p><b>Note:</b> Although this class is not final, it cannot be subclassed as
   * it has no public or protected constructors. Thus, instances of this class
   * are guaranteed to be immutable.
   *
   * <p>See the Guava User Guide article on <a href=
   * "http://code.google.com/p/guava-libraries/wiki/ImmutableCollectionsExplained">
   * immutable collections</a>.
   *
   * @author Mike Ward
   * @since 2.0 (imported from Google Collections Library)
   */
  @GwtCompatible(serializable = true, emulated = true)
  public class ImmutableSetMultimap<K, V>
      extends ImmutableMultimap<K, V>
      implements SetMultimap<K, V> {
  
    /** Returns the empty multimap. */
    // Casting is safe because the multimap will never hold any elements.
    @SuppressWarnings("unchecked")
    public static <K, V> ImmutableSetMultimap<K, V> of() {
      return (ImmutableSetMultimap<K, V>) EmptyImmutableSetMultimap.INSTANCE;
    }
  
    /**
     * Returns an immutable multimap containing a single entry.
     */
    public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1) {
      ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
      builder.put(k1, v1);
      return builder.build();
    }
  
    /**
     * Returns an immutable multimap containing the given entries, in order.
     * Repeated occurrences of an entry (according to {@link Object#equals}) after
     * the first are ignored.
     */
    public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {
      ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
      builder.put(k1, v1);
      builder.put(k2, v2);
      return builder.build();
    }
  
    /**
     * Returns an immutable multimap containing the given entries, in order.
     * Repeated occurrences of an entry (according to {@link Object#equals}) after
     * the first are ignored.
     */
    public static <K, V> ImmutableSetMultimap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3) {
      ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
      builder.put(k1, v1);
      builder.put(k2, v2);
      builder.put(k3, v3);
      return builder.build();
    }
  
    /**
     * Returns an immutable multimap containing the given entries, in order.
     * Repeated occurrences of an entry (according to {@link Object#equals}) after
     * the first are ignored.
     */
    public static <K, V> ImmutableSetMultimap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
      ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
      builder.put(k1, v1);
      builder.put(k2, v2);
      builder.put(k3, v3);
      builder.put(k4, v4);
      return builder.build();
    }
  
    /**
     * Returns an immutable multimap containing the given entries, in order.
     * Repeated occurrences of an entry (according to {@link Object#equals}) after
     * the first are ignored.
     */
    public static <K, V> ImmutableSetMultimap<K, V> of(
        K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
      ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
      builder.put(k1, v1);
      builder.put(k2, v2);
      builder.put(k3, v3);
      builder.put(k4, v4);
      builder.put(k5, v5);
      return builder.build();
    }
  
    // looking for of() with > 5 entries? Use the builder instead.
  
    /**
     * Returns a new {@link Builder}.
     */
    public static <K, V> Builder<K, V> builder() {
      return new Builder<K, V>();
    }
  
    /**
     * Multimap for {@link ImmutableSetMultimap.Builder} that maintains key
     * and value orderings and performs better than {@link LinkedHashMultimap}.
     */
    private static class BuilderMultimap<K, V> extends AbstractMultimap<K, V> {
      BuilderMultimap() {
        super(new LinkedHashMap<K, Collection<V>>());
      }
      @Override Collection<V> createCollection() {
        return Sets.newLinkedHashSet();
      }
      private static final long serialVersionUID = 0;
    }
  
    /**
     * Multimap for {@link ImmutableSetMultimap.Builder} that sorts keys and
     * maintains value orderings.
     */
    private static class SortedKeyBuilderMultimap<K, V>
        extends AbstractMultimap<K, V> {
      SortedKeyBuilderMultimap(
          Comparator<? super K> keyComparator, Multimap<K, V> multimap) {
        super(new TreeMap<K, Collection<V>>(keyComparator));
        putAll(multimap);
      }
      @Override Collection<V> createCollection() {
        return Sets.newLinkedHashSet();
      }
      private static final long serialVersionUID = 0;
    }
  
    /**
     * A builder for creating immutable {@code SetMultimap} instances, especially
     * {@code public static final} multimaps ("constant multimaps"). Example:
     * <pre>   {@code
     *
     *   static final Multimap<String, Integer> STRING_TO_INTEGER_MULTIMAP =
     *       new ImmutableSetMultimap.Builder<String, Integer>()
     *           .put("one", 1)
     *           .putAll("several", 1, 2, 3)
     *           .putAll("many", 1, 2, 3, 4, 5)
     *           .build();}</pre>
     *
     * Builder instances can be reused; it is safe to call {@link #build} multiple
     * times to build multiple multimaps in series. Each multimap contains the
     * key-value mappings in the previously created multimaps.
     *
     * @since 2.0 (imported from Google Collections Library)
     */
    public static final class Builder<K, V>
        extends ImmutableMultimap.Builder<K, V> {
      /**
       * Creates a new builder. The returned builder is equivalent to the builder
       * generated by {@link ImmutableSetMultimap#builder}.
       */
      public Builder() {
        builderMultimap = new BuilderMultimap<K, V>();
      }
  
      /**
       * Adds a key-value mapping to the built multimap if it is not already
       * present.
       */
      @Override public Builder<K, V> put(K key, V value) {
        builderMultimap.put(checkNotNull(key), checkNotNull(value));
        return this;
      }
  
      /**
       * Adds an entry to the built multimap if it is not already present.
       *
       * @since 11.0
       */
      @Override public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
        builderMultimap.put(
            checkNotNull(entry.getKey()), checkNotNull(entry.getValue()));
        return this;
      }
  
      @Override public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
        Collection<V> collection = builderMultimap.get(checkNotNull(key));
        for (V value : values) {
          collection.add(checkNotNull(value));
        }
        return this;
      }
  
      @Override public Builder<K, V> putAll(K key, V... values) {
        return putAll(key, Arrays.asList(values));
      }
  
      @Override public Builder<K, V> putAll(
          Multimap<? extends K, ? extends V> multimap) {
        for (Entry<? extends K, ? extends Collection<? extends V>> entry
            : multimap.asMap().entrySet()) {
          putAll(entry.getKey(), entry.getValue());
        }
        return this;
      }
  
      /**
       * {@inheritDoc}
       *
       * @since 8.0
       */
      @Beta @Override
      public Builder<K, V> orderKeysBy(Comparator<? super K> keyComparator) {
        this.keyComparator = checkNotNull(keyComparator);
        return this;
      }
  
      /**
       * Specifies the ordering of the generated multimap's values for each key.
       *
       * <p>If this method is called, the sets returned by the {@code get()}
       * method of the generated multimap and its {@link Multimap#asMap()} view
       * are {@link ImmutableSortedSet} instances. However, serialization does not
       * preserve that property, though it does maintain the key and value
       * ordering.
       *
       * @since 8.0
       */
      // TODO: Make serialization behavior consistent.
      @Beta @Override
      public Builder<K, V> orderValuesBy(Comparator<? super V> valueComparator) {
        super.orderValuesBy(valueComparator);
        return this;
      }
  
      /**
       * Returns a newly-created immutable set multimap.
       */
      @Override public ImmutableSetMultimap<K, V> build() {
        if (keyComparator != null) {
          Multimap<K, V> sortedCopy = new BuilderMultimap<K, V>();
          List<Map.Entry<K, Collection<V>>> entries = Lists.newArrayList(
              builderMultimap.asMap().entrySet());
          Collections.sort(
              entries,
              Ordering.from(keyComparator).onResultOf(new Function<Entry<K, Collection<V>>, K>() {
                @Override
                public K apply(Entry<K, Collection<V>> entry) {
                  return entry.getKey();
                }
              }));
          for (Map.Entry<K, Collection<V>> entry : entries) {
            sortedCopy.putAll(entry.getKey(), entry.getValue());
          }
          builderMultimap = sortedCopy;
        }
        return copyOf(builderMultimap, valueComparator);
      }
    }
  
    /**
     * Returns an immutable set multimap containing the same mappings as
     * {@code multimap}. The generated multimap's key and value orderings
     * correspond to the iteration ordering of the {@code multimap.asMap()} view.
     * Repeated occurrences of an entry in the multimap after the first are
     * ignored.
     *
     * <p>Despite the method name, this method attempts to avoid actually copying
     * the data when it is safe to do so. The exact circumstances under which a
     * copy will or will not be performed are undocumented and subject to change.
     *
     * @throws NullPointerException if any key or value in {@code multimap} is
     *     null
     */
    public static <K, V> ImmutableSetMultimap<K, V> copyOf(
        Multimap<? extends K, ? extends V> multimap) {
      return copyOf(multimap, null);
    }
  
    private static <K, V> ImmutableSetMultimap<K, V> copyOf(
        Multimap<? extends K, ? extends V> multimap,
        Comparator<? super V> valueComparator) {
      checkNotNull(multimap); // eager for GWT
      if (multimap.isEmpty() && valueComparator == null) {
        return of();
      }
  
      if (multimap instanceof ImmutableSetMultimap) {
        @SuppressWarnings("unchecked") // safe since multimap is not writable
        ImmutableSetMultimap<K, V> kvMultimap
            = (ImmutableSetMultimap<K, V>) multimap;
        if (!kvMultimap.isPartialView()) {
          return kvMultimap;
        }
      }
  
      ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
      int size = 0;
  
      for (Entry<? extends K, ? extends Collection<? extends V>> entry
          : multimap.asMap().entrySet()) {
        K key = entry.getKey();
        Collection<? extends V> values = entry.getValue();
        ImmutableSet<V> set = (valueComparator == null)
            ? ImmutableSet.copyOf(values)
            : ImmutableSortedSet.copyOf(valueComparator, values);
        if (!set.isEmpty()) {
          builder.put(key, set);
          size += set.size();
        }
      }
  
      return new ImmutableSetMultimap<K, V>(
          builder.build(), size, valueComparator);
    }
  
    // Returned by get() when values are sorted and a missing key is provided.
    private final transient ImmutableSortedSet<V> emptySet;
  
    ImmutableSetMultimap(ImmutableMap<K, ImmutableSet<V>> map, int size,
        @Nullable Comparator<? super V> valueComparator) {
      super(map, size);
      this.emptySet = (valueComparator == null)
          ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
    }
  
    // views
  
    /**
     * Returns an immutable set of the values for the given key.  If no mappings
     * in the multimap have the provided key, an empty immutable set is returned.
     * The values are in the same order as the parameters used to build this
     * multimap.
     */
    @Override public ImmutableSet<V> get(@Nullable K key) {
      // This cast is safe as its type is known in constructor.
      ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
      if (set != null) {
        return set;
      } else if (emptySet != null) {
        return emptySet;
      } else {
        return ImmutableSet.<V>of();
      }
    }
  
    private transient ImmutableSetMultimap<V, K> inverse;
  
    /**
     * {@inheritDoc}
     *
     * <p>Because an inverse of a set multimap cannot contain multiple pairs with
     * the same key and value, this method returns an {@code ImmutableSetMultimap}
     * rather than the {@code ImmutableMultimap} specified in the {@code
     * ImmutableMultimap} class.
     *
     * @since 11.0
     */
    @Beta
    public ImmutableSetMultimap<V, K> inverse() {
      ImmutableSetMultimap<V, K> result = inverse;
      return (result == null) ? (inverse = invert()) : result;
    }
  
    private ImmutableSetMultimap<V, K> invert() {
      Builder<V, K> builder = builder();
      for (Entry<K, V> entry : entries()) {
        builder.put(entry.getValue(), entry.getKey());
      }
      ImmutableSetMultimap<V, K> invertedMultimap = builder.build();
      invertedMultimap.inverse = this;
      return invertedMultimap;
    }
  
    /**
     * Guaranteed to throw an exception and leave the multimap unmodified.
     *
     * @throws UnsupportedOperationException always
     */
    @Override public ImmutableSet<V> removeAll(Object key) {
      throw new UnsupportedOperationException();
    }
  
    /**
     * Guaranteed to throw an exception and leave the multimap unmodified.
     *
     * @throws UnsupportedOperationException always
     */
    @Override public ImmutableSet<V> replaceValues(
        K key, Iterable<? extends V> values) {
      throw new UnsupportedOperationException();
    }
  
    private transient ImmutableSet<Entry<K, V>> entries;
  
    /**
     * Returns an immutable collection of all key-value pairs in the multimap.
     * Its iterator traverses the values for the first key, the values for the
     * second key, and so on.
     */
    // TODO(kevinb): Fix this so that two copies of the entries are not created.
    @Override public ImmutableSet<Entry<K, V>> entries() {
      ImmutableSet<Entry<K, V>> result = entries;
      return (result == null)
          ? (entries = ImmutableSet.copyOf(super.entries()))
          : result;
    }
  
    /**
     * @serialData number of distinct keys, and then for each distinct key: the
     *     key, the number of values for that key, and the key's values
     */
    @GwtIncompatible("java.io.ObjectOutputStream")
    private void writeObject(ObjectOutputStream stream) throws IOException {
      stream.defaultWriteObject();
      Serialization.writeMultimap(this, stream);
    }
  
    @GwtIncompatible("java.io.ObjectInputStream")
    private void readObject(ObjectInputStream stream)
        throws IOException, ClassNotFoundException {
      stream.defaultReadObject();
      int keyCount = stream.readInt();
      if (keyCount < 0) {
        throw new InvalidObjectException("Invalid key count " + keyCount);
      }
      ImmutableMap.Builder<Object, ImmutableSet<Object>> builder
          = ImmutableMap.builder();
      int tmpSize = 0;
  
      for (int i = 0; i < keyCount; i++) {
        Object key = stream.readObject();
        int valueCount = stream.readInt();
        if (valueCount <= 0) {
          throw new InvalidObjectException("Invalid value count " + valueCount);
        }
  
  