如何用反射创建比较器类？

Question

我想创建一个比较两个对象的比较器类的一般化方式。意味着它将检查两个对象内的字段，属性，对象，对象列表。我创建了将两个对象与其公共属性和字段进行比较的代码。但是想通过比较给定输入对象内的对象（和对象列表）来添加它。

public static class Comparer<T> 
    { 
     /// <summary> 
     /// Comparer method formcomparing two objects 
     /// </summary> 
     /// <param name="x">Object x of type T</param> 
     /// <param name="y">Object y of type T</param> 
     /// <returns>int value 0/1</returns> 
     public static int Compare(T x, T y) 
     { 
      Type type = typeof(T); 

      //Collecting public properties and fields 
      PropertyInfo[] properties = type.GetProperties(); 
      FieldInfo[] fields = type.GetFields(); 

      int compareValue = 0; 

      // Loop for comparing one by one properties values of two objects. 
      foreach (PropertyInfo property in properties) 
      { 
       IComparable valx = property.GetValue(x, null) as IComparable; 
       if (valx == null) 
        continue; 
       object valy = property.GetValue(y, null); 

       compareValue = valx.CompareTo(valy); 

       if (compareValue != 0) 
        return compareValue; 
      } 


      // Loop for comparing one by one fields values of two objects. 
      foreach (FieldInfo field in fields) 
      { 
       IComparable valx = field.GetValue(x) as IComparable; 
       if (valx == null) 
        continue; 
       object valy = field.GetValue(y); 

       compareValue = valx.CompareTo(valy); 
       if (compareValue != 0) 
        return compareValue; 
      } 

      return compareValue; 
     } 

     /// <summary> 
     /// Comparer method for comparing to list objects 
     /// </summary> 
     /// <param name="x">List object of T type</param> 
     /// <param name="y">List object of T type</param> 
     /// <returns>Result of comparision as true/false</returns> 
     public static bool Compare(List<T> x, List<T> y) 
     { 
      // Checking input lists as a null. 
      if (x == null || y == null) 
      { 
       return false; 
      } 

      // Checking input lists count is equal or not. 
      if (x.Count() != y.Count()) 
      { 
       return false; 
      } 

      // Loop that invoke compare method for each of list objects. 
      for (int iCntr = 0; iCntr < x.Count(); iCntr++) 
      { 
       int result = Compare(x[iCntr], y[iCntr]); 
       if (result != 0) 
       { 
        return false; 
       } 
      } 
      return true; 
     } 
} 

你有什么想法来解决问题吗？请回复我，如果你发现任何裁判。

问候， 吉里什

Answer 1

您需要使用递归发现每个属性。

Pseudocode 
public static int Compare(object x, object y) 
{ 
    ... handle if one or both are null 
    ... handle if both same type 
    if (IsArray(x)) 
    { 
     ?? equal also means same order?? 
     for i=0 to min(x.lenght, y.length)-1 { 
      int subcompareresult = Compare(x[i], y[i]) 
      if subcompareresult != 0 
       return subcompareresult // difference found 
     } 

     // elements compared so far are same 
     ... handle different length 
    } else if IsClass(x) 
       foreach subproperty in x.Properties 
     int subcompareresult = Compare(x[subproperty ], y[subproperty ]) 
     if subcompareresult != 0 
      return subcompareresult // difference found 
      else 
     ... handle value compare 

请注意对数组和类中的子项进行比较的递归调用。

您可以看看SharpSerializer源代码。 SharpSerializer将对象图序列化为xml或二进制格式。具有递归遍历的部分可以在 SharpSerializer/.../PropertyFactory.cs