Modeling - New BRrep Graph representation (#1166)

Implement new representation of topology and BRep into OCCT.
New foundation represent 2 levels:
  BRepGraph - public interfaces which making the topology graph representation
  BRepGraphInc - internal structure which represent topology as an incident tables.
The foundation provides basic logic for conversion from TopoDS_Shape to BRepGraph and back.
The foundation provides the iteration and exploring interfaces to travel in both directions on any level of topology.
The internal id type of inc tables is 'int', which is not for long term and can be updated, better to use typed id aliases, even for the iterations, they provide all necessary operators.
The access to the BRepGraph is done using multiple View classes available by methods from main class.
The extensions on graphs is possible with 'Layer' and 'Cache', where first is persistent, second - temporary,
Some basic operations on graph also provided for compact, analyze and copy.

src/ModelingData/TKBRep/BRepGraph/BRepGraph_LayerRegistry.hxx

@@ -0,0 +1,105 @@
+// Copyright (c) 2026 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _BRepGraph_LayerRegistry_HeaderFile
+#define _BRepGraph_LayerRegistry_HeaderFile
+
+#include <BRepGraph_Layer.hxx>
+
+#include <NCollection_DataMap.hxx>
+#include <NCollection_Vector.hxx>
+#include <Standard_DefineAlloc.hxx>
+#include <Standard_GUID.hxx>
+
+//! @brief Dense GUID-keyed runtime registry of graph layers.
+//!
+//! Stores registered layers in a compact vector for O(1) slot access and a
+//! GUID-to-slot map for O(1) lookup by stable public identity.
+class BRepGraph_LayerRegistry
+{
+public:
+  DEFINE_STANDARD_ALLOC
+
+  BRepGraph_LayerRegistry() = default;
+
+  BRepGraph_LayerRegistry(const BRepGraph_LayerRegistry&)            = delete;
+  BRepGraph_LayerRegistry& operator=(const BRepGraph_LayerRegistry&) = delete;
+
+  BRepGraph_LayerRegistry(BRepGraph_LayerRegistry&&) noexcept            = default;
+  BRepGraph_LayerRegistry& operator=(BRepGraph_LayerRegistry&&) noexcept = default;
+
+  //! Register a layer. Replaces an existing layer with the same GUID.
+  //! @return slot index in the internal dense vector, or -1 for null input.
+  Standard_EXPORT int RegisterLayer(const occ::handle<BRepGraph_Layer>& theLayer);
+
+  //! Remove a layer by GUID.
+  Standard_EXPORT void UnregisterLayer(const Standard_GUID& theGUID);
+
+  //! Find a layer by GUID. Returns null handle if not found.
+  [[nodiscard]] Standard_EXPORT occ::handle<BRepGraph_Layer> FindLayer(
+    const Standard_GUID& theGUID) const;
+
+  //! Typed convenience lookup by layer GUID.
+  template <typename T>
+  [[nodiscard]] occ::handle<T> FindLayer() const
+  {
+    return occ::down_cast<T>(FindLayer(T::GetID()));
+  }
+
+  //! Return current slot for a GUID, or -1 if not registered.
+  [[nodiscard]] Standard_EXPORT int FindSlot(const Standard_GUID& theGUID) const;
+
+  //! Return layer by slot index.
+  [[nodiscard]] Standard_EXPORT const occ::handle<BRepGraph_Layer>& Layer(const int theSlot) const;
+
+  //! Number of registered layers.
+  [[nodiscard]] int NbLayers() const { return myLayers.Length(); }
+
+  //! True if any registered layer subscribes to modification events.
+  [[nodiscard]] bool HasModificationSubscribers() const { return mySubscribedKindsMask != 0; }
+
+  //! Bitwise OR of all registered layer subscription masks.
+  [[nodiscard]] int SubscribedKindsMask() const { return mySubscribedKindsMask; }
+
+  //! Dispatch OnNodeRemoved to all registered layers.
+  Standard_EXPORT void DispatchOnNodeRemoved(const BRepGraph_NodeId theNode,
+                                             const BRepGraph_NodeId theReplacement) noexcept;
+
+  //! Dispatch OnNodeModified to subscribed layers.
+  Standard_EXPORT void DispatchNodeModified(const BRepGraph_NodeId theNode) noexcept;
+
+  //! Dispatch OnNodesModified to subscribed layers.
+  Standard_EXPORT void DispatchNodesModified(
+    const NCollection_Vector<BRepGraph_NodeId>& theModifiedNodes,
+    const int                                   theModifiedKindsMask) noexcept;
+
+  //! Dispatch OnCompact to all registered layers.
+  Standard_EXPORT void DispatchOnCompact(
+    const NCollection_DataMap<BRepGraph_NodeId, BRepGraph_NodeId>& theRemapMap) noexcept;
+
+  //! Clear all registered layer payloads without unregistering them.
+  Standard_EXPORT void ClearAll() noexcept;
+
+  //! Invalidate all registered layer payloads.
+  Standard_EXPORT void InvalidateAll() noexcept;
+
+private:
+  Standard_EXPORT void recomputeSubscribedKindsMask();
+
+private:
+  NCollection_Vector<occ::handle<BRepGraph_Layer>> myLayers;
+  NCollection_DataMap<Standard_GUID, int>          myGuidToSlot;
+  int                                              mySubscribedKindsMask = 0;
+};
+
+#endif // _BRepGraph_LayerRegistry_HeaderFile