NanoVDB Python: remove memory-handle ceremony

nanovdb/nanovdb/python/CMakeLists.txt

@@ -22,7 +22,6 @@ nanobind_add_module(nanovdb_python NB_STATIC
     PyGridHandle.cc
     PyGridStats.cc
     PyGridValidator.cc
-    PyHostBuffer.cc
     PyIO.cc
     PyMath.cc
     PyNanoToOpenVDB.cc
@@ -31,7 +30,6 @@ nanobind_add_module(nanovdb_python NB_STATIC
     PyTools.cc
     PyTree.cc
     PyVoxelBlockManager.cc
-    cuda/PyDeviceBuffer.cc
     cuda/PyDeviceGridHandle.cu
     cuda/PyPointsToGrid.cu
     cuda/PySampleFromVoxels.cu

nanovdb/nanovdb/python/NanoVDBModule.cc

@@ -14,10 +14,8 @@
 
 #include <sstream>
 
-#include "cuda/PyDeviceBuffer.h"
 #include "PyBuildGrid.h"
 #include "PyGridHandle.h"
-#include "PyHostBuffer.h"
 #include "PyIO.h"
 #include "PyMath.h"
 #include "PyTools.h"
@@ -1189,8 +1187,7 @@ NB_MODULE(nanovdb, m)
     defineAccessor<T>(m, #Suffix "ReadAccessor");
 #include "BuildTypes.def"
 
-    // Host-side NodeManagerHandle + module-scope createNodeManager.
-    defineNodeManagerHandle(m);
+    // Module-scope createNodeManager (returns the typed NodeManager).
     defineCreateNodeManager(m);
 
     // PointAccessor variants — PointIndex grids carry uint32 indices,
@@ -1214,11 +1211,9 @@ NB_MODULE(nanovdb, m)
           "channel of an IndexGrid or OnIndexGrid, dispatching on the "
           "channel's recorded dataType. The accessor keeps the grid alive.");
 
-    defineHostBuffer(m);
     defineHostGridHandle(m);
 
 #ifdef NANOVDB_USE_CUDA
-    defineDeviceBuffer(m);
     defineDeviceGridHandle(m);
 #endif
 

nanovdb/nanovdb/python/PyGridHandle.h

@@ -95,7 +95,7 @@ template<typename BufferT> nb::class_<nanovdb::GridHandle<BufferT>> defineGridHa
     return nb::class_<nanovdb::GridHandle<BufferT>>(m, name,
             "Owns a buffer holding one or more serialized NanoVDB grids. "
             "Construct via nanovdb.tools.create* factories or nanovdb.io.readGrid(s); "
-            "access individual grids via handle.grid(n).")
+            "access individual grids via handle.grid(n), handle[i], or iteration.")
         .def(nb::init<>(),
             "Construct an empty handle. Use the nanovdb.tools.create* "
             "factories or nanovdb.io.readGrid(s) instead in normal use.")
@@ -124,6 +124,26 @@ template<typename BufferT> nb::class_<nanovdb::GridHandle<BufferT>> defineGridHa
              "Return the n-th grid as a typed Grid subclass selected by "
              "gridType(n), or None if the BuildT is not bound in Python. "
              "The returned grid keeps this handle alive.")
+        .def("__len__", &nanovdb::GridHandle<BufferT>::gridCount,
+            "Number of grids stored in this handle (same as gridCount()).")
+        .def(
+            "__getitem__",
+            [](nb::handle py_handle, Py_ssize_t i) {
+                auto& handle = nb::cast<nanovdb::GridHandle<BufferT>&>(py_handle);
+                const Py_ssize_t count = static_cast<Py_ssize_t>(handle.gridCount());
+                if (i < 0) i += count;
+                if (i < 0 || i >= count)
+                    throw nb::index_error("GridHandle index out of range [-gridCount(), gridCount()).");
+                return pyHostGrid<BufferT>(py_handle, static_cast<uint32_t>(i));
+            },
+            nb::arg("i"),
+            nb::keep_alive<0, 1>(),
+            "handle[i] -> the i-th grid as a typed Grid subclass (same "
+            "dispatch as grid(n)); negative indices count from the end. "
+            "Raises IndexError when out of range, which also makes handles "
+            "iterable via the sequence protocol (`for grid in handle`). "
+            "Grids whose BuildT is not bound in Python are returned as "
+            "None, matching grid(n).")
         .def("isPadded", &nanovdb::GridHandle<BufferT>::isPadded,
             "True iff this handle's buffer is aligned past the natural "
             "GridData alignment (used by the I/O code path).")

nanovdb/nanovdb/python/PyIO.cc

@@ -84,9 +84,9 @@ template<typename BufferT> void defineReadWriteGrid(nb::module_& m)
           "Return a FileGridMetaDataVector describing every grid stored in the .nvdb file.");
 }
 
-template<typename BufferT> nb::list readGrids(const std::string& fileName, int verbose, const BufferT& buffer)
+template<typename BufferT> nb::list readGrids(const std::string& fileName, int verbose)
 {
-    auto     handles = nanovdb::io::readGrids(fileName, verbose, buffer);
+    auto     handles = nanovdb::io::readGrids<BufferT>(fileName, verbose);
     nb::list handleList;
     for (size_t i = 0; i < handles.size(); ++i) {
         handleList.append(std::move(handles[i]));
@@ -123,20 +123,22 @@ void defineHostReadWriteGrid(nb::module_& m)
     m.def("writeGrids", &writeGrids<BufferT>, "fileName"_a, "handles"_a, "codec"_a = io::Codec::NONE, "verbose"_a = 0,
           "Write every GridHandle in the handles list to the .nvdb file at fileName.");
     m.def("readGrid",
-          nb::overload_cast<const std::string&, int, int, const BufferT&>(&io::template readGrid<BufferT>),
+          [](const std::string& fileName, int n, int verbose) {
+              return io::template readGrid<BufferT>(fileName, n, verbose);
+          },
           "fileName"_a,
           "n"_a = 0,
           "verbose"_a = 0,
-          "buffer"_a = BufferT(),
           "Read the n-th grid from the .nvdb file at fileName into a fresh GridHandle.");
     m.def("readGrid",
-          nb::overload_cast<const std::string&, const std::string&, int, const BufferT&>(&io::template readGrid<BufferT>),
+          [](const std::string& fileName, const std::string& gridName, int verbose) {
+              return io::template readGrid<BufferT>(fileName, gridName, verbose);
+          },
           "fileName"_a,
           "gridName"_a,
           "verbose"_a = 0,
-          "buffer"_a = BufferT(),
           "Read the grid named gridName from the .nvdb file at fileName into a fresh GridHandle.");
-    m.def("readGrids", &readGrids<BufferT>, "fileName"_a, "verbose"_a = 0, "buffer"_a = BufferT(),
+    m.def("readGrids", &readGrids<BufferT>, "fileName"_a, "verbose"_a = 0,
           "Read every grid from the .nvdb file at fileName, returning a list of GridHandles.");
 }
 
@@ -156,20 +158,22 @@ void defineDeviceReadWriteGrid(nb::module_& m)
     m.def("deviceWriteGrids", &writeGrids<BufferT>, "fileName"_a, "handles"_a, "codec"_a = io::Codec::NONE, "verbose"_a = 0,
           "Write every device-backed GridHandle in handles to the .nvdb file at fileName.");
     m.def("deviceReadGrid",
-          nb::overload_cast<const std::string&, int, int, const BufferT&>(&io::template readGrid<BufferT>),
+          [](const std::string& fileName, int n, int verbose) {
+              return io::template readGrid<BufferT>(fileName, n, verbose);
+          },
           "fileName"_a,
           "n"_a = 0,
           "verbose"_a = 0,
-          "buffer"_a = BufferT(),
           "Read the n-th grid from the .nvdb file at fileName into a fresh DeviceGridHandle.");
     m.def("deviceReadGrid",
-          nb::overload_cast<const std::string&, const std::string&, int, const BufferT&>(&io::template readGrid<BufferT>),
+          [](const std::string& fileName, const std::string& gridName, int verbose) {
+              return io::template readGrid<BufferT>(fileName, gridName, verbose);
+          },
           "fileName"_a,
           "gridName"_a,
           "verbose"_a = 0,
-          "buffer"_a = BufferT(),
           "Read the grid named gridName from the .nvdb file at fileName into a fresh DeviceGridHandle.");
-    m.def("deviceReadGrids", &readGrids<BufferT>, "fileName"_a, "verbose"_a = 0, "buffer"_a = BufferT(),
+    m.def("deviceReadGrids", &readGrids<BufferT>, "fileName"_a, "verbose"_a = 0,
           "Read every grid from the .nvdb file at fileName into device-backed handles.");
 }
 #endif