using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Reflection;

using System.Runtime.InteropServices;

using System.Diagnostics;

using Python.Runtime.Native;

using Python.Runtime.StateSerialization;

namespace Python.Runtime

{

/// <summary>

/// The TypeManager class is responsible for building binary-compatible

/// Python type objects that are implemented in managed code.

/// </summary>

internal class TypeManager

{

internal static IntPtr subtype_traverse;

internal static IntPtr subtype_clear;

#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.

/// <remarks>initialized in <see cref="Initialize"/> rather than in constructor</remarks>

internal static IPythonBaseTypeProvider pythonBaseTypeProvider;

#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.

private const BindingFlags tbFlags = BindingFlags.Public | BindingFlags.Static;

// Multi-step creation in GetType is serialised via _cacheCreateLock.

internal static readonly ConcurrentDictionary<MaybeType, PyType> cache = new();

internal static readonly object _cacheCreateLock = new();

// Concurrent: documents the multi-writer contract previously enforced

// by callers happening to hold _cacheCreateLock.

static readonly ConcurrentDictionary<PyType, SlotsHolder> _slotsHolders = new(PythonReferenceComparer.Instance);

// Slots which must be set

private static readonly string[] _requiredSlots = new string[]

{

"tp_traverse",

"tp_clear",

};

static readonly DynamicObjectMemberAccessor dynamicMemberAccessor = new();

// tp_getattro_dlr_proxy / tp_setattro_dlr_proxy hit HasClrMember on every

// attribute access; cache the reflection result per (Type, name).

static readonly ConcurrentDictionary<(Type, string), bool> _hasClrMemberCache = new();

static bool HasClrMember(object instance, string memberName) =>

_hasClrMemberCache.GetOrAdd(

(instance.GetType(), memberName),

k => k.Item1.GetMember(k.Item2, BindingFlags.Public | BindingFlags.Instance).Length > 0);

static bool IsPythonSpecialAttributeName(string memberName) =>

memberName.Length > 4 && memberName.StartsWith("__") && memberName.EndsWith("__");

static bool TryGetDynamicInstance(BorrowedReference ob, out object instance, out IDynamicMetaObjectProvider dynamicObject)

{

if (ManagedType.GetManagedObject(ob) is CLRObject co && co.inst is IDynamicMetaObjectProvider coDynamic)

{

instance = co.inst;

dynamicObject = coDynamic;

return true;

}

if (Converter.ToManaged(ob, typeof(IDynamicMetaObjectProvider), out object? managedDynamic, false)

&& managedDynamic is IDynamicMetaObjectProvider convertedDynamic)

{

instance = managedDynamic;

dynamicObject = convertedDynamic;

return true;

}

if (Converter.ToManaged(ob, typeof(object), out object? managedInstance, false)

&& managedInstance is IDynamicMetaObjectProvider boxedDynamic)

{

instance = managedInstance;

dynamicObject = boxedDynamic;

return true;

}

instance = null!;

dynamicObject = null!;

return false;

}

public static NewReference tp_getattro_dlr_proxy(BorrowedReference ob, BorrowedReference key)

{

var isDynamic = TryGetDynamicInstance(ob, out object instance, out IDynamicMetaObjectProvider dynamicObject);

// The whole DLR machinery only makes sense with string keys and dynamic objects

if (!isDynamic || !Runtime.PyString_Check(key))

{

return Runtime.PyObject_GenericGetAttr(ob, key);

}

string memberName = Runtime.GetManagedString(key)!;

// Forward requests to GetDynamicMemberNames to the mixin implementation

if (memberName == nameof(DynamicObjectMemberAccessor.GetDynamicMemberNames)

&& !HasClrMember(instance, memberName))

{

using var pyMemberNames = new Func<IReadOnlyCollection<string>>(

() => dynamicMemberAccessor.GetDynamicMemberNames(dynamicObject)

).ToPython();

return pyMemberNames.NewReferenceOrNull();

}

// Now, first try to access the Python attribute

var attr = Runtime.PyObject_GenericGetAttr(ob, key);

if (!attr.IsNull())

return attr;

// attr is null, so an exception must be set. If that exception is not an AttributeError,

// we return from this function immediately without clearing. All later returns until the

// very end will lead to the AttributeError getting raised.

if (Runtime.PyErr_ExceptionMatches(Exceptions.AttributeError) == 0)

{

return default;

}

if (HasClrMember(instance, memberName) || IsPythonSpecialAttributeName(memberName))

{

return default;

}

bool resolved = false;

object? value = null;

try

{

resolved = dynamicMemberAccessor.TryGetMember(dynamicObject, memberName, out value);

}

catch (Exception e)

{

// Avoid wrapping the CLR exception via Converter.ToPython here: that would trigger

// CLR type initialisation which can re-enter this slot on the same live object,

// causing infinite recursion. A plain RuntimeError with the message is safe.

Runtime.PyErr_Clear();

Exceptions.SetError(Exceptions.RuntimeError, e.Message);

return default;

}

if (!resolved)

{

return default;

}

Runtime.PyErr_Clear();

using var pyValue = value.ToPython();

return pyValue.NewReferenceOrNull();

}

public static int tp_setattro_dlr_proxy(BorrowedReference ob, BorrowedReference key, BorrowedReference val)

{

var isDynamic = TryGetDynamicInstance(ob, out object instance, out IDynamicMetaObjectProvider dynamicObject);

// The whole DLR machinery only makes sense with string keys and dynamic objects

if (!isDynamic || !Runtime.PyString_Check(key))

{

return Runtime.PyObject_GenericSetAttr(ob, key, val);

}

string memberName = Runtime.GetManagedString(key)!;

// For Python-derived types (IPythonDerivedType), the Python descriptor protocol

// (e.g. @property setters) takes priority over DLR member storage.

if (instance is IPythonDerivedType)

{

int pyResult = Runtime.PyObject_GenericSetAttr(ob, key, val);

if (pyResult == 0)

return 0;

if (Runtime.PyErr_ExceptionMatches(Exceptions.AttributeError) == 0)

return pyResult;

Runtime.PyErr_Clear();

// Fall through to DLR fallback below

}

if (!HasClrMember(instance, memberName) && !IsPythonSpecialAttributeName(memberName))

{

// Try DLR member storage first

bool handled;

try

{

if (val.IsNull)

{

handled = dynamicMemberAccessor.TryDeleteMember(dynamicObject, memberName);

}

else

{

object? managedValue = null;

if (val != Runtime.PyNone && !Converter.ToManaged(val, typeof(object), out managedValue, true))

return -1;

handled = dynamicMemberAccessor.TrySetMember(dynamicObject, memberName, managedValue);

if (!handled)

{

Exceptions.SetError(Exceptions.AttributeError, $"'{instance.GetType().Name}' object has no attribute '{memberName}'");

return -1;

}

}

}

catch (Exception e)

{

// Same reasoning as the getter: avoid Converter.ToPython(e) to keep this

// slot re-entry-safe on live dynamic objects.

Exceptions.SetError(Exceptions.RuntimeError, e.Message);

return -1;

}

if (handled)

return 0;

}

// Fall back to Python attribute setting

return Runtime.PyObject_GenericSetAttr(ob, key, val);

}

internal static void Initialize()

{

Debug.Assert(cache.Count == 0, "Cache should be empty",

"Some errors may occurred on last shutdown");

dynamicMemberAccessor.Clear();

using (var plainType = SlotHelper.CreateObjectType())

{

subtype_traverse = Util.ReadIntPtr(plainType.Borrow(), TypeOffset.tp_traverse);

subtype_clear = Util.ReadIntPtr(plainType.Borrow(), TypeOffset.tp_clear);

}

pythonBaseTypeProvider = PythonEngine.InteropConfiguration.pythonBaseTypeProviders;

}

internal static void RemoveTypes()

{

if (Runtime.HostedInPython)

{

foreach (var holder in _slotsHolders)

{

// If refcount > 1, it needs to reset the managed slot,

// otherwise it can dealloc without any trick.

if (holder.Key.Refcount > 1)

{

holder.Value.ResetSlots();

}

}

}

dynamicMemberAccessor.Clear();

foreach (var type in cache.Values)

{

type.Dispose();

}

cache.Clear();

_slotsHolders.Clear();

}

internal static TypeManagerState SaveRuntimeData()

=> new()

{

Cache = new Dictionary<MaybeType, PyType>(cache),

};

internal static void RestoreRuntimeData(TypeManagerState storage)

{

Debug.Assert(cache == null || cache.Count == 0);

var typeCache = storage.Cache;

foreach (var entry in typeCache)

{

var type = entry.Key.Value;

cache![type] = entry.Value;

SlotsHolder holder = CreateSlotsHolder(entry.Value);

InitializeSlots(entry.Value, type, holder);

Runtime.PyType_Modified(entry.Value);

}

}

internal static PyType GetType(Type type)

{

// Cached with refcount 1; effectively lives until the CPython runtime is finalised.

if (cache.TryGetValue(type, out var pyType)) return pyType;

// CreateType + cache write must be atomic so two threads do not both allocate.

lock (_cacheCreateLock)

{

if (cache.TryGetValue(type, out pyType)) return pyType;

pyType = CreateType(type);

cache[type] = pyType;

return pyType;

}

}

/// <summary>

/// Given a managed Type derived from ExtensionType, get the handle to

/// a Python type object that delegates its implementation to the Type

/// object. These Python type instances are used to implement internal

/// descriptor and utility types like ModuleObject, PropertyObject, etc.

/// </summary>

internal static BorrowedReference GetTypeReference(Type type) => GetType(type).Reference;

/// <summary>

/// The following CreateType implementations do the necessary work to

/// create Python types to represent managed extension types, reflected

/// types, subclasses of reflected types and the managed metatype. The

/// dance is slightly different for each kind of type due to different

/// behavior needed and the desire to have the existing Python runtime

/// do as much of the allocation and initialization work as possible.

/// </summary>

internal static unsafe PyType CreateType(Type impl)

{

// TODO: use PyType(TypeSpec) constructor

PyType type = AllocateTypeObject(impl.Name, metatype: Runtime.PyCLRMetaType);

BorrowedReference base_ = impl == typeof(CLRModule)

? Runtime.PyModuleType

: Runtime.PyBaseObjectType;

type.BaseReference = base_;

int newFieldOffset = InheritOrAllocateStandardFields(type, base_);

int tp_clr_inst_offset = newFieldOffset;

newFieldOffset += IntPtr.Size;

int ob_size = newFieldOffset;

// Set tp_basicsize to the size of our managed instance objects.

Util.WriteIntPtr(type, TypeOffset.tp_basicsize, (IntPtr)ob_size);

Util.WriteInt32(type, ManagedType.Offsets.tp_clr_inst_offset, tp_clr_inst_offset);

Util.WriteIntPtr(type, TypeOffset.tp_new, (IntPtr)Runtime.Delegates.PyType_GenericNew);

SlotsHolder slotsHolder = CreateSlotsHolder(type);

InitializeSlots(type, impl, slotsHolder);

type.Flags = TypeFlags.Default | TypeFlags.HasClrInstance |

TypeFlags.HeapType | TypeFlags.HaveGC;

if (Runtime.PyType_Ready(type) != 0)

{

throw PythonException.ThrowLastAsClrException();

}

using (var dict = Runtime.PyObject_GenericGetDict(type.Reference))

using (var mod = Runtime.PyString_FromString("CLR"))

{

Runtime.PyDict_SetItem(dict.Borrow(), PyIdentifier.__module__, mod.Borrow());

}

// The type has been modified after PyType_Ready has been called

// Refresh the type

Runtime.PyType_Modified(type.Reference);

return type;

}

internal static void InitializeClassCore(Type clrType, PyType pyType, ClassBase impl)

{

if (pyType.BaseReference != null)

{

return;

}

// Hide the gchandle of the implementation in a magic type slot.

GCHandle gc = GCHandle.Alloc(impl);

ManagedType.InitGCHandle(pyType, Runtime.CLRMetaType, gc);

using var baseTuple = GetBaseTypeTuple(clrType);

InitializeBases(pyType, baseTuple);

// core fields must be initialized in partially constructed classes,

// otherwise it would be impossible to manipulate GCHandle and check type size

InitializeCoreFields(pyType);

}

internal static string GetPythonTypeName(Type clrType)

{

var result = new System.Text.StringBuilder();

GetPythonTypeName(clrType, target: result);

return result.ToString();

}

static void GetPythonTypeName(Type clrType, System.Text.StringBuilder target)

{

if (clrType.IsGenericType)

{

string fullName = clrType.GetGenericTypeDefinition().FullName;

int argCountIndex = fullName.LastIndexOf('`');

if (argCountIndex >= 0)

{

string nonGenericFullName = fullName.Substring(0, argCountIndex);

string nonGenericName = CleanupFullName(nonGenericFullName);

target.Append(nonGenericName);

var arguments = clrType.GetGenericArguments();

target.Append('[');

for (int argIndex = 0; argIndex < arguments.Length; argIndex++)

{

if (argIndex != 0)

{

target.Append(',');

}

GetPythonTypeName(arguments[argIndex], target);

}

target.Append(']');

int nestedStart = fullName.IndexOf('+');

while (nestedStart >= 0)

{

target.Append('.');

int nextNested = fullName.IndexOf('+', nestedStart + 1);

if (nextNested < 0)

{

target.Append(fullName.Substring(nestedStart + 1));

}

else

{

target.Append(fullName.Substring(nestedStart + 1, length: nextNested - nestedStart - 1));

}

nestedStart = nextNested;

}

return;

}

}

string name = CleanupFullName(clrType.FullName);

target.Append(name);

}

static string CleanupFullName(string fullTypeName)

{

// Cleanup the type name to get rid of funny nested type names.

string name = "clr." + fullTypeName;

int i = name.LastIndexOf('+');

if (i > -1)

{

name = name.Substring(i + 1);

}

i = name.LastIndexOf('.');

if (i > -1)

{

name = name.Substring(i + 1);

}

return name;

}

static BorrowedReference InitializeBases(PyType pyType, PyTuple baseTuple)

{

Debug.Assert(baseTuple.Length() > 0);

var primaryBase = baseTuple[0].Reference;

pyType.BaseReference = primaryBase;

if (baseTuple.Length() > 1)

{

Util.WriteIntPtr(pyType, TypeOffset.tp_bases, baseTuple.NewReferenceOrNull().DangerousMoveToPointer());

}

return primaryBase;

}

static void InitializeCoreFields(PyType type)

{

int newFieldOffset = InheritOrAllocateStandardFields(type);

if (ManagedType.IsManagedType(type.BaseReference))

{

int baseClrInstOffset = Util.ReadInt32(type.BaseReference, ManagedType.Offsets.tp_clr_inst_offset);

Util.WriteInt32(type, ManagedType.Offsets.tp_clr_inst_offset, baseClrInstOffset);

}

else

{

Util.WriteInt32(type, ManagedType.Offsets.tp_clr_inst_offset, newFieldOffset);

newFieldOffset += IntPtr.Size;

}

int ob_size = newFieldOffset;

Util.WriteIntPtr(type, TypeOffset.tp_basicsize, (IntPtr)ob_size);

Util.WriteIntPtr(type, TypeOffset.tp_itemsize, IntPtr.Zero);

}

internal static void InitializeClass(PyType type, ClassBase impl, Type clrType)

{

// we want to do this after the slot stuff above in case the class itself implements a slot method

SlotsHolder slotsHolder = CreateSlotsHolder(type);

InitializeSlots(type, impl.GetType(), slotsHolder);

impl.InitializeSlots(type, slotsHolder);

OperatorMethod.FixupSlots(type, clrType);

// Leverage followup initialization from the Python runtime. Note

// that the type of the new type must PyType_Type at the time we

// call this, else PyType_Ready will skip some slot initialization.

if (!type.IsReady && Runtime.PyType_Ready(type) != 0)

{

throw PythonException.ThrowLastAsClrException();

}

if (typeof(IDynamicMetaObjectProvider).IsAssignableFrom(clrType))

{

InitializeSlot(type, TypeOffset.tp_getattro, new Interop.BB_N(tp_getattro_dlr_proxy), slotsHolder);

InitializeSlot(type, TypeOffset.tp_setattro, new Interop.BBB_I32(tp_setattro_dlr_proxy), slotsHolder);

Runtime.PyType_Modified(type.Reference);

}

var dict = Util.ReadRef(type, TypeOffset.tp_dict);

string mn = clrType.Namespace ?? "";

using (var mod = Runtime.PyString_FromString(mn))

Runtime.PyDict_SetItem(dict, PyIdentifier.__module__, mod.Borrow());

Runtime.PyType_Modified(type.Reference);

//DebugUtil.DumpType(type);

}

static int InheritOrAllocateStandardFields(BorrowedReference type)

{

var @base = Util.ReadRef(type, TypeOffset.tp_base);

return InheritOrAllocateStandardFields(type, @base);

}

static int InheritOrAllocateStandardFields(BorrowedReference typeRef, BorrowedReference @base)

{

IntPtr baseAddress = @base.DangerousGetAddress();

IntPtr type = typeRef.DangerousGetAddress();

int baseSize = Util.ReadInt32(@base, TypeOffset.tp_basicsize);

int newFieldOffset = baseSize;

void InheritOrAllocate(int typeField)

{

int value = Marshal.ReadInt32(baseAddress, typeField);

if (value == 0)

{

Marshal.WriteIntPtr(type, typeField, new IntPtr(newFieldOffset));

newFieldOffset += IntPtr.Size;

}

else

{

Marshal.WriteIntPtr(type, typeField, new IntPtr(value));

}

}

InheritOrAllocate(TypeOffset.tp_dictoffset);

InheritOrAllocate(TypeOffset.tp_weaklistoffset);

return newFieldOffset;

}

static PyTuple GetBaseTypeTuple(Type clrType)

{

var bases = pythonBaseTypeProvider

.GetBaseTypes(clrType, new PyType[0])

?.ToArray();

if (bases is null || bases.Length == 0)

{

throw new InvalidOperationException("At least one base type must be specified");

}

var nonBases = bases.Where(@base => !@base.Flags.HasFlag(TypeFlags.BaseType)).ToList();

if (nonBases.Count > 0)

{

throw new InvalidProgramException("The specified Python type(s) can not be inherited from: "

+ string.Join(", ", nonBases));

}

return new PyTuple(bases);

}

internal static NewReference CreateSubType(BorrowedReference py_name, ClassBase py_base_type, IList<Type> interfaces, BorrowedReference dictRef)

{

// Utility to create a subtype of a managed type with the ability for the

// a python subtype able to override the managed implementation

string? name = Runtime.GetManagedString(py_name);

if (name is null)

{

Exceptions.SetError(Exceptions.ValueError, "Class name must not be None");

return default;

}

// the derived class can have class attributes __assembly__ and __module__ which

// control the name of the assembly and module the new type is created in.

object? assembly = null;

object? namespaceStr = null;

using (var assemblyKey = new PyString("__assembly__"))

{

var assemblyPtr = Runtime.PyDict_GetItemWithError(dictRef, assemblyKey.Reference);

if (assemblyPtr.IsNull)

{

if (Exceptions.ErrorOccurred()) return default;

}

else if (!Converter.ToManagedValue(assemblyPtr, typeof(string), out assembly, true))

{

return Exceptions.RaiseTypeError("Couldn't convert __assembly__ value to string");

}

using var namespaceKey = new PyString("__namespace__");

var pyNamespace = Runtime.PyDict_GetItemWithError(dictRef, namespaceKey.Reference);

if (pyNamespace.IsNull)

{

if (Exceptions.ErrorOccurred()) return default;

}

else if (!Converter.ToManagedValue(pyNamespace, typeof(string), out namespaceStr, true))

{

return Exceptions.RaiseTypeError("Couldn't convert __namespace__ value to string");

}

}

// create the new managed type subclassing the base managed type

return ReflectedClrType.CreateSubclass(py_base_type, interfaces, name,

ns: (string?)namespaceStr,

assembly: (string?)assembly,

dict: dictRef);

}

internal static IntPtr WriteMethodDef(IntPtr mdef, IntPtr name, IntPtr func, PyMethodFlags flags, IntPtr doc)

{

Marshal.WriteIntPtr(mdef, name);

Marshal.WriteIntPtr(mdef, 1 * IntPtr.Size, func);

Marshal.WriteInt32(mdef, 2 * IntPtr.Size, (int)flags);

Marshal.WriteIntPtr(mdef, 3 * IntPtr.Size, doc);

return mdef + 4 * IntPtr.Size;

}

internal static IntPtr WriteMethodDef(IntPtr mdef, string name, IntPtr func, PyMethodFlags flags = PyMethodFlags.VarArgs,

string? doc = null)

{

IntPtr namePtr = Marshal.StringToHGlobalAnsi(name);

IntPtr docPtr = doc != null ? Marshal.StringToHGlobalAnsi(doc) : IntPtr.Zero;

return WriteMethodDef(mdef, namePtr, func, flags, docPtr);

}

internal static IntPtr WriteMethodDefSentinel(IntPtr mdef)

{

return WriteMethodDef(mdef, IntPtr.Zero, IntPtr.Zero, 0, IntPtr.Zero);

}

internal static void FreeMethodDef(IntPtr mdef)

{

unsafe

{

var def = (PyMethodDef*)mdef;

if (def->ml_name != IntPtr.Zero)

{

Marshal.FreeHGlobal(def->ml_name);

def->ml_name = IntPtr.Zero;

}

if (def->ml_doc != IntPtr.Zero)

{

Marshal.FreeHGlobal(def->ml_doc);

def->ml_doc = IntPtr.Zero;

}

}

}

internal static PyType CreateMetatypeWithGCHandleOffset()

{

var py_type = new PyType(Runtime.PyTypeType, prevalidated: true);

int size = Util.ReadInt32(Runtime.PyTypeType, TypeOffset.tp_basicsize)

+ IntPtr.Size // tp_clr_inst_offset

;

var slots = new[] {

new TypeSpec.Slot(TypeSlotID.tp_traverse, subtype_traverse),

new TypeSpec.Slot(TypeSlotID.tp_clear, subtype_clear)

};

var result = new PyType(

new TypeSpec(

"clr._internal.GCOffsetBase",

basicSize: size,

slots: slots,

TypeFlags.Default | TypeFlags.HeapType | TypeFlags.HaveGC

),

bases: new PyTuple(new[] { py_type })

);

return result;

}

internal static PyType CreateMetaType(Type impl, out SlotsHolder slotsHolder)

{

// The managed metatype is functionally little different than the

// standard Python metatype (PyType_Type). It overrides certain of

// the standard type slots, and has to subclass PyType_Type for

// certain functions in the C runtime to work correctly with it.

PyType gcOffsetBase = CreateMetatypeWithGCHandleOffset();

PyType type = AllocateTypeObject("CLRMetatype", metatype: gcOffsetBase);

Util.WriteRef(type, TypeOffset.tp_base, new NewReference(gcOffsetBase).Steal());

nint size = Util.ReadInt32(gcOffsetBase, TypeOffset.tp_basicsize)

+ IntPtr.Size // tp_clr_inst

;

Util.WriteIntPtr(type, TypeOffset.tp_basicsize, size);

Util.WriteInt32(type, ManagedType.Offsets.tp_clr_inst_offset, ManagedType.Offsets.tp_clr_inst);

const TypeFlags flags = TypeFlags.Default

| TypeFlags.HeapType

| TypeFlags.HaveGC

| TypeFlags.HasClrInstance;

Util.WriteCLong(type, TypeOffset.tp_flags, (int)flags);

// Slots will inherit from TypeType, it's not neccesary for setting them.

// Inheried slots:

// tp_basicsize, tp_itemsize,

// tp_dictoffset, tp_weaklistoffset,

// tp_traverse, tp_clear, tp_is_gc, etc.

slotsHolder = SetupMetaSlots(impl, type);

if (Runtime.PyType_Ready(type) != 0)

{

throw PythonException.ThrowLastAsClrException();

}

BorrowedReference dict = Util.ReadRef(type, TypeOffset.tp_dict);

using (var mod = Runtime.PyString_FromString("clr._internal"))

Runtime.PyDict_SetItemString(dict, "__module__", mod.Borrow());

// The type has been modified after PyType_Ready has been called

// Refresh the type

Runtime.PyType_Modified(type);

//DebugUtil.DumpType(type);

return type;

}

internal static SlotsHolder SetupMetaSlots(Type impl, PyType type)

{

// Override type slots with those of the managed implementation.

var slotsHolder = new SlotsHolder(type);

InitializeSlots(type, impl, slotsHolder);

// We need space for 3 PyMethodDef structs.

int mdefSize = (MetaType.CustomMethods.Length + 1) * Marshal.SizeOf(typeof(PyMethodDef));

IntPtr mdef = Runtime.PyMem_Malloc(mdefSize);

IntPtr mdefStart = mdef;

foreach (var methodName in MetaType.CustomMethods)

{

mdef = AddCustomMetaMethod(methodName, type, mdef, slotsHolder);

}

mdef = WriteMethodDefSentinel(mdef);

Debug.Assert((long)(mdefStart + mdefSize) <= (long)mdef);

Util.WriteIntPtr(type, TypeOffset.tp_methods, mdefStart);

// XXX: Hard code with mode check.

if (Runtime.HostedInPython)

{

slotsHolder.Set(TypeOffset.tp_methods, (t, offset) =>

{

var p = Util.ReadIntPtr(t, offset);

Runtime.PyMem_Free(p);

Util.WriteIntPtr(t, offset, IntPtr.Zero);

});

}

return slotsHolder;

}

private static IntPtr AddCustomMetaMethod(string name, PyType type, IntPtr mdef, SlotsHolder slotsHolder)

{

MethodInfo mi = typeof(MetaType).GetMethod(name);

ThunkInfo thunkInfo = Interop.GetThunk(mi);

slotsHolder.KeeapAlive(thunkInfo);

// XXX: Hard code with mode check.

if (Runtime.HostedInPython)

{

IntPtr mdefAddr = mdef;

slotsHolder.AddDealloctor(() =>

{

var tp_dict = Util.ReadRef(type, TypeOffset.tp_dict);

if (Runtime.PyDict_DelItemString(tp_dict, name) != 0)

{

Runtime.PyErr_Print();

Debug.Fail($"Cannot remove {name} from metatype");

}

FreeMethodDef(mdefAddr);

});

}

mdef = WriteMethodDef(mdef, name, thunkInfo.Address);

return mdef;

}

/// <summary>

/// Utility method to allocate a type object &amp; do basic initialization.

/// </summary>

internal static PyType AllocateTypeObject(string name, PyType metatype)

{

var newType = Runtime.PyType_GenericAlloc(metatype, 0);

var type = new PyType(newType.StealOrThrow());

// Clr type would not use __slots__,

// and the PyMemberDef after PyHeapTypeObject will have other uses(e.g. type handle),

// thus set the ob_size to 0 for avoiding slots iterations.

Util.WriteIntPtr(type, TypeOffset.ob_size, IntPtr.Zero);

// Cheat a little: we'll set tp_name to the internal char * of

// the Python version of the type name - otherwise we'd have to

// allocate the tp_name and would have no way to free it.

using var temp = Runtime.PyString_FromString(name);

IntPtr raw = Runtime.PyUnicode_AsUTF8(temp.BorrowOrThrow());

Util.WriteIntPtr(type, TypeOffset.tp_name, raw);

Util.WriteRef(type, TypeOffset.name, new NewReference(temp).Steal());

Util.WriteRef(type, TypeOffset.qualname, temp.Steal());

// Ensure that tp_traverse and tp_clear are always set, since their

// existence is enforced in newer Python versions in PyType_Ready

Util.WriteIntPtr(type, TypeOffset.tp_traverse, subtype_traverse);

Util.WriteIntPtr(type, TypeOffset.tp_clear, subtype_clear);

// This is a new mechanism in Python 3.14. We should eventually use it to implement

// a nicer type check, but for now we just need to ensure that it is set to NULL.

if (TypeOffset.ht_token != -1)

Util.WriteIntPtr(type, TypeOffset.ht_token, IntPtr.Zero);

InheritSubstructs(type.Reference.DangerousGetAddress());

return type;

}

/// <summary>

/// Inherit substructs, that are not inherited by default:

/// https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_as_number

/// </summary>

static void InheritSubstructs(IntPtr type)

{

IntPtr substructAddress = type + TypeOffset.nb_add;

Marshal.WriteIntPtr(type, TypeOffset.tp_as_number, substructAddress);

substructAddress = type + TypeOffset.sq_length;

Marshal.WriteIntPtr(type, TypeOffset.tp_as_sequence, substructAddress);

substructAddress = type + TypeOffset.mp_length;

Marshal.WriteIntPtr(type, TypeOffset.tp_as_mapping, substructAddress);

substructAddress = type + TypeOffset.bf_getbuffer;

Marshal.WriteIntPtr(type, TypeOffset.tp_as_buffer, substructAddress);

}

/// <summary>

/// Given a newly allocated Python type object and a managed Type that

/// provides the implementation for the type, connect the type slots of

/// the Python object to the managed methods of the implementing Type.

/// </summary>

internal static void InitializeSlots(PyType type, Type impl, SlotsHolder? slotsHolder = null)

{

// We work from the most-derived class up; make sure to get

// the most-derived slot and not to override it with a base

// class's slot.

var seen = new HashSet<string>();

while (impl != null)

{

MethodInfo[] methods = impl.GetMethods(tbFlags);

foreach (MethodInfo method in methods)

{

string name = method.Name;

if (!name.StartsWith("tp_") && !TypeOffset.IsSupportedSlotName(name))

{

Debug.Assert(!name.Contains("_") || name.StartsWith("_") || method.IsSpecialName);

continue;

}

if (seen.Contains(name))

{

continue;

}

InitializeSlot(type, Interop.GetThunk(method), name, slotsHolder);

seen.Add(name);

}

var initSlot = impl.GetMethod("InitializeSlots", BindingFlags.Static | BindingFlags.Public);

initSlot?.Invoke(null, parameters: new object?[] { type, seen, slotsHolder });

impl = impl.BaseType;

}

SetRequiredSlots(type, seen);

}

private static void SetRequiredSlots(PyType type, HashSet<string> seen)

{

foreach (string slot in _requiredSlots)

{

if (seen.Contains(slot))

{

continue;

}

var offset = TypeOffset.GetSlotOffset(slot);

Util.WriteIntPtr(type, offset, SlotsHolder.GetDefaultSlot(offset));

}

}

static void InitializeSlot(BorrowedReference type, ThunkInfo thunk, string name, SlotsHolder? slotsHolder)

{

if (!Enum.TryParse<TypeSlotID>(name, out _))

{

throw new NotSupportedException("Bad slot name " + name);

}

int offset = TypeOffset.GetSlotOffset(name);

InitializeSlot(type, offset, thunk, slotsHolder);

}

static void InitializeSlot(BorrowedReference type, int slotOffset, MethodInfo method, SlotsHolder slotsHolder)

{

var thunk = Interop.GetThunk(method);

InitializeSlot(type, slotOffset, thunk, slotsHolder);

}

internal static void InitializeSlot(BorrowedReference type, int slotOffset, Delegate impl, SlotsHolder slotsHolder)

{

var thunk = Interop.GetThunk(impl);

InitializeSlot(type, slotOffset, thunk, slotsHolder);

}

internal static void InitializeSlotIfEmpty(BorrowedReference type, int slotOffset, Delegate impl, SlotsHolder slotsHolder)

{

if (slotsHolder.IsHolding(slotOffset)) return;

InitializeSlot(type, slotOffset, impl, slotsHolder);

}

static void InitializeSlot(BorrowedReference type, int slotOffset, ThunkInfo thunk, SlotsHolder? slotsHolder)

{

Util.WriteIntPtr(type, slotOffset, thunk.Address);

if (slotsHolder != null)

{

slotsHolder.Set(slotOffset, thunk);

}

}

/// <summary>

/// Utility method to copy slots from a given type to another type.

/// </summary>

internal static void CopySlot(BorrowedReference from, BorrowedReference to, int offset)

{

IntPtr fp = Util.ReadIntPtr(from, offset);

Util.WriteIntPtr(to, offset, fp);

}

internal static SlotsHolder CreateSlotsHolder(PyType type)

{

type = new PyType(type);

var holder = new SlotsHolder(type);

_slotsHolders[type] = holder;

return holder;

}

}

class SlotsHolder

{

public delegate void Resetor(PyType type, int offset);

private readonly Dictionary<int, ThunkInfo> _slots = new();

private readonly List<ThunkInfo> _keepalive = new();

private readonly Dictionary<int, Resetor> _customResetors = new();

private readonly List<Action> _deallocators = new();

private bool _alreadyReset = false;

private readonly PyType Type;

public string?[] Holds => _slots.Keys.Select(TypeOffset.GetSlotName).ToArray();

/// <summary>

/// Create slots holder for holding the delegate of slots and be able to reset them.

/// </summary>

/// <param name="type">Steals a reference to target type</param>

public SlotsHolder(PyType type)

{

this.Type = type;

}

public bool IsHolding(int offset) => _slots.ContainsKey(offset);

public ICollection<int> Slots => _slots.Keys;

public void Set(int offset, ThunkInfo thunk)

{

_slots[offset] = thunk;

}

public void Set(int offset, Resetor resetor)

{

_customResetors[offset] = resetor;

}

public void AddDealloctor(Action deallocate)

{

_deallocators.Add(deallocate);

}