private static void EmitNullableToNullableConversion(this ILGenerator ilGenerator, Type typeFrom, Type typeTo, bool isChecked)
{
Label labIfNull = default(Label);
Label labEnd = default(Label);
LocalBuilder locFrom = null;
LocalBuilder locTo = null;
locFrom = ilGenerator.DeclareLocal(typeFrom);
ilGenerator.Emit(OpCodes.Stloc, locFrom);
locTo = ilGenerator.DeclareLocal(typeTo);
// test for null
ilGenerator.Emit(OpCodes.Ldloca, locFrom);
ilGenerator.EmitHasValue(typeFrom);
labIfNull = ilGenerator.DefineLabel();
ilGenerator.Emit(OpCodes.Brfalse_S, labIfNull);
ilGenerator.Emit(OpCodes.Ldloca, locFrom);
ilGenerator.EmitGetValueOrDefault(typeFrom);
Type nnTypeFrom = TypeInfoUtils.GetNonNullableType(typeFrom);
Type nnTypeTo = TypeInfoUtils.GetNonNullableType(typeTo);
ilGenerator.EmitConvertToType(nnTypeFrom, nnTypeTo, isChecked);
// construct result type
ConstructorInfo ci = typeTo.GetConstructor(new Type[] { nnTypeTo });
ilGenerator.Emit(OpCodes.Newobj, ci);
ilGenerator.Emit(OpCodes.Stloc, locTo);
labEnd = ilGenerator.DefineLabel();
ilGenerator.Emit(OpCodes.Br_S, labEnd);
// if null then create a default one
ilGenerator.MarkLabel(labIfNull);
ilGenerator.Emit(OpCodes.Ldloca, locTo);
ilGenerator.Emit(OpCodes.Initobj, typeTo);
ilGenerator.MarkLabel(labEnd);
ilGenerator.Emit(OpCodes.Ldloc, locTo);
}
private static void EmitNullableToNonNullableStructConversion(this ILGenerator ilGenerator, Type typeFrom, Type typeTo, bool isChecked)
{
LocalBuilder locFrom = null;
locFrom = ilGenerator.DeclareLocal(typeFrom);
ilGenerator.Emit(OpCodes.Stloc, locFrom);
ilGenerator.Emit(OpCodes.Ldloca, locFrom);
ilGenerator.EmitGetValue(typeFrom);
Type nnTypeFrom = TypeInfoUtils.GetNonNullableType(typeFrom);
ilGenerator.EmitConvertToType(nnTypeFrom, typeTo, isChecked);
}
internal static bool HasReferenceConversion(Type source, Type dest)
{
// void -> void conversion is handled elsewhere
// (it's an identity conversion)
// All other void conversions are disallowed.
if (source == typeof(void) || dest == typeof(void))
{
return(false);
}
var nnSourceType = TypeInfoUtils.GetNonNullableType(source).GetTypeInfo();
var nnDestType = TypeInfoUtils.GetNonNullableType(dest).GetTypeInfo();
// Down conversion
if (nnSourceType.IsAssignableFrom(nnDestType))
{
return(true);
}
// Up conversion
if (nnDestType.IsAssignableFrom(nnSourceType))
{
return(true);
}
// Interface conversion
if (source.IsInterface || dest.IsInterface)
{
return(true);
}
// Variant delegate conversion
if (IsLegalExplicitVariantDelegateConversion(source, dest))
{
return(true);
}
// Object conversion
if (source == typeof(object) || dest == typeof(object))
{
return(true);
}
return(false);
}
