C# MethodBuilder.GetILGenerator方法代码示例

//引入命名空间
using System;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

class TestILGenerator {
 
    public static Type DynamicDotProductGen() {
      
       Type ivType = null;
       Type[] ctorParams = new Type[] { typeof(int),
                                typeof(int),
                        typeof(int)};
    
       AppDomain myDomain = Thread.GetDomain();
       AssemblyName myAsmName = new AssemblyName();
       myAsmName.Name = "IntVectorAsm";
    
       AssemblyBuilder myAsmBuilder = myDomain.DefineDynamicAssembly(
                      myAsmName, 
                      AssemblyBuilderAccess.RunAndSave);

       ModuleBuilder IntVectorModule = myAsmBuilder.DefineDynamicModule("IntVectorModule",
                                        "Vector.dll");

       TypeBuilder ivTypeBld = IntVectorModule.DefineType("IntVector",
                                      TypeAttributes.Public);

       FieldBuilder xField = ivTypeBld.DefineField("x", typeof(int),
                                                       FieldAttributes.Private);
       FieldBuilder yField = ivTypeBld.DefineField("y", typeof(int), 
                                                       FieldAttributes.Private);
       FieldBuilder zField = ivTypeBld.DefineField("z", typeof(int),
                                                       FieldAttributes.Private);

           Type objType = Type.GetType("System.Object"); 
           ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);

       ConstructorBuilder ivCtor = ivTypeBld.DefineConstructor(
                      MethodAttributes.Public,
                      CallingConventions.Standard,
                      ctorParams);
       ILGenerator ctorIL = ivCtor.GetILGenerator();
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Call, objCtor);
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_1);
           ctorIL.Emit(OpCodes.Stfld, xField); 
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_2);
           ctorIL.Emit(OpCodes.Stfld, yField); 
           ctorIL.Emit(OpCodes.Ldarg_0);
           ctorIL.Emit(OpCodes.Ldarg_3);
           ctorIL.Emit(OpCodes.Stfld, zField); 
       ctorIL.Emit(OpCodes.Ret); 

       // This method will find the dot product of the stored vector
       // with another.

       Type[] dpParams = new Type[] { ivTypeBld };

           // Here, you create a MethodBuilder containing the
       // name, the attributes (public, static, private, and so on),
       // the return type (int, in this case), and a array of Type
       // indicating the type of each parameter. Since the sole parameter
       // is a IntVector, the very class you're creating, you will
       // pass in the TypeBuilder (which is derived from Type) instead of 
       // a Type object for IntVector, avoiding an exception. 

       // -- This method would be declared in C# as:
       //    public int DotProduct(IntVector aVector)

           MethodBuilder dotProductMthd = ivTypeBld.DefineMethod(
                                  "DotProduct", 
                          MethodAttributes.Public,
                                          typeof(int), 
                                          dpParams);

       // A ILGenerator can now be spawned, attached to the MethodBuilder.

       ILGenerator mthdIL = dotProductMthd.GetILGenerator();
       
       // Here's the body of our function, in MSIL form. We're going to find the
       // "dot product" of the current vector instance with the passed vector 
       // instance. For reference purposes, the equation is:
       // (x1 * x2) + (y1 * y2) + (z1 * z2) = the dot product

       // First, you'll load the reference to the current instance "this"
       // stored in argument 0 (ldarg.0) onto the stack. Ldfld, the subsequent
       // instruction, will pop the reference off the stack and look up the
       // field "x", specified by the FieldInfo token "xField".

       mthdIL.Emit(OpCodes.Ldarg_0);
       mthdIL.Emit(OpCodes.Ldfld, xField);

       // That completed, the value stored at field "x" is now atop the stack.
       // Now, you'll do the same for the object reference we passed as a
       // parameter, stored in argument 1 (ldarg.1). After Ldfld executed,
       // you'll have the value stored in field "x" for the passed instance
       // atop the stack.

       mthdIL.Emit(OpCodes.Ldarg_1);
       mthdIL.Emit(OpCodes.Ldfld, xField);

           // There will now be two values atop the stack - the "x" value for the
       // current vector instance, and the "x" value for the passed instance.
       // You'll now multiply them, and push the result onto the evaluation stack.

       mthdIL.Emit(OpCodes.Mul_Ovf_Un);

       // Now, repeat this for the "y" fields of both vectors.

       mthdIL.Emit(OpCodes.Ldarg_0);
       mthdIL.Emit(OpCodes.Ldfld, yField);
       mthdIL.Emit(OpCodes.Ldarg_1);
       mthdIL.Emit(OpCodes.Ldfld, yField);
       mthdIL.Emit(OpCodes.Mul_Ovf_Un);

       // At this time, the results of both multiplications should be atop
       // the stack. You'll now add them and push the result onto the stack.

       mthdIL.Emit(OpCodes.Add_Ovf_Un);

       // Multiply both "z" field and push the result onto the stack.
       mthdIL.Emit(OpCodes.Ldarg_0);
       mthdIL.Emit(OpCodes.Ldfld, zField);
       mthdIL.Emit(OpCodes.Ldarg_1);
       mthdIL.Emit(OpCodes.Ldfld, zField);
       mthdIL.Emit(OpCodes.Mul_Ovf_Un);

       // Finally, add the result of multiplying the "z" fields with the
       // result of the earlier addition, and push the result - the dot product -
       // onto the stack.
       mthdIL.Emit(OpCodes.Add_Ovf_Un);

       // The "ret" opcode will pop the last value from the stack and return it
       // to the calling method. You're all done!

       mthdIL.Emit(OpCodes.Ret);

       ivType = ivTypeBld.CreateType();

       return ivType;
    }

    public static void Main() {
    
       Type IVType = null;
           object aVector1 = null;
           object aVector2 = null;
       Type[] aVtypes = new Type[] {typeof(int), typeof(int), typeof(int)};
           object[] aVargs1 = new object[] {10, 10, 10};
           object[] aVargs2 = new object[] {20, 20, 20};
    
       // Call the  method to build our dynamic class.

       IVType = DynamicDotProductGen();

           Console.WriteLine("---");

       ConstructorInfo myDTctor = IVType.GetConstructor(aVtypes);
       aVector1 = myDTctor.Invoke(aVargs1);
       aVector2 = myDTctor.Invoke(aVargs2);

       object[] passMe = new object[1];
           passMe[0] = (object)aVector2; 

       Console.WriteLine("(10, 10, 10) . (20, 20, 20) = {0}",
                 IVType.InvokeMember("DotProduct",
                          BindingFlags.InvokeMethod,
                          null,
                          aVector1,
                          passMe));

       // +++ OUTPUT +++
       // ---
       // (10, 10, 10) . (20, 20, 20) = 600 
    }
}