private static void EmitNullableToNullableConversion(this ILGenerator il, Type typeFrom, Type typeTo, bool isChecked, ILocalCache locals)
{
Debug.Assert(typeFrom.IsNullableType());
Debug.Assert(typeTo.IsNullableType());
Label labIfNull;
Label labEnd;
LocalBuilder locFrom = locals.GetLocal(typeFrom);
il.Emit(OpCodes.Stloc, locFrom);
LocalBuilder locTo = locals.GetLocal(typeTo);
// test for null
il.Emit(OpCodes.Ldloca, locFrom);
il.EmitHasValue(typeFrom);
labIfNull = il.DefineLabel();
il.Emit(OpCodes.Brfalse_S, labIfNull);
il.Emit(OpCodes.Ldloca, locFrom);
locals.FreeLocal(locFrom);
il.EmitGetValueOrDefault(typeFrom);
Type nnTypeFrom = typeFrom.GetNonNullableType();
Type nnTypeTo = typeTo.GetNonNullableType();
il.EmitConvertToType(nnTypeFrom, nnTypeTo, isChecked, locals);
// construct result type
ConstructorInfo ci = typeTo.GetConstructor(new Type[] { nnTypeTo });
il.Emit(OpCodes.Newobj, ci);
il.Emit(OpCodes.Stloc, locTo);
labEnd = il.DefineLabel();
il.Emit(OpCodes.Br_S, labEnd);
// if null then create a default one
il.MarkLabel(labIfNull);
il.Emit(OpCodes.Ldloca, locTo);
il.Emit(OpCodes.Initobj, typeTo);
il.MarkLabel(labEnd);
il.Emit(OpCodes.Ldloc, locTo);
locals.FreeLocal(locTo);
}
private static void EmitNullableToNonNullableStructConversion(this ILGenerator il, Type typeFrom, Type typeTo, bool isChecked, ILocalCache locals)
{
Debug.Assert(typeFrom.IsNullableType());
Debug.Assert(!typeTo.IsNullableType());
Debug.Assert(typeTo.GetTypeInfo().IsValueType);
LocalBuilder locFrom = locals.GetLocal(typeFrom);
il.Emit(OpCodes.Stloc, locFrom);
il.Emit(OpCodes.Ldloca, locFrom);
locals.FreeLocal(locFrom);
il.EmitGetValue(typeFrom);
Type nnTypeFrom = typeFrom.GetNonNullableType();
il.EmitConvertToType(nnTypeFrom, typeTo, isChecked, locals);
}
private static void EmitNonNullableToNullableConversion(this ILGenerator il, Type typeFrom, Type typeTo, bool isChecked, ILocalCache locals)
{
Debug.Assert(!typeFrom.IsNullableType());
Debug.Assert(typeTo.IsNullableType());
LocalBuilder locTo = locals.GetLocal(typeTo);
Type nnTypeTo = typeTo.GetNonNullableType();
il.EmitConvertToType(typeFrom, nnTypeTo, isChecked, locals);
ConstructorInfo ci = typeTo.GetConstructor(new Type[] { nnTypeTo });
il.Emit(OpCodes.Newobj, ci);
il.Emit(OpCodes.Stloc, locTo);
il.Emit(OpCodes.Ldloc, locTo);
locals.FreeLocal(locTo);
}
/// <summary>
/// Emits default(T)
/// Semantics match C# compiler behavior
/// </summary>
internal static void EmitDefault(this ILGenerator il, Type type, ILocalCache locals)
{
switch (type.GetTypeCode())
{
case TypeCode.DateTime:
il.Emit(OpCodes.Ldsfld, DateTime_MinValue);
break;
case TypeCode.Object:
if (type.GetTypeInfo().IsValueType)
{
// Type.GetTypeCode on an enum returns the underlying
// integer TypeCode, so we won't get here.
Debug.Assert(!type.GetTypeInfo().IsEnum);
// This is the IL for default(T) if T is a generic type
// parameter, so it should work for any type. It's also
// the standard pattern for structs.
LocalBuilder lb = locals.GetLocal(type);
il.Emit(OpCodes.Ldloca, lb);
il.Emit(OpCodes.Initobj, type);
il.Emit(OpCodes.Ldloc, lb);
locals.FreeLocal(lb);
break;
}
goto case TypeCode.Empty;
case TypeCode.Empty:
case TypeCode.String:
case TypeCode.DBNull:
il.Emit(OpCodes.Ldnull);
break;
case TypeCode.Boolean:
case TypeCode.Char:
case TypeCode.SByte:
case TypeCode.Byte:
case TypeCode.Int16:
case TypeCode.UInt16:
case TypeCode.Int32:
case TypeCode.UInt32:
il.Emit(OpCodes.Ldc_I4_0);
break;
case TypeCode.Int64:
case TypeCode.UInt64:
il.Emit(OpCodes.Ldc_I4_0);
il.Emit(OpCodes.Conv_I8);
break;
case TypeCode.Single:
il.Emit(OpCodes.Ldc_R4, default(float));
break;
case TypeCode.Double:
il.Emit(OpCodes.Ldc_R8, default(double));
break;
case TypeCode.Decimal:
il.Emit(OpCodes.Ldsfld, Decimal_Zero);
break;
default:
throw ContractUtils.Unreachable;
}
}