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// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.lib.collect;
import java.util.Iterator;
/**
* A minimal map interface that avoids methods whose implementation tends to force GC churn, or
* otherwise overly constrain implementation freedom.
*
* <p>TODO: Convert to interface once we move to Java 8.
*/
public abstract class CompactImmutableMap<K, V> implements Iterable<K> {
public boolean containsKey(K key) {
return get(key) != null;
}
public abstract V get(K key);
public abstract int size();
public abstract K keyAt(int index);
public abstract V valueAt(int index);
@Override
public Iterator<K> iterator() {
return new ImmutableMapSharedKeysIterator();
}
private class ImmutableMapSharedKeysIterator implements Iterator<K> {
int index = 0;
@Override
public boolean hasNext() {
return index < size();
}
@Override
public K next() {
K key = keyAt(index);
++index;
return key;
}
}
}
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