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.formulas.printer;
  
  import org.logicng.formulas.CType;
  
  /**
   * The default string representation for formulas.
   * @version 1.0
   * @since 1.0
   */
  public class DefaultStringRepresentation extends FormulaStringRepresentation {
  
      @Override
      protected String falsum() {
          return "$false";
      }
  
      @Override
      protected String verum() {
          return "$true";
      }
  
      @Override
      protected String negation() {
          return "~";
      }
  
      @Override
      protected String implication() {
          return " => ";
      }
  
      @Override
      protected String equivalence() {
          return " <=> ";
      }
  
      @Override
      protected String and() {
          return " & ";
      }
  
      @Override
      protected String or() {
          return " | ";
      }
  
      @Override
      protected String pbComparator(final CType comparator) {
          switch (comparator) {
              case EQ:
                  return " = ";
              case LE:
                  return " <= ";
              case LT:
                  return " < ";
              case GE:
                  return " >= ";
              case GT:
                  return " > ";
              default:
                  throw new IllegalArgumentException("Unknown pseudo-Boolean comparison: " + comparator);
          }
      }
  
      @Override
      protected String pbMul() {
          return "*";
      }
  
      @Override
      protected String pbAdd() {
          return " + ";
      }
  
      @Override
      protected String lbr() {
          return "(";
      }
  
      @Override
      protected String rbr() {
          return ")";
      }
  
      @Override
      public String toString() {
          return this.getClass().getSimpleName();
      }
  }
  