CPPDataMember.cxx

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// Bindings
#include "CPyCppyy.h"
#include "PyStrings.h"
#include "CPPDataMember.h"
#include "CPPInstance.h"
#include "LowLevelViews.h"
#include "PyStrings.h"
#include "Utility.h"
 
// Standard
#include <algorithm>
#include <vector>
#include <limits.h>
 
 
namespace CPyCppyy {
 
enum ETypeDetails {
    kNone          = 0x0000,
    kIsStaticData  = 0x0001,
    kIsConstData   = 0x0002,
    kIsArrayType   = 0x0004,
    kIsCachable    = 0x0008
};
 
//= CPyCppyy data member as Python property behavior =========================
static PyObject* pp_get(CPPDataMember* pyprop, CPPInstance* pyobj, PyObject* /* kls */)
{
// cache lookup for low level views
    if (pyprop->fFlags & kIsCachable) {
        CPyCppyy::CI_DatamemberCache_t& cache = pyobj->GetDatamemberCache();
        for (auto it = cache.begin(); it != cache.end(); ++it) {
            if (it->first == pyprop->fOffset) {
                if (it->second) {
                    Py_INCREF(it->second);
                    return it->second;
                } else
                    cache.erase(it);
                break;
            }
        }
    }
 
// normal getter access
    void* address = pyprop->GetAddress(pyobj);
    if (!address || (intptr_t)address == -1 /* Cling error */)
        return nullptr;
 
// for fixed size arrays
    void* ptr = address;
    if (pyprop->fFlags & kIsArrayType)
        ptr = &address;
 
// non-initialized or public data accesses through class (e.g. by help())
    if (!ptr || (intptr_t)ptr == -1 /* Cling error */) {
        Py_INCREF(pyprop);
        return (PyObject*)pyprop;
    }
 
    if (pyprop->fConverter != 0) {
        PyObject* result = pyprop->fConverter->FromMemory(ptr);
        if (!result)
            return result;
 
    // low level views are expensive to create, so cache them on the object instead
        bool isLLView = LowLevelView_CheckExact(result);
        if (isLLView && CPPInstance_Check(pyobj)) {
            Py_INCREF(result);
            pyobj->GetDatamemberCache().push_back(std::make_pair(pyprop->fOffset, result));
            pyprop->fFlags |= kIsCachable;
        }
 
    // ensure that the encapsulating class does not go away for the duration
    // of the data member's lifetime, if it is a bound type (it doesn't matter
    // for builtin types, b/c those are copied over into python types and thus
    // end up being "stand-alone")
    // TODO: should be done for LLViews as well
        else if (pyobj && CPPInstance_Check(result)) {
            if (PyObject_SetAttr(result, PyStrings::gLifeLine, (PyObject*)pyobj) == -1)
                PyErr_Clear();     // ignored
        }
 
        return result;
    }
 
    PyErr_Format(PyExc_NotImplementedError,
        "no converter available for \"%s\"", pyprop->GetName().c_str());
    return nullptr;
}
 
//-----------------------------------------------------------------------------
static int pp_set(CPPDataMember* pyprop, CPPInstance* pyobj, PyObject* value)
{
// Set the value of the C++ datum held.
    const int errret = -1;
 
// filter const objects to prevent changing their values
    if (pyprop->fFlags & kIsConstData) {
        PyErr_SetString(PyExc_TypeError, "assignment to const data not allowed");
        return errret;
    }
 
// remove cached low level view, if any (will be restored upon reaeding)
    if (pyprop->fFlags & kIsCachable) {
        CPyCppyy::CI_DatamemberCache_t& cache = pyobj->GetDatamemberCache();
        for (auto it = cache.begin(); it != cache.end(); ++it) {
            if (it->first == pyprop->fOffset) {
                Py_XDECREF(it->second);
                cache.erase(it);
                break;
            }
        }
    }
 
    intptr_t address = (intptr_t)pyprop->GetAddress(pyobj);
    if (!address || address == -1 /* Cling error */)
        return errret;
 
// for fixed size arrays
    void* ptr = (void*)address;
    if (pyprop->fFlags & kIsArrayType)
        ptr = &address;
 
// actual conversion; return on success
    if (pyprop->fConverter && pyprop->fConverter->ToMemory(value, ptr, (PyObject*)pyobj))
        return 0;
 
// set a python error, if not already done
    if (!PyErr_Occurred())
        PyErr_SetString(PyExc_RuntimeError, "property type mismatch or assignment not allowed");
 
// failure ...
    return errret;
}
 
//= CPyCppyy data member construction/destruction ===========================
static CPPDataMember* pp_new(PyTypeObject* pytype, PyObject*, PyObject*)
{
// Create and initialize a new property descriptor.
    CPPDataMember* pyprop = (CPPDataMember*)pytype->tp_alloc(pytype, 0);
 
    pyprop->fOffset         = 0;
    pyprop->fFlags          = 0;
    pyprop->fConverter      = nullptr;
    pyprop->fEnclosingScope = 0;
    pyprop->fName           = nullptr;
 
    return pyprop;
}
 
//----------------------------------------------------------------------------
static void pp_dealloc(CPPDataMember* pyprop)
{
// Deallocate memory held by this descriptor.
    using namespace std;
    if (pyprop->fConverter && pyprop->fConverter->HasState()) delete pyprop->fConverter;
    Py_XDECREF(pyprop->fName);    // never exposed so no GC necessary
 
    Py_TYPE(pyprop)->tp_free((PyObject*)pyprop);
}
 
 
//= CPyCppyy data member type ================================================
PyTypeObject CPPDataMember_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    (char*)"cppyy.CPPDataMember",  // tp_name
    sizeof(CPPDataMember),         // tp_basicsize
    0,                             // tp_itemsize
    (destructor)pp_dealloc,        // tp_dealloc
    0,                             // tp_print
    0,                             // tp_getattr
    0,                             // tp_setattr
    0,                             // tp_compare
    0,                             // tp_repr
    0,                             // tp_as_number
    0,                             // tp_as_sequence
    0,                             // tp_as_mapping
    0,                             // tp_hash
    0,                             // tp_call
    0,                             // tp_str
    0,                             // tp_getattro
    0,                             // tp_setattro
    0,                             // tp_as_buffer
    Py_TPFLAGS_DEFAULT,            // tp_flags
    (char*)"cppyy data member (internal)",       // tp_doc
    0,                             // tp_traverse
    0,                             // tp_clear
    0,                             // tp_richcompare
    0,                             // tp_weaklistoffset
    0,                             // tp_iter
    0,                             // tp_iternext
    0,                             // tp_methods
    0,                             // tp_members
    0,                             // tp_getset
    0,                             // tp_base
    0,                             // tp_dict
    (descrgetfunc)pp_get,          // tp_descr_get
    (descrsetfunc)pp_set,          // tp_descr_set
    0,                             // tp_dictoffset
    0,                             // tp_init
    0,                             // tp_alloc
    (newfunc)pp_new,               // tp_new
    0,                             // tp_free
    0,                             // tp_is_gc
    0,                             // tp_bases
    0,                             // tp_mro
    0,                             // tp_cache
    0,                             // tp_subclasses
    0                              // tp_weaklist
#if PY_VERSION_HEX >= 0x02030000
    , 0                            // tp_del
#endif
#if PY_VERSION_HEX >= 0x02060000
    , 0                            // tp_version_tag
#endif
#if PY_VERSION_HEX >= 0x03040000
    , 0                            // tp_finalize
#endif
};
 
} // namespace CPyCppyy
 
 
//- public members -----------------------------------------------------------
void CPyCppyy::CPPDataMember::Set(Cppyy::TCppScope_t scope, Cppyy::TCppIndex_t idata)
{
    fEnclosingScope = scope;
    fName           = CPyCppyy_PyText_FromString(Cppyy::GetDatamemberName(scope, idata).c_str());
    fOffset         = Cppyy::GetDatamemberOffset(scope, idata); // TODO: make lazy
    fFlags          = Cppyy::IsStaticData(scope, idata) ? kIsStaticData : 0;
 
    std::vector<dim_t> dims;
    int ndim = 0; dim_t size = 0;
    while (0 < (size = Cppyy::GetDimensionSize(scope, idata, ndim))) {
         ndim += 1;
         if (size == INT_MAX)      // meaning: incomplete array type
             size = -1;
         if (ndim == 1) { dims.reserve(4); dims.push_back(0); }
         dims.push_back(size);
    }
    if (ndim) {
        dims[0] = ndim;
        fFlags |= kIsArrayType;
    }
 
    std::string fullType = Cppyy::GetDatamemberType(scope, idata);
    if (Cppyy::IsEnumData(scope, idata)) {
        fullType = Cppyy::ResolveEnum(fullType);  // enum might be any type of int
        fFlags |= kIsConstData;
    } else if (Cppyy::IsConstData(scope, idata)) {
        fFlags |= kIsConstData;
    }
 
    fConverter = CreateConverter(fullType, dims.empty() ? nullptr : dims.data());
}
 
//-----------------------------------------------------------------------------
void CPyCppyy::CPPDataMember::Set(Cppyy::TCppScope_t scope, const std::string& name, void* address)
{
    fEnclosingScope = scope;
    fName           = CPyCppyy_PyText_FromString(name.c_str());
    fOffset         = (intptr_t)address;
    fFlags          = kIsStaticData | kIsConstData;
    fConverter      = CreateConverter("internal_enum_type_t");
}
 
 
//-----------------------------------------------------------------------------
void* CPyCppyy::CPPDataMember::GetAddress(CPPInstance* pyobj)
{
// class attributes, global properties
    if (fFlags & kIsStaticData)
        return (void*)fOffset;
 
// special case: non-static lookup through class
    if (!pyobj) {
        PyErr_SetString(PyExc_AttributeError, "attribute access requires an instance");
        return nullptr;
    }
 
// instance attributes; requires valid object for full address
    if (!CPPInstance_Check(pyobj)) {
        PyErr_Format(PyExc_TypeError,
            "object instance required for access to property \"%s\"", GetName().c_str());
        return nullptr;
    }
 
    void* obj = pyobj->GetObject();
    if (!obj) {
        PyErr_SetString(PyExc_ReferenceError, "attempt to access a null-pointer");
        return nullptr;
   }
 
// the proxy's internal offset is calculated from the enclosing class
    ptrdiff_t offset = 0;
    if (pyobj->ObjectIsA() != fEnclosingScope)
        offset = Cppyy::GetBaseOffset(pyobj->ObjectIsA(), fEnclosingScope, obj, 1 /* up-cast */);
 
    return (void*)((intptr_t)obj + offset + fOffset);
}