CSharp: Interpreter Pattern in donet core 3

 

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/// <summary>    ///  解释器模式 Interpreter Pattern    ///  geovindu, Geovin Du edit    /// </summary>    interface Employee    {        /// <summary>        /// 是否解释        /// </summary>        /// <param name="context">输入背景</param>        /// <returns></returns>        bool Interpret(Context context);    }    /// <summary>    /// IndividualEmployee class    /// 单独雇员    /// </summary>    class IndividualEmployee : Employee    {        /// <summary>        /// 年经验        /// </summary>        private int yearOfExperience;        /// <summary>        /// 当前等级        /// </summary>        private string currentGrade;        /// <summary>        ///        /// </summary>        /// <param name="experience">经验年数</param>        /// <param name="grade">等级</param>        public IndividualEmployee(int experience, string grade)        {            this.yearOfExperience = experience;            this.currentGrade = grade;        }        /// <summary>        /// 是否解释        /// </summary>        /// <param name="context">输入背景</param>        /// <returns></returns>        public bool Interpret(Context context)        {            if (this.yearOfExperience >= context.GetYearofExperience()                 && context.GetPermissibleGrades().Contains(this.currentGrade))            {                return true;            }            return false;        }    }    /// <summary>    /// OrExpression class    /// 或经验    /// </summary>    class OrExpression : Employee    {        private Employee emp1;        private Employee emp2;        /// <summary>        ///        /// </summary>        /// <param name="emp1">输入雇员</param>        /// <param name="emp2">输入雇员</param>        public OrExpression(Employee emp1, Employee emp2)        {            this.emp1 = emp1;            this.emp2 = emp2;        }        /// <summary>        /// 是否解释        /// </summary>        /// <param name="context">输入背景</param>        /// <returns></returns>        public bool Interpret(Context context)        {            return emp1.Interpret(context) || emp2.Interpret(context);        }    }    /// <summary>    /// AndExpression class    /// 添加经验    /// </summary>    class AndExpression : Employee    {        private Employee emp1;        private Employee emp2;          /// <summary>        /// 添加经验        /// </summary>        /// <param name="emp1">输入雇员</param>        /// <param name="emp2">输入雇员</param>        public AndExpression(Employee emp1, Employee emp2)        {            this.emp1 = emp1;            this.emp2 = emp2;        }        /// <summary>        /// 是否解释        /// </summary>        /// <param name="context">输入背景</param>        /// <returns></returns>        public bool Interpret(Context context)        {            return emp1.Interpret(context) && emp2.Interpret(context);        }    }    /// <summary>    /// NotExpression class    /// 没有经验    /// </summary>    class NotExpression : Employee    {        private Employee emp;          /// <summary>        /// 构造        /// </summary>        /// <param name="expr">输入雇员</param>        public NotExpression(Employee expr)        {            this.emp = expr;        }        /// <summary>        /// 是否解释        /// </summary>        /// <param name="context">输入背景</param>        /// <returns></returns>        public bool Interpret(Context context)        {            return !emp.Interpret(context);        }    }    /// <summary>    /// Context class    ///背景    /// </summary>    class Context    {        /// <summary>        /// 晋升所需的经验        /// </summary>        private int experienceReqdForPromotion;        /// <summary>        /// 允许成绩列表        /// </summary>        private List<string> allowedGrades;        /// <summary>        ///        /// </summary>        /// <param name="experience">经验年数</param>        /// <param name="allowedGrades">允许成绩列表</param>        public Context(int experience, List<string> allowedGrades)        {            this.experienceReqdForPromotion = experience;            this.allowedGrades = new List<string>();            foreach (string grade in allowedGrades)            {                this.allowedGrades.Add(grade);            }        }        /// <summary>        /// 赋值经验年数        /// </summary>        /// <returns></returns>        public int GetYearofExperience()        {            return experienceReqdForPromotion;        }        /// <summary>        /// 赋值允许的成绩        /// </summary>        /// <returns></returns>        public List<string> GetPermissibleGrades()        {            return allowedGrades;        }    }    /// <summary>    /// EmployeeBuilder class    /// </summary>    class EmployeeBuilder    {        // Building the tree        //Complex Rule-1: emp1 and (emp2 or (emp3 or emp4))        /// <summary>        /// 创建规则        /// </summary>        /// <param name="emp1"></param>        /// <param name="emp2"></param>        /// <param name="emp3"></param>        /// <param name="emp4"></param>        /// <returns></returns>        public Employee BuildTreeBasedOnRule1(Employee emp1, Employee emp2, Employee emp3, Employee emp4)        {            // emp3 or emp4            Employee firstPhase = new OrExpression(emp3, emp4);            // emp2 or (emp3 or emp4)            Employee secondPhase = new OrExpression(emp2, firstPhase);            // emp1 and (emp2 or (emp3 or emp4))            Employee finalPhase = new AndExpression(emp1, secondPhase);            return finalPhase;        }        //Complex Rule-2: emp1 or (emp2 and (not emp3 ))          /// <summary>        /// 创建规则        /// </summary>        /// <param name="emp1"></param>        /// <param name="emp2"></param>        /// <param name="emp3"></param>        /// <returns></returns>        public Employee BuildTreeBasedOnRule2(Employee emp1, Employee emp2, Employee emp3)        {            // Not emp3            Employee firstPhase = new NotExpression(emp3);            // emp2 or (not emp3)            Employee secondPhase = new AndExpression(emp2, firstPhase);            // emp1 and (emp2 or (not emp3 ))            Employee finalPhase = new OrExpression(emp1, secondPhase);            return finalPhase;        }    }

　　

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/// <summary>  ///  解释器模式 Interpreter Pattern  ///  geovindu, Geovin Du edit  /// </summary>  public interface IElement  {      int Value { get; }  }  /// <summary>  ///  /// </summary>  public class Integer : IElement  {      public Integer(int value)      {          Value = value;      }        public int Value { get; }  }  /// <summary>  ///  /// </summary>  public class BinaryOperation : IElement  {      public enum Type      {          Addition,          Subtraction      }        public Type MyType;      public IElement Left, Right;        public int Value      {          get          {              switch (MyType)              {                  case Type.Addition:                      return Left.Value + Right.Value;                  case Type.Subtraction:                      return Left.Value - Right.Value;                  default:                      throw new ArgumentOutOfRangeException();              }          }      }  }  /// <summary>  ///  /// </summary>  public class Token  {      public enum Type      {          Integer, Plus, Minus, Lparen, Rparen      }        public Type MyType;      public string Text;        public Token(Type type, string text)      {          MyType = type;          Text = text;      }        public override string ToString()      {          return $"`{Text}`";      }  }  /// <summary>  ///  /// </summary>  public class GevovinDu  {      public static List<Token> Lex(string input)      {          var result = new List<Token>();            for (int i = 0; i < input.Length; i++)          {              switch (input[i])              {                  case '+':                      result.Add(new Token(Token.Type.Plus, "+"));                      break;                  case '-':                      result.Add(new Token(Token.Type.Minus, "-"));                      break;                  case '(':                      result.Add(new Token(Token.Type.Lparen, "("));                      break;                  case ')':                      result.Add(new Token(Token.Type.Rparen, ")"));                      break;                  default:                      var sb = new StringBuilder(input[i].ToString());                      for (int j = i + 1; j < input.Length; ++j)                      {                          if (char.IsDigit(input[j]))                          {                              sb.Append(input[j]);                              ++i;                          }                          else                          {                              result.Add(new Token(Token.Type.Integer, sb.ToString()));                              break;                          }                      }                      break;              }          }            return result;      }      /// <summary>      ///      /// </summary>      /// <param name="tokens"></param>      /// <returns></returns>      /// <exception cref="ArgumentOutOfRangeException"></exception>      public  static IElement Parse(IReadOnlyList<Token> tokens)      {          var result = new BinaryOperation();          bool haveLHS = false;          for (int i = 0; i < tokens.Count; i++)          {              var token = tokens[i];                // look at the type of token              switch (token.MyType)              {                  case Token.Type.Integer:                      var integer = new Integer(int.Parse(token.Text));                      if (!haveLHS)                      {                          result.Left = integer;                          haveLHS = true;                      }                      else                      {                          result.Right = integer;                      }                      break;                  case Token.Type.Plus:                      result.MyType = BinaryOperation.Type.Addition;                      break;                  case Token.Type.Minus:                      result.MyType = BinaryOperation.Type.Subtraction;                      break;                  case Token.Type.Lparen:                      int j = i;                      for (; j < tokens.Count; ++j)                          if (tokens[j].MyType == Token.Type.Rparen)                              break; // found it!                                     // process subexpression w/o opening                      var subexpression = tokens.Skip(i + 1).Take(j - i - 1).ToList();                      var element = Parse(subexpression);                      if (!haveLHS)                      {                          result.Left = element;                          haveLHS = true;                      }                      else result.Right = element;                      i = j; // advance                      break;                  default:                      throw new ArgumentOutOfRangeException();              }          }          return result;      }  }

　　

调用：

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//解释器模式 Console.WriteLine("*** 解释器模式 Interpreter Pattern Demonstration-2***\n");   // Minimum Criteria for promoton is: // The year of experience is minimum 10 yrs. and // Employee grade should be either G2 or G3 List<string> allowedGrades = new List<string> { "G2", "G3" }; Context context = new Context(10, allowedGrades); Employee emp1 = new IndividualEmployee(5, "G1"); Employee emp2 = new IndividualEmployee(10, "G2"); Employee emp3 = new IndividualEmployee(15, "G3"); Employee emp4 = new IndividualEmployee(20, "G4");   EmployeeBuilder builder = new EmployeeBuilder();   //Validating the 1st complex rule Console.WriteLine("----- 验证第一个复杂规则.-----"); Console.WriteLine("emp1和emp2、emp3、emp4中的任何一个是否有资格晋升?"     + builder.BuildTreeBasedOnRule1(emp1, emp2, emp3, emp4).Interpret(context)); Console.WriteLine("emp2和emp1、emp3、emp4中的任何一个是否有资格晋升?"     + builder.BuildTreeBasedOnRule1(emp2, emp1, emp3, emp4).Interpret(context)); Console.WriteLine("emp3和emp1、emp2、emp3中的任何一个是否有资格晋升?"     + builder.BuildTreeBasedOnRule1(emp3, emp1, emp2, emp4).Interpret(context)); Console.WriteLine("emp4和emp1、emp2、emp3中的任何一个是否有资格晋升?"     + builder.BuildTreeBasedOnRule1(emp4, emp1, emp2, emp3).Interpret(context));   Console.WriteLine("-----现在验证第二个复杂的规则.-----"); //Validating the 2nd complex rule Console.WriteLine("emp1或(emp2而不是emp3)是否有资格晋升?"     + builder.BuildTreeBasedOnRule2(emp1, emp2, emp3).Interpret(context)); Console.WriteLine("emp2或(emp3但不是emp4)是否有资格晋升?"     + builder.BuildTreeBasedOnRule2(emp2, emp3, emp4).Interpret(context));   Console.WriteLine();   var input = "(13+4)-(12+1)"; var tokens = GevovinDu.Lex(input); Console.WriteLine(string.Join("\t", tokens));   var parsed = GevovinDu.Parse(tokens); Console.WriteLine($"{input} = {parsed.Value}");

　　

输出：

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***?解释器模式 Interpreter Pattern Demonstration-2***   ----- 验证第一个复杂规则.----- emp1和emp2、emp3、emp4中的任何一个是否有资格晋升?False emp2和emp1、emp3、emp4中的任何一个是否有资格晋升?True emp3和emp1、emp2、emp3中的任何一个是否有资格晋升?True emp4和emp1、emp2、emp3中的任何一个是否有资格晋升?False -----现在验证第二个复杂的规则.----- emp1或(emp2而不是emp3)是否有资格晋升?False emp2或(emp3但不是emp4)是否有资格晋升?True   `(`     `13`    `+`     `4`     `)`     `-`     `(`     `12`    `+`     `1`     `)` (13+4)-(12+1) = 4