/*
 * Copyright (c) 2002 - 2012 IBM Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 */
package com.ibm.wala.cast.js.callgraph.fieldbased.flowgraph.vertices;

/**
 * The unknown vertex is used to model complicated data flow. For instance, thrown exceptions flow
 * into Unknown, and catch blocks read their values from it.
 *
 * @author mschaefer
 */
public class UnknownVertex extends Vertex {
  public static final UnknownVertex INSTANCE = new UnknownVertex();

  private UnknownVertex() {}

  @Override
  public <T> T accept(VertexVisitor<T> visitor) {
    return visitor.visitUnknownVertex(this);
  }

  @Override
  public String toString() {
    return "Unknown";
  }
}
