運算符的通用值和類型比較器

Question

我有一個基於預定義條件（OperatorType和比較值）的業務邏輯，驗證它是真或假。這裏的問題是值是「鍵入」，並與運算符（大/小/等）等。

如果ValueType是整數，那麼值和比較值需要先轉換爲Integer，然後再根據OperatorType做比較。

我想知道如果我能有一個通用功能，傳球CompareValue，Value，ValueType，OperatorType並返回真/假。

using System; 
using System.Collections.Generic; 

namespace Test 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      var compare1 = 3; 
      var foo1 = new Foo { Value = "2", OperatorType = OperatorTypes.GreaterOrEqual, ValueType = ValueTypes.Long }; 
      //compare compare1 and foo1.Value, output should be false (2 < 3) 

      var compare2 = true; 
      var foo2 = new Foo { Value = "True", OperatorType = OperatorTypes.Equal, ValueType = ValueTypes.Bool }; 
      //compare compare2 and foo2.Value, output should be true (true = true) 

      var compare3 = DateTime.Parse("2013-03-19 15:00"); 
      var foo3 = new Foo { Value = "2013-03-19 16:00", OperatorType = OperatorTypes.Less, ValueType = ValueTypes.Date }; 
      //compare compare3 and foo3.Value, output should be false (2013-03-19 16:00 < 2013-03-19 15:00) 
     } 
    } 

    public enum OperatorTypes : uint 
    { 
     Equal = 1, 
     Greater = 2, 
     GreaterOrEqual = 3, 
     Less = 4, 
     LessOrEqual = 5 
    } 

    public enum ValueTypes : uint 
    { 
     None = 0, 
     Integer = 1, 
     Long = 2, 
     Numeric = 3, 
     Date = 4, 
     Text = 5, 
     Bool = 6 
    } 

    class Foo 
    { 
     public string Value { get; set; } 
     public ValueTypes ValueType { get; set; } 
     public OperatorTypes OperatorType { get; set; } 
    } 
} 

Answer 1

事不宜遲，讓你開始：

using System; 
using System.Diagnostics; 
using System.Collections.Generic; 

namespace Test 
{ 
    class Program 
    { 
     public static dynamic CompareVal(Foo logic) 
     { 
      switch(logic.ValueType) 
      { 
       case ValueTypes.Integer: return Convert.ToInt32(logic.Value); 
       case ValueTypes.Long: return Convert.ToInt64(logic.Value); 
       case ValueTypes.Numeric: return Convert.ToDecimal(logic.Value); 
       case ValueTypes.Date: return Convert.ToDateTime(logic.Value); 
       case ValueTypes.Text: return logic.Value; 
       case ValueTypes.Bool: return Convert.ToBoolean(logic.Value); 
      } 
      throw new InvalidProgramException("Unsupported ValueType"); 
     } 

     public static bool Evaluate(dynamic val, Foo logic) 
     { 
      dynamic cmpval = CompareVal(logic); 

      switch(logic.OperatorType) 
      { 
       case OperatorTypes.Equal:   return val == cmpval; 
       case OperatorTypes.Greater:  return val > cmpval; 
       case OperatorTypes.GreaterOrEqual: return val >= cmpval; 
       case OperatorTypes.Less:   return val < cmpval; 
       case OperatorTypes.LessOrEqual: return val <= cmpval; 
      } 

      return false; 
     } 

     static void Main(string[] args) 
     { 
      //compare compare1 and foo1.Value, output should be false (2 < 3) 
      Debug.Assert(false == Evaluate(3, new Foo 
         { 
          Value = "2", 
          OperatorType = OperatorTypes.GreaterOrEqual, 
          ValueType = ValueTypes.Long 
         })); 

      //compare compare2 and foo2.Value, output should be true (true = true) 
      Debug.Assert(true == Evaluate(true, new Foo 
         { 
          Value = "True", 
          OperatorType = OperatorTypes.Equal, 
          ValueType = ValueTypes.Bool 
         })); 

      //compare compare3 and foo3.Value, output should be false (2013-03-19 16:00 < 2013-03-19 15:00) 
      Debug.Assert(false == Evaluate(DateTime.Parse("2013-03-19 15:00"), new Foo 
         { 
          Value = "2013-03-19 16:00", 
          OperatorType = OperatorTypes.Less, 
          ValueType = ValueTypes.Date 
         })); 
     } 
    } 

    public enum OperatorTypes : uint 
    { 
     Equal = 1, 
     Greater = 2, 
     GreaterOrEqual = 3, 
     Less = 4, 
     LessOrEqual = 5 
    } 

    public enum ValueTypes : uint 
    { 
     None = 0, 
     Integer = 1, 
     Long = 2, 
     Numeric = 3, 
     Date = 4, 
     Text = 5, 
     Bool = 6 
    } 

    class Foo 
    { 
     public string Value { get; set; } 
     public ValueTypes ValueType { get; set; } 
     public OperatorTypes OperatorType { get; set; } 
    } 
} 

這可能有很多的改進（更好的類型檢查，CultureInfo的認識和錯誤處理）做的。但是，這是一個開始

Answer 2

class Program 
{ 
    static void Main(string[] args) 
    { 
     Console.WriteLine(Compare<double>("123.1", 125.3, (a, b) => a > b)); 
     Console.WriteLine(Compare<DateTime>("19/03/2013", DateTime.Now, (a, b) => a == b)); 
    } 

    private static bool Compare<T>(string valueAsString, T valueToComapare, Func<T,T,bool> check) 
    { 
     var asObject = (T)Convert.ChangeType(valueAsString, typeof(T)); 

     if (asObject != null) 
     { 
      return check(asObject, valueToComapare); 
     } 

     return false; 
    } 
}