/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkPythonUtil.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/

#include "vtkPythonUtil.h"
#include "vtkPythonOverload.h"

#include "vtkSystemIncludes.h"

#include "vtkObject.h"
#include "vtkSmartPointerBase.h"
#include "vtkWeakPointerBase.h"
#include "vtkVariant.h"
#include "vtkStdString.h"
#include "vtkUnicodeString.h"
#include "vtkWindows.h"
#include "vtkToolkits.h"

#include <vtksys/ios/sstream>
#include <vtkstd/map>
#include <vtkstd/vector>
#include <vtkstd/string>
#include <vtkstd/utility>

#ifdef VTK_WRAP_PYTHON_SIP
#include "sip.h"
#endif


//--------------------------------------------------------------------
// A ghost object, can be used to recreate a deleted PyVTKObject
class PyVTKObjectGhost
{
public:
  PyVTKObjectGhost() : vtk_ptr(), vtk_class(0), vtk_dict(0) {};

  vtkWeakPointerBase vtk_ptr;
  PyVTKClass *vtk_class;
  PyObject *vtk_dict;
};

//--------------------------------------------------------------------
// There are five maps associated with the Python wrappers

// Map VTK objects to python objects (this is also the cornerstone
// of the vtk/python garbage collection system, because it contains
// exactly one pointer reference for each VTK object known to python)
class vtkPythonObjectMap
  : public vtkstd::map<vtkSmartPointerBase, PyObject*>
{
};

// Keep weak pointers to VTK objects that python no longer has
// references to.  Python keeps the python 'dict' for VTK objects
// even when they pass leave the python realm, so that if those
// VTK objects come back, their 'dict' can be restored to them.
// Periodically the weak pointers are checked and the dicts of
// VTK objects that have been deleted are tossed away.
class vtkPythonGhostMap
  : public vtkstd::map<vtkObjectBase*, PyVTKObjectGhost>
{
};

// Keep track of all the VTK classes that python knows about.
class vtkPythonClassMap
  : public vtkstd::map<vtkstd::string, PyObject*>
{
};

// Like the ClassMap, for types not derived from vtkObjectBase.
class vtkPythonSpecialTypeMap
  : public vtkstd::map<vtkstd::string, PyVTKSpecialType>
{
};


//--------------------------------------------------------------------
// The singleton for vtkPythonUtil

vtkPythonUtil *vtkPythonMap = NULL;

// destructs the singleton when python exits
void vtkPythonUtilDelete()
{
  delete vtkPythonMap;
  vtkPythonMap = NULL;
}

//--------------------------------------------------------------------
vtkPythonUtil::vtkPythonUtil()
{
  this->ObjectMap = new vtkPythonObjectMap;
  this->GhostMap = new vtkPythonGhostMap;
  this->ClassMap = new vtkPythonClassMap;
  this->SpecialTypeMap = new vtkPythonSpecialTypeMap;
}

//--------------------------------------------------------------------
vtkPythonUtil::~vtkPythonUtil()
{
  delete this->ObjectMap;
  delete this->GhostMap;
  delete this->ClassMap;
  delete this->SpecialTypeMap;
}

//--------------------------------------------------------------------
// Concatenate an array of strings into a single string.  The resulting
// string is allocated via new.  The array of strings must be null-terminated,
// e.g. static char *strings[] = {"string1", "string2", NULL};
PyObject *vtkPythonUtil::BuildDocString(const char *docstring[])
{
  PyObject *result;
  char *data;
  size_t i, j, n;
  size_t *m;
  size_t total = 0;

  for (n = 0; docstring[n] != NULL; n++)
    {
    ;
    }

  m = new size_t[n];

  for (i = 0; i < n; i++)
    {
    m[i] = strlen(docstring[i]);
    total += m[i];
    }

  result = PyString_FromStringAndSize((char *)docstring[0], (Py_ssize_t)m[0]);

  if (n > 1)
    {
    _PyString_Resize(&result, (Py_ssize_t)total);
    }

  data = PyString_AsString(result);

  j = m[0];
  for (i = 1; i < n; i++)
    {
    strcpy(&data[j], docstring[i]);
    j += m[i];
    }

  delete [] m;

  return result;
}

//--------------------------------------------------------------------
PyVTKSpecialType *vtkPythonUtil::AddSpecialTypeToMap(
  PyTypeObject *pytype, PyMethodDef *methods, PyMethodDef *constructors,
  const char *docstring[], PyVTKSpecialCopyFunc copyfunc)
{
  const char *classname = pytype->tp_name;

  if (vtkPythonMap == NULL)
    {
    vtkPythonMap = new vtkPythonUtil();
    Py_AtExit(vtkPythonUtilDelete);
    }

#ifdef VTKPYTHONDEBUG
  //  vtkGenericWarningMacro("Adding an type " << type << " to map ptr");
#endif

  // lets make sure it isn't already there
  vtkPythonSpecialTypeMap::iterator i =
    vtkPythonMap->SpecialTypeMap->find(classname);
  if(i != vtkPythonMap->SpecialTypeMap->end())
    {
#ifdef VTKPYTHONDEBUG
    vtkGenericWarningMacro("Attempt to add type to the map when already there!!!");
#endif
    return 0;
    }

  i = vtkPythonMap->SpecialTypeMap->insert(i,
    vtkPythonSpecialTypeMap::value_type(
      classname,
      PyVTKSpecialType(pytype, methods, constructors,
                       docstring, copyfunc)));

#ifdef VTKPYTHONDEBUG
  //  vtkGenericWarningMacro("Added type to map type = " << typeObject);
#endif

  return &i->second;
}

//--------------------------------------------------------------------
PyVTKSpecialType *vtkPythonUtil::FindSpecialType(const char *classname)
{
  if (vtkPythonMap)
    {
    vtkPythonSpecialTypeMap::iterator it =
      vtkPythonMap->SpecialTypeMap->find(classname);

    if (it != vtkPythonMap->SpecialTypeMap->end())
      {
      return &it->second;
      }
    }

  return NULL;
}

//--------------------------------------------------------------------
void vtkPythonUtil::AddObjectToMap(PyObject *obj, vtkObjectBase *ptr)
{
  if (vtkPythonMap == NULL)
    {
    vtkPythonMap = new vtkPythonUtil();
    Py_AtExit(vtkPythonUtilDelete);
    }

#ifdef VTKPYTHONDEBUG
  vtkGenericWarningMacro("Adding an object to map ptr = " << ptr);
#endif

  ((PyVTKObject *)obj)->vtk_ptr = ptr;
  (*vtkPythonMap->ObjectMap)[ptr] = obj;

#ifdef VTKPYTHONDEBUG
  vtkGenericWarningMacro("Added object to map obj= " << obj << " "
                         << ptr);
#endif
}

//--------------------------------------------------------------------
void vtkPythonUtil::RemoveObjectFromMap(PyObject *obj)
{
  PyVTKObject *pobj = (PyVTKObject *)obj;

#ifdef VTKPYTHONDEBUG
  vtkGenericWarningMacro("Deleting an object from map obj = "
                         << pobj << " " << pobj->vtk_ptr);
#endif

  if (vtkPythonMap)
    {
    vtkWeakPointerBase wptr;

    // check for customized class or dict
    if (pobj->vtk_class->vtk_methods == 0 ||
        PyDict_Size(pobj->vtk_dict))
      {
      wptr = pobj->vtk_ptr;
      }

    vtkPythonMap->ObjectMap->erase(pobj->vtk_ptr);

    // if the VTK object still exists, then make a ghost
    if (wptr.GetPointer())
      {
      // List of attrs to be deleted
      vtkstd::vector<PyObject*> delList;

      // Erase ghosts of VTK objects that have been deleted
      vtkstd::map<vtkObjectBase*, PyVTKObjectGhost>::iterator i =
        vtkPythonMap->GhostMap->begin();
      while (i != vtkPythonMap->GhostMap->end())
        {
        if (!i->second.vtk_ptr.GetPointer())
          {
          delList.push_back((PyObject *)i->second.vtk_class);
          delList.push_back(i->second.vtk_dict);
          vtkPythonMap->GhostMap->erase(i++);
          }
        else
          {
          ++i;
          }
        }

      // Add this new ghost to the map
      PyVTKObjectGhost &g = (*vtkPythonMap->GhostMap)[pobj->vtk_ptr];
      g.vtk_ptr = wptr;
      g.vtk_class = pobj->vtk_class;
      g.vtk_dict = pobj->vtk_dict;
      Py_INCREF(g.vtk_class);
      Py_INCREF(g.vtk_dict);

      // Delete attrs of erased objects.  Must be done at the end.
      for (size_t j = 0; j < delList.size(); j++)
        {
        Py_DECREF(delList[j]);
        }
      }
    }
}

//--------------------------------------------------------------------
PyObject *vtkPythonUtil::GetObjectFromPointer(vtkObjectBase *ptr)
{
  PyObject *obj = NULL;

  if (ptr)
    {
    vtkstd::map<vtkSmartPointerBase, PyObject*>::iterator i =
      vtkPythonMap->ObjectMap->find(ptr);
    if (i != vtkPythonMap->ObjectMap->end())
      {
      obj = i->second;
      }
    if (obj)
      {
      Py_INCREF(obj);
      return obj;
      }
    }
  else
    {
    Py_INCREF(Py_None);
    return Py_None;
    }

  // search weak list for object, resurrect if it is there
  vtkstd::map<vtkObjectBase*, PyVTKObjectGhost>::iterator j =
    vtkPythonMap->GhostMap->find(ptr);
  if (j != vtkPythonMap->GhostMap->end())
    {
    if (j->second.vtk_ptr.GetPointer())
      {
      obj = PyVTKObject_New((PyObject *)j->second.vtk_class,
                            j->second.vtk_dict, ptr);
      }
    Py_DECREF(j->second.vtk_class);
    Py_DECREF(j->second.vtk_dict);
    vtkPythonMap->GhostMap->erase(j);
    }

  if (obj == NULL)
    {
    // create a new object
    PyObject *vtkclass = NULL;
    vtkstd::map<vtkstd::string, PyObject*>::iterator k =
      vtkPythonMap->ClassMap->find(ptr->GetClassName());
    if (k != vtkPythonMap->ClassMap->end())
      {
      vtkclass = k->second;
      }

    // if the class was not in the map, then find the nearest base class
    // that is and associate ptr->GetClassName() with that base class
    if (vtkclass == NULL)
      {
      vtkclass = vtkPythonUtil::FindNearestBaseClass(ptr);
      vtkPythonUtil::AddClassToMap(vtkclass, ptr->GetClassName());
      }

    obj = PyVTKObject_New(vtkclass, NULL, ptr);
    }

  return obj;
}

//--------------------------------------------------------------------
const char *vtkPythonUtil::PythonicClassName(const char *classname)
{
  const char *cp = classname;

  /* check for non-alphanumeric chars */
  if (isalpha(*cp) || *cp == '_')
    {
    do { cp++; } while (isalnum(*cp) || *cp == '_');
    }

  if (*cp != '\0')
    {
    /* look up class and get its pythonic name */
    PyObject *o = vtkPythonUtil::FindClass(classname);
    if (o)
      {
      classname = PyString_AsString(((PyVTKClass *)o)->vtk_name);
      }
    }

  return classname;
}

//--------------------------------------------------------------------
void vtkPythonUtil::AddClassToMap(PyObject *vtkclass, const char *classname)
{
  if (vtkPythonMap == NULL)
    {
    vtkPythonMap = new vtkPythonUtil();
    Py_AtExit(vtkPythonUtilDelete);
    }

#ifdef VTKPYTHONDEBUG
  //  vtkGenericWarningMacro("Adding an type " << type << " to map ptr");
#endif

  // lets make sure it isn't already there
  vtkPythonClassMap::iterator i =
    vtkPythonMap->ClassMap->find(classname);
  if(i != vtkPythonMap->ClassMap->end())
    {
#ifdef VTKPYTHONDEBUG
    vtkGenericWarningMacro("Attempt to add type to the map when already there!!!");
#endif
    return;
    }

  (*vtkPythonMap->ClassMap)[classname] = vtkclass;

#ifdef VTKPYTHONDEBUG
  //  vtkGenericWarningMacro("Added type to map type = " << typeObject);
#endif
}

//--------------------------------------------------------------------
PyObject *vtkPythonUtil::FindClass(const char *classname)
{
  if (vtkPythonMap)
    {
    vtkPythonClassMap::iterator it =
      vtkPythonMap->ClassMap->find(classname);
    if (it != vtkPythonMap->ClassMap->end())
      {
      return it->second;
      }
    }

  return NULL;
}

//--------------------------------------------------------------------
// this is a helper function to find the nearest base class for an
// object whose class is not in the ClassDict
PyObject *vtkPythonUtil::FindNearestBaseClass(vtkObjectBase *ptr)
{
  PyObject *nearestbase = NULL;
  int maxdepth = 0;
  int depth;

  for(vtkPythonClassMap::iterator classes =
        vtkPythonMap->ClassMap->begin();
      classes != vtkPythonMap->ClassMap->end(); ++classes)
    {
    PyObject *pyclass = classes->second;

    if (ptr->IsA(((PyVTKClass *)pyclass)->vtk_cppname))
      {
      PyObject *cls = pyclass;
      PyObject *bases = ((PyVTKClass *)pyclass)->vtk_bases;
      // count the heirarchy depth for this class
      for (depth = 0; PyTuple_GET_SIZE(bases) != 0; depth++)
        {
        cls = PyTuple_GET_ITEM(bases,0);
        bases = ((PyVTKClass *)cls)->vtk_bases;
        }
      // we want the class that is furthest from vtkObjectBase
      if (depth > maxdepth)
        {
        maxdepth = depth;
        nearestbase = pyclass;
        }
      }
    }

  return nearestbase;
}

//--------------------------------------------------------------------
vtkObjectBase *vtkPythonUtil::GetPointerFromObject(
  PyObject *obj, const char *result_type)
{
  vtkObjectBase *ptr;

  // convert Py_None to NULL every time
  if (obj == Py_None)
    {
    return NULL;
    }

  // check to ensure it is a vtk object
  if (!PyVTKObject_Check(obj))
    {
    obj = PyObject_GetAttrString(obj,(char*)"__vtk__");
    if (obj)
      {
      PyObject *arglist = Py_BuildValue((char*)"()");
      PyObject *result = PyEval_CallObject(obj, arglist);
      Py_DECREF(arglist);
      Py_DECREF(obj);
      if (result == NULL)
        {
        return NULL;
        }
      if (!PyVTKObject_Check(result))
        {
        PyErr_SetString(PyExc_TypeError, "__vtk__() doesn't return a VTK object");
        Py_DECREF(result);
        return NULL;
        }
      else
        {
        ptr = ((PyVTKObject *)result)->vtk_ptr;
        Py_DECREF(result);
        }
      }
    else
      {
#ifdef VTKPYTHONDEBUG
      vtkGenericWarningMacro("Object " << obj << " is not a VTK object!!");
#endif
      PyErr_SetString(PyExc_TypeError, "method requires a VTK object");
      return NULL;
      }
    }
  else
    {
    ptr = ((PyVTKObject *)obj)->vtk_ptr;
    }

#ifdef VTKPYTHONDEBUG
  vtkGenericWarningMacro("Checking into obj " << obj << " ptr = " << ptr);
#endif

  if (ptr->IsA(result_type))
    {
#ifdef VTKPYTHONDEBUG
    vtkGenericWarningMacro("Got obj= " << obj << " ptr= " << ptr << " " << result_type);
#endif
    return ptr;
    }
  else
    {
    char error_string[2048];
#ifdef VTKPYTHONDEBUG
    vtkGenericWarningMacro("vtk bad argument, type conversion failed.");
#endif
    sprintf(error_string, "method requires a %.500s, a %.500s was provided.",
            vtkPythonUtil::PythonicClassName(result_type),
            vtkPythonUtil::PythonicClassName(
              ((vtkObjectBase *)ptr)->GetClassName()));
    PyErr_SetString(PyExc_TypeError, error_string);
    return NULL;
    }
}

//----------------
// union of long int and pointer
union vtkPythonUtilPointerUnion
{
  void *p;
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
  unsigned long l;
#elif defined(VTK_TYPE_USE_LONG_LONG)
  unsigned long long l;
#elif defined(VTK_TYPE_USE___INT64)
  unsigned __int64 l;
#endif
};

//----------------
// union of long int and pointer
union vtkPythonUtilConstPointerUnion
{
  const void *p;
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
  unsigned long l;
#elif defined(VTK_TYPE_USE_LONG_LONG)
  unsigned long long l;
#elif defined(VTK_TYPE_USE___INT64)
  unsigned __int64 l;
#endif
};

//--------------------------------------------------------------------
PyObject *vtkPythonUtil::GetObjectFromObject(
  PyObject *arg, const char *type)
{
  union vtkPythonUtilPointerUnion u;

  if (PyString_Check(arg))
    {
    vtkObjectBase *ptr;
    char *ptrText = PyString_AsString(arg);

    char typeCheck[1024];  // typeCheck is currently not used
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
    int i = sscanf(ptrText,"_%lx_%s", &u.l, typeCheck);
#elif defined(VTK_TYPE_USE_LONG_LONG)
    int i = sscanf(ptrText,"_%llx_%s", &u.l, typeCheck);
#elif defined(VTK_TYPE_USE___INT64)
    int i = sscanf(ptrText,"_%I64x_%s", &u.l, typeCheck);
#endif

    if (i <= 0)
      {
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
      i = sscanf(ptrText,"Addr=0x%lx", &u.l);
#elif defined(VTK_TYPE_USE_LONG_LONG)
      i = sscanf(ptrText,"Addr=0x%llx", &u.l);
#elif defined(VTK_TYPE_USE___INT64)
      i = sscanf(ptrText,"Addr=0x%I64x", &u.l);
#endif
      }
    if (i <= 0)
      {
      i = sscanf(ptrText, "%p", &u.p);
      }
    if (i <= 0)
      {
      PyErr_SetString(PyExc_ValueError, "could not extract hexidecimal address from argument string");
      return NULL;
      }

    ptr = static_cast<vtkObjectBase *>(u.p);

    if (!ptr->IsA(type))
      {
      char error_string[2048];
      sprintf(error_string,"method requires a %.500s address, a %.500s address was provided.",
              type, ptr->GetClassName());
      PyErr_SetString(PyExc_TypeError, error_string);
      return NULL;
      }

    return vtkPythonUtil::GetObjectFromPointer(ptr);
    }

  PyErr_SetString(PyExc_TypeError, "method requires a string argument");
  return NULL;
}

//--------------------------------------------------------------------
void *vtkPythonUtil::GetPointerFromSpecialObject(
  PyObject *obj, const char *result_type, PyObject **newobj)
{
  // The type name
  const char *object_type = obj->ob_type->tp_name;

  // check to make sure that it is the right type
  if (strcmp(object_type, result_type) == 0)
    {
    return ((PyVTKSpecialObject *)obj)->vtk_ptr;
    }

#if PY_VERSION_HEX >= 0x02020000
  // check superclasses
  for (PyTypeObject *basetype = obj->ob_type->tp_base;
       basetype != NULL;
       basetype = basetype->tp_base)
    {
    if (strcmp(basetype->tp_name, result_type) == 0)
      {
      return ((PyVTKSpecialObject *)obj)->vtk_ptr;
      }
    }
#endif

  if (PyVTKObject_Check(obj))
    {
    // use the VTK type name, instead of "vtkobject"
    object_type =
      PyString_AS_STRING(((PyVTKObject *)obj)->vtk_class->vtk_name);
    }

  // try to construct the special object from the supplied object
  vtkstd::map<vtkstd::string, PyVTKSpecialType>::iterator it =
    vtkPythonMap->SpecialTypeMap->find(result_type);
  if(it != vtkPythonMap->SpecialTypeMap->end())
    {
    PyObject *sobj = 0;

    PyVTKSpecialType *info = &it->second;
    PyMethodDef *meth =
      vtkPythonOverload::FindConversionMethod(info->constructors, obj);

    // If a constructor signature exists for "obj", call it
    if (meth && meth->ml_meth)
      {
      PyObject *args = PyTuple_New(1);
      PyTuple_SET_ITEM(args, 0, obj);
      Py_INCREF(obj);

      sobj = meth->ml_meth(0, args);

      Py_DECREF(args);
      }

    if (sobj && newobj)
      {
      *newobj = sobj;
      return ((PyVTKSpecialObject *)sobj)->vtk_ptr;
      }
    else if (sobj)
      {
      char error_text[2048];
      Py_DECREF(sobj);
      sprintf(error_text, "cannot pass %.500s as a non-const %.500s reference",
              object_type, result_type);
      PyErr_SetString(PyExc_TypeError, error_text);
      return NULL;
      }

    // If a TypeError occurred, clear it and set our own error
    PyObject *ex = PyErr_Occurred();
    if (ex != NULL)
      {
      if (PyErr_GivenExceptionMatches(ex, PyExc_TypeError))
        {
        PyErr_Clear();
        }
      else
        {
        return NULL;
        }
      }
    }

#ifdef VTKPYTHONDEBUG
  vtkGenericWarningMacro("vtk bad argument, type conversion failed.");
#endif

  char error_string[2048];
  sprintf(error_string,"method requires a %.500s, a %.500s was provided.",
          result_type, object_type);
  PyErr_SetString(PyExc_TypeError, error_string);

  return NULL;
}

//--------------------------------------------------------------------
// mangle a void pointer into a SWIG-style string
char *vtkPythonUtil::ManglePointer(const void *ptr, const char *type)
{
  static char ptrText[128];
  int ndigits = 2*(int)sizeof(void *);
  union vtkPythonUtilConstPointerUnion u;
  u.p = ptr;
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
  sprintf(ptrText, "_%*.*lx_%s", ndigits, ndigits, u.l, type);
#elif defined(VTK_TYPE_USE_LONG_LONG)
  sprintf(ptrText, "_%*.*llx_%s", ndigits, ndigits, u.l, type);
#elif defined(VTK_TYPE_USE___INT64)
  sprintf(ptrText, "_%*.*I64x_%s", ndigits, ndigits, u.l, type);
#endif

  return ptrText;
}

//--------------------------------------------------------------------
// unmangle a void pointer from a SWIG-style string
void *vtkPythonUtil::UnmanglePointer(char *ptrText, int *len, const char *type)
{
  int i;
  union vtkPythonUtilPointerUnion u;
  char text[1024];
  char typeCheck[1024];
  typeCheck[0] = '\0';

  // Do some minimal checks that it might be a swig pointer.
  if (*len < 256 && *len > 4 && ptrText[0] == '_')
    {
    strncpy(text, ptrText, *len);
    text[*len] = '\0';
    i = *len;
    // Allow one null byte, in case trailing null is part of *len
    if (i > 0 && text[i-1] == '\0')
      {
      i--;
      }
    // Verify that there are no other null bytes
    while (i > 0 && text[i-1] != '\0')
      {
      i--;
      }

    // If no null bytes, then do a full check for a swig pointer
    if (i == 0)
      {
#if VTK_SIZEOF_VOID_P == VTK_SIZEOF_LONG
      i = sscanf(text, "_%lx_%s", &u.l ,typeCheck);
#elif defined(VTK_TYPE_USE_LONG_LONG)
      i = sscanf(text, "_%llx_%s", &u.l ,typeCheck);
#elif defined(VTK_TYPE_USE___INT64)
      i = sscanf(text, "_%I64x_%s", &u.l ,typeCheck);
#endif
      if (strcmp(type,typeCheck) == 0)
        { // sucessfully unmangle
        *len = 0;
        return u.p;
        }
      else if (i == 2)
        { // mangled pointer of wrong type
        *len = -1;
        return NULL;
        }
      }
    }

  // couldn't unmangle: return string as void pointer if it didn't look
  // like a SWIG mangled pointer
  return (void *)ptrText;
}

//--------------------------------------------------------------------
long vtkPythonUtil::VariantHash(const vtkVariant *v)
{
  long h = -1;

  // This uses the same rules as the vtkVariant "==" operator.
  // All types except for vtkObject are converted to strings.
  // Quite inefficient, but it gets the job done.  Fortunately,
  // the python vtkVariant is immutable, so its hash can be cached.

  switch (v->GetType())
    {
    case VTK_OBJECT:
      {
#if PY_MAJOR_VERSION >= 2
      h = _Py_HashPointer(v->ToVTKObject());
#else
      h = (long)(v->ToVTKObject());
#endif
      break;
      }

#ifdef Py_USING_UNICODE
    case VTK_UNICODE_STRING:
      {
      vtkUnicodeString u = v->ToUnicodeString();
      const char *s = u.utf8_str();
      PyObject *tmp = PyUnicode_DecodeUTF8(s, strlen(s), "strict");
      if (tmp == 0)
        {
        PyErr_Clear();
        return 0;
        }
      h = PyObject_Hash(tmp);
      Py_DECREF(tmp);
      break;
      }
#endif

    default:
      {
      vtkStdString s = v->ToString();
      PyObject *tmp = PyString_FromString(s.c_str());
      h = PyObject_Hash(tmp);
      Py_DECREF(tmp);
      break;
      }
    }

  return h;
}

//--------------------------------------------------------------------
void vtkPythonVoidFunc(void *arg)
{
  PyObject *arglist, *result;
  PyObject *func = (PyObject *)arg;

  // Sometimes it is possible for the function to be invoked after
  // Py_Finalize is called, this will cause nasty errors so we return if
  // the interpreter is not initialized.
  if (Py_IsInitialized() == 0)
    {
    return;
    }

#ifndef VTK_NO_PYTHON_THREADS
#if (PY_MAJOR_VERSION > 2) || \
((PY_MAJOR_VERSION == 2) && (PY_MINOR_VERSION >= 3))
  PyGILState_STATE state = PyGILState_Ensure();
#endif
#endif

  arglist = Py_BuildValue((char*)"()");

  result = PyEval_CallObject(func, arglist);
  Py_DECREF(arglist);

  if (result)
    {
    Py_XDECREF(result);
    }
  else
    {
    if (PyErr_ExceptionMatches(PyExc_KeyboardInterrupt))
      {
      cerr << "Caught a Ctrl-C within python, exiting program.\n";
      Py_Exit(1);
      }
    PyErr_Print();
    }

#ifndef VTK_NO_PYTHON_THREADS
#if (PY_MAJOR_VERSION > 2) || \
((PY_MAJOR_VERSION == 2) && (PY_MINOR_VERSION >= 3))
  PyGILState_Release(state);
#endif
#endif
}

//--------------------------------------------------------------------
void vtkPythonVoidFuncArgDelete(void *arg)
{
  PyObject *func = (PyObject *)arg;

  // Sometimes it is possible for the function to be invoked after
  // Py_Finalize is called, this will cause nasty errors so we return if
  // the interpreter is not initialized.
  if (Py_IsInitialized() == 0)
    {
    return;
    }

#ifndef VTK_NO_PYTHON_THREADS
#if (PY_MAJOR_VERSION > 2) || \
((PY_MAJOR_VERSION == 2) && (PY_MINOR_VERSION >= 3))
  PyGILState_STATE state = PyGILState_Ensure();
#endif
#endif

  if (func)
    {
    Py_DECREF(func);
    }

#ifndef VTK_NO_PYTHON_THREADS
#if (PY_MAJOR_VERSION > 2) || \
((PY_MAJOR_VERSION == 2) && (PY_MINOR_VERSION >= 3))
  PyGILState_Release(state);
#endif
#endif
}




#ifdef VTK_WRAP_PYTHON_SIP
// utilities to provide access to Python objects wrapped with SIP
static const sipAPIDef *get_sip_api()
{
  static sipAPIDef *sip_api = NULL;

  if(!sip_api)
    {
    PyObject *c_api = NULL;
    PyObject *sip_module;
    PyObject *sip_module_dict;

    /* Import the SIP module. */
    sip_module = PyImport_ImportModule("sip");

    if (sip_module == NULL)
      return NULL;

    /* Get the module's dictionary. */
    sip_module_dict = PyModule_GetDict(sip_module);

    /* Get the "_C_API" attribute. */
    c_api = PyDict_GetItemString(sip_module_dict, "_C_API");

    if (c_api == NULL)
      return NULL;

    /* Sanity check that it is the right type. */
    if (PyCObject_Check(c_api))
      sip_api = (sipAPIDef *)PyCObject_AsVoidPtr(c_api);

    /* some versions of SIP use PyCapsule instead of PyCObject */
#if PY_VERSION_HEX >= 0x02070000
    if (PyCapsule_CheckExact(c_api))
      sip_api = (sipAPIDef *)PyCapsule_GetPointer(c_api, "sip._C_API");
#endif
    }

  /* Get the actual pointer from the object. */
  return sip_api;
}
#endif

void* vtkPythonUtil::SIPGetPointerFromObject(PyObject *obj, const char *classname)
{
#ifdef VTK_WRAP_PYTHON_SIP
  char etext[512];
  const sipAPIDef * api = get_sip_api();
  if(!api)
    {
    sprintf(etext, "unable to convert to %.200s without SIP api", classname);
    PyErr_SetString(PyExc_TypeError, etext);
    return NULL;
    }

  const sipTypeDef * td = api->api_find_type(classname);
  if(!td)
    {
    sprintf(etext, "unable to convert to %.200s without a typedef", classname);
    PyErr_SetString(PyExc_TypeError, etext);
    return NULL;
    }

  if(sipTypeIsEnum(td))
    {
    if (!api->api_can_convert_to_enum(obj, td))
      {
      sprintf(etext, "unable to convert to %.200s enum", classname);
      PyErr_SetString(PyExc_TypeError, etext);
      return NULL;
      }
    // Call PyInt_AsLong() to retrieve the value
    return obj;
    }

  if(!api->api_can_convert_to_type(obj, td, 0))
    {
    sprintf(etext, "unable to convert to %.200s", classname);
    PyErr_SetString(PyExc_TypeError, etext);
    return NULL;
    }

  int iserr = 0;
  void* ptr = api->api_convert_to_type(obj, td, NULL, 0, NULL, &iserr);
  if(iserr)
    {
    sprintf(etext, "error while converting to %.200s", classname);
    PyErr_SetString(PyExc_TypeError, etext);
    return NULL;
    }
  return ptr;
#else
  (void)obj;
  (void)classname;
  PyErr_SetString(PyExc_TypeError, "method requires VTK built with SIP support");
  return NULL;
#endif
}


PyObject* vtkPythonUtil::SIPGetObjectFromPointer(const void *ptr, const char* classname, bool is_new)
{
#ifdef VTK_WRAP_PYTHON_SIP
  const sipAPIDef * api = get_sip_api();
  if(!api)
    {
    PyErr_SetString(PyExc_TypeError, "Unable to convert to SIP type without api");
    return NULL;
    }

  const sipTypeDef * td = api->api_find_type(classname);
  if(!td)
    {
    PyErr_SetString(PyExc_TypeError, "Unable to convert to SIP type without typedef");
    return NULL;
    }

  if(sipTypeIsEnum(td))
    {
    size_t v = reinterpret_cast<size_t>(ptr);
    return api->api_convert_from_enum(v, td);
    }

  if(is_new)
    {
    return api->api_convert_from_new_type(const_cast<void*>(ptr), td, NULL);
    }

  return api->api_convert_from_type(const_cast<void*>(ptr), td, NULL);

#else
  (void)ptr;
  (void)classname;
  (void)is_new;
  PyErr_SetString(PyExc_TypeError, "method requires VTK built with SIP support");
  return NULL;
#endif
}
