将字节数组转换为通用值类型？ [英] Convert byte array to generic value type?

问题描述

我有一个 Stream ，我想从中读取数据（作为值类型段）并根据给定类型的大小移动位置（声明为

我目前的做法是：

pre code public byte ReadUInt8（ Stream stream）{
return（byte）stream.ReadByte（）; （ReadUInt8（）<< 8）| ReadUInt8（））;

$ b public ushort ReadUInt16（Stream stream）{
return（ushort）
}

...

我想要什么实现：
$ b $ pre $ public TValue Read< TValue>（stream stream）
where TValue：struct
{
var bufferSize = Marshal.SizeOf（typeof（TValue））;
var buffer = new byte [bufferSize];

if（stream.Read（buffer，0，bufferSize）== 0）
throw new EndOfStreamException（）;

返回（TValue）缓冲区; //这里是我被卡住的地方

// EDIT1：可能的方法是
// return（TValue）（object）buffer;
//但是感觉像踢小狗：/
}


这是不知何故可能？是否存在使用 Marshal.SizeOf（）（性能等）的缺点？

解决方案

  return（TValue）buffer; //这里是我被卡住的地方
  

是的，你刚才转移了问题。从没有 Stream.Read< T>（）没有 Convert< T>（byte []）在标准库中。

无论如何，你必须将它称为 Read< int>（），所以不存在直接优势 BinaryReader.ReadInt32（）

现在当你想从另一个泛型类/方法中使用它时，读取< T>（）语法是有用的，但对于实现，您可能会将它映射到BinaryReader调用。恐怕这将需要拳击：

  obcject result = null; 
 if（typeof（TValue）== typeof（int））
 result = reader.ReadInt32（）; 
 else if（typeof（TValue）== typeof（double））
 result = reader.ReadDouble（）; 
 else ... 
 
 return（TValue）result; 
  

I have a Stream where I'd like to read data from (as value type segments) and move the position according to the size of the given type (declared as generics).

My current approach:

public byte ReadUInt8(Stream stream) {
    return (byte)stream.ReadByte();
}

public ushort ReadUInt16(Stream stream) {
    return (ushort)((ReadUInt8() << 8) | ReadUInt8());
}

...

What I'd like to achieve:

public TValue Read<TValue>(Stream stream)
    where TValue : struct
{
    var bufferSize    = Marshal.SizeOf(typeof(TValue));
    var buffer        = new byte[bufferSize];

    if(stream.Read(buffer, 0, bufferSize) == 0)
        throw new EndOfStreamException();

    return (TValue)buffer; // here's where I'm stuck

    // EDIT1: A possible way would be
    //        return (TValue)(object)buffer;
    //        but that feels like kicking puppies :/
}

Is this somehow possible? Are there any drawbacks from using Marshal.SizeOf() (performance-wise etc.)?

解决方案

return (TValue)buffer; // here's where I'm stuck

Yes, you have just shifted the problem. From not having a Stream.Read<T>() to not having a Convert<T>(byte[]) in the std library.
And you would have to call it like Read<int>() anyway so there isn't a direct advantage over BinaryReader.ReadInt32()

Now when you want to use it from another generic class/method, the Read<T>() syntax is useful but for the implementation you might as well map it to BinaryReader calls. I'm afraid that will require boxing:

obcject result = null;
if (typeof(TValue) == typeof(int))
  result = reader.ReadInt32();
else if (typeof(TValue) == typeof(double))
  result = reader.ReadDouble();
else ...

return (TValue) result;

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