src/jdk.compiler/share/classes/com/sun/tools/javac/util/GraphUtils.java - platform/libcore - Gitiles

 /*
  * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package com.sun.tools.javac.util;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Properties;

 /** <p><b>This is NOT part of any supported API.
  *  If you write code that depends on this, you do so at your own risk.
  *  This code and its internal interfaces are subject to change or
  *  deletion without notice.</b>
  */
 public class GraphUtils {

     /**
      * Basic interface for defining various dependency kinds.
      */
     public interface DependencyKind { }

     /**
      * Common superinterfaces to all graph nodes.
      */
     public interface Node<D, N extends Node<D, N>> {
         /**
          * visitor method.
          */
         <A> void accept(NodeVisitor<D, N, A> visitor, A arg);
     }

     /**
      * Visitor for graph nodes.
      */
     static abstract class NodeVisitor<D, N extends Node<D, N>, A> {
         /**
          * Visitor action for nodes.
          */
         public abstract void visitNode(N node, A arg);
         /**
          * Visitor action for a dependency between 'from' and 'to' with given kind.
          */
         public abstract void visitDependency(DependencyKind dk, N from, N to, A arg);

         /**
          * Visitor entry point.
          */
         public void visit(Collection<? extends N> nodes, A arg) {
             for (N n : new ArrayList<>(nodes)) {
                 n.accept(this, arg);
             }
         }
     }

     /**
      * Optional interface for nodes supporting dot-based representation.
      */
     public interface DottableNode<D, N extends DottableNode<D, N>> extends Node<D, N> {
         /**
          * Retrieves the set of dot attributes associated with the node.
          */
         Properties nodeAttributes();
         /**
          * Retrieves the set of dot attributes associated with a given dependency.
          */
         Properties dependencyAttributes(N to, DependencyKind dk);
     }

     /**
      * This class is a basic abstract class for representing a node.
      * A node is associated with a given data.
      */
     public static abstract class AbstractNode<D, N extends AbstractNode<D, N>> implements Node<D, N> {
         public final D data;

         public AbstractNode(D data) {
             this.data = data;
         }

         /**
          * Get an array of the dependency kinds supported by this node.
          */
         public abstract DependencyKind[] getSupportedDependencyKinds();

         /**
          * Get all dependencies of a given kind
          */
         public abstract Collection<? extends N> getDependenciesByKind(DependencyKind dk);

         @Override
         public String toString() {
             return data.toString();
         }

         @SuppressWarnings("unchecked")
         public <A> void accept(NodeVisitor<D, N, A> visitor, A arg) {
             visitor.visitNode((N)this, arg);
             for (DependencyKind dk : getSupportedDependencyKinds()) {
                 for (N dep : new ArrayList<>(getDependenciesByKind(dk))) {
                     visitor.visitDependency(dk, (N)this, dep, arg);
                 }
             }
         }
     }

     /**
      * This class specialized Node, by adding elements that are required in order
      * to perform Tarjan computation of strongly connected components.
      */
     public static abstract class TarjanNode<D, N extends TarjanNode<D, N>> extends AbstractNode<D, N>
             implements Comparable<N> {
         int index = -1;
         int lowlink;
         boolean active;

         public TarjanNode(D data) {
             super(data);
         }

         public abstract Iterable<? extends N> getAllDependencies();

         public int compareTo(N o) {
             return (index < o.index) ? -1 : (index == o.index) ? 0 : 1;
         }
     }

     /**
      * Tarjan's algorithm to determine strongly connected components of a
      * directed graph in linear time. Works on TarjanNode.
      */
     public static <D, N extends TarjanNode<D, N>> List<? extends List<? extends N>> tarjan(Iterable<? extends N> nodes) {
         Tarjan<D, N> tarjan = new Tarjan<>();
         return tarjan.findSCC(nodes);
     }
     //where
     private static class Tarjan<D, N extends TarjanNode<D, N>> {

         /** Unique node identifier. */
         int index = 0;

         /** List of SCCs found fso far. */
         ListBuffer<List<N>> sccs = new ListBuffer<>();

         /** Stack of all reacheable nodes from given root. */
         ListBuffer<N> stack = new ListBuffer<>();

         private List<? extends List<? extends N>> findSCC(Iterable<? extends N> nodes) {
             for (N node : nodes) {
                 if (node.index == -1) {
                     findSCC(node);
                 }
             }
             return sccs.toList();
         }

         private void findSCC(N v) {
             visitNode(v);
             for (N n: v.getAllDependencies()) {
                 if (n.index == -1) {
                     //it's the first time we see this node
                     findSCC(n);
                     v.lowlink = Math.min(v.lowlink, n.lowlink);
                 } else if (stack.contains(n)) {
                     //this node is already reachable from current root
                     v.lowlink = Math.min(v.lowlink, n.index);
                 }
             }
             if (v.lowlink == v.index) {
                 //v is the root of a SCC
                 addSCC(v);
             }
         }

         private void visitNode(N n) {
             n.index = index;
             n.lowlink = index;
             index++;
             stack.prepend(n);
             n.active = true;
         }

         private void addSCC(N v) {
             N n;
             ListBuffer<N> cycle = new ListBuffer<>();
             do {
                 n = stack.remove();
                 n.active = false;
                 cycle.add(n);
             } while (n != v);
             sccs.add(cycle.toList());
         }
     }

     /**
      * Debugging: dot representation of a set of connected nodes. The resulting
      * dot representation will use {@code Node.toString} to display node labels
      * and {@code Node.printDependency} to display edge labels. The resulting
      * representation is also customizable with a graph name and a header.
      */
     public static <D, N extends DottableNode<D, N>> String toDot(Collection<? extends N> nodes, String name, String header) {
         StringBuilder buf = new StringBuilder();
         buf.append(String.format("digraph %s {\n", name));
         buf.append(String.format("label = %s;\n", DotVisitor.wrap(header)));
         DotVisitor<D, N> dotVisitor = new DotVisitor<>();
         dotVisitor.visit(nodes, buf);
         buf.append("}\n");
         return buf.toString();
     }

     /**
      * This visitor is used to dump the contents of a set of nodes of type {@link DottableNode}
      * onto a string builder.
      */
     public static class DotVisitor<D, N extends DottableNode<D, N>> extends NodeVisitor<D, N, StringBuilder> {

         @Override
         public void visitDependency(DependencyKind dk, N from, N to, StringBuilder buf) {
             buf.append(String.format("%s -> %s", from.hashCode(), to.hashCode()));
             buf.append(formatProperties(from.dependencyAttributes(to, dk)));
             buf.append('\n');
         }

         @Override
         public void visitNode(N node, StringBuilder buf) {
             buf.append(String.format("%s ", node.hashCode()));
             buf.append(formatProperties(node.nodeAttributes()));
             buf.append('\n');
         }

         protected String formatProperties(Properties p) {
             return p.toString().replaceAll(",", " ")
                 .replaceAll("\\{", "[")
                 .replaceAll("\\}", "]");
         }

         protected static String wrap(String s) {
             String res = "\"" + s + "\"";
             return res.replaceAll("\n", "");
         }
     }
 }
	/*
	* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package com.sun.tools.javac.util;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Properties;

	/** <p><b>This is NOT part of any supported API.
	* If you write code that depends on this, you do so at your own risk.
	* This code and its internal interfaces are subject to change or
	* deletion without notice.</b>
	*/
	public class GraphUtils {

	/**
	* Basic interface for defining various dependency kinds.
	*/
	public interface DependencyKind { }

	/**
	* Common superinterfaces to all graph nodes.
	*/
	public interface Node<D, N extends Node<D, N>> {
	/**
	* visitor method.
	*/
	<A> void accept(NodeVisitor<D, N, A> visitor, A arg);
	}

	/**
	* Visitor for graph nodes.
	*/
	static abstract class NodeVisitor<D, N extends Node<D, N>, A> {
	/**
	* Visitor action for nodes.
	*/
	public abstract void visitNode(N node, A arg);
	/**
	* Visitor action for a dependency between 'from' and 'to' with given kind.
	*/
	public abstract void visitDependency(DependencyKind dk, N from, N to, A arg);

	/**
	* Visitor entry point.
	*/
	public void visit(Collection<? extends N> nodes, A arg) {
	for (N n : new ArrayList<>(nodes)) {
	n.accept(this, arg);
	}
	}
	}

	/**
	* Optional interface for nodes supporting dot-based representation.
	*/
	public interface DottableNode<D, N extends DottableNode<D, N>> extends Node<D, N> {
	/**
	* Retrieves the set of dot attributes associated with the node.
	*/
	Properties nodeAttributes();
	/**
	* Retrieves the set of dot attributes associated with a given dependency.
	*/
	Properties dependencyAttributes(N to, DependencyKind dk);
	}

	/**
	* This class is a basic abstract class for representing a node.
	* A node is associated with a given data.
	*/
	public static abstract class AbstractNode<D, N extends AbstractNode<D, N>> implements Node<D, N> {
	public final D data;

	public AbstractNode(D data) {
	this.data = data;
	}

	/**
	* Get an array of the dependency kinds supported by this node.
	*/
	public abstract DependencyKind[] getSupportedDependencyKinds();

	/**
	* Get all dependencies of a given kind
	*/
	public abstract Collection<? extends N> getDependenciesByKind(DependencyKind dk);

	@Override
	public String toString() {
	return data.toString();
	}

	@SuppressWarnings("unchecked")
	public <A> void accept(NodeVisitor<D, N, A> visitor, A arg) {
	visitor.visitNode((N)this, arg);
	for (DependencyKind dk : getSupportedDependencyKinds()) {
	for (N dep : new ArrayList<>(getDependenciesByKind(dk))) {
	visitor.visitDependency(dk, (N)this, dep, arg);
	}
	}
	}
	}

	/**
	* This class specialized Node, by adding elements that are required in order
	* to perform Tarjan computation of strongly connected components.
	*/
	public static abstract class TarjanNode<D, N extends TarjanNode<D, N>> extends AbstractNode<D, N>
	implements Comparable<N> {
	int index = -1;
	int lowlink;
	boolean active;

	public TarjanNode(D data) {
	super(data);
	}

	public abstract Iterable<? extends N> getAllDependencies();

	public int compareTo(N o) {
	return (index < o.index) ? -1 : (index == o.index) ? 0 : 1;
	}
	}

	/**
	* Tarjan's algorithm to determine strongly connected components of a
	* directed graph in linear time. Works on TarjanNode.
	*/
	public static <D, N extends TarjanNode<D, N>> List<? extends List<? extends N>> tarjan(Iterable<? extends N> nodes) {
	Tarjan<D, N> tarjan = new Tarjan<>();
	return tarjan.findSCC(nodes);
	}
	//where
	private static class Tarjan<D, N extends TarjanNode<D, N>> {

	/** Unique node identifier. */
	int index = 0;

	/** List of SCCs found fso far. */
	ListBuffer<List<N>> sccs = new ListBuffer<>();

	/** Stack of all reacheable nodes from given root. */
	ListBuffer<N> stack = new ListBuffer<>();

	private List<? extends List<? extends N>> findSCC(Iterable<? extends N> nodes) {
	for (N node : nodes) {
	if (node.index == -1) {
	findSCC(node);
	}
	}
	return sccs.toList();
	}

	private void findSCC(N v) {
	visitNode(v);
	for (N n: v.getAllDependencies()) {
	if (n.index == -1) {
	//it's the first time we see this node
	findSCC(n);
	v.lowlink = Math.min(v.lowlink, n.lowlink);
	} else if (stack.contains(n)) {
	//this node is already reachable from current root
	v.lowlink = Math.min(v.lowlink, n.index);
	}
	}
	if (v.lowlink == v.index) {
	//v is the root of a SCC
	addSCC(v);
	}
	}

	private void visitNode(N n) {
	n.index = index;
	n.lowlink = index;
	index++;
	stack.prepend(n);
	n.active = true;
	}

	private void addSCC(N v) {
	N n;
	ListBuffer<N> cycle = new ListBuffer<>();
	do {
	n = stack.remove();
	n.active = false;
	cycle.add(n);
	} while (n != v);
	sccs.add(cycle.toList());
	}
	}

	/**
	* Debugging: dot representation of a set of connected nodes. The resulting
	* dot representation will use {@code Node.toString} to display node labels
	* and {@code Node.printDependency} to display edge labels. The resulting
	* representation is also customizable with a graph name and a header.
	*/
	public static <D, N extends DottableNode<D, N>> String toDot(Collection<? extends N> nodes, String name, String header) {
	StringBuilder buf = new StringBuilder();
	buf.append(String.format("digraph %s {\n", name));
	buf.append(String.format("label = %s;\n", DotVisitor.wrap(header)));
	DotVisitor<D, N> dotVisitor = new DotVisitor<>();
	dotVisitor.visit(nodes, buf);
	buf.append("}\n");
	return buf.toString();
	}

	/**
	* This visitor is used to dump the contents of a set of nodes of type {@link DottableNode}
	* onto a string builder.
	*/
	public static class DotVisitor<D, N extends DottableNode<D, N>> extends NodeVisitor<D, N, StringBuilder> {

	@Override
	public void visitDependency(DependencyKind dk, N from, N to, StringBuilder buf) {
	buf.append(String.format("%s -> %s", from.hashCode(), to.hashCode()));
	buf.append(formatProperties(from.dependencyAttributes(to, dk)));
	buf.append('\n');
	}

	@Override
	public void visitNode(N node, StringBuilder buf) {
	buf.append(String.format("%s ", node.hashCode()));
	buf.append(formatProperties(node.nodeAttributes()));
	buf.append('\n');
	}

	protected String formatProperties(Properties p) {
	return p.toString().replaceAll(",", " ")
	.replaceAll("\\{", "[")
	.replaceAll("\\}", "]");
	}

	protected static String wrap(String s) {
	String res = "\"" + s + "\"";
	return res.replaceAll("\n", "");
	}
	}
	}