visit/src/main/java/org/apache/commons/graph/visit/DefaultVisitSourceSelector.java

package org.apache.commons.graph.visit;

/*
 * 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.
 */

import static org.apache.commons.graph.utils.Assertions.checkNotNull;
import static org.apache.commons.graph.utils.Assertions.checkState;

import org.apache.commons.graph.Graph;

/**
 * {@link VisitSourceSelector} implementation.
 *
 * @param <V> the Graph vertices type
 * @param <E> the Graph edges type
 * @param <G> the Graph type
 */
final class DefaultVisitSourceSelector<V, E, G extends Graph<V, E>>
    implements VisitSourceSelector<V, E, G>
{

    private final G graph;

    public DefaultVisitSourceSelector( G graph )
    {
        this.graph = graph;
    }

    /**
     * {@inheritDoc}
     */
    public <S extends V> VisitAlgorithmsSelector<V, E, G> from( S source )
    {
        source = checkNotNull( source, "Impossible to visit input graph %s with null source", graph );
        checkState( graph.containsVertex( source ), "Vertex %s does not exist in the Graph", source );
        return new DefaultVisitAlgorithmsSelector<V, E, G>( graph, source );
    }

}