public static void DeclareFields(this ILGenerator @this, FieldSet fields)
{
foreach (var field in fields.Fields)
{
@this.DeclareField(field);
}
}
public static void Main()
{
var an = new AssemblyName()
{
Version = new Version(1, 0, 0, 0),
Name = "QuoteOfTheDay"
};
var ab = AppDomain.CurrentDomain.DefineDynamicAssembly(an, AssemblyBuilderAccess.Save);
var modBuilder = ab.DefineDynamicModule("QuoteOfTheDay", "QuoteOftheDay.dll");
var tb = modBuilder.DefineType("QuoteOfTheDay.QuoteOfTheDay", TypeAttributes.Class | TypeAttributes.Public);
var fields = new FieldSet(tb);
fields.DefinePrivateField <ArrayList>("_quotes");
fields.DefinePrivateField <Random>("_random");
var ilgen = Generate_Constructor(tb, fields);
//////////////////////////////////////////////////
Generate_GetRandomQuote(ilgen, tb, fields);
tb.CreateType();
ab.Save("QuoteOfTheDay.dll");
}
public ILContext(FieldSet fields)
: this()
{
foreach (var field in fields.Fields)
{
Fields.Add(field.Name, field);
}
}
private static ILGenerator Generate_Constructor(TypeBuilder tb, FieldSet fields)
{
var cb = tb.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard, new Type[] { typeof(string) });
var ilgen = cb.GetILGenerator();
ilgen.PushContext(new ILContext(fields));
// --- DECLARE PARAMETERS ---
ilgen.DeclareParameter("filename");
// --- DECLARE LOCALS ---
ilgen.DeclareLocal <TextReader>("tr");
ilgen.DeclareLocal <string>("quote");
ilgen.EmitCallToBaseConstructor(); // base();
ilgen.ConstructVariable <ArrayList>("_quotes"); // _quotes = new ArrayList();
ilgen.ConstructVariable <Random>("_random"); // _random = new Random();
ilgen.EmitLoadVariable("filename"); // "filename" - first constructor parameter
ilgen.EmitCall(typeof(File), "OpenText"); // invoke File.OpenText with "filename" parameter
ilgen.EmitStoreVariable("tr");
// Mark the loop label
ilgen.EmitLoop((gen, exit) =>
{
gen.EmitLoadVariable("tr"); // load local "tr"
gen.EmitCallvirt <TextReader>("ReadLine"); // call tr.ReadLine() (virtual)
gen.EmitStoreVariable("quote"); // store the result in the local "quote"
gen.EmitLoadVariable("quote"); // load the local "quote"
gen.Emit(OpCodes.Brfalse_S, exit); // branch to the exit label if "quote" is null
gen.EmitLoadVariable("_quotes"); // load "_quotes" field
gen.EmitLoadVariable("quote"); // load local "quote"
gen.EmitCallvirt <ArrayList, object>("Add"); // call _quotes.Add(object) (virtual)
gen.Emit(OpCodes.Pop); // pop the result of _quotes.Add(object) (unused)
});
ilgen.EmitLoadVariable("tr"); // load local "tr"
ilgen.EmitCallvirt <TextReader>("Close"); // call tr.Close() (virtual)
ilgen.Emit(OpCodes.Ret); // emit return opcode
ilgen.PopContext();
return(ilgen);
}
private static void Generate_GetRandomQuote(ILGenerator ilgen, TypeBuilder tb, FieldSet fields)
{
var mb = tb.DefineMethod <string>("GetRandomQuote", MethodAttributes.Public, CallingConventions.Standard);
ilgen = mb.GetILGenerator();
ilgen.PushContext(new ILContext(fields));
// --- DECLARE LOCALS ---
ilgen.DeclareLocal <int>("count");
ilgen.EmitLoadVariable("_quotes"); // load field "m_Quotes"
ilgen.EmitCallvirt <ArrayList>("get_Count"); // call _quotes.get_Count() (virtual)
ilgen.EmitStoreVariable("count"); // store in local "count"
ilgen.EmitLoadVariable("count"); // load local "count"
ilgen.EmitIfFalse(gen =>
{
ilgen.Emit(OpCodes.Ldstr, ""); // load the string ""
ilgen.Emit(OpCodes.Ret); // return
});
ilgen.EmitLoadVariable("_quotes"); // load field "_quotes"
ilgen.EmitLoadVariable("_random"); // load field "_random"
ilgen.EmitLoadVariable("count"); // load local "count"
ilgen.EmitCallvirt <Random, int>("Next"); // call _random.Next(int) (virtual)
ilgen.EmitCallvirt <ArrayList>("get_Item"); // call _quotes.get_Item(int) (virtual)
ilgen.Emit(OpCodes.Castclass, typeof(string)); // cast the result to string
ilgen.Emit(OpCodes.Ret); // return
ilgen.PopContext();
}
