public void Test1()
{
var overflow = typeof(OverflowException);
var exCtorInfo = overflow.GetConstructor(new[] { typeof(string) });
var exToStrMI = overflow.GetMethod("ToString");
var writeLineMI = typeof(Console).GetMethod("WriteLine",
new[]
{
typeof(string),
typeof(object)
});
var method = new DynamicMethod(Guid.NewGuid().ToString(), typeof(int), new[] { typeof(int), typeof(int) }, typeof(TestTryCatch));
using (var il = new GroboIL(method))
{
GroboIL.Local tmp1 = il.DeclareLocal(typeof(int));
GroboIL.Local tmp2 = il.DeclareLocal(overflow);
// In order to successfully branch, we need to create labels
// representing the offset IL instruction block to branch to.
// These labels, when the MarkLabel(Label) method is invoked,
// will specify the IL instruction to branch to.
//
GroboIL.Label failed = il.DefineLabel("failed");
GroboIL.Label endOfMthd = il.DefineLabel("end");
// Begin the try block.
il.BeginExceptionBlock();
// First, load argument 0 and the integer value of "100" onto the
// stack. If arg0 > 100, branch to the label "failed", which is marked
// as the address of the block that throws an exception.
//
il.Ldarg(0);
il.Ldc_I4(100);
il.Bgt(failed, false);
// Now, check to see if argument 1 was greater than 100. If it was,
// branch to "failed." Otherwise, fall through and perform the addition,
// branching unconditionally to the instruction at the label "endOfMthd".
//
il.Ldarg(1);
il.Ldc_I4(100);
il.Bgt(failed, false);
il.Ldarg(0);
il.Ldarg(1);
il.Add_Ovf(true);
// Store the result of the addition.
il.Stloc(tmp1);
il.Leave(endOfMthd);
// If one of the arguments was greater than 100, we need to throw an
// exception. We'll use "OverflowException" with a customized message.
// First, we load our message onto the stack, and then create a new
// exception object using the constructor overload that accepts a
// string message.
//
il.MarkLabel(failed);
il.Ldstr("Cannot accept values over 100 for add.");
il.Newobj(exCtorInfo);
// We're going to need to refer to that exception object later, so let's
// store it in a temporary variable. Since the store function pops the
// the value/reference off the stack, and we'll need it to throw the
// exception, we will subsequently load it back onto the stack as well.
il.Stloc(tmp2);
il.Ldloc(tmp2);
// Throw the exception now on the stack.
il.Throw();
// Start the catch block for OverflowException.
//
il.BeginCatchBlock(overflow);
// When we enter the catch block, the thrown exception
// is on the stack. Store it, then load the format string
// for WriteLine.
//
il.Stloc(tmp2);
il.Ldstr("Caught {0}");
// Push the thrown exception back on the stack, then
// call its ToString() method. Note that if this catch block
// were for a more general exception type, like Exception,
// it would be necessary to use the ToString for that type.
//
il.Ldloc(tmp2);
il.Call(exToStrMI);
// The format string and the return value from ToString() are
// now on the stack. Call WriteLine(string, object).
//
il.Call(writeLineMI);
// Since our function has to return an integer value, we'll load -1 onto
// the stack to indicate an error, and store it in local variable tmp1.
//
il.Ldc_I4(-1);
il.Stloc(tmp1);
// End the exception handling block.
il.EndExceptionBlock();
// The end of the method. If no exception was thrown, the correct value
// will be saved in tmp1. If an exception was thrown, tmp1 will be equal
// to -1. Either way, we'll load the value of tmp1 onto the stack and return.
//
il.MarkLabel(endOfMthd);
il.Ldloc(tmp1);
il.Ret();
Console.WriteLine(il.GetILCode());
}
}
public void Test2()
{
AssemblyName myAssemblyName = new AssemblyName();
myAssemblyName.Name = "AdderExceptionAsm";
// Create dynamic assembly.
AppDomain myAppDomain = Thread.GetDomain();
AssemblyBuilder myAssemblyBuilder = myAppDomain.DefineDynamicAssembly(myAssemblyName, AssemblyBuilderAccess.RunAndSave);
// Create a dynamic module.
ModuleBuilder myModuleBuilder = myAssemblyBuilder.DefineDynamicModule("AdderExceptionMod", true);
var symbolDocumentWriter = myModuleBuilder.GetSymWriter().DefineDocument("AdderException.cil", Guid.Empty, Guid.Empty, Guid.Empty);
TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("Adder");
Type[] adderParams = { typeof(int), typeof(int) };
ConstructorInfo myConstructorInfo = typeof(OverflowException).GetConstructor(new[] { typeof(string) });
MethodInfo myExToStrMI = typeof(OverflowException).GetMethod("ToString");
MethodInfo myWriteLineMI = typeof(Console).GetMethod("WriteLine", new[] { typeof(string), typeof(object) });
// Define method to add two numbers.
MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("DoAdd", MethodAttributes.Public |
MethodAttributes.Static, typeof(int), adderParams);
using (var il = new GroboIL(myMethodBuilder, symbolDocumentWriter))
{
// Declare local variable.
GroboIL.Local myLocalBuilder1 = il.DeclareLocal(typeof(int));
GroboIL.Local myLocalBuilder2 = il.DeclareLocal(typeof(OverflowException));
// Define label.
GroboIL.Label myFailedLabel = il.DefineLabel("failed");
GroboIL.Label myEndOfMethodLabel = il.DefineLabel("end");
// Begin exception block.
il.BeginExceptionBlock();
il.Ldarg(0);
il.Ldc_I4(10);
il.Bgt(myFailedLabel, false);
il.Ldarg(1);
il.Ldc_I4(10);
il.Bgt(myFailedLabel, false);
il.Ldarg(0);
il.Ldarg(1);
il.Add_Ovf(true);
il.Stloc(myLocalBuilder1);
il.Leave(myEndOfMethodLabel);
il.MarkLabel(myFailedLabel);
il.Ldstr("Cannot accept values over 10 for add.");
il.Newobj(myConstructorInfo);
il.Stloc(myLocalBuilder2);
il.Ldloc(myLocalBuilder2);
// Throw the exception.
il.Throw();
// Call 'BeginExceptFilterBlock'.
il.BeginExceptFilterBlock();
il.WriteLine("Except filter block called.");
// Call catch block.
il.BeginCatchBlock(null);
// Call other catch block.
il.BeginCatchBlock(typeof(OverflowException));
il.Ldstr("{0}");
il.Ldloc(myLocalBuilder2);
il.Call(myExToStrMI);
il.Call(myWriteLineMI);
il.Ldc_I4(-1);
il.Stloc(myLocalBuilder1);
// Call finally block.
il.BeginFinallyBlock();
il.WriteLine("Finally block called.");
// End the exception block.
il.EndExceptionBlock();
il.MarkLabel(myEndOfMethodLabel);
il.Ldloc(myLocalBuilder1);
il.Ret();
Console.WriteLine(il.GetILCode());
}
}