/
RegularImmutableList.java
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/
RegularImmutableList.java
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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.checkElementIndex;
import static java.util.Objects.requireNonNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.annotations.VisibleForTesting;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* Implementation of {@link ImmutableList} backed by a simple array.
*
* @author Kevin Bourrillion
*/
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
class RegularImmutableList<E> extends ImmutableList<E> {
static final ImmutableList<Object> EMPTY = new RegularImmutableList<>(new Object[0], 0);
// The first `size` elements are non-null.
@VisibleForTesting final transient @Nullable Object[] array;
private final transient int size;
RegularImmutableList(@Nullable Object[] array, int size) {
this.array = array;
this.size = size;
}
@Override
public int size() {
return size;
}
@Override
boolean isPartialView() {
return false;
}
@Override
@Nullable
Object[] internalArray() {
return array;
}
@Override
int internalArrayStart() {
return 0;
}
@Override
int internalArrayEnd() {
return size;
}
@Override
int copyIntoArray(@Nullable Object[] dst, int dstOff) {
System.arraycopy(array, 0, dst, dstOff, size);
return dstOff + size;
}
// The fake cast to E is safe because the creation methods only allow E's
@Override
@SuppressWarnings("unchecked")
public E get(int index) {
checkElementIndex(index, size);
// requireNonNull is safe because we guarantee that the first `size` elements are non-null.
return (E) requireNonNull(array[index]);
}
// TODO(lowasser): benchmark optimizations for equals() and see if they're worthwhile
// redeclare to help optimizers with b/310253115
@SuppressWarnings("RedundantOverride")
@Override
@J2ktIncompatible // serialization
@GwtIncompatible // serialization
Object writeReplace() {
return super.writeReplace();
}
}