com.sun.tools.xjc.reader.gbind.Graph Maven / Gradle / Ivy
The newest version!
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can obtain
* a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
* or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
* Sun designates this particular file as subject to the "Classpath" exception
* as provided by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the License
* Header, with the fields enclosed by brackets [] replaced by your own
* identifying information: "Portions Copyrighted [year]
* [name of copyright owner]"
*
* Contributor(s):
*
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
package com.sun.tools.xjc.reader.gbind;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
* Graph of {@link Element}s.
*
* @author Kohsuke Kawaguchi
*/
public final class Graph implements Iterable {
private final Element source = new SourceNode();
private final Element sink = new SinkNode();
/**
* Strongly connected components of this graph.
*/
private final List ccs = new ArrayList();
/**
* Builds a {@link Graph} from an {@link Expression} tree.
*
* {@link Expression} given to the graph will be modified forever,
* and it will not be able to create another {@link Graph}.
*/
public Graph(Expression body) {
// attach source and sink
Expression whole = new Sequence(new Sequence(source,body),sink);
// build up a graph
whole.buildDAG(ElementSet.EMPTY_SET);
// decompose into strongly connected components.
// the algorithm is standard DFS-based algorithm,
// one illustration of this algorithm is available at
// http://www.personal.kent.edu/~rmuhamma/Algorithms/MyAlgorithms/GraphAlgor/strongComponent.htm
source.assignDfsPostOrder(sink);
source.buildStronglyConnectedComponents(ccs);
// cut-set check
Set visited = new HashSet();
for (ConnectedComponent cc : ccs) {
visited.clear();
if(source.checkCutSet(cc,visited)) {
cc.isRequired = true;
}
}
}
/**
* List up {@link ConnectedComponent}s of this graph in an order.
*/
public Iterator iterator() {
return ccs.iterator();
}
public String toString() {
return ccs.toString();
}
}