/*
 * (C) Copyright 2016 Pantheon Technologies, s.r.o. and others.
 *
 * 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 org.opendaylight.yangtools.triemap;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.AbstractSet;
import java.util.Collection;

/**
 * Abstract base class for key set views of a TrieMap.
 *
 * @author Robert Varga
 *
 * @param <K> the type of keys
 */
abstract class AbstractKeySet<K> extends AbstractSet<K> {
    private final TrieMap<K, ?> map;

    AbstractKeySet(final TrieMap<K, ?> map) {
        this.map = checkNotNull(map);
    }

    final TrieMap<K, ?> map() {
        return map;
    }

    @Override
    public final boolean add(final K e) {
        throw new UnsupportedOperationException();
    }

    @Override
    public final boolean addAll(final Collection<? extends K> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public final boolean contains(final Object o) {
        return map.containsKey(o);
    }

    @Override
    public final boolean isEmpty() {
        return map.isEmpty();
    }

    @Override
    public final int size() {
        return map.size();
    }
}