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/*
 * 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 static com.google.common.collect.ObjectArrays.checkElementsNotNull;

import com.google.common.annotations.Beta;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.RandomAccess;
import java.util.stream.Collector;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * GWT emulated version of {@link com.google.common.collect.ImmutableList}. TODO(cpovirk): more doc
 *
 * @author Hayward Chan
 */
@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableList extends ImmutableCollection
    implements List, RandomAccess {
  static final ImmutableList EMPTY =
      new RegularImmutableList(Collections.emptyList());

  ImmutableList() {}

  @Beta
  public static  Collector> toImmutableList() {
    return CollectCollectors.toImmutableList();
  }

  // Casting to any type is safe because the list will never hold any elements.
  @SuppressWarnings("unchecked")
  public static  ImmutableList of() {
    return (ImmutableList) EMPTY;
  }

  public static  ImmutableList of(E element) {
    return new SingletonImmutableList(checkNotNull(element));
  }

  public static  ImmutableList of(E e1, E e2) {
    return new RegularImmutableList(ImmutableList.nullCheckedList(e1, e2));
  }

  public static  ImmutableList of(E e1, E e2, E e3) {
    return new RegularImmutableList(ImmutableList.nullCheckedList(e1, e2, e3));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4) {
    return new RegularImmutableList(ImmutableList.nullCheckedList(e1, e2, e3, e4));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4, E e5) {
    return new RegularImmutableList(ImmutableList.nullCheckedList(e1, e2, e3, e4, e5));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4, E e5, E e6) {
    return new RegularImmutableList(ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4, E e5, E e6, E e7) {
    return new RegularImmutableList(
        ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6, e7));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8) {
    return new RegularImmutableList(
        ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6, e7, e8));
  }

  public static  ImmutableList of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9) {
    return new RegularImmutableList(
        ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6, e7, e8, e9));
  }

  public static  ImmutableList of(
      E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10) {
    return new RegularImmutableList(
        ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6, e7, e8, e9, e10));
  }

  public static  ImmutableList of(
      E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10, E e11) {
    return new RegularImmutableList(
        ImmutableList.nullCheckedList(e1, e2, e3, e4, e5, e6, e7, e8, e9, e10, e11));
  }

  public static  ImmutableList of(
      E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10, E e11, E e12, E... others) {
    final int paramCount = 12;
    Object[] array = new Object[paramCount + others.length];
    arrayCopy(array, 0, e1, e2, e3, e4, e5, e6, e7, e8, e9, e10, e11, e12);
    arrayCopy(array, paramCount, others);
    return new RegularImmutableList(ImmutableList.nullCheckedList(array));
  }

  private static void arrayCopy(Object[] dest, int pos, Object... source) {
    System.arraycopy(source, 0, dest, pos, source.length);
  }

  public static  ImmutableList copyOf(Iterable elements) {
    checkNotNull(elements); // for GWT
    return (elements instanceof Collection)
        ? copyOf((Collection) elements)
        : copyOf(elements.iterator());
  }

  public static  ImmutableList copyOf(Iterator elements) {
    return copyFromCollection(Lists.newArrayList(elements));
  }

  public static  ImmutableList copyOf(Collection elements) {
    if (elements instanceof ImmutableCollection) {
      /*
       * TODO: When given an ImmutableList that's a sublist, copy the referenced
       * portion of the array into a new array to save space?
       */
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableCollection list = (ImmutableCollection) elements;
      return list.asList();
    }
    return copyFromCollection(elements);
  }

  public static  ImmutableList copyOf(E[] elements) {
    checkNotNull(elements); // eager for GWT
    return copyOf(Arrays.asList(elements));
  }

  private static  ImmutableList copyFromCollection(Collection collection) {
    Object[] elements = collection.toArray();
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        return of((E) elements[0]);
      default:
        return new RegularImmutableList(ImmutableList.nullCheckedList(elements));
    }
  }

  // Factory method that skips the null checks.  Used only when the elements
  // are guaranteed to be non-null.
  static  ImmutableList unsafeDelegateList(List list) {
    switch (list.size()) {
      case 0:
        return of();
      case 1:
        return of(list.get(0));
      default:
        @SuppressWarnings("unchecked")
        List castedList = (List) list;
        return new RegularImmutableList(castedList);
    }
  }

  /**
   * Views the array as an immutable list. The array must have only {@code E} elements.
   *
   * 

The array must be internally created. */ @SuppressWarnings("unchecked") // caller is reponsible for getting this right static ImmutableList asImmutableList(Object[] elements) { return unsafeDelegateList((List) Arrays.asList(elements)); } public static > ImmutableList sortedCopyOf( Iterable elements) { Comparable[] array = Iterables.toArray(elements, new Comparable[0]); checkElementsNotNull(array); Arrays.sort(array); return asImmutableList(array); } public static ImmutableList sortedCopyOf( Comparator comparator, Iterable elements) { checkNotNull(comparator); @SuppressWarnings("unchecked") // all supported methods are covariant E[] array = (E[]) Iterables.toArray(elements); checkElementsNotNull(array); Arrays.sort(array, comparator); return asImmutableList(array); } private static List nullCheckedList(Object... array) { for (int i = 0, len = array.length; i < len; i++) { if (array[i] == null) { throw new NullPointerException("at index " + i); } } @SuppressWarnings("unchecked") E[] castedArray = (E[]) array; return Arrays.asList(castedArray); } @Override public int indexOf(@Nullable Object object) { return (object == null) ? -1 : Lists.indexOfImpl(this, object); } @Override public int lastIndexOf(@Nullable Object object) { return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object); } public final boolean addAll(int index, Collection newElements) { throw new UnsupportedOperationException(); } public final E set(int index, E element) { throw new UnsupportedOperationException(); } public final void add(int index, E element) { throw new UnsupportedOperationException(); } public final E remove(int index) { throw new UnsupportedOperationException(); } @Override public UnmodifiableIterator iterator() { return listIterator(); } @Override public ImmutableList subList(int fromIndex, int toIndex) { return unsafeDelegateList(Lists.subListImpl(this, fromIndex, toIndex)); } @Override public UnmodifiableListIterator listIterator() { return listIterator(0); } @Override public UnmodifiableListIterator listIterator(int index) { return new AbstractIndexedListIterator(size(), index) { @Override protected E get(int index) { return ImmutableList.this.get(index); } }; } @Override public ImmutableList asList() { return this; } @Override public boolean equals(@Nullable Object obj) { return Lists.equalsImpl(this, obj); } @Override public int hashCode() { return Lists.hashCodeImpl(this); } public ImmutableList reverse() { List list = Lists.newArrayList(this); Collections.reverse(list); return unsafeDelegateList(list); } public static Builder builder() { return new Builder(); } public static Builder builderWithExpectedSize(int expectedSize) { return new Builder(expectedSize); } public static final class Builder extends ImmutableCollection.Builder { private final ArrayList contents; public Builder() { contents = Lists.newArrayList(); } Builder(int capacity) { contents = Lists.newArrayListWithCapacity(capacity); } @CanIgnoreReturnValue @Override public Builder add(E element) { contents.add(checkNotNull(element)); return this; } @CanIgnoreReturnValue @Override public Builder addAll(Iterable elements) { super.addAll(elements); return this; } @CanIgnoreReturnValue @Override public Builder add(E... elements) { checkNotNull(elements); // for GWT super.add(elements); return this; } @CanIgnoreReturnValue @Override public Builder addAll(Iterator elements) { super.addAll(elements); return this; } @CanIgnoreReturnValue Builder combine(Builder builder) { checkNotNull(builder); contents.addAll(builder.contents); return this; } @Override public ImmutableList build() { return copyOf(contents); } } }