/*
    * 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 com.google.common.collect;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import java.io.Serializable;
  import java.util.AbstractCollection;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  
  import javax.annotation.Nullable;
  
  /**
   * GWT emulated version of {@link ImmutableCollection}.
   *
   * @author Jesse Wilson
   */
  @SuppressWarnings("serial") // we're overriding default serialization
  public abstract class ImmutableCollection<E> extends AbstractCollection<E>
      implements Serializable {
  
    static final ImmutableCollection<Object> EMPTY_IMMUTABLE_COLLECTION
        = new ForwardingImmutableCollection<Object>(Collections.emptyList());
  
    ImmutableCollection() {}
  
    public abstract UnmodifiableIterator<E> iterator();
  
    public boolean contains(@Nullable Object object) {
      return object != null && super.contains(object);
    }
  
    public final boolean add(E e) {
      throw new UnsupportedOperationException();
    }
  
    public final boolean remove(Object object) {
      throw new UnsupportedOperationException();
    }
  
    public final boolean addAll(Collection<? extends E> newElements) {
      throw new UnsupportedOperationException();
    }
  
    public final boolean removeAll(Collection<?> oldElements) {
      throw new UnsupportedOperationException();
    }
  
    public final boolean retainAll(Collection<?> elementsToKeep) {
      throw new UnsupportedOperationException();
    }
  
    public final void clear() {
      throw new UnsupportedOperationException();
    }
  
    private transient ImmutableList<E> asList;
  
    public ImmutableList<E> asList() {
      ImmutableList<E> list = asList;
      return (list == null) ? (asList = createAsList()) : list;
    }
  
    ImmutableList<E> createAsList() {
      switch (size()) {
        case 0:
          return ImmutableList.of();
        case 1:
          return ImmutableList.of(iterator().next());
        default:
          return new RegularImmutableAsList<E>(this, toArray());
      }
    }
    static <E> ImmutableCollection<E> unsafeDelegate(Collection<E> delegate) {
      return new ForwardingImmutableCollection<E>(delegate);
    }
  
    boolean isPartialView() {
      return false;
    }
  
    /**
     * GWT emulated version of {@link ImmutableCollection.Builder}.
    */
   public abstract static class Builder<E> {
 
     Builder() {}
 
     public abstract Builder<E> add(E element);
 
     public Builder<E> add(E... elements) {
       checkNotNull(elements); // for GWT
       for (E element : elements) {
         add(checkNotNull(element));
       }
       return this;
     }
 
     public Builder<E> addAll(Iterable<? extends E> elements) {
       checkNotNull(elements); // for GWT
       for (E element : elements) {
         add(checkNotNull(element));
       }
       return this;
     }
 
     public Builder<E> addAll(Iterator<? extends E> elements) {
       checkNotNull(elements); // for GWT
       while (elements.hasNext()) {
         add(checkNotNull(elements.next()));
       }
       return this;
     }
 
     public abstract ImmutableCollection<E> build();
   }
 }