如何将枚举值转换为压缩字符串？

发布于 2025-01-05 16:56:10 字数 660 浏览 0 评论 0原文

我有一个枚举，其定义如下：

[Flags]
public enum MyEnum
{
    None = 0,

    ValueOne                = 1 << 0,
    ValueTwo                = 1 << 1,
    ValueThree              = 1 << 2,
    ValueFour               = 1 << 3,
    ...
    ValueTwoEightyOne           = 1 << 280,
}

我希望能够将用法转换为可能的最短字符串，类似于：

var compressedString = ConvertToCompressedString(MyEnum.ValueOne | MyEnum.ValueThree | MyEnum.ValueFour);

然后在程序的不同部分，我想将compressedString 转换回枚举

var enumValue = ConvertBack(compressedString);

什么是转换具有如此多值的枚举的有效方法？如果有更好的方法来处理此类用例，我很感兴趣。

原文

I have an enum that is defined like:

[Flags]
public enum MyEnum
{
    None = 0,

    ValueOne                = 1 << 0,
    ValueTwo                = 1 << 1,
    ValueThree              = 1 << 2,
    ValueFour               = 1 << 3,
    ...
    ValueTwoEightyOne           = 1 << 280,
}

I would like to be able to convert usage to the shortest string possible, similar to:

var compressedString = ConvertToCompressedString(MyEnum.ValueOne | MyEnum.ValueThree | MyEnum.ValueFour);

And then in a different part of the program, I would like to convert the compressedString back to the enum

var enumValue = ConvertBack(compressedString);

What is an efficient method to convert an enum with so many values? If there is a better way of handling this type of use case, I'm interested.

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随遇而安 2025-01-12 16:56:10

enum 值由内存中的整数字段支持。那么除了整数本身之外，您还需要什么更多的压缩呢？

MyEnum value = MyEnum.ValueOne | MyEnum.ValueThree | MyEnum.ValueFour;
int i = (int)value;
// transport i

但要小心，因为 1 << 280 (2^280) 是一个相当大的数字，无法存储在 Int32 甚至 Int64 中。

enum values are backed by an integer field in memory. So what more compression you need than the integer itself?

MyEnum value = MyEnum.ValueOne | MyEnum.ValueThree | MyEnum.ValueFour;
int i = (int)value;
// transport i

But be careful because 1 << 280 (2^280) is a pretty large number that cannot be stored in an Int32 or even Int64.

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枕梦 2025-01-12 16:56:10

如果我需要一个具有超过 64 个标志的“标志枚举”，我可能会仅使用枚举来表示位索引，然后将 BitArray 包装在类中以保存值。

要获得紧凑的表示形式，可以将位数组转换为字节数组。我从代码中省略了该步骤，但您可以执行例如像这样（注意字节序！）

public class LargeFlagsEnum<T> where T : struct
{
   private BitArray bits;

   public LargeFlagsEnum(int numBits)
   {
      if (!(typeof(T).IsEnum))
        throw new ArgumentException("Expected enum type");
      bits = new BitArray(numBits);
   }

   public byte[] GetBytes()
   {
      return bits.ConvertToByteArray();
   }

   public void Set(T flag, bool value)
   {
      bits[Convert.ToInt32(flag)] = value;
   }

   public bool Get(T flag)
   {
      return bits[Convert.ToInt32(flag)];
   }    
}

// Example:

enum MyFlags
{
   First = 1,
   SomethingElse = 280,    
}

class Example
{
   void Main()
   {
      var someFlags = new LargeFlagsEnum<MyFlags>(281);
      someFlags.Set(MyFlags.SomethingElse, true);
      Transmit(someFlags.GetBytes()); 
   }
}

If I needed a "Flags enum" with more than 64 flags, I'd probably use an enum for only the bit indices, and then wrap a BitArray inside a class to hold the values.

To get the compact representation, you can convert the bit array to a byte array. I omitted that step from the code, but you can do e.g. like this (pay attention to the endianness!)

public class LargeFlagsEnum<T> where T : struct
{
   private BitArray bits;

   public LargeFlagsEnum(int numBits)
   {
      if (!(typeof(T).IsEnum))
        throw new ArgumentException("Expected enum type");
      bits = new BitArray(numBits);
   }

   public byte[] GetBytes()
   {
      return bits.ConvertToByteArray();
   }

   public void Set(T flag, bool value)
   {
      bits[Convert.ToInt32(flag)] = value;
   }

   public bool Get(T flag)
   {
      return bits[Convert.ToInt32(flag)];
   }    
}

// Example:

enum MyFlags
{
   First = 1,
   SomethingElse = 280,    
}

class Example
{
   void Main()
   {
      var someFlags = new LargeFlagsEnum<MyFlags>(281);
      someFlags.Set(MyFlags.SomethingElse, true);
      Transmit(someFlags.GetBytes()); 
   }
}

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