Pythonize.cxx

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// Bindings
#include "CPyCppyy.h"
#include "Pythonize.h"
#include "Converters.h"
#include "CPPInstance.h"
#include "CPPFunction.h"
#include "CPPOverload.h"
#include "CustomPyTypes.h"
#include "LowLevelViews.h"
#include "ProxyWrappers.h"
#include "PyCallable.h"
#include "PyStrings.h"
#include "TypeManip.h"
#include "Utility.h"
 
// Standard
#include <algorithm>
#include <complex>
#include <set>
#include <stdexcept>
#include <sstream>
#include <string>
#include <utility>
 
 
//- data and local helpers ---------------------------------------------------
namespace CPyCppyy {
    extern PyObject* gThisModule;
    std::map<std::string, std::vector<PyObject*>> &pythonizations();
}
 
namespace {
 
// for convenience
using namespace CPyCppyy;
 
//-----------------------------------------------------------------------------
bool HasAttrDirect(PyObject* pyclass, PyObject* pyname, bool mustBeCPyCppyy = false) {
// prevents calls to Py_TYPE(pyclass)->tp_getattr, which is unnecessary for our
// purposes here and could tickle problems w/ spurious lookups into ROOT meta
    PyObject* dct = PyObject_GetAttr(pyclass, PyStrings::gDict);
    if (dct) {
        PyObject* attr = PyObject_GetItem(dct, pyname);
        Py_DECREF(dct);
        if (attr) {
            bool ret = !mustBeCPyCppyy || CPPOverload_Check(attr);
            Py_DECREF(attr);
            return ret;
        }
    }
    PyErr_Clear();
    return false;
}
 
PyObject* GetAttrDirect(PyObject* pyclass, PyObject* pyname) {
// get an attribute without causing getattr lookups
    PyObject* dct = PyObject_GetAttr(pyclass, PyStrings::gDict);
    if (dct) {
        PyObject* attr = PyObject_GetItem(dct, pyname);
        Py_DECREF(dct);
        return attr;
    }
    return nullptr;
}
 
//-----------------------------------------------------------------------------
inline bool IsTemplatedSTLClass(const std::string& name, const std::string& klass) {
// Scan the name of the class and determine whether it is a template instantiation.
    auto pos = name.find(klass);
    return (pos == 0 || pos == 5) && name.find("::", name.rfind(">")) == std::string::npos;
}
 
// to prevent compiler warnings about const char* -> char*
inline PyObject* CallPyObjMethod(PyObject* obj, const char* meth)
{
// Helper; call method with signature: obj->meth().
    Py_INCREF(obj);
    PyObject* result = PyObject_CallMethod(obj, const_cast<char*>(meth), const_cast<char*>(""));
    Py_DECREF(obj);
    return result;
}
 
//-----------------------------------------------------------------------------
inline PyObject* CallPyObjMethod(PyObject* obj, const char* meth, PyObject* arg1)
{
// Helper; call method with signature: obj->meth(arg1).
    Py_INCREF(obj);
    PyObject* result = PyObject_CallMethod(
        obj, const_cast<char*>(meth), const_cast<char*>("O"), arg1);
    Py_DECREF(obj);
    return result;
}
 
//-----------------------------------------------------------------------------
PyObject* PyStyleIndex(PyObject* self, PyObject* index)
{
// Helper; converts python index into straight C index.
    Py_ssize_t idx = PyInt_AsSsize_t(index);
    if (idx == (Py_ssize_t)-1 && PyErr_Occurred())
        return nullptr;
 
    Py_ssize_t size = PySequence_Size(self);
    if (idx >= size || (idx < 0 && idx < -size)) {
        PyErr_SetString(PyExc_IndexError, "index out of range");
        return nullptr;
    }
 
    PyObject* pyindex = nullptr;
    if (idx >= 0) {
        Py_INCREF(index);
        pyindex = index;
    } else
        pyindex = PyLong_FromSsize_t(size+idx);
 
    return pyindex;
}
 
//-----------------------------------------------------------------------------
inline bool AdjustSlice(const Py_ssize_t nlen, Py_ssize_t& start, Py_ssize_t& stop, Py_ssize_t& step)
{
// Helper; modify slice range to match the container.
    if ((step > 0 && stop <= start) || (step < 0 && start <= stop))
        return false;
 
    if (start < 0) start = 0;
    if (start >= nlen) start = nlen-1;
    if (step >= nlen) step = nlen;
 
    stop = step > 0 ? std::min(nlen, stop) : (stop >= 0 ? stop : -1);
    return true;
}
 
//-----------------------------------------------------------------------------
inline PyObject* CallSelfIndex(CPPInstance* self, PyObject* idx, PyObject* pymeth)
{
// Helper; call method with signature: meth(pyindex).
    Py_INCREF((PyObject*)self);
    PyObject* pyindex = PyStyleIndex((PyObject*)self, idx);
    if (!pyindex) {
        Py_DECREF((PyObject*)self);
        return nullptr;
    }
 
    PyObject* result = PyObject_CallMethodOneArg((PyObject*)self, pymeth, pyindex);
    Py_DECREF(pyindex);
    Py_DECREF((PyObject*)self);
    return result;
}
 
//- "smart pointer" behavior ---------------------------------------------------
static PyObject* smart_follow(PyObject* self, PyObject* name, PyObject* method)
{
    if (!CPyCppyy_PyText_Check(name))
        PyErr_SetString(PyExc_TypeError, "getattr(): attribute name must be string");
 
    PyObject* pyptr = PyObject_CallMethodNoArgs(self, method);
    if (!pyptr)
        return nullptr;
 
// prevent a potential infinite loop
    if (Py_TYPE(pyptr) == Py_TYPE(self)) {
        PyObject* val1 = PyObject_Str((PyObject*)Py_TYPE(self));
        PyObject* val2 = PyObject_Str(name);
        PyErr_Format(PyExc_AttributeError, "%s object has no attribute \'%s\'",
            CPyCppyy_PyText_AsString(val1), CPyCppyy_PyText_AsString(val2));
        Py_DECREF(val2);
        Py_DECREF(val1);
 
        Py_DECREF(pyptr);
        return nullptr;
    }
 
    PyObject* result = PyObject_GetAttr(pyptr, name);
    Py_DECREF(pyptr);
    return result;
}
 
PyObject* DeRefGetAttr(PyObject* self, PyObject* name)
{
// Follow operator*() if present (available in python as __deref__), so that
// smart pointers behave as expected.
    if (name == PyStrings::gTypeCode || name == PyStrings::gCTypesType) {
    // TODO: these calls come from TemplateProxy and are unlikely to be needed in practice,
    // whereas as-is, they can accidentally dereference the result of end() on some STL
    // containers. Obviously, this is a dumb hack that should be resolved more fundamentally.
        PyErr_SetString(PyExc_AttributeError, CPyCppyy_PyText_AsString(name));
        return nullptr;
    }
 
 
    return smart_follow(self, name, PyStrings::gDeref);
}
 
//-----------------------------------------------------------------------------
PyObject* FollowGetAttr(PyObject* self, PyObject* name)
{
// Follow operator->() if present (available in python as __follow__), so that
// smart pointers behave as expected.
    return smart_follow(self, name, PyStrings::gFollow);
}
 
//- pointer checking bool converter -------------------------------------------
PyObject* NullCheckBool(PyObject* self)
{
    if (!CPPInstance_Check(self)) {
        PyErr_SetString(PyExc_TypeError, "C++ object proxy expected");
        return nullptr;
    }
 
    if (!((CPPInstance*)self)->GetObject())
        Py_RETURN_FALSE;
 
    return PyObject_CallMethodNoArgs(self, PyStrings::gCppBool);
}
 
//- vector behavior as primitives ----------------------------------------------
#if PY_VERSION_HEX < 0x03040000
#define PyObject_LengthHint _PyObject_LengthHint
#endif
 
// TODO: can probably use the below getters in the InitializerListConverter
struct ItemGetter {
    ItemGetter(PyObject* pyobj) : fPyObject(pyobj) { Py_INCREF(fPyObject); }
    virtual ~ItemGetter() { Py_DECREF(fPyObject); }
    virtual Py_ssize_t size() = 0;
    virtual PyObject* get() = 0;
    PyObject* fPyObject;
};
 
struct CountedItemGetter : public ItemGetter {
    CountedItemGetter(PyObject* pyobj) : ItemGetter(pyobj), fCur(0) {}
    Py_ssize_t fCur;
};
 
struct TupleItemGetter : public CountedItemGetter {
    using CountedItemGetter::CountedItemGetter;
    Py_ssize_t size() override { return PyTuple_GET_SIZE(fPyObject); }
    PyObject* get() override {
        if (fCur < PyTuple_GET_SIZE(fPyObject)) {
            PyObject* item = PyTuple_GET_ITEM(fPyObject, fCur++);
            Py_INCREF(item);
            return item;
        }
        PyErr_SetString(PyExc_StopIteration, "end of tuple");
        return nullptr;
    }
};
 
struct ListItemGetter : public CountedItemGetter {
    using CountedItemGetter::CountedItemGetter;
    Py_ssize_t size() override { return PyList_GET_SIZE(fPyObject); }
    PyObject* get() override {
        if (fCur < PyList_GET_SIZE(fPyObject)) {
            PyObject* item = PyList_GET_ITEM(fPyObject, fCur++);
            Py_INCREF(item);
            return item;
        }
        PyErr_SetString(PyExc_StopIteration, "end of list");
        return nullptr;
    }
};
 
struct SequenceItemGetter : public CountedItemGetter {
    using CountedItemGetter::CountedItemGetter;
    Py_ssize_t size() override {
        Py_ssize_t sz = PySequence_Size(fPyObject);
        if (sz < 0) {
            PyErr_Clear();
            return PyObject_LengthHint(fPyObject, 8);
        }
        return sz;
    }
    PyObject* get() override { return PySequence_GetItem(fPyObject, fCur++); }
};
 
struct IterItemGetter : public ItemGetter {
    using ItemGetter::ItemGetter;
    Py_ssize_t size() override { return PyObject_LengthHint(fPyObject, 8); }
    PyObject* get() override { return (*(Py_TYPE(fPyObject)->tp_iternext))(fPyObject); }
};
 
static ItemGetter* GetGetter(PyObject* args)
{
// Create an ItemGetter to loop over the iterable argument, if any.
    ItemGetter* getter = nullptr;
 
    if (PyTuple_GET_SIZE(args) == 1) {
        PyObject* fi = PyTuple_GET_ITEM(args, 0);
        if (CPyCppyy_PyText_Check(fi) || PyBytes_Check(fi))
            return nullptr;       // do not accept string to fill std::vector<char>
 
    // TODO: this only tests for new-style buffers, which is too strict, but a
    // generic check for Py_TYPE(fi)->tp_as_buffer is too loose (note that the
    // main use case is numpy, which offers the new interface)
        if (PyObject_CheckBuffer(fi))
            return nullptr;
 
        if (PyTuple_CheckExact(fi))
            getter = new TupleItemGetter(fi);
        else if (PyList_CheckExact(fi))
            getter = new ListItemGetter(fi);
        else if (PySequence_Check(fi))
            getter = new SequenceItemGetter(fi);
        else {
            PyObject* iter = PyObject_GetIter(fi);
            if (iter) {
                getter = new IterItemGetter{iter};
                Py_DECREF(iter);
            }
            else PyErr_Clear();
        }
    }
 
    return getter;
}
 
namespace {
 
void compileSpanHelpers()
{
   static bool compiled = false;
 
   if (compiled)
      return;
 
   compiled = true;
 
   auto code = R"(
namespace __cppyy_internal {
 
template <class T>
struct ptr_iterator {
   T *cur;
   T *end;
 
   ptr_iterator(T *c, T *e) : cur(c), end(e) {}
 
   T &operator*() const { return *cur; }
   ptr_iterator &operator++()
   {
      ++cur;
      return *this;
   }
   bool operator==(const ptr_iterator &other) const { return cur == other.cur; }
   bool operator!=(const ptr_iterator &other) const { return !(*this == other); }
};
 
template <class T>
ptr_iterator<T> make_iter(T *begin, T *end)
{
   return {begin, end};
}
 
} // namespace __cppyy_internal
 
// Note: for const span<T>, T is const-qualified here
template <class T>
auto __cppyy_internal_begin(T &s) noexcept
{
   return __cppyy_internal::make_iter(s.data(), s.data() + s.size());
}
 
// Note: for const span<T>, T is const-qualified here
template <class T>
auto __cppyy_internal_end(T &s) noexcept
{
   // end iterator = begin iterator with cur == end
   return __cppyy_internal::make_iter(s.data() + s.size(), s.data() + s.size());
}
    )";
   Cppyy::Compile(code, /*silent*/ true);
}
 
PyObject *spanBegin()
{
   static PyObject *pyFunc = nullptr;
   if (!pyFunc) {
      compileSpanHelpers();
      PyObject *py_ns = CPyCppyy::GetScopeProxy(Cppyy::gGlobalScope);
      pyFunc = PyObject_GetAttrString(py_ns, "__cppyy_internal_begin");
      if (!pyFunc) {
         PyErr_Format(PyExc_RuntimeError, "cppyy internal error: failed to locate helper "
                                          "'__cppyy_internal_begin' for std::span pythonization");
      }
   }
   return pyFunc;
}
 
PyObject *spanEnd()
{
   static PyObject *pyFunc = nullptr;
   if (!pyFunc) {
      compileSpanHelpers();
      PyObject *py_ns = CPyCppyy::GetScopeProxy(Cppyy::gGlobalScope);
      pyFunc = PyObject_GetAttrString(py_ns, "__cppyy_internal_end");
      if (!pyFunc) {
         PyErr_Format(PyExc_RuntimeError, "cppyy internal error: failed to locate helper "
                                          "'__cppyy_internal_end' for std::span pythonization");
      }
   }
   return pyFunc;
}
 
} // namespace
 
static PyObject *SpanBegin(PyObject *self, PyObject *)
{
   auto begin = spanBegin();
   if (!begin)
      return nullptr;
   return PyObject_CallOneArg(begin, self);
}
 
static PyObject *SpanEnd(PyObject *self, PyObject *)
{
   auto end = spanEnd();
   if (!end)
      return nullptr;
   return PyObject_CallOneArg(end, self);
}
 
static bool FillVector(PyObject* vecin, PyObject* args, ItemGetter* getter)
{
    Py_ssize_t sz = getter->size();
    if (sz < 0)
        return false;
 
// reserve memory as applicable
    if (0 < sz) {
        PyObject* res = PyObject_CallMethod(vecin, (char*)"reserve", (char*)"n", sz);
        Py_DECREF(res);
    } else   // i.e. sz == 0, so empty container: done
        return true;
 
    bool fill_ok = true;
 
// two main options: a list of lists (or tuples), or a list of objects; the former
// are emplace_back'ed, the latter push_back'ed
    PyObject* fi = PySequence_GetItem(PyTuple_GET_ITEM(args, 0), 0);
    if (!fi) PyErr_Clear();
    if (fi && (PyTuple_CheckExact(fi) || PyList_CheckExact(fi))) {
    // use emplace_back to construct the vector entries one by one
        PyObject* eb_call = PyObject_GetAttrString(vecin, (char*)"emplace_back");
        PyObject* vtype = GetAttrDirect((PyObject*)Py_TYPE(vecin), PyStrings::gValueType);
        bool value_is_vector = false;
        if (vtype && CPyCppyy_PyText_Check(vtype)) {
        // if the value_type is a vector, then allow for initialization from sequences
            if (std::string(CPyCppyy_PyText_AsString(vtype)).rfind("std::vector", 0) != std::string::npos)
                value_is_vector = true;
        } else
            PyErr_Clear();
        Py_XDECREF(vtype);
 
        if (eb_call) {
            PyObject* eb_args;
            for (int i = 0; /* until break */; ++i) {
                PyObject* item = getter->get();
                if (item) {
                    if (value_is_vector && PySequence_Check(item)) {
                        eb_args = PyTuple_New(1);
                        PyTuple_SET_ITEM(eb_args, 0, item);
                    } else if (PyTuple_CheckExact(item)) {
                        eb_args = item;
                    } else if (PyList_CheckExact(item)) {
                        Py_ssize_t isz = PyList_GET_SIZE(item);
                        eb_args = PyTuple_New(isz);
                        for (Py_ssize_t j = 0; j < isz; ++j) {
                            PyObject* iarg = PyList_GET_ITEM(item, j);
                            Py_INCREF(iarg);
                            PyTuple_SET_ITEM(eb_args, j, iarg);
                        }
                        Py_DECREF(item);
                    } else {
                        Py_DECREF(item);
                        PyErr_Format(PyExc_TypeError, "argument %d is not a tuple or list", i);
                        fill_ok = false;
                        break;
                    }
                    PyObject* ebres = PyObject_CallObject(eb_call, eb_args);
                    Py_DECREF(eb_args);
                    if (!ebres) {
                        fill_ok = false;
                        break;
                    }
                    Py_DECREF(ebres);
                } else {
                    if (PyErr_Occurred()) {
                        if (!(PyErr_ExceptionMatches(PyExc_IndexError) ||
                              PyErr_ExceptionMatches(PyExc_StopIteration)))
                            fill_ok = false;
                        else { PyErr_Clear(); }
                    }
                    break;
                }
            }
            Py_DECREF(eb_call);
        }
    } else {
    // use push_back to add the vector entries one by one
        PyObject* pb_call = PyObject_GetAttrString(vecin, (char*)"push_back");
        if (pb_call) {
            for (;;) {
                PyObject* item = getter->get();
                if (item) {
                    PyObject* pbres = PyObject_CallFunctionObjArgs(pb_call, item, nullptr);
                    Py_DECREF(item);
                    if (!pbres) {
                        fill_ok = false;
                        break;
                    }
                    Py_DECREF(pbres);
                } else {
                    if (PyErr_Occurred()) {
                        if (!(PyErr_ExceptionMatches(PyExc_IndexError) ||
                              PyErr_ExceptionMatches(PyExc_StopIteration)))
                            fill_ok = false;
                        else { PyErr_Clear(); }
                    }
                    break;
                }
            }
            Py_DECREF(pb_call);
        }
    }
    Py_XDECREF(fi);
 
    return fill_ok;
}
 
PyObject* VectorIAdd(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// Implement fast __iadd__ on std::vector (generic __iadd__ is in Python)
    ItemGetter* getter = GetGetter(args);
 
    if (getter) {
        bool fill_ok = FillVector(self, args, getter);
        delete getter;
 
        if (!fill_ok)
            return nullptr;
 
        Py_INCREF(self);
        return self;
    }
 
// if no getter, it could still be b/c we have a buffer (e.g. numpy); looping over
// a buffer here is slow, so use insert() instead
    if (PyTuple_GET_SIZE(args) == 1) {
        PyObject* fi = PyTuple_GET_ITEM(args, 0);
        if (PyObject_CheckBuffer(fi) && !(CPyCppyy_PyText_Check(fi) || PyBytes_Check(fi))) {
            PyObject* vend = PyObject_CallMethodNoArgs(self, PyStrings::gEnd);
            if (vend) {
            // when __iadd__ is overriden, the operation does not end with
            // calling the __iadd__ method, but also assigns the result to the
            // lhs of the iadd. For example, performing vec += arr, Python
            // first calls our override, and then does vec = vec.iadd(arr).
                PyObject *it = PyObject_CallMethodObjArgs(self, PyStrings::gInsert, vend, fi, nullptr);
                Py_DECREF(vend);
 
                if (!it)
                    return nullptr;
 
                Py_DECREF(it);
            // Assign the result of the __iadd__ override to the std::vector
                Py_INCREF(self);
                return self;
            }
        }
    }
 
    if (!PyErr_Occurred())
        PyErr_SetString(PyExc_TypeError, "argument is not iterable");
    return nullptr;               // error already set
}
 
 
PyObject* VectorInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// Specialized vector constructor to allow construction from containers; allowing
// such construction from initializer_list instead would possible, but can be
// error-prone. This use case is common enough for std::vector to implement it
// directly, except for arrays (which can be passed wholesale) and strings (which
// won't convert properly as they'll be seen as buffers)
 
    ItemGetter* getter = GetGetter(args);
 
    if (getter) {
    // construct an empty vector, then back-fill it
        PyObject* result = PyObject_CallMethodNoArgs(self, PyStrings::gRealInit);
        if (!result) {
            delete getter;
            return nullptr;
        }
 
        bool fill_ok = FillVector(self, args, getter);
        delete getter;
 
        if (!fill_ok) {
            Py_DECREF(result);
            return nullptr;
        }
 
        return result;
    }
 
// The given argument wasn't iterable: simply forward to regular constructor
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject* result = PyObject_Call(realInit, args, nullptr);
        Py_DECREF(realInit);
        return result;
    }
 
    return nullptr;
}
 
//---------------------------------------------------------------------------
PyObject* VectorData(PyObject* self, PyObject*)
{
    PyObject* pydata = CallPyObjMethod(self, "__real_data");
    if (!LowLevelView_Check(pydata) && !CPPInstance_Check(pydata))
        return pydata;
 
    PyObject* pylen = PyObject_CallMethodNoArgs(self, PyStrings::gSize);
    if (!pylen) {
        PyErr_Clear();
        return pydata;
    }
 
    long clen = PyInt_AsLong(pylen);
    Py_DECREF(pylen);
 
    if (CPPInstance_Check(pydata)) {
        ((CPPInstance*)pydata)->CastToArray(clen);
        return pydata;
    }
 
    ((LowLevelView*)pydata)->resize((size_t)clen);
    return pydata;
}
 
 
// This function implements __array__, added to std::vector python proxies and causes
// a bug (see explanation at Utility::AddToClass(pyclass, "__array__"...) in CPyCppyy::Pythonize)
// The recursive nature of this function, passes each subarray (pydata) to the next call and only
// the final buffer is cast to a lowlevel view and resized (in VectorData), resulting in only the
// first 1D array to be returned. See https://github.com/root-project/root/issues/17729
// It is temporarily removed to prevent errors due to -Wunused-function, since it is no longer added.
#if 0
//---------------------------------------------------------------------------
PyObject* VectorArray(PyObject* self, PyObject* args, PyObject* kwargs)
{
    PyObject* pydata = VectorData(self, nullptr);
    PyObject* arrcall = PyObject_GetAttr(pydata, PyStrings::gArray);
    PyObject* newarr = PyObject_Call(arrcall, args, kwargs);
    Py_DECREF(arrcall);
    Py_DECREF(pydata);
    return newarr;
}
#endif
 
//-----------------------------------------------------------------------------
static PyObject* vector_iter(PyObject* v) {
    vectoriterobject* vi = PyObject_GC_New(vectoriterobject, &VectorIter_Type);
    if (!vi) return nullptr;
 
    vi->ii_container = v;
 
// tell the iterator code to set a life line if this container is a temporary
    vi->vi_flags = vectoriterobject::kDefault;
#if PY_VERSION_HEX >= 0x030e0000
    if (PyUnstable_Object_IsUniqueReferencedTemporary(v) || (((CPPInstance*)v)->fFlags & CPPInstance::kIsValue))
#else
    if (Py_REFCNT(v) <= 1 || (((CPPInstance*)v)->fFlags & CPPInstance::kIsValue))
#endif
        vi->vi_flags = vectoriterobject::kNeedLifeLine;
 
    Py_INCREF(v);
 
    PyObject* pyvalue_type = PyObject_GetAttr((PyObject*)Py_TYPE(v), PyStrings::gValueType);
    if (pyvalue_type) {
        PyObject* pyvalue_size = GetAttrDirect((PyObject*)Py_TYPE(v), PyStrings::gValueSize);
        if (pyvalue_size) {
            vi->vi_stride = PyLong_AsLong(pyvalue_size);
            Py_DECREF(pyvalue_size);
        } else {
            PyErr_Clear();
            vi->vi_stride = 0;
        }
 
        if (CPyCppyy_PyText_Check(pyvalue_type)) {
            std::string value_type = CPyCppyy_PyText_AsString(pyvalue_type);
            value_type = Cppyy::ResolveName(value_type);
            vi->vi_klass = Cppyy::GetScope(value_type);
            if (!vi->vi_klass) {
            // look for a special case of pointer to a class type (which is a builtin, but it
            // is more useful to treat it polymorphically by allowing auto-downcasts)
                const std::string& clean_type = TypeManip::clean_type(value_type, false, false);
                Cppyy::TCppScope_t c = Cppyy::GetScope(clean_type);
                if (c && TypeManip::compound(value_type) == "*") {
                    vi->vi_klass = c;
                    vi->vi_flags = vectoriterobject::kIsPolymorphic;
                }
            }
            if (vi->vi_klass) {
                vi->vi_converter = nullptr;
                if (!vi->vi_flags) {
                    if (value_type.back() != '*')     // meaning, object stored by-value
                        vi->vi_flags = vectoriterobject::kNeedLifeLine;
                }
            } else
                vi->vi_converter = CPyCppyy::CreateConverter(value_type);
            if (!vi->vi_stride) vi->vi_stride = Cppyy::SizeOf(value_type);
 
        } else if (CPPScope_Check(pyvalue_type)) {
            vi->vi_klass = ((CPPClass*)pyvalue_type)->fCppType;
            vi->vi_converter = nullptr;
            if (!vi->vi_stride) vi->vi_stride = Cppyy::SizeOf(vi->vi_klass);
            if (!vi->vi_flags)  vi->vi_flags  = vectoriterobject::kNeedLifeLine;
        }
 
        PyObject* pydata = CallPyObjMethod(v, "__real_data");
        if (!pydata || Utility::GetBuffer(pydata, '*', 1, vi->vi_data, false) == 0)
            vi->vi_data = CPPInstance_Check(pydata) ? ((CPPInstance*)pydata)->GetObjectRaw() : nullptr;
        Py_XDECREF(pydata);
 
    } else {
        PyErr_Clear();
        vi->vi_data      = nullptr;
        vi->vi_stride    = 0;
        vi->vi_converter = nullptr;
        vi->vi_klass     = 0;
        vi->vi_flags     = 0;
    }
 
    Py_XDECREF(pyvalue_type);
 
    vi->ii_pos = 0;
    vi->ii_len = PySequence_Size(v);
 
    PyObject_GC_Track(vi);
    return (PyObject*)vi;
}
 
PyObject* VectorGetItem(CPPInstance* self, PySliceObject* index)
{
// Implement python's __getitem__ for std::vector<>s.
    if (PySlice_Check(index)) {
        if (!self->GetObject()) {
            PyErr_SetString(PyExc_TypeError, "unsubscriptable object");
            return nullptr;
        }
 
        PyObject* pyclass = (PyObject*)Py_TYPE((PyObject*)self);
        PyObject* nseq = PyObject_CallObject(pyclass, nullptr);
 
        Py_ssize_t start, stop, step;
        PySlice_GetIndices((CPyCppyy_PySliceCast)index, PyObject_Length((PyObject*)self), &start, &stop, &step);
 
        const Py_ssize_t nlen = PySequence_Size((PyObject*)self);
        if (!AdjustSlice(nlen, start, stop, step))
            return nseq;
 
        const Py_ssize_t sign = step < 0 ? -1 : 1;
        for (Py_ssize_t i = start; i*sign < stop*sign; i += step) {
            PyObject* pyidx = PyInt_FromSsize_t(i);
            PyObject* item = PyObject_CallMethodOneArg((PyObject*)self, PyStrings::gGetNoCheck, pyidx);
            CallPyObjMethod(nseq, "push_back", item);
            Py_DECREF(item);
            Py_DECREF(pyidx);
        }
 
        return nseq;
    }
 
    return CallSelfIndex(self, (PyObject*)index, PyStrings::gGetNoCheck);
}
 
 
static Cppyy::TCppType_t sVectorBoolTypeID = (Cppyy::TCppType_t)0;
 
PyObject* VectorBoolGetItem(CPPInstance* self, PyObject* idx)
{
// std::vector<bool> is a special-case in C++, and its return type depends on
// the compiler: treat it special here as well
    if (!CPPInstance_Check(self) || self->ObjectIsA() != sVectorBoolTypeID) {
        PyErr_Format(PyExc_TypeError,
            "require object of type std::vector<bool>, but %s given",
            Cppyy::GetScopedFinalName(self->ObjectIsA()).c_str());
        return nullptr;
    }
 
    if (!self->GetObject()) {
        PyErr_SetString(PyExc_TypeError, "unsubscriptable object");
        return nullptr;
    }
 
    if (PySlice_Check(idx)) {
        PyObject* pyclass = (PyObject*)Py_TYPE((PyObject*)self);
        PyObject* nseq = PyObject_CallObject(pyclass, nullptr);
 
        Py_ssize_t start, stop, step;
        PySlice_GetIndices((CPyCppyy_PySliceCast)idx, PyObject_Length((PyObject*)self), &start, &stop, &step);
        const Py_ssize_t nlen = PySequence_Size((PyObject*)self);
        if (!AdjustSlice(nlen, start, stop, step))
            return nseq;
 
        const Py_ssize_t sign = step < 0 ? -1 : 1;
        for (Py_ssize_t i = start; i*sign < stop*sign; i += step) {
            PyObject* pyidx = PyInt_FromSsize_t(i);
            PyObject* item = PyObject_CallMethodOneArg((PyObject*)self, PyStrings::gGetItem, pyidx);
            CallPyObjMethod(nseq, "push_back", item);
            Py_DECREF(item);
            Py_DECREF(pyidx);
        }
 
        return nseq;
    }
 
    PyObject* pyindex = PyStyleIndex((PyObject*)self, idx);
    if (!pyindex)
        return nullptr;
 
    int index = (int)PyLong_AsLong(pyindex);
    Py_DECREF(pyindex);
 
// get hold of the actual std::vector<bool> (no cast, as vector is never a base)
    std::vector<bool>* vb = (std::vector<bool>*)self->GetObject();
 
// finally, return the value
    if (bool((*vb)[index]))
        Py_RETURN_TRUE;
    Py_RETURN_FALSE;
}
 
PyObject* VectorBoolSetItem(CPPInstance* self, PyObject* args)
{
// std::vector<bool> is a special-case in C++, and its return type depends on
// the compiler: treat it special here as well
    if (!CPPInstance_Check(self) || self->ObjectIsA() != sVectorBoolTypeID) {
        PyErr_Format(PyExc_TypeError,
            "require object of type std::vector<bool>, but %s given",
            Cppyy::GetScopedFinalName(self->ObjectIsA()).c_str());
        return nullptr;
    }
 
    if (!self->GetObject()) {
        PyErr_SetString(PyExc_TypeError, "unsubscriptable object");
        return nullptr;
    }
 
    int bval = 0; PyObject* idx = nullptr;
    if (!PyArg_ParseTuple(args, const_cast<char*>("Oi:__setitem__"), &idx, &bval))
        return nullptr;
 
    PyObject* pyindex = PyStyleIndex((PyObject*)self, idx);
    if (!pyindex)
        return nullptr;
 
    int index = (int)PyLong_AsLong(pyindex);
    Py_DECREF(pyindex);
 
// get hold of the actual std::vector<bool> (no cast, as vector is never a base)
    std::vector<bool>* vb = (std::vector<bool>*)self->GetObject();
 
// finally, set the value
    (*vb)[index] = (bool)bval;
 
    Py_RETURN_NONE;
}
 
 
//- array behavior as primitives ----------------------------------------------
PyObject* ArrayInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// std::array is normally only constructed using aggregate initialization, which
// is a concept that does not exist in python, so use this custom constructor to
// to fill the array using setitem
 
    if (args && PyTuple_GET_SIZE(args) == 1 && PySequence_Check(PyTuple_GET_ITEM(args, 0))) {
    // construct the empty array, then fill it
        PyObject* result = PyObject_CallMethodNoArgs(self, PyStrings::gRealInit);
        if (!result)
            return nullptr;
 
        PyObject* items = PyTuple_GET_ITEM(args, 0);
        Py_ssize_t fillsz = PySequence_Size(items);
        if (PySequence_Size(self) != fillsz) {
            PyErr_Format(PyExc_ValueError, "received sequence of size %zd where %zd expected",
                         fillsz, PySequence_Size(self));
            Py_DECREF(result);
            return nullptr;
        }
 
        PyObject* si_call = PyObject_GetAttr(self, PyStrings::gSetItem);
        for (Py_ssize_t i = 0; i < fillsz; ++i) {
            PyObject* item = PySequence_GetItem(items, i);
            PyObject* index = PyInt_FromSsize_t(i);
            PyObject* sires = PyObject_CallFunctionObjArgs(si_call, index, item, nullptr);
            Py_DECREF(index);
            Py_DECREF(item);
            if (!sires) {
                Py_DECREF(si_call);
                Py_DECREF(result);
                return nullptr;
            } else
                Py_DECREF(sires);
        }
        Py_DECREF(si_call);
 
        return result;
    } else
        PyErr_Clear();
 
// The given argument wasn't iterable: simply forward to regular constructor
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject* result = PyObject_Call(realInit, args, nullptr);
        Py_DECREF(realInit);
        return result;
    }
 
    return nullptr;
}
 
 
//- map behavior as primitives ------------------------------------------------
static PyObject* MapFromPairs(PyObject* self, PyObject* pairs)
{
// construct an empty map, then fill it with the key, value pairs
    PyObject* result = PyObject_CallMethodNoArgs(self, PyStrings::gRealInit);
    if (!result)
        return nullptr;
 
    PyObject* si_call = PyObject_GetAttr(self, PyStrings::gSetItem);
    for (Py_ssize_t i = 0; i < PySequence_Size(pairs); ++i) {
        PyObject* pair = PySequence_GetItem(pairs, i);
        PyObject* sires = nullptr;
        if (pair && PySequence_Check(pair) && PySequence_Size(pair) == 2) {
            PyObject* key   = PySequence_GetItem(pair, 0);
            PyObject* value = PySequence_GetItem(pair, 1);
            sires = PyObject_CallFunctionObjArgs(si_call, key, value, nullptr);
            Py_DECREF(value);
            Py_DECREF(key);
        }
        Py_DECREF(pair);
        if (!sires) {
            Py_DECREF(si_call);
            Py_DECREF(result);
            if (!PyErr_Occurred())
                PyErr_SetString(PyExc_TypeError, "Failed to fill map (argument not a dict or sequence of pairs)");
            return nullptr;
        } else
            Py_DECREF(sires);
    }
    Py_DECREF(si_call);
 
    return result;
}
 
PyObject* MapInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// Specialized map constructor to allow construction from mapping containers and
// from tuples of pairs ("initializer_list style").
 
// PyMapping_Check is not very discriminatory, as it basically only checks for the
// existence of  __getitem__, hence the most common cases of tuple and list are
// dropped straight-of-the-bat (the PyMapping_Items call will fail on them).
    if (PyTuple_GET_SIZE(args) == 1 && PyMapping_Check(PyTuple_GET_ITEM(args, 0)) && \
           !(PyTuple_Check(PyTuple_GET_ITEM(args, 0)) || PyList_Check(PyTuple_GET_ITEM(args, 0)))) {
        PyObject* assoc = PyTuple_GET_ITEM(args, 0);
#if PY_VERSION_HEX < 0x03000000
    // to prevent warning about literal string, expand macro
        PyObject* items = PyObject_CallMethod(assoc, (char*)"items", nullptr);
#else
    // in p3, PyMapping_Items isn't a macro, but a function that short-circuits dict
        PyObject* items = PyMapping_Items(assoc);
#endif
        if (items && PySequence_Check(items)) {
            PyObject* result = MapFromPairs(self, items);
            Py_DECREF(items);
            return result;
        }
 
        Py_XDECREF(items);
        PyErr_Clear();
 
    // okay to fall through as long as 'self' has not been created (is done in MapFromPairs)
    }
 
// tuple of pairs case (some mapping types are sequences)
    if (PyTuple_GET_SIZE(args) == 1 && PySequence_Check(PyTuple_GET_ITEM(args, 0)))
        return MapFromPairs(self, PyTuple_GET_ITEM(args, 0));
 
// The given argument wasn't a mapping or tuple of pairs: forward to regular constructor
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject* result = PyObject_Call(realInit, args, nullptr);
        Py_DECREF(realInit);
        return result;
    }
 
    return nullptr;
}
 
#if __cplusplus <= 202002L
PyObject* STLContainsWithFind(PyObject* self, PyObject* obj)
{
// Implement python's __contains__ for std::map/std::set
    PyObject* result = nullptr;
 
    PyObject* iter = CallPyObjMethod(self, "find", obj);
    if (CPPInstance_Check(iter)) {
        PyObject* end = PyObject_CallMethodNoArgs(self, PyStrings::gEnd);
        if (CPPInstance_Check(end)) {
            if (!PyObject_RichCompareBool(iter, end, Py_EQ)) {
                Py_INCREF(Py_True);
                result = Py_True;
            }
        }
        Py_XDECREF(end);
    }
    Py_XDECREF(iter);
 
    if (!result) {
        PyErr_Clear();            // e.g. wrong argument type, which should always lead to False
        Py_INCREF(Py_False);
        result = Py_False;
    }
 
    return result;
}
#endif
 
 
//- set behavior as primitives ------------------------------------------------
PyObject* SetInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// Specialized set constructor to allow construction from Python sets.
    if (PyTuple_GET_SIZE(args) == 1 && PySet_Check(PyTuple_GET_ITEM(args, 0))) {
        PyObject* pyset = PyTuple_GET_ITEM(args, 0);
 
    // construct an empty set, then fill it
        PyObject* result = PyObject_CallMethodNoArgs(self, PyStrings::gRealInit);
        if (!result)
            return nullptr;
 
        PyObject* iter = PyObject_GetIter(pyset);
        if (iter) {
            PyObject* ins_call = PyObject_GetAttrString(self, (char*)"insert");
 
            IterItemGetter getter{iter};
            Py_DECREF(iter);
 
            PyObject* item = getter.get();
            while (item) {
                PyObject* insres = PyObject_CallFunctionObjArgs(ins_call, item, nullptr);
                Py_DECREF(item);
                if (!insres) {
                    Py_DECREF(ins_call);
                    Py_DECREF(result);
                    return nullptr;
                } else
                    Py_DECREF(insres);
                item = getter.get();
            }
            Py_DECREF(ins_call);
        }
 
        return result;
    }
 
// The given argument wasn't iterable: simply forward to regular constructor
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject* result = PyObject_Call(realInit, args, nullptr);
        Py_DECREF(realInit);
        return result;
    }
 
    return nullptr;
}
 
 
//- STL container iterator support --------------------------------------------
static const ptrdiff_t PS_END_ADDR  =  7;   // non-aligned address, so no clash
static const ptrdiff_t PS_FLAG_ADDR = 11;   // id.
static const ptrdiff_t PS_COLL_ADDR = 13;   // id.
 
PyObject* LLSequenceIter(PyObject* self)
{
// Implement python's __iter__ for low level views used through STL-type begin()/end()
    PyObject* iter = PyObject_CallMethodNoArgs(self, PyStrings::gBegin);
 
    if (LowLevelView_Check(iter)) {
    // builtin pointer iteration: can only succeed if a size is available
        Py_ssize_t sz = PySequence_Size(self);
        if (sz == -1) {
            Py_DECREF(iter);
            return nullptr;
        }
        PyObject* lliter = Py_TYPE(iter)->tp_iter(iter);
        ((indexiterobject*)lliter)->ii_len = sz;
        Py_DECREF(iter);
        return lliter;
    }
 
    if (iter) {
        Py_DECREF(iter);
        PyErr_SetString(PyExc_TypeError, "unrecognized iterator type for low level views");
    }
 
    return nullptr;
}
 
PyObject* STLSequenceIter(PyObject* self)
{
// Implement python's __iter__ for std::iterator<>s
    PyObject* iter = PyObject_CallMethodNoArgs(self, PyStrings::gBegin);
    if (iter) {
        PyObject* end = PyObject_CallMethodNoArgs(self, PyStrings::gEnd);
        if (end) {
            if (CPPInstance_Check(iter)) {
            // use the data member cache to store extra state on the iterator object,
            // without it being visible on the Python side
                auto& dmc = ((CPPInstance*)iter)->GetDatamemberCache();
                dmc.push_back(std::make_pair(PS_END_ADDR, end));
 
            // set a flag, indicating first iteration (reset in __next__)
                Py_INCREF(Py_False);
                dmc.push_back(std::make_pair(PS_FLAG_ADDR, Py_False));
 
            // make sure the iterated over collection remains alive for the duration
                Py_INCREF(self);
                dmc.push_back(std::make_pair(PS_COLL_ADDR, self));
            } else {
            // could store "end" on the object's dictionary anyway, but if end() returns
            // a user-customized object, then its __next__ is probably custom, too
                Py_DECREF(end);
            }
        }
    }
    return iter;
}
 
//- generic iterator support over a sequence with operator[] and size ---------
//-----------------------------------------------------------------------------
static PyObject* index_iter(PyObject* c) {
    indexiterobject* ii = PyObject_GC_New(indexiterobject, &IndexIter_Type);
    if (!ii) return nullptr;
 
    Py_INCREF(c);
    ii->ii_container = c;
    ii->ii_pos = 0;
    ii->ii_len = PySequence_Size(c);
 
    PyObject_GC_Track(ii);
    return (PyObject*)ii;
}
 
 
//- safe indexing for STL-like vector w/o iterator dictionaries ---------------
/* replaced by indexiterobject iteration, but may still have some future use ...
PyObject* CheckedGetItem(PyObject* self, PyObject* obj)
{
// Implement a generic python __getitem__ for STL-like classes that are missing the
// reflection info for their iterators. This is then used for iteration by means of
// consecutive indices, it such index is of integer type.
    Py_ssize_t size = PySequence_Size(self);
    Py_ssize_t idx  = PyInt_AsSsize_t(obj);
    if ((size == (Py_ssize_t)-1 || idx == (Py_ssize_t)-1) && PyErr_Occurred()) {
    // argument conversion problem: let method itself resolve anew and report
        PyErr_Clear();
        return PyObject_CallMethodOneArg(self, PyStrings::gGetNoCheck, obj);
    }
 
    bool inbounds = false;
    if (idx < 0) idx += size;
    if (0 <= idx && 0 <= size && idx < size)
        inbounds = true;
 
    if (inbounds)
        return PyObject_CallMethodOneArg(self, PyStrings::gGetNoCheck, obj);
    else
        PyErr_SetString( PyExc_IndexError, "index out of range" );
 
    return nullptr;
}*/
 
 
//- pair as sequence to allow tuple unpacking --------------------------------
PyObject* PairUnpack(PyObject* self, PyObject* pyindex)
{
// For std::map<> iteration, unpack std::pair<>s into tuples for the loop.
    long idx = PyLong_AsLong(pyindex);
    if (idx == -1 && PyErr_Occurred())
        return nullptr;
 
    if (!CPPInstance_Check(self) || !((CPPInstance*)self)->GetObject()) {
        PyErr_SetString(PyExc_TypeError, "unsubscriptable object");
        return nullptr;
    }
 
    if ((int)idx == 0)
        return PyObject_GetAttr(self, PyStrings::gFirst);
    else if ((int)idx == 1)
        return PyObject_GetAttr(self, PyStrings::gSecond);
 
// still here? Trigger stop iteration
    PyErr_SetString(PyExc_IndexError, "out of bounds");
    return nullptr;
}
 
//- simplistic len() functions -----------------------------------------------
PyObject* ReturnTwo(CPPInstance*, PyObject*) {
    return PyInt_FromLong(2);
}
 
 
//- shared/unique_ptr behavior -----------------------------------------------
PyObject* SmartPtrInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// since the shared/unique pointer will take ownership, we need to relinquish it
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject* result = PyObject_Call(realInit, args, nullptr);
        Py_DECREF(realInit);
        if (result && PyTuple_GET_SIZE(args) == 1 && CPPInstance_Check(PyTuple_GET_ITEM(args, 0))) {
            CPPInstance* cppinst = (CPPInstance*)PyTuple_GET_ITEM(args, 0);
            if (!(cppinst->fFlags & CPPInstance::kIsSmartPtr)) cppinst->CppOwns();
        }
        return result;
    }
    return nullptr;
}
 
 
//- string behavior as primitives --------------------------------------------
#if PY_VERSION_HEX >= 0x03000000
// TODO: this is wrong, b/c it doesn't order
static int PyObject_Compare(PyObject* one, PyObject* other) {
    return !PyObject_RichCompareBool(one, other, Py_EQ);
}
#endif
static inline
PyObject* CPyCppyy_PyString_FromCppString(std::string_view s, bool native=true) {
    if (native)
        return PyBytes_FromStringAndSize(s.data(), s.size());
    return CPyCppyy_PyText_FromStringAndSize(s.data(), s.size());
}
 
static inline
PyObject* CPyCppyy_PyString_FromCppString(std::wstring_view s, bool native=true) {
    PyObject* pyobj = PyUnicode_FromWideChar(s.data(), s.size());
    if (pyobj && native) {
        PyObject* pybytes = PyUnicode_AsEncodedString(pyobj, "UTF-8", "strict");
        Py_DECREF(pyobj);
        pyobj = pybytes;
    }
    return pyobj;
}
 
#define CPPYY_IMPL_STRING_PYTHONIZATION(type, name)                          \
static inline                                                                \
PyObject* name##StringGetData(PyObject* self, bool native=true)              \
{                                                                            \
    if (CPyCppyy::CPPInstance_Check(self)) {                                 \
        type* obj = ((type*)((CPPInstance*)self)->GetObject());              \
        if (obj) return CPyCppyy_PyString_FromCppString(*obj, native);        \
    }                                                                        \
    PyErr_Format(PyExc_TypeError, "object mismatch (%s expected)", #type);   \
    return nullptr;                                                          \
}                                                                            \
                                                                             \
PyObject* name##StringStr(PyObject* self)                                    \
{                                                                            \
    PyObject* pyobj = name##StringGetData(self, false);                      \
    if (!pyobj) {                                                            \
      /* do a native conversion to make printing possible (debatable) */     \
        PyErr_Clear();                                                       \
        PyObject* pybytes = name##StringGetData(self, true);                 \
        if (pybytes) { /* should not fail */                                 \
            pyobj = PyObject_Str(pybytes);                                   \
            Py_DECREF(pybytes);                                              \
        }                                                                    \
    }                                                                        \
    return pyobj;                                                            \
}                                                                            \
                                                                             \
PyObject* name##StringBytes(PyObject* self)                                  \
{                                                                            \
    return name##StringGetData(self, true);                                  \
}                                                                            \
                                                                             \
PyObject* name##StringRepr(PyObject* self)                                   \
{                                                                            \
    PyObject* data = name##StringGetData(self, true);                        \
    if (data) {                                                              \
        PyObject* repr = PyObject_Repr(data);                                \
        Py_DECREF(data);                                                     \
        return repr;                                                         \
    }                                                                        \
    return nullptr;                                                          \
}                                                                            \
                                                                             \
PyObject* name##StringIsEqual(PyObject* self, PyObject* obj)                 \
{                                                                            \
    PyObject* data = name##StringGetData(self, PyBytes_Check(obj));          \
    if (data) {                                                              \
        PyObject* result = PyObject_RichCompare(data, obj, Py_EQ);           \
        Py_DECREF(data);                                                     \
        return result;                                                       \
    }                                                                        \
    return nullptr;                                                          \
}                                                                            \
                                                                             \
PyObject* name##StringIsNotEqual(PyObject* self, PyObject* obj)              \
{                                                                            \
    PyObject* data = name##StringGetData(self, PyBytes_Check(obj));          \
    if (data) {                                                              \
        PyObject* result = PyObject_RichCompare(data, obj, Py_NE);           \
        Py_DECREF(data);                                                     \
        return result;                                                       \
    }                                                                        \
    return nullptr;                                                          \
}
 
// Only define STLStringCompare:
#define CPPYY_IMPL_STRING_PYTHONIZATION_CMP(type, name)                      \
CPPYY_IMPL_STRING_PYTHONIZATION(type, name)                                  \
PyObject* name##StringCompare(PyObject* self, PyObject* obj)                 \
{                                                                            \
    PyObject* data = name##StringGetData(self, PyBytes_Check(obj));          \
    int result = 0;                                                          \
    if (data) {                                                              \
        result = PyObject_Compare(data, obj);                                \
        Py_DECREF(data);                                                     \
    }                                                                        \
    if (PyErr_Occurred())                                                    \
        return nullptr;                                                      \
    return PyInt_FromLong(result);                                           \
}
 
CPPYY_IMPL_STRING_PYTHONIZATION_CMP(std::string, STL)
CPPYY_IMPL_STRING_PYTHONIZATION_CMP(std::wstring, STLW)
CPPYY_IMPL_STRING_PYTHONIZATION_CMP(std::string_view, STLView)
 
static inline std::string* GetSTLString(CPPInstance* self) {
    if (!CPPInstance_Check(self)) {
        PyErr_SetString(PyExc_TypeError, "std::string object expected");
        return nullptr;
    }
 
    std::string* obj = (std::string*)self->GetObject();
    if (!obj)
        PyErr_SetString(PyExc_ReferenceError, "attempt to access a null-pointer");
 
    return obj;
}
 
PyObject* STLStringDecode(CPPInstance* self, PyObject* args, PyObject* kwds)
{
    std::string* obj = GetSTLString(self);
    if (!obj)
        return nullptr;
 
    char* keywords[] = {(char*)"encoding", (char*)"errors", (char*)nullptr};
    const char* encoding = nullptr; const char* errors = nullptr;
    if (!PyArg_ParseTupleAndKeywords(args, kwds,
            const_cast<char*>("s|s"), keywords, &encoding, &errors))
        return nullptr;
 
    return PyUnicode_Decode(obj->data(), obj->size(), encoding, errors);
}
 
#if __cplusplus <= 202302L
PyObject* STLStringContains(CPPInstance* self, PyObject* pyobj)
{
    std::string* obj = GetSTLString(self);
    if (!obj)
        return nullptr;
 
    const char* needle = CPyCppyy_PyText_AsString(pyobj);
    if (!needle)
        return nullptr;
 
    if (obj->find(needle) != std::string::npos) {
        Py_RETURN_TRUE;
    }
 
    Py_RETURN_FALSE;
}
#endif
 
PyObject* STLStringReplace(CPPInstance* self, PyObject* args, PyObject* /*kwds*/)
{
    std::string* obj = GetSTLString(self);
    if (!obj)
        return nullptr;
 
// both str and std::string have a method "replace", but the Python version only
// accepts strings and takes no keyword arguments, whereas the C++ version has no
// overload that takes a string
 
    if (2 <= PyTuple_GET_SIZE(args) && CPyCppyy_PyText_Check(PyTuple_GET_ITEM(args, 0))) {
        PyObject* pystr = CPyCppyy_PyText_FromStringAndSize(obj->data(), obj->size());
        PyObject* meth = PyObject_GetAttrString(pystr, (char*)"replace");
        Py_DECREF(pystr);
        PyObject* result = PyObject_CallObject(meth, args);
        Py_DECREF(meth);
        return result;
    }
 
    PyObject* cppreplace = PyObject_GetAttrString((PyObject*)self, (char*)"__cpp_replace");
    if (cppreplace) {
        PyObject* result = PyObject_Call(cppreplace, args, nullptr);
        Py_DECREF(cppreplace);
        return result;
    }
 
    PyErr_SetString(PyExc_AttributeError, "\'std::string\' object has no attribute \'replace\'");
    return nullptr;
}
 
#define CPYCPPYY_STRING_FINDMETHOD(name, cppname, pyname)                    \
PyObject* STLString##name(CPPInstance* self, PyObject* args, PyObject* /*kwds*/) \
{                                                                            \
    std::string* obj = GetSTLString(self);                                   \
    if (!obj)                                                                \
        return nullptr;                                                      \
                                                                             \
    PyObject* cppmeth = PyObject_GetAttrString((PyObject*)self, (char*)#cppname);\
    if (cppmeth) {                                                           \
        PyObject* result = PyObject_Call(cppmeth, args, nullptr);            \
        Py_DECREF(cppmeth);                                                  \
        if (result) {                                                        \
            if (PyLongOrInt_AsULong64(result) == (PY_ULONG_LONG)std::string::npos) {\
                Py_DECREF(result);                                           \
                return PyInt_FromLong(-1);                                   \
            }                                                                \
            return result;                                                   \
        }                                                                    \
        PyErr_Clear();                                                       \
    }                                                                        \
                                                                             \
    PyObject* pystr = CPyCppyy_PyText_FromStringAndSize(obj->data(), obj->size());\
    PyObject* pymeth = PyObject_GetAttrString(pystr, (char*)#pyname);        \
    Py_DECREF(pystr);                                                        \
    PyObject* result = PyObject_CallObject(pymeth, args);                    \
    Py_DECREF(pymeth);                                                       \
    return result;                                                           \
}
 
// both str and std::string have method "find" and "rfin"; try the C++ version first
// and fall back on the Python one in case of failure
CPYCPPYY_STRING_FINDMETHOD( Find, __cpp_find,  find)
CPYCPPYY_STRING_FINDMETHOD(RFind, __cpp_rfind, rfind)
 
PyObject* STLStringGetAttr(CPPInstance* self, PyObject* attr_name)
{
    std::string* obj = GetSTLString(self);
    if (!obj)
        return nullptr;
 
    PyObject* pystr = CPyCppyy_PyText_FromStringAndSize(obj->data(), obj->size());
    PyObject* attr = PyObject_GetAttr(pystr, attr_name);
    Py_DECREF(pystr);
    return attr;
}
 
 
#if 0
PyObject* UTF8Repr(PyObject* self)
{
// force C++ string types conversion to Python str per Python __repr__ requirements
    PyObject* res = PyObject_CallMethodNoArgs(self, PyStrings::gCppRepr);
    if (!res || CPyCppyy_PyText_Check(res))
        return res;
    PyObject* str_res = PyObject_Str(res);
    Py_DECREF(res);
    return str_res;
}
 
PyObject* UTF8Str(PyObject* self)
{
// force C++ string types conversion to Python str per Python __str__ requirements
    PyObject* res = PyObject_CallMethodNoArgs(self, PyStrings::gCppStr);
    if (!res || CPyCppyy_PyText_Check(res))
        return res;
    PyObject* str_res = PyObject_Str(res);
    Py_DECREF(res);
    return str_res;
}
#endif
 
Py_hash_t STLStringHash(PyObject* self)
{
// std::string objects hash to the same values as Python strings to allow
// matches in dictionaries etc.
    PyObject* data = STLStringGetData(self, false);
    Py_hash_t h = CPyCppyy_PyText_Type.tp_hash(data);
    Py_DECREF(data);
    return h;
}
 
 
//- string_view behavior as primitive ----------------------------------------
PyObject* StringViewInit(PyObject* self, PyObject* args, PyObject* /* kwds */)
{
// if constructed from a Python unicode object, the constructor will convert it
// to a temporary byte string, which is likely to go out of scope too soon; so
// buffer it as needed
    PyObject* realInit = PyObject_GetAttr(self, PyStrings::gRealInit);
    if (realInit) {
        PyObject *strbuf = nullptr, *newArgs = nullptr;
        if (PyTuple_GET_SIZE(args) == 1) {
            PyObject* arg0 = PyTuple_GET_ITEM(args, 0);
            if (PyUnicode_Check(arg0)) {
            // convert to the expected bytes array to control the temporary
                strbuf = PyUnicode_AsEncodedString(arg0, "UTF-8", "strict");
                newArgs = PyTuple_New(1);
                Py_INCREF(strbuf);
                PyTuple_SET_ITEM(newArgs, 0, strbuf);
            } else if (PyBytes_Check(arg0)) {
            // tie the life time of the provided string to the string_view
                Py_INCREF(arg0);
                strbuf = arg0;
            }
        }
 
        PyObject* result = PyObject_Call(realInit, newArgs ? newArgs : args, nullptr);
 
        Py_XDECREF(newArgs);
        Py_DECREF(realInit);
 
    // if construction was successful and a string buffer was used, add a
    // life line to it from the string_view bound object
        if (result && self && strbuf)
            PyObject_SetAttr(self, PyStrings::gLifeLine, strbuf);
        Py_XDECREF(strbuf);
 
        return result;
    }
    return nullptr;
}
 
 
//- STL iterator behavior ----------------------------------------------------
PyObject* STLIterNext(PyObject* self)
{
// Python iterator protocol __next__ for STL forward iterators.
    bool mustIncrement = true;
    PyObject* last = nullptr;
    if (CPPInstance_Check(self)) {
        auto& dmc = ((CPPInstance*)self)->GetDatamemberCache();
        for (auto& p: dmc) {
            if (p.first == PS_END_ADDR) {
                last = p.second;
                Py_INCREF(last);
            } else if (p.first == PS_FLAG_ADDR) {
                mustIncrement = p.second == Py_True;
                if (!mustIncrement) {
                    Py_DECREF(p.second);
                    Py_INCREF(Py_True);
                    p.second = Py_True;
                }
            }
        }
    }
 
    PyObject* next = nullptr;
    if (last) {
    // handle special case of empty container (i.e. self is end)
        if (!PyObject_RichCompareBool(last, self, Py_EQ)) {
            bool iter_valid = true;
            if (mustIncrement) {
            // prefer preinc, but allow post-inc; in both cases, it is "self" that has
            // the updated state to dereference
                PyObject* iter = PyObject_CallMethodNoArgs(self, PyStrings::gPreInc);
                if (!iter) {
                    PyErr_Clear();
                    static PyObject* dummy = PyInt_FromLong(1l);
                    iter = PyObject_CallMethodOneArg(self, PyStrings::gPostInc, dummy);
                }
                iter_valid = iter && PyObject_RichCompareBool(last, self, Py_NE);
                Py_XDECREF(iter);
            }
 
            if (iter_valid) {
                next = PyObject_CallMethodNoArgs(self, PyStrings::gDeref);
                if (!next) PyErr_Clear();
            }
        }
        Py_DECREF(last);
    }
 
    if (!next) PyErr_SetString(PyExc_StopIteration, "");
    return next;
}
 
 
//- STL complex<T> behavior --------------------------------------------------
#define COMPLEX_METH_GETSET(name, cppname)                                   \
static PyObject* name##ComplexGet(PyObject* self, void*) {                   \
    return PyObject_CallMethodNoArgs(self, cppname);                         \
}                                                                            \
static int name##ComplexSet(PyObject* self, PyObject* value, void*) {        \
    PyObject* result = PyObject_CallMethodOneArg(self, cppname, value);      \
    if (result) {                                                            \
        Py_DECREF(result);                                                   \
        return 0;                                                            \
    }                                                                        \
    return -1;                                                               \
}                                                                            \
PyGetSetDef name##Complex{(char*)#name, (getter)name##ComplexGet, (setter)name##ComplexSet, nullptr, nullptr};
 
COMPLEX_METH_GETSET(real, PyStrings::gCppReal)
COMPLEX_METH_GETSET(imag, PyStrings::gCppImag)
 
static PyObject* ComplexComplex(PyObject* self) {
    PyObject* real = PyObject_CallMethodNoArgs(self, PyStrings::gCppReal);
    if (!real) return nullptr;
    double r = PyFloat_AsDouble(real);
    Py_DECREF(real);
    if (r == -1. && PyErr_Occurred())
        return nullptr;
 
    PyObject* imag = PyObject_CallMethodNoArgs(self, PyStrings::gCppImag);
    if (!imag) return nullptr;
    double i = PyFloat_AsDouble(imag);
    Py_DECREF(imag);
    if (i == -1. && PyErr_Occurred())
        return nullptr;
 
    return PyComplex_FromDoubles(r, i);
}
 
static PyObject* ComplexRepr(PyObject* self) {
    PyObject* real = PyObject_CallMethodNoArgs(self, PyStrings::gCppReal);
    if (!real) return nullptr;
    double r = PyFloat_AsDouble(real);
    Py_DECREF(real);
    if (r == -1. && PyErr_Occurred())
        return nullptr;
 
    PyObject* imag = PyObject_CallMethodNoArgs(self, PyStrings::gCppImag);
    if (!imag) return nullptr;
    double i = PyFloat_AsDouble(imag);
    Py_DECREF(imag);
    if (i == -1. && PyErr_Occurred())
        return nullptr;
 
    std::ostringstream s;
    s << '(' << r << '+' << i << "j)";
    return CPyCppyy_PyText_FromString(s.str().c_str());
}
 
static PyObject* ComplexDRealGet(CPPInstance* self, void*)
{
    return PyFloat_FromDouble(((std::complex<double>*)self->GetObject())->real());
}
 
static int ComplexDRealSet(CPPInstance* self, PyObject* value, void*)
{
    double d = PyFloat_AsDouble(value);
    if (d == -1.0 && PyErr_Occurred())
        return -1;
    ((std::complex<double>*)self->GetObject())->real(d);
    return 0;
}
 
PyGetSetDef ComplexDReal{(char*)"real", (getter)ComplexDRealGet, (setter)ComplexDRealSet, nullptr, nullptr};
 
 
static PyObject* ComplexDImagGet(CPPInstance* self, void*)
{
    return PyFloat_FromDouble(((std::complex<double>*)self->GetObject())->imag());
}
 
static int ComplexDImagSet(CPPInstance* self, PyObject* value, void*)
{
    double d = PyFloat_AsDouble(value);
    if (d == -1.0 && PyErr_Occurred())
        return -1;
    ((std::complex<double>*)self->GetObject())->imag(d);
    return 0;
}
 
PyGetSetDef ComplexDImag{(char*)"imag", (getter)ComplexDImagGet, (setter)ComplexDImagSet, nullptr, nullptr};
 
static PyObject* ComplexDComplex(CPPInstance* self)
{
    double r = ((std::complex<double>*)self->GetObject())->real();
    double i = ((std::complex<double>*)self->GetObject())->imag();
    return PyComplex_FromDoubles(r, i);
}
 
 
} // unnamed namespace
 
 
//- public functions ---------------------------------------------------------
namespace CPyCppyy {
    std::set<std::string> gIteratorTypes;
}
 
static inline
bool run_pythonizors(PyObject* pyclass, PyObject* pyname, const std::vector<PyObject*>& v)
{
    PyObject* args = PyTuple_New(2);
    Py_INCREF(pyclass); PyTuple_SET_ITEM(args, 0, pyclass);
    Py_INCREF(pyname);  PyTuple_SET_ITEM(args, 1, pyname);
 
    bool pstatus = true;
    for (auto pythonizor : v) {
        PyObject* result = PyObject_CallObject(pythonizor, args);
        if (!result) {
            pstatus = false; // TODO: detail the error handling
            break;
        }
        Py_DECREF(result);
    }
    Py_DECREF(args);
 
    return pstatus;
}
 
bool CPyCppyy::Pythonize(PyObject* pyclass, const std::string& name)
{
// Add pre-defined pythonizations (for STL and ROOT) to classes based on their
// signature and/or class name.
    if (!pyclass)
        return false;
 
   CPPScope* klass = (CPPScope*)pyclass;
 
//- method name based pythonization ------------------------------------------
 
// for smart pointer style classes that are otherwise not known as such; would
// prefer operator-> as that returns a pointer (which is simpler since it never
// has to deal with ref-assignment), but operator* plays better with STL iters
// and algorithms
    if (HasAttrDirect(pyclass, PyStrings::gDeref) && !Cppyy::IsSmartPtr(klass->fCppType))
        Utility::AddToClass(pyclass, "__getattr__", (PyCFunction)DeRefGetAttr, METH_O);
    else if (HasAttrDirect(pyclass, PyStrings::gFollow) && !Cppyy::IsSmartPtr(klass->fCppType))
        Utility::AddToClass(pyclass, "__getattr__", (PyCFunction)FollowGetAttr, METH_O);
 
// for pre-check of nullptr for boolean types
    if (HasAttrDirect(pyclass, PyStrings::gCppBool)) {
#if PY_VERSION_HEX >= 0x03000000
        const char* pybool_name = "__bool__";
#else
        const char* pybool_name = "__nonzero__";
#endif
        Utility::AddToClass(pyclass, pybool_name, (PyCFunction)NullCheckBool, METH_NOARGS);
    }
 
// for STL containers, and user classes modeled after them
// the attribute must be a CPyCppyy overload, otherwise the check gives false
// positives in the case where the class has a non-function attribute that is
// called "size".
    if (HasAttrDirect(pyclass, PyStrings::gSize, /*mustBeCPyCppyy=*/ true)) {
        Utility::AddToClass(pyclass, "__len__", "size");
    }
 
    if (HasAttrDirect(pyclass, PyStrings::gContains)) {
        Utility::AddToClass(pyclass, "__contains__", "contains");
    }
 
    if (!IsTemplatedSTLClass(name, "vector")  &&      // vector is dealt with below
           !((PyTypeObject*)pyclass)->tp_iter) {
        if (HasAttrDirect(pyclass, PyStrings::gBegin) && HasAttrDirect(pyclass, PyStrings::gEnd)) {
        // obtain the name of the return type
            const auto& v = Cppyy::GetMethodIndicesFromName(klass->fCppType, "begin");
            if (!v.empty()) {
            // check return type; if not explicitly an iterator, add it to the "known" return
            // types to add the "next" method on use
                Cppyy::TCppMethod_t meth = Cppyy::GetMethod(klass->fCppType, v[0]);
                const std::string& resname = Cppyy::GetMethodResultType(meth);
                bool isIterator = gIteratorTypes.find(resname) != gIteratorTypes.end();
                if (!isIterator && Cppyy::GetScope(resname)) {
                    if (resname.find("iterator") == std::string::npos)
                        gIteratorTypes.insert(resname);
                    isIterator = true;
                }
 
                if (isIterator) {
                // install iterator protocol a la STL
                    ((PyTypeObject*)pyclass)->tp_iter = (getiterfunc)STLSequenceIter;
                    Utility::AddToClass(pyclass, "__iter__", (PyCFunction)STLSequenceIter, METH_NOARGS);
                } else {
                // still okay if this is some pointer type of builtin persuasion (general class
                // won't work: the return type needs to understand the iterator protocol)
                    std::string resolved = Cppyy::ResolveName(resname);
                    if (resolved.back() == '*' && Cppyy::IsBuiltin(resolved.substr(0, resolved.size()-1))) {
                        ((PyTypeObject*)pyclass)->tp_iter = (getiterfunc)LLSequenceIter;
                        Utility::AddToClass(pyclass, "__iter__", (PyCFunction)LLSequenceIter, METH_NOARGS);
                    }
                }
            }
        }
        if (!((PyTypeObject*)pyclass)->tp_iter &&     // no iterator resolved
                HasAttrDirect(pyclass, PyStrings::gGetItem) && PyObject_HasAttr(pyclass, PyStrings::gLen)) {
        // Python will iterate over __getitem__ using integers, but C++ operator[] will never raise
        // a StopIteration. A checked getitem (raising IndexError if beyond size()) works in some
        // cases but would mess up if operator[] is meant to implement an associative container. So,
        // this has to be implemented as an iterator protocol.
            ((PyTypeObject*)pyclass)->tp_iter = (getiterfunc)index_iter;
            Utility::AddToClass(pyclass, "__iter__", (PyCFunction)index_iter, METH_NOARGS);
        }
    }
 
// operator==/!= are used in op_richcompare of CPPInstance, which subsequently allows
// comparisons to None; if no operator is available, a hook is installed for lazy
// lookups in the global and/or class namespace
    if (HasAttrDirect(pyclass, PyStrings::gEq, true) && \
            Cppyy::GetMethodIndicesFromName(klass->fCppType, "__eq__").empty()) {
        PyObject* cppol = PyObject_GetAttr(pyclass, PyStrings::gEq);
        if (!klass->fOperators) klass->fOperators = new Utility::PyOperators();
        klass->fOperators->fEq = cppol;
    // re-insert the forwarding __eq__ from the CPPInstance in case there was a Python-side
    // override in the base class
        static PyObject* top_eq = nullptr;
        if (!top_eq) {
            PyObject* top_cls = PyObject_GetAttrString(gThisModule, "CPPInstance");
            top_eq = PyObject_GetAttr(top_cls, PyStrings::gEq);
            Py_DECREF(top_eq);    // make it borrowed
            Py_DECREF(top_cls);
        }
        PyObject_SetAttr(pyclass, PyStrings::gEq, top_eq);
    }
 
    if (HasAttrDirect(pyclass, PyStrings::gNe, true) && \
            Cppyy::GetMethodIndicesFromName(klass->fCppType, "__ne__").empty()) {
        PyObject* cppol = PyObject_GetAttr(pyclass, PyStrings::gNe);
        if (!klass->fOperators) klass->fOperators = new Utility::PyOperators();
        klass->fOperators->fNe = cppol;
    // re-insert the forwarding __ne__ (same reason as above for __eq__)
        static PyObject* top_ne = nullptr;
        if (!top_ne) {
            PyObject* top_cls = PyObject_GetAttrString(gThisModule, "CPPInstance");
            top_ne = PyObject_GetAttr(top_cls, PyStrings::gNe);
            Py_DECREF(top_ne);    // make it borrowed
            Py_DECREF(top_cls);
        }
        PyObject_SetAttr(pyclass, PyStrings::gNe, top_ne);
    }
 
#if 0
    if (HasAttrDirect(pyclass, PyStrings::gRepr, true)) {
    // guarantee that the result of __repr__ is a Python string
        Utility::AddToClass(pyclass, "__cpp_repr", "__repr__");
        Utility::AddToClass(pyclass, "__repr__", (PyCFunction)UTF8Repr, METH_NOARGS);
    }
 
    if (HasAttrDirect(pyclass, PyStrings::gStr, true)) {
    // guarantee that the result of __str__ is a Python string
        Utility::AddToClass(pyclass, "__cpp_str", "__str__");
        Utility::AddToClass(pyclass, "__str__", (PyCFunction)UTF8Str, METH_NOARGS);
    }
#endif
 
    if (Cppyy::IsAggregate(((CPPClass*)pyclass)->fCppType) && name.compare(0, 5, "std::", 5) != 0 &&
        name.compare(0, 6, "tuple<", 6) != 0) {
    // create a pseudo-constructor to allow initializer-style object creation
        Cppyy::TCppType_t kls = ((CPPClass*)pyclass)->fCppType;
        Cppyy::TCppIndex_t ndata = Cppyy::GetNumDatamembers(kls);
        if (ndata) {
            std::string rname = name;
            TypeManip::cppscope_to_legalname(rname);
 
            std::ostringstream initdef;
            initdef << "namespace __cppyy_internal {\n"
                    << "void init_" << rname << "(" << name << "*& self";
            bool codegen_ok = true;
            std::vector<std::string> arg_types, arg_names, arg_defaults;
            arg_types.reserve(ndata); arg_names.reserve(ndata); arg_defaults.reserve(ndata);
            for (Cppyy::TCppIndex_t i = 0; i < ndata; ++i) {
                if (Cppyy::IsStaticData(kls, i) || !Cppyy::IsPublicData(kls, i))
                    continue;
 
                const std::string& txt = Cppyy::GetDatamemberType(kls, i);
                const std::string& res = Cppyy::IsEnum(txt) ? txt : Cppyy::ResolveName(txt);
                const std::string& cpd = TypeManip::compound(res);
                std::string res_clean = TypeManip::clean_type(res, false, true);
 
                if (res_clean == "internal_enum_type_t")
                    res_clean = txt;        // restore (properly scoped name)
 
                if (res.rfind(']') == std::string::npos && res.rfind(')') == std::string::npos) {
                    if (!cpd.empty()) arg_types.push_back(res_clean+cpd);
                    else arg_types.push_back("const "+res_clean+"&");
                    arg_names.push_back(Cppyy::GetDatamemberName(kls, i));
                    if ((!cpd.empty() && cpd.back() == '*') || Cppyy::IsBuiltin(res_clean))
                        arg_defaults.push_back("0");
                    else {
                        Cppyy::TCppScope_t klsid = Cppyy::GetScope(res_clean);
                        if (Cppyy::IsDefaultConstructable(klsid)) arg_defaults.push_back(res_clean+"{}");
                    }
                } else {
                    codegen_ok = false;     // TODO: how to support arrays, anonymous enums, etc?
                    break;
                }
            }
 
            if (codegen_ok && !arg_types.empty()) {
                bool defaults_ok = arg_defaults.size() == arg_types.size();
                for (std::vector<std::string>::size_type i = 0; i < arg_types.size(); ++i) {
                    initdef << ", " << arg_types[i] << " " << arg_names[i];
                    if (defaults_ok) initdef << " = " << arg_defaults[i];
                }
                initdef << ") {\n  self = new " << name << "{";
                for (std::vector<std::string>::size_type i = 0; i < arg_names.size(); ++i) {
                    if (i != 0) initdef << ", ";
                    initdef << arg_names[i];
                }
                initdef << "};\n} }";
 
                if (Cppyy::Compile(initdef.str(), true /* silent */)) {
                    Cppyy::TCppScope_t cis = Cppyy::GetScope("__cppyy_internal");
                    const auto& mix = Cppyy::GetMethodIndicesFromName(cis, "init_"+rname);
                    if (mix.size()) {
                        if (!Utility::AddToClass(pyclass, "__init__",
                                new CPPFunction(cis, Cppyy::GetMethod(cis, mix[0]))))
                            PyErr_Clear();
                    }
                }
            }
        }
    }
 
 
//- class name based pythonization -------------------------------------------
 
    if (IsTemplatedSTLClass(name, "span")) {
    // libstdc++ (GCC >= 15) implements std::span::iterator using a private
    // nested tag type, which makes the iterator non-instantiable by
    // CallFunc-generated wrappers (the return type cannot be named without
    // violating access rules).
    //
    // To preserve correct Python iteration semantics, we replace begin()/end()
    // for std::span to return a custom pointer-based iterator instead. This
    // avoids relying on std::span::iterator while still providing a real C++
    // iterator object that CPyCppyy can also wrap and expose via
    // __iter__/__next__.
        Utility::AddToClass(pyclass, "begin", (PyCFunction)SpanBegin, METH_NOARGS);
        Utility::AddToClass(pyclass, "end", (PyCFunction)SpanEnd, METH_NOARGS);
    }
 
    if (IsTemplatedSTLClass(name, "vector")) {
 
    // std::vector<bool> is a special case in C++
        if (!sVectorBoolTypeID) sVectorBoolTypeID = (Cppyy::TCppType_t)Cppyy::GetScope("std::vector<bool>");
        if (klass->fCppType == sVectorBoolTypeID) {
            Utility::AddToClass(pyclass, "__getitem__", (PyCFunction)VectorBoolGetItem, METH_O);
            Utility::AddToClass(pyclass, "__setitem__", (PyCFunction)VectorBoolSetItem);
        } else {
        // constructor that takes python collections
            Utility::AddToClass(pyclass, "__real_init", "__init__");
            Utility::AddToClass(pyclass, "__init__", (PyCFunction)VectorInit, METH_VARARGS | METH_KEYWORDS);
 
        // data with size
            Utility::AddToClass(pyclass, "__real_data", "data");
            PyErr_Clear(); // AddToClass might have failed for data
            Utility::AddToClass(pyclass, "data", (PyCFunction)VectorData);
 
        // The addition of the __array__ utility to std::vector Python proxies causes a
        // bug where the resulting array is a single dimension, causing loss of data when
        // converting to numpy arrays, for >1dim vectors. Since this C++ pythonization
        // was added with the upgrade in 6.32, and is only defined and used recursively,
        // the safe option is to disable this function and no longer add it.
#if 0
        // numpy array conversion
            Utility::AddToClass(pyclass, "__array__", (PyCFunction)VectorArray, METH_VARARGS | METH_KEYWORDS /* unused */);
#endif
 
        // checked getitem
            if (HasAttrDirect(pyclass, PyStrings::gLen)) {
                Utility::AddToClass(pyclass, "_getitem__unchecked", "__getitem__");
                Utility::AddToClass(pyclass, "__getitem__", (PyCFunction)VectorGetItem, METH_O);
            }
 
        // vector-optimized iterator protocol
            ((PyTypeObject*)pyclass)->tp_iter = (getiterfunc)vector_iter;
 
        // optimized __iadd__
            Utility::AddToClass(pyclass, "__iadd__", (PyCFunction)VectorIAdd, METH_VARARGS | METH_KEYWORDS);
 
        // helpers for iteration
            const std::string& vtype = Cppyy::ResolveName(name+"::value_type");
            if (vtype.rfind("value_type") == std::string::npos) {    // actually resolved?
                PyObject* pyvalue_type = CPyCppyy_PyText_FromString(vtype.c_str());
                PyObject_SetAttr(pyclass, PyStrings::gValueType, pyvalue_type);
                Py_DECREF(pyvalue_type);
            }
 
            size_t typesz = Cppyy::SizeOf(name+"::value_type");
            if (typesz) {
                PyObject* pyvalue_size = PyLong_FromSsize_t(typesz);
                PyObject_SetAttr(pyclass, PyStrings::gValueSize, pyvalue_size);
                Py_DECREF(pyvalue_size);
            }
        }
    }
 
    else if (IsTemplatedSTLClass(name, "array")) {
    // constructor that takes python associative collections
        Utility::AddToClass(pyclass, "__real_init", "__init__");
        Utility::AddToClass(pyclass, "__init__", (PyCFunction)ArrayInit, METH_VARARGS | METH_KEYWORDS);
    }
 
    else if (IsTemplatedSTLClass(name, "map") || IsTemplatedSTLClass(name, "unordered_map")) {
    // constructor that takes python associative collections
        Utility::AddToClass(pyclass, "__real_init", "__init__");
        Utility::AddToClass(pyclass, "__init__", (PyCFunction)MapInit, METH_VARARGS | METH_KEYWORDS);
#if __cplusplus <= 202002L
    // From C++20, std::map and std::unordered_map already implement a contains() method.
        Utility::AddToClass(pyclass, "__contains__", (PyCFunction)STLContainsWithFind, METH_O);
#endif
    }
 
    else if (IsTemplatedSTLClass(name, "set")) {
    // constructor that takes python associative collections
        Utility::AddToClass(pyclass, "__real_init", "__init__");
        Utility::AddToClass(pyclass, "__init__", (PyCFunction)SetInit, METH_VARARGS | METH_KEYWORDS);
 
#if __cplusplus <= 202002L
    // From C++20, std::set already implements a contains() method.
        Utility::AddToClass(pyclass, "__contains__", (PyCFunction)STLContainsWithFind, METH_O);
#endif
    }
 
    else if (IsTemplatedSTLClass(name, "pair")) {
        Utility::AddToClass(pyclass, "__getitem__", (PyCFunction)PairUnpack, METH_O);
        Utility::AddToClass(pyclass, "__len__", (PyCFunction)ReturnTwo, METH_NOARGS);
    }
 
    if (IsTemplatedSTLClass(name, "shared_ptr") || IsTemplatedSTLClass(name, "unique_ptr")) {
        Utility::AddToClass(pyclass, "__real_init", "__init__");
        Utility::AddToClass(pyclass, "__init__", (PyCFunction)SmartPtrInit, METH_VARARGS | METH_KEYWORDS);
    }
 
    else if (!((PyTypeObject*)pyclass)->tp_iter && \
             (name.find("iterator") != std::string::npos || gIteratorTypes.find(name) != gIteratorTypes.end())) {
        ((PyTypeObject*)pyclass)->tp_iternext = (iternextfunc)STLIterNext;
        Utility::AddToClass(pyclass, CPPYY__next__, (PyCFunction)STLIterNext, METH_NOARGS);
        ((PyTypeObject*)pyclass)->tp_iter = (getiterfunc)PyObject_SelfIter;
        Utility::AddToClass(pyclass, "__iter__", (PyCFunction)PyObject_SelfIter, METH_NOARGS);
    }
 
    else if (name == "string" || name == "std::string") { // TODO: ask backend as well
        Utility::AddToClass(pyclass, "__repr__",      (PyCFunction)STLStringRepr,       METH_NOARGS);
        Utility::AddToClass(pyclass, "__str__",       (PyCFunction)STLStringStr,        METH_NOARGS);
        Utility::AddToClass(pyclass, "__bytes__",     (PyCFunction)STLStringBytes,      METH_NOARGS);
        Utility::AddToClass(pyclass, "__cmp__",       (PyCFunction)STLStringCompare,    METH_O);
        Utility::AddToClass(pyclass, "__eq__",        (PyCFunction)STLStringIsEqual,    METH_O);
        Utility::AddToClass(pyclass, "__ne__",        (PyCFunction)STLStringIsNotEqual, METH_O);
#if __cplusplus <= 202302L
    // From C++23, std::sting already implements a contains() method.
        Utility::AddToClass(pyclass, "__contains__",  (PyCFunction)STLStringContains,   METH_O);
#endif
        Utility::AddToClass(pyclass, "decode",        (PyCFunction)STLStringDecode,     METH_VARARGS | METH_KEYWORDS);
        Utility::AddToClass(pyclass, "__cpp_find",    "find");
        Utility::AddToClass(pyclass, "find",          (PyCFunction)STLStringFind,       METH_VARARGS | METH_KEYWORDS);
        Utility::AddToClass(pyclass, "__cpp_rfind",   "rfind");
        Utility::AddToClass(pyclass, "rfind",         (PyCFunction)STLStringRFind,      METH_VARARGS | METH_KEYWORDS);
        Utility::AddToClass(pyclass, "__cpp_replace", "replace");
        Utility::AddToClass(pyclass, "replace",       (PyCFunction)STLStringReplace,    METH_VARARGS | METH_KEYWORDS);
        Utility::AddToClass(pyclass, "__getattr__",   (PyCFunction)STLStringGetAttr,    METH_O);
 
    // to allow use of std::string in dictionaries and findable with str
        ((PyTypeObject*)pyclass)->tp_hash = (hashfunc)STLStringHash;
    }
 
    else if (name == "basic_string_view<char,char_traits<char> >" || name == "std::basic_string_view<char>") {
        Utility::AddToClass(pyclass, "__real_init", "__init__");
        Utility::AddToClass(pyclass, "__init__",  (PyCFunction)StringViewInit, METH_VARARGS | METH_KEYWORDS);
        Utility::AddToClass(pyclass, "__bytes__", (PyCFunction)STLViewStringBytes,      METH_NOARGS);
        Utility::AddToClass(pyclass, "__cmp__",   (PyCFunction)STLViewStringCompare,    METH_O);
        Utility::AddToClass(pyclass, "__eq__",    (PyCFunction)STLViewStringIsEqual,    METH_O);
        Utility::AddToClass(pyclass, "__ne__",    (PyCFunction)STLViewStringIsNotEqual, METH_O);
        Utility::AddToClass(pyclass, "__repr__",  (PyCFunction)STLViewStringRepr,       METH_NOARGS);
        Utility::AddToClass(pyclass, "__str__",   (PyCFunction)STLViewStringStr,        METH_NOARGS);
    }
 
// The first condition was already present in upstream CPyCppyy. The other two
// are special to ROOT, because its reflection layer gives us the types without
// the "std::" namespace. On some platforms, that applies only to the template
// arguments, and on others also to the "basic_string".
    else if (name == "std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >"
          || name == "basic_string<wchar_t,char_traits<wchar_t>,allocator<wchar_t> >"
          || name == "std::basic_string<wchar_t,char_traits<wchar_t>,allocator<wchar_t> >"
    ) {
        Utility::AddToClass(pyclass, "__repr__",  (PyCFunction)STLWStringRepr,       METH_NOARGS);
        Utility::AddToClass(pyclass, "__str__",   (PyCFunction)STLWStringStr,        METH_NOARGS);
        Utility::AddToClass(pyclass, "__bytes__", (PyCFunction)STLWStringBytes,      METH_NOARGS);
        Utility::AddToClass(pyclass, "__cmp__",   (PyCFunction)STLWStringCompare,    METH_O);
        Utility::AddToClass(pyclass, "__eq__",    (PyCFunction)STLWStringIsEqual,    METH_O);
        Utility::AddToClass(pyclass, "__ne__",    (PyCFunction)STLWStringIsNotEqual, METH_O);
    }
 
    else if (name == "complex<double>" || name == "std::complex<double>") {
        Utility::AddToClass(pyclass, "__cpp_real", "real");
        PyObject_SetAttrString(pyclass, "real",  PyDescr_NewGetSet((PyTypeObject*)pyclass, &ComplexDReal));
        Utility::AddToClass(pyclass, "__cpp_imag", "imag");
        PyObject_SetAttrString(pyclass, "imag",  PyDescr_NewGetSet((PyTypeObject*)pyclass, &ComplexDImag));
        Utility::AddToClass(pyclass, "__complex__", (PyCFunction)ComplexDComplex, METH_NOARGS);
        Utility::AddToClass(pyclass, "__repr__", (PyCFunction)ComplexRepr, METH_NOARGS);
    }
 
    else if (IsTemplatedSTLClass(name, "complex")) {
        Utility::AddToClass(pyclass, "__cpp_real", "real");
        PyObject_SetAttrString(pyclass, "real", PyDescr_NewGetSet((PyTypeObject*)pyclass, &realComplex));
        Utility::AddToClass(pyclass, "__cpp_imag", "imag");
        PyObject_SetAttrString(pyclass, "imag", PyDescr_NewGetSet((PyTypeObject*)pyclass, &imagComplex));
        Utility::AddToClass(pyclass, "__complex__", (PyCFunction)ComplexComplex, METH_NOARGS);
        Utility::AddToClass(pyclass, "__repr__", (PyCFunction)ComplexRepr, METH_NOARGS);
    }
 
// direct user access; there are two calls here:
//   - explicit pythonization: won't fall through to the base classes and is preferred if present
//   - normal pythonization: only called if explicit isn't present, falls through to base classes
    bool bUserOk = true; PyObject* res = nullptr;
    PyObject* pyname = CPyCppyy_PyText_FromString(name.c_str());
    if (HasAttrDirect(pyclass, PyStrings::gExPythonize)) {
        res = PyObject_CallMethodObjArgs(pyclass, PyStrings::gExPythonize, pyclass, pyname, nullptr);
        bUserOk = (bool)res;
    } else {
        PyObject* func = PyObject_GetAttr(pyclass, PyStrings::gPythonize);
        if (func) {
            res = PyObject_CallFunctionObjArgs(func, pyclass, pyname, nullptr);
            Py_DECREF(func);
            bUserOk = (bool)res;
        } else
            PyErr_Clear();
    }
    if (!bUserOk) {
        Py_DECREF(pyname);
        return false;
    } else {
        Py_XDECREF(res);
        // pyname handed to args tuple below
    }
 
// call registered pythonizors, if any: first run the namespace-specific pythonizors, then
// the global ones (the idea is to allow writing a pythonizor that see all classes)
    bool pstatus = true;
    std::string outer_scope = TypeManip::extract_namespace(name);
    auto &pyzMap = pythonizations();
    if (!outer_scope.empty()) {
        auto p = pyzMap.find(outer_scope);
        if (p != pyzMap.end()) {
            PyObject* subname = CPyCppyy_PyText_FromString(
                name.substr(outer_scope.size()+2, std::string::npos).c_str());
            pstatus = run_pythonizors(pyclass, subname, p->second);
            Py_DECREF(subname);
        }
    }
 
    if (pstatus) {
        auto p = pyzMap.find("");
        if (p != pyzMap.end())
            pstatus = run_pythonizors(pyclass, pyname, p->second);
    }
 
    Py_DECREF(pyname);
 
// phew! all done ...
    return pstatus;
}