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      1 /*
      2  * Copyright (C) 2009 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.collect;
     18 
     19 import com.google.common.annotations.GwtCompatible;
     20 import com.google.common.base.Preconditions;
     21 
     22 import javax.annotation.Nullable;
     23 
     24 /**
     25  * Implementation of {@link ImmutableList} with one or more elements.
     26  *
     27  * @author Kevin Bourrillion
     28  */
     29 @GwtCompatible(serializable = true, emulated = true)
     30 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
     31 class RegularImmutableList<E> extends ImmutableList<E> {
     32   private final transient int offset;
     33   private final transient int size;
     34   private final transient Object[] array;
     35 
     36   RegularImmutableList(Object[] array, int offset, int size) {
     37     this.offset = offset;
     38     this.size = size;
     39     this.array = array;
     40   }
     41 
     42   RegularImmutableList(Object[] array) {
     43     this(array, 0, array.length);
     44   }
     45 
     46   @Override
     47   public int size() {
     48     return size;
     49   }
     50 
     51   @Override boolean isPartialView() {
     52     return size != array.length;
     53   }
     54 
     55   @Override
     56   int copyIntoArray(Object[] dst, int dstOff) {
     57     System.arraycopy(array, offset, dst, dstOff, size);
     58     return dstOff + size;
     59   }
     60 
     61   // The fake cast to E is safe because the creation methods only allow E's
     62   @Override
     63   @SuppressWarnings("unchecked")
     64   public E get(int index) {
     65     Preconditions.checkElementIndex(index, size);
     66     return (E) array[index + offset];
     67   }
     68 
     69   @Override
     70   public int indexOf(@Nullable Object object) {
     71     if (object == null) {
     72       return -1;
     73     }
     74     for (int i = 0; i < size; i++) {
     75       if (array[offset + i].equals(object)) {
     76         return i;
     77       }
     78     }
     79     return -1;
     80   }
     81 
     82   @Override
     83   public int lastIndexOf(@Nullable Object object) {
     84     if (object == null) {
     85       return -1;
     86     }
     87     for (int i = size - 1; i >= 0; i--) {
     88       if (array[offset + i].equals(object)) {
     89         return i;
     90       }
     91     }
     92     return -1;
     93   }
     94 
     95   @Override
     96   ImmutableList<E> subListUnchecked(int fromIndex, int toIndex) {
     97     return new RegularImmutableList<E>(
     98         array, offset + fromIndex, toIndex - fromIndex);
     99   }
    100 
    101   @SuppressWarnings("unchecked")
    102   @Override
    103   public UnmodifiableListIterator<E> listIterator(int index) {
    104     // for performance
    105     // The fake cast to E is safe because the creation methods only allow E's
    106     return (UnmodifiableListIterator<E>)
    107         Iterators.forArray(array, offset, size, index);
    108   }
    109 
    110   // TODO(user): benchmark optimizations for equals() and see if they're worthwhile
    111 }
    112