/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.compilers.opt.util;
/**
* This class implements miscellaneous utilities for graphs.
*/
public class GraphUtilities {
/**
* Return an enumeration of the nodes, or a subset of the nodes, in an
* acyclic graph in topological order .
*
* Note: if G is cyclic, results are undefined
*/
public static GraphNodeEnumeration enumerateTopSort(Graph G) {
return enumerateTopSort(G, G.enumerateNodes());
}
public static GraphNodeEnumeration enumerateTopSort(Graph G, GraphNodeEnumeration ie) {
return enumerateTopSortInternal(G, new DFSenumerateByFinish(G, ie));
}
public static GraphNodeEnumeration enumerateTopSort(Graph G, GraphNodeEnumeration ie,
GraphEdgeFilter f) {
return enumerateTopSortInternal(G, new FilteredDFSenumerateByFinish(G, ie, f));
}
private static GraphNodeEnumeration enumerateTopSortInternal(Graph G, GraphNodeEnumeration e) {
final GraphNode[] elts = new GraphNode[G.numberOfNodes()];
int i = 0;
while (e.hasMoreElements()) {
elts[i++] = e.next();
}
final int i1 = i;
return new GraphNodeEnumerator() {
private int top = i1;
public boolean hasMoreElements() {
return top > 0;
}
public GraphNode next() {
return elts[--top];
}
};
}
}