private AnyClass ReadInstance(int index)
{
Debug.Assert(index > 0);
if (index > 1)
{
if (_instanceMap != null && _instanceMap.Count > index - 2)
{
return(_instanceMap[index - 2]);
}
throw new InvalidDataException($"could not find index {index} in {nameof(_instanceMap)}");
}
if (++_classGraphDepth > Communicator.ClassGraphDepthMax)
{
throw new InvalidDataException("maximum class graph depth reached");
}
InstanceData?previousCurrent = Push(InstanceType.Class);
Debug.Assert(_current != null);
AnyClass?instance = null;
do
{
// Read the slice header.
string?typeIdOpt = ReadSliceHeaderIntoCurrent();
// We cannot read the indirection table at this point as it may reference the new instance that is
// not created yet.
IClassFactory?factory = null;
if (typeIdOpt is string typeId)
{
Debug.Assert(_current.SliceCompactId == null);
factory = Communicator.FindClassFactory(typeId);
}
else if (_current.SliceCompactId is int compactId)
{
factory = Communicator.FindClassFactory(compactId);
}
if (factory != null)
{
instance = factory.Read(this);
}
else if (SkipSlice()) // Slice off what we don't understand.
{
instance = new UnknownSlicedClass(this);
}
}while (instance == null);
Pop(previousCurrent);
--_classGraphDepth;
return(instance);
}
/// <summary>Reads a class instance from the stream.</summary>
/// <param name="index">The index of the class instance. If greater than 1, it's a reference to a previously
/// seen class; if 1, the class's bytes are next on the stream. Cannot be 0 or less.</param>
/// <param name="formalTypeId">The type ID of the formal type of the parameter or data member being read.
/// </param>
private AnyClass ReadInstance(int index, string?formalTypeId)
{
Debug.Assert(Communicator != null);
Debug.Assert(index > 0);
if (index > 1)
{
if (_instanceMap != null && _instanceMap.Count > index - 2)
{
return(_instanceMap[index - 2]);
}
throw new InvalidDataException($"could not find index {index} in {nameof(_instanceMap)}");
}
if (++_classGraphDepth > Communicator.ClassGraphMaxDepth)
{
throw new InvalidDataException("maximum class graph depth reached");
}
// Save current in case we're reading a nested instance.
InstanceData previousCurrent = _current;
_current = default;
_current.InstanceType = InstanceType.Class;
AnyClass?instance = null;
_instanceMap ??= new List <AnyClass>();
if (OldEncoding)
{
bool readIndirectionTable = true;
do
{
// Read the slice header.
(string?typeId, int?compactId) = ReadSliceHeaderIntoCurrent11();
// We cannot read the indirection table at this point as it may reference the new instance that is
// not created yet.
Func <AnyClass>?factory = null;
if (typeId != null)
{
factory = Communicator.FindClassFactory(typeId);
}
else if (compactId is int compactIdValue)
{
factory = Communicator.FindClassFactory(compactIdValue);
}
if (factory != null)
{
instance = factory();
}
else if (SkipSlice(typeId, compactId)) // Slice off what we don't understand.
{
instance = new UnknownSlicedClass();
// Don't read the indirection table as it's the last entry in DeferredIndirectionTableList11.
readIndirectionTable = false;
}
}while (instance == null);
// Add the instance to the map/list of instances. This must be done before reading the instances (for
// circular references).
_instanceMap.Add(instance);
// Read all the deferred indirection tables now that the instance is inserted in _instanceMap.
if (_current.DeferredIndirectionTableList11?.Count > 0)
{
int savedPos = Pos;
Debug.Assert(_current.Slices?.Count == _current.DeferredIndirectionTableList11.Count);
for (int i = 0; i < _current.DeferredIndirectionTableList11.Count; ++i)
{
int pos = _current.DeferredIndirectionTableList11[i];
if (pos > 0)
{
Pos = pos;
_current.Slices[i].Instances = Array.AsReadOnly(ReadIndirectionTable());
}
// else remains empty
}
Pos = savedPos;
}
if (readIndirectionTable)
{
ReadIndirectionTableIntoCurrent();
}
}
else
{
// With the 2.0 encoding, we don't need a DeferredIndirectionTableList because all the type IDs are
// provided by the first slice (when using the sliced format).
(string[]? allTypeIds, _, _) = ReadFirstSliceHeaderIntoCurrent20();
if (allTypeIds != null)
{
int skipCount = 0;
foreach (string typeId in allTypeIds)
{
if (Communicator.FindClassFactory(typeId) is Func <AnyClass> factory)
{
instance = factory();
break; // foreach
}
else
{
skipCount++;
}
}
instance ??= new UnknownSlicedClass();
_instanceMap.Add(instance);
ReadIndirectionTableIntoCurrent(); // read the indirection table immediately
for (int i = 0; i < skipCount; ++i)
{
// SkipSlice saves the slice data including the current indirection table, if any.
if (SkipSlice(allTypeIds[i]))
{
if (i != skipCount - 1)
{
throw new InvalidDataException(
"class slice marked as the last slice is not the last slice");
}
break;
}
else
{
ReadNextSliceHeaderIntoCurrent();
ReadIndirectionTableIntoCurrent();
}
}
}
else if (formalTypeId != null)
{
// received null and formalTypeId is not null, apply formal type optimization.
if (Communicator.FindClassFactory(formalTypeId) is Func <AnyClass> factory)
{
instance = factory();
_instanceMap.Add(instance);
ReadIndirectionTableIntoCurrent();
// Nothing to skip
}
else
{
throw new ArgumentException($"cannot find class factory for `{formalTypeId}'",
nameof(formalTypeId));
}
}
else
{
throw new InvalidDataException(
@$ "cannot read a class instance with no type ID; did you forget to specify the {
nameof(formalTypeId)}?");
}
}