/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.jena.atlas.lib.persistent;
import java.util.stream.Stream;
/**
* A persistent set data structure.
*
* @param <E> the type of element in this set
*/
public interface PersistentSet<E> {
/**
* @return an empty set
*/
static <T> PersistentSet<T> empty() {
return PSet.empty();
}
/**
* @param e an element
* @return a new set with the elements of this set and {@code e}
*/
PersistentSet<E> plus(E e);
/**
* @param e an element
* @return a new set with the elements of this set except {@code e}
*/
PersistentSet<E> minus(E e);
/**
* @param e an element
* @return whether this set contains {@code e}
*/
boolean contains(E e);
/**
* @return a {@link Stream} of the elements in this set
*/
Stream<E> stream();
}