commons-rdf-api/src/main/java/org/apache/commons/rdf/api/GraphLike.java

/**
 * 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.commons.rdf.api;

import java.util.ConcurrentModificationException;
import java.util.stream.Stream;

/**
 * A "graph-like" interface that contains {@link TripleLike} statements.
 * <p>
 * Extended by {@link Graph} (for {@link Triple}) and {@link Dataset} (for
 * {@link Quad}).
 * <p>
 * Unlike {@link Graph} and {@link Dataset}, this interface can support
 * generalised {@link TripleLike} or {@link QuadLike} statements, but does not
 * imply semantics like {@link #size()} or the requirement of mapping
 * {@link RDFTerm} instances from different implementations.
 * <p>
 * As {@link TripleLike} do not have a specific {@link Object#equals(Object)}
 * semantics, the behaviour of methods like {@link #contains(TripleLike)} and
 * {@link #remove(TripleLike)} is undefined for arguments that are not object
 * identical to previously added or returned {@link TripleLike} statements.
 *
 * @param <T>
 *            A {@link TripleLike} type used by the graph methods, typically
 *            {@link Triple} or {@link Quad}
 *
 * @since 0.3.0-incubating
 * @see Graph
 * @see Dataset
 * @see TripleLike
 */
public interface GraphLike<T extends TripleLike> {

    /**
     * Add a statement.
     *
     * @param statement
     *            The TripleLike statement to add
     */
    void add(T statement);

    /**
     * Check if statement is contained.
     *
     * @param statement
     *            The {@link TripleLike} statement to check
     * @return True if the statement is contained
     */
    boolean contains(T statement);

    /**
     * Add a statement.
     *
     * @param statement
     *            The TripleLike statement to add
     */
    void remove(T statement);

    /**
     * Remove all statements.
     */
    void clear();

    /**
     * Number of statements.
     *
     * @return Number of statements
     */
    long size();

    /**
     * Return a Stream of contained statements.
     *
     * @return A {@link Stream} of {@link TripleLike} statements.
     */
    Stream<? extends T> stream();

    /**
     * Iterate over contained statements.
     *
     * @return An {@link Iterable} of {@link TripleLike} statements.
     * @throws IllegalStateException
     *             if the {@link Iterable} has been reused
     * @throws ConcurrentModificationException
     *             if a concurrency conflict occurs while the Iterator is
     *             active.
     */
    Iterable<T> iterate() throws ConcurrentModificationException, IllegalStateException;

}