private static void ImplementMethod(TypeBuilder typeBuilder, DllImportXOptions options)
{
var method = options.Method;
var parameters = method.GetParameters().Select(x => x.ParameterType).ToArray();
var callee = DefinePInvokeMethod(typeBuilder, options);
var caller = typeBuilder.DefineMethod(method.Name, MethodAttributes.Virtual, method.ReturnType, parameters);
var il = caller.GetILGenerator();
for (int i = 1, c = parameters.Length; i <= c; i++)
{
il.Emit(OpCodes.Ldarg, i);
}
il.Emit(OpCodes.Call, callee);
il.Emit(OpCodes.Ret);
typeBuilder.DefineMethodOverride(caller, options.Method);
}
public static MethodInfo DefinePInvokeMethod(TypeBuilder typeBuilder, DllImportXOptions options)
{
var clrImportType = typeof(DllImportAttribute);
var ctor = clrImportType.GetConstructor(new[] { typeof(string) });
var fields = new[] {
clrImportType.GetField("EntryPoint"),
clrImportType.GetField("ExactSpelling"),
clrImportType.GetField("PreserveSig"),
clrImportType.GetField("SetLastError"),
clrImportType.GetField("CallingConvention"),
clrImportType.GetField("CharSet"),
clrImportType.GetField("BestFitMapping"),
clrImportType.GetField("ThrowOnUnmappableChar")
};
var fieldValues = new object[] {
options.EntryPoint,
options.ExactSpelling,
options.PreserveSig,
options.SetLastError,
options.CallingConvention,
options.CharSet,
options.BestFitMapping,
options.ThrowOnUnmappableChar
};
var clrImport = new CustomAttributeBuilder(ctor, new[] { options.DllName }, fields, fieldValues);
var ifaceMethod = options.Method;
var parameters = ifaceMethod.GetParameters();
var method = typeBuilder.DefineMethod(
ifaceMethod.Name,
MethodAttributes.Private | MethodAttributes.Static,
ifaceMethod.ReturnType,
ifaceMethod.GetParameters().Select(x => x.ParameterType).ToArray()
);
if (!options.IgnoreAttributes)
{
DefineAttributes(ifaceMethod, method);
}
method.SetCustomAttribute(clrImport);
return(method);
}