org.eclipse.osbp.xtext.datainterchange/src/org/eclipse/osbp/xtext/datainterchange/jvmmodel/JoinGraph.java

/*
 *                                                                            
 *  Copyright (c) 2011 - 2018 - Loetz GmbH & Co KG, 69115 Heidelberg, Germany 
 *                                                                            
 *  All rights reserved. This program and the accompanying materials           
 *  are made available under the terms of the Eclipse Public License 2.0        
 *  which accompanies this distribution, and is available at                  
 *  https://www.eclipse.org/legal/epl-2.0/                                 
 *                                 
 *  SPDX-License-Identifier: EPL-2.0                                 
 *                                                                            
 *  Initial contribution:                                                      
 *     Loetz GmbH & Co. KG                              
 * 
 */
package org.eclipse.osbp.xtext.datainterchange.jvmmodel;

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;

/**
 * The Class JoinGraph
 *
 * @param <J> the generic type
 */
public class JoinGraph<J> implements Iterable<J> {
	
    /** The graph that maps nodes and their edges. */
    private final Map<J, Map<J, String>> graph = new HashMap<>();

    /**
     * Adds a node.
     *
     * @param node the node
     * @return true, if successful
     */
    public boolean addNode(J node) {
        if (node == null) {
            throw new NullPointerException("node must not be null.");
        }
        if (graph.containsKey(node)) {
        	return false;
        }
        graph.put(node, new HashMap<J, String>());
        return true;
    }

    /**
     * Adds a join.
     *
     * @param source the source
     * @param destination the destination
     * @param joinName the join name
     */
    public void addJoin (J source, J destination, String joinName) {
        if (source == null || destination == null) {
            throw new NullPointerException("source or destination must not be null.");
        }
        if (!graph.containsKey(source) || !graph.containsKey(destination)) {
            throw new NoSuchElementException("source and destination must be part of graph.");
        }
        graph.get(source).put(destination, joinName);
    }

    /**
     * Removes a join.
     *
     * @param source the source
     * @param destination the destination
     */
    public void removeJoin (J source, J destination) {
        if (source == null || destination == null) {
            throw new NullPointerException("source or destination must not be null.");
        }
        if (!graph.containsKey(source) || !graph.containsKey(destination)) {
            throw new NoSuchElementException("source and destination must be part of graph.");
        }
        graph.get(source).remove(destination);
    }

    /**
     * get all joins outgoing from a node.
     *
     * @param node the node
     * @return the list
     */
    public Map<J, String> joinsFrom(J node) {
        if (node == null) {
            throw new NullPointerException("node must not be null.");
        }
        Map<J, String> joins = graph.get(node);
        if (joins == null) {
            throw new NoSuchElementException("source node doesn't exist.");
        }
        return Collections.unmodifiableMap(joins);
    }

    /* (non-Javadoc)
     * @see java.lang.Iterable#iterator()
     */
    @Override public Iterator<J> iterator() {
        return graph.keySet().iterator();
    }
}