生成一个结构在运行时基于字符串中定义的数据类型 [英] Generating a struct at run-time based on data types defined in a string

问题描述

我如何能产生一个结构在运行时从类型字符串中定义的序列？

How can I generate a struct at run-time from a sequence of types defined in a string?

我有一个标头，例如包括浮球，浮球，字节[255]。 我有如下这个头，并保持数据序列的二进制数据。 我不知道这个数据类型，直到我读在运行时的标题，我想生成，我可以用编组二进制数据转化为结构的数组的结构体。

I have a header that e.g. contains "float, float, byte[255]". I have binary data that follows this header and keeps the data in sequence. I don't know the data type until I read the header at run-time, and I would like to generate a struct that I can used to Marshal the binary data into an array of structs.

任何想法？

推荐答案

显然，你知道你的应用程序的要求，但作为lejon规定的问题是如何访问结构，一旦你创建它。在C＃中，你将不得不赴汤蹈火，而不是vb的，你并不需要显式声明的类型。

Obviously you know what the requirements of your application are, but as lejon stated the problem is how to access the struct once you create it. In c# you will have to jump through hoops, as opposed to vb where you don't need to explicitly declare types.

我能想到的几种方法来完成你想要的。你可以使用codeDOM产生的code，请参阅本 HTTP：// WWW。 15seconds.com/issue/020917.htm

I can think of several ways to accomplish what you want. You could use CodeDom to generate your code, see this http://www.15seconds.com/issue/020917.htm

亲自为一个简单的结构体，我会constuct的code mandually

Personally for a simply struct, I would constuct the code mandually

  string szCode =@"using System;
  using System.Windows.Forms;

  namespace RunTimeCompile
  {
      [StructLayoutAttribute(LayoutKind.Sequential)]
      public string MyStruct
      {"

然后在你的头文件中的每个数据类型添加成员到SZ code字符串。 （你需要建立一个基本的功能来分析你的类型本）：

Then for each data type in your head file append the member to the szCode String. (You'll need to build a basic function to parse your types this):

szCode += "float Field1;\n"; 
szCode += "float Field2;\n"; 
szCode += "byte[255] Field3;\n";

和关闭了你的code ...

and close off your code...

szeCode+=";\n;\n";

现在，你有源$ C ​​$ C使用codeDOM进行编译。

now that you have the source code use CodeDom to compile it.

oCodeDomProvider = CodeDomProvider.CreateProvider("CSharp");
// Add what referenced assemblies
CompilerParameters oCompilerParameters = new CompilerParameters();
oCompilerParameters.ReferencedAssemblies.Add("system.dll");
// set the compiler to create a DLL
oCompilerParameters.GenerateExecutable = false;
// set the dll to be created in memory and not on the hard drive
oCompilerParameters.GenerateInMemory = true;
oCompilerResults =
  oCodeDomProvider.CompileAssemblyFromSource(oCompilerParameters, szCode);

请注意：您也可以从一个文件编译为使用CompileAssemblyFromFile反对在存储源$ C ​​$ C

Note: You could also compile from a file as opposed to in memory source code using CompileAssemblyFromFile

现在继续检查之前没有编译错误

Now before continuing check there are no compilation errors

if (oCompilerResults.Errors.Count!=0) return; // add you own error handling

现在你可以检索像这样动态生成的结构的实例

now you can retrieve an instance of the dynamically generated struct like this

oAssembly = oCompilerResults.CompiledAssembly;
oObject = oAssembly.CreateInstance("RunTimeCompile.MyStruct");
oType = oObject.GetType();

现在你可以看到所有的二进制文件，其中元帅的行成MYSTRUCT [使用元帅或任何其他方法你想序列化的二进制数据（二进制序列也许）]数组。

Now you can read all of the rows of your binary file and Marshal them into an array of MyStruct[] using Marshal or any other method your would like to serialize the binary data (binary serializer perhaps).

例如使用Runtime.Interop.Marshal你可以做这样的事情（你需要这个拨弄了一下，特别是你不能声明MYSTRUCT []在code，所以你需要做的事情像oObjectArray = oAssembly.CreateInstance（RunTimeCompile.MyStruct []）申报destValues​​结果数组）：

For example using Runtime.Interop.Marshal you could do something like this (you'll need to fiddle with this a bit, specifically you can't declare MyStruct[] in your code so you need to do something like oObjectArray = oAssembly.CreateInstance("RunTimeCompile.MyStruct[]") to declare the destValues result array):

byte[] sourceData = ReadSourceData(); // TODO: generate method to load your BLOB
MyStruct[] destValues = new MyStruct[Marshal.SizeOf(oType) + 1]
int arrayIndex = 0;

GCHandle handle = GCHandle.Alloc(sourceData, GCHandleType.Pinned);
try
{
IntPtr buffer = handle.AddrOfPinnedObject();
buffer = (IntPtr)(buffer.ToInt32() +
(arrayIndex*Marshal.SizeOf(typeof(MyStruct))));
destStruct = (MyStruct)Marshal.PtrToStructure(buffer, typeof(MyStruct));
}
finally
{
handle.Free();
}

 return MyStruct;

现在你有你的结构数组。

Now you have your array of struct.

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