code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
  //                / /___/ /_/ / /_/ / / /__/ /|  / /_/ /                 //
  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  Licensed under the Apache License, Version 2.0 (the "License");      //
  //  you may not use this file except in compliance with the License.     //
  //  You may obtain a copy of the License at                              //
  //                                                                       //
  //  http://www.apache.org/licenses/LICENSE-2.0                           //
  //                                                                       //
  //  Unless required by applicable law or agreed to in writing, software  //
  //  distributed under the License is distributed on an "AS IS" BASIS,    //
  //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or      //
  //  implied.  See the License for the specific language governing        //
  //  permissions and limitations under the License.                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  
  package org.logicng.io.graphical;
  
  import java.util.Objects;
  
  /**
   * The style of an edge in a graphical representation of a formula, BDD, or graph.  The style consists of the
   * line type and the color of the edge.
   * @version 2.4.0
   * @since 2.4.0
   */
  public class GraphicalEdgeStyle {
  
      /**
       * A special edge style which does not set any style, so the framework's (dot/Mermaid.js)
       * default theming is applied.
       */
      private static final GraphicalEdgeStyle NO_EDGE_STYLE = new GraphicalEdgeStyle(null, null);
  
      /**
       * The different edge types.
       */
      public enum EdgeType {SOLID, DOTTED, BOLD}
  
      private final EdgeType type;
      private final GraphicalColor color;
  
      /**
       * Private constructor.  Use factory methods to construct an instance.
       * @param type  the edge type
       * @param color the color
       */
      private GraphicalEdgeStyle(final EdgeType type, final GraphicalColor color) {
          this.type = type;
          this.color = color;
      }
  
      /**
       * Returns a special edge style which does not set any style, so the framework's (dot/Mermaid.js)
       * default theming is applied.
       * @return special edge style which does not set any style
       */
      public static GraphicalEdgeStyle noStyle() {
          return NO_EDGE_STYLE;
      }
  
      /**
       * Constructs a new edge style with a given edge type and color.
       * @param type  the edge type
       * @param color the color
       * @return the new edge style
       */
      public static GraphicalEdgeStyle style(final EdgeType type, final GraphicalColor color) {
          if (type == null && color == null) {
              return NO_EDGE_STYLE;
          } else {
              return new GraphicalEdgeStyle(type, color);
          }
      }
  
      /**
       * Constructs a new solid edge style with a color.
       * @param color the color
       * @return the new edge style
       */
      public static GraphicalEdgeStyle solid(final GraphicalColor color) {
          return new GraphicalEdgeStyle(EdgeType.SOLID, color);
      }
  
      /**
       * Constructs a new dotted edge style with a color.
       * @param color the color
       * @return the new edge style
       */
      public static GraphicalEdgeStyle dotted(final GraphicalColor color) {
          return new GraphicalEdgeStyle(EdgeType.DOTTED, color);
      }
  
      /**
       * Constructs a new bold edge style with a color.
       * @param color the color
       * @return the new edge style
       */
      public static GraphicalEdgeStyle bold(final GraphicalColor color) {
          return new GraphicalEdgeStyle(EdgeType.BOLD, color);
      }
  
      /**
       * Returns whether this style has any value set.  If not it is equivalent to {@link GraphicalEdgeStyle#NO_EDGE_STYLE}.
       * @return whether this style has any value set
       */
      public boolean hasStyle() {
          return !this.equals(NO_EDGE_STYLE);
      }
  
      /**
       * Returns the type of this edge style.
       * @return the type of this edge style
       */
      public EdgeType getType() {
          return this.type;
      }
  
      /**
       * Returns the color of this edge style.
       * @return the color of this edge style
       */
      public GraphicalColor getColor() {
          return this.color;
      }
  
      @Override
      public boolean equals(final Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
          final GraphicalEdgeStyle that = (GraphicalEdgeStyle) o;
          return this.type == that.type && Objects.equals(this.color, that.color);
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(this.type, this.color);
      }
  
      @Override
      public String toString() {
          return "GraphicalEdgeStyle{" +
                  "edgeType=" + this.type +
                  ", color=" + this.color +
                  '}';
      }
  }
  