Phoenix/sip/siplib/descriptors.c

/*
 * The implementation of the different descriptors.
 *
 * Copyright (c) 2019 Riverbank Computing Limited <info@riverbankcomputing.com>
 *
 * This file is part of SIP.
 *
 * This copy of SIP is licensed for use under the terms of the SIP License
 * Agreement.  See the file LICENSE for more details.
 *
 * This copy of SIP may also used under the terms of the GNU General Public
 * License v2 or v3 as published by the Free Software Foundation which can be
 * found in the files LICENSE-GPL2 and LICENSE-GPL3 included in this package.
 *
 * SIP is supplied WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 */


#include <Python.h>

#include "sipint.h"


/*****************************************************************************
 * A method descriptor.  We don't use the similar Python descriptor because it
 * doesn't support a method having static and non-static overloads, and we
 * handle mixins via a delegate.
 *****************************************************************************/


/* Forward declarations of slots. */
static PyObject *sipMethodDescr_descr_get(PyObject *self, PyObject *obj,
        PyObject *type);
static PyObject *sipMethodDescr_repr(PyObject *self);
static int sipMethodDescr_traverse(PyObject *self, visitproc visit, void *arg);
static int sipMethodDescr_clear(PyObject *self);
static void sipMethodDescr_dealloc(PyObject *self);


/*
 * The object data structure.
 */
typedef struct _sipMethodDescr {
    PyObject_HEAD

    /* The method definition. */
    PyMethodDef *pmd;

    /* The mixin name, if any. */
    PyObject *mixin_name;
} sipMethodDescr;


/*
 * The type data structure.
 */
PyTypeObject sipMethodDescr_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "sip.methoddescriptor", /* tp_name */
    sizeof (sipMethodDescr),    /* tp_basicsize */
    0,                      /* tp_itemsize */
    sipMethodDescr_dealloc, /* tp_dealloc */
    0,                      /* tp_print */
    0,                      /* tp_getattr */
    0,                      /* tp_setattr */
    0,                      /* tp_compare */
    sipMethodDescr_repr,    /* 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|Py_TPFLAGS_HAVE_GC,  /* tp_flags */
    0,                      /* tp_doc */
    sipMethodDescr_traverse,/* tp_traverse */
    sipMethodDescr_clear,   /* 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 */
    sipMethodDescr_descr_get,   /* tp_descr_get */
    0,                      /* tp_descr_set */
    0,                      /* tp_dictoffset */
    0,                      /* tp_init */
    0,                      /* tp_alloc */
    0,                      /* tp_new */
    0,                      /* tp_free */
    0,                      /* tp_is_gc */
    0,                      /* tp_bases */
    0,                      /* tp_mro */
    0,                      /* tp_cache */
    0,                      /* tp_subclasses */
    0,                      /* tp_weaklist */
    0,                      /* tp_del */
    0,                      /* tp_version_tag */
    0,                      /* tp_finalize */
#if PY_VERSION_HEX >= 0x03080000
    0,                      /* tp_vectorcall */
#endif
};


/*
 * Return a new method descriptor for the given method.
 */
PyObject *sipMethodDescr_New(PyMethodDef *pmd)
{
    PyObject *descr = PyType_GenericAlloc(&sipMethodDescr_Type, 0);

    if (descr != NULL)
    {
        ((sipMethodDescr *)descr)->pmd = pmd;
        ((sipMethodDescr *)descr)->mixin_name = NULL;
    }

    return descr;
}


/*
 * Return a new method descriptor based on an existing one and a mixin name.
 */
PyObject *sipMethodDescr_Copy(PyObject *orig, PyObject *mixin_name)
{
    PyObject *descr = PyType_GenericAlloc(&sipMethodDescr_Type, 0);

    if (descr != NULL)
    {
        ((sipMethodDescr *)descr)->pmd = ((sipMethodDescr *)orig)->pmd;
        ((sipMethodDescr *)descr)->mixin_name = mixin_name;
        Py_INCREF(mixin_name);
    }

    return descr;
}


/*
 * The descriptor's descriptor get slot.
 */
static PyObject *sipMethodDescr_descr_get(PyObject *self, PyObject *obj,
        PyObject *type)
{
    sipMethodDescr *md = (sipMethodDescr *)self;

    (void)type;

    if (obj == Py_None)
        obj = NULL;
    else if (md->mixin_name != NULL)
        obj = PyObject_GetAttr(obj, md->mixin_name);

    return PyCFunction_New(md->pmd, obj);
}


/*
 * The descriptor's repr slot.  This is for the benefit of cProfile which seems
 * to determine attribute names differently to the rest of Python.
 */
static PyObject *sipMethodDescr_repr(PyObject *self)
{
    sipMethodDescr *md = (sipMethodDescr *)self;

    return PyUnicode_FromFormat("<built-in method %s>", md->pmd->ml_name);
}


/*
 * The descriptor's traverse slot.
 */
static int sipMethodDescr_traverse(PyObject *self, visitproc visit, void *arg)
{
    if (((sipMethodDescr *)self)->mixin_name != NULL)
    {
        int vret = visit(((sipMethodDescr *)self)->mixin_name, arg);

        if (vret != 0)
            return vret;
    }

    return 0;
}


/*
 * The descriptor's clear slot.
 */
static int sipMethodDescr_clear(PyObject *self)
{
    PyObject *tmp = ((sipMethodDescr *)self)->mixin_name;

    ((sipMethodDescr *)self)->mixin_name = NULL;
    Py_XDECREF(tmp);

    return 0;
}


/*
 * The descriptor's dealloc slot.
 */
static void sipMethodDescr_dealloc(PyObject *self)
{
    sipMethodDescr_clear(self);
    Py_TYPE(self)->tp_free(self);
}


/*****************************************************************************
 * A variable descriptor.  We don't use the similar Python descriptor because
 * it doesn't support static variables.
 *****************************************************************************/


/* Forward declarations of slots. */
static PyObject *sipVariableDescr_descr_get(PyObject *self, PyObject *obj,
        PyObject *type);
static int sipVariableDescr_descr_set(PyObject *self, PyObject *obj,
        PyObject *value);
static int sipVariableDescr_traverse(PyObject *self, visitproc visit,
        void *arg);
static int sipVariableDescr_clear(PyObject *self);
static void sipVariableDescr_dealloc(PyObject *self);


/*
 * The object data structure.
 */
typedef struct _sipVariableDescr {
    PyObject_HEAD

    /* The getter/setter definition. */
    sipVariableDef *vd;

    /* The generated type definition. */
    const sipTypeDef *td;

    /* The generated container definition. */
    const sipContainerDef *cod;

    /* The mixin name, if any. */
    PyObject *mixin_name;
} sipVariableDescr;


/*
 * The type data structure.
 */
PyTypeObject sipVariableDescr_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "sip.variabledescriptor",   /* tp_name */
    sizeof (sipVariableDescr),  /* tp_basicsize */
    0,                      /* tp_itemsize */
    sipVariableDescr_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|Py_TPFLAGS_HAVE_GC,  /* tp_flags */
    0,                      /* tp_doc */
    sipVariableDescr_traverse,  /* tp_traverse */
    sipVariableDescr_clear, /* 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 */
    sipVariableDescr_descr_get, /* tp_descr_get */
    sipVariableDescr_descr_set, /* tp_descr_set */
    0,                      /* tp_dictoffset */
    0,                      /* tp_init */
    0,                      /* tp_alloc */
    0,                      /* tp_new */
    0,                      /* tp_free */
    0,                      /* tp_is_gc */
    0,                      /* tp_bases */
    0,                      /* tp_mro */
    0,                      /* tp_cache */
    0,                      /* tp_subclasses */
    0,                      /* tp_weaklist */
    0,                      /* tp_del */
    0,                      /* tp_version_tag */
    0,                      /* tp_finalize */
#if PY_VERSION_HEX >= 0x03080000
    0,                      /* tp_vectorcall */
#endif
};


/* Forward declarations. */
static int get_instance_address(sipVariableDescr *vd, PyObject *obj,
        void **addrp);


/*
 * Return a new method descriptor for the given getter/setter.
 */
PyObject *sipVariableDescr_New(sipVariableDef *vd, const sipTypeDef *td,
        const sipContainerDef *cod)
{
    PyObject *descr = PyType_GenericAlloc(&sipVariableDescr_Type, 0);

    if (descr != NULL)
    {
        ((sipVariableDescr *)descr)->vd = vd;
        ((sipVariableDescr *)descr)->td = td;
        ((sipVariableDescr *)descr)->cod = cod;
        ((sipVariableDescr *)descr)->mixin_name = NULL;
    }

    return descr;
}


/*
 * Return a new variable descriptor based on an existing one and a mixin name.
 */
PyObject *sipVariableDescr_Copy(PyObject *orig, PyObject *mixin_name)
{
    PyObject *descr = PyType_GenericAlloc(&sipVariableDescr_Type, 0);

    if (descr != NULL)
    {
        ((sipVariableDescr *)descr)->vd = ((sipVariableDescr *)orig)->vd;
        ((sipVariableDescr *)descr)->td = ((sipVariableDescr *)orig)->td;
        ((sipVariableDescr *)descr)->cod = ((sipVariableDescr *)orig)->cod;
        ((sipVariableDescr *)descr)->mixin_name = mixin_name;
        Py_INCREF(mixin_name);
    }

    return descr;
}


/*
 * The descriptor's descriptor get slot.
 */
static PyObject *sipVariableDescr_descr_get(PyObject *self, PyObject *obj,
        PyObject *type)
{
    sipVariableDescr *vd = (sipVariableDescr *)self;
    void *addr;

    if (get_instance_address(vd, obj, &addr) < 0)
        return NULL;

    return ((sipVariableGetterFunc)vd->vd->vd_getter)(addr, obj, type);
}


/*
 * The descriptor's descriptor set slot.
 */
static int sipVariableDescr_descr_set(PyObject *self, PyObject *obj,
        PyObject *value)
{
    sipVariableDescr *vd = (sipVariableDescr *)self;
    void *addr;

    /* Check that the value isn't const. */
    if (vd->vd->vd_setter == NULL)
    {
        PyErr_Format(PyExc_AttributeError,
                "'%s' object attribute '%s' is read-only",
                sipPyNameOfContainer(vd->cod, vd->td), vd->vd->vd_name);

        return -1;
    }

    if (get_instance_address(vd, obj, &addr) < 0)
        return -1;

    return ((sipVariableSetterFunc)vd->vd->vd_setter)(addr, value, obj);
}


/*
 * Return the C/C++ address of any instance.
 */
static int get_instance_address(sipVariableDescr *vd, PyObject *obj,
        void **addrp)
{
    void *addr;

    if (vd->vd->vd_type == ClassVariable)
    {
        addr = NULL;
    }
    else
    {
        /* Check that access was via an instance. */
        if (obj == NULL || obj == Py_None)
        {
            PyErr_Format(PyExc_AttributeError,
                    "'%s' object attribute '%s' is an instance attribute",
                    sipPyNameOfContainer(vd->cod, vd->td), vd->vd->vd_name);

            return -1;
        }

        if (vd->mixin_name != NULL)
            obj = PyObject_GetAttr(obj, vd->mixin_name);

        /* Get the C++ instance. */
        if ((addr = sip_api_get_cpp_ptr((sipSimpleWrapper *)obj, vd->td)) == NULL)
            return -1;
    }

    *addrp = addr;

    return 0;
}


/*
 * The descriptor's traverse slot.
 */
static int sipVariableDescr_traverse(PyObject *self, visitproc visit, void *arg)
{
    if (((sipVariableDescr *)self)->mixin_name != NULL)
    {
        int vret = visit(((sipVariableDescr *)self)->mixin_name, arg);

        if (vret != 0)
            return vret;
    }

    return 0;
}


/*
 * The descriptor's clear slot.
 */
static int sipVariableDescr_clear(PyObject *self)
{
    PyObject *tmp = ((sipVariableDescr *)self)->mixin_name;

    ((sipVariableDescr *)self)->mixin_name = NULL;
    Py_XDECREF(tmp);

    return 0;
}


/*
 * The descriptor's dealloc slot.
 */
static void sipVariableDescr_dealloc(PyObject *self)
{
    sipVariableDescr_clear(self);
    Py_TYPE(self)->tp_free(self);
}