cpython/Objects/methodobject.c

/* Method object implementation */

#include "Python.h"
#include "structmember.h"

/* Free list for method objects to safe malloc/free overhead
 * The m_self element is used to chain the objects.
 */
static PyCFunctionObject *free_list = NULL;
static int numfree = 0;
#ifndef PyCFunction_MAXFREELIST
#define PyCFunction_MAXFREELIST 256
#endif

PyObject *
PyCFunction_NewEx(PyMethodDef *ml, PyObject *self, PyObject *module)
{
    PyCFunctionObject *op;
    op = free_list;
    if (op != NULL) {
        free_list = (PyCFunctionObject *)(op->m_self);
        (void)PyObject_INIT(op, &PyCFunction_Type);
        numfree--;
    }
    else {
        op = PyObject_GC_New(PyCFunctionObject, &PyCFunction_Type);
        if (op == NULL)
            return NULL;
    }
    op->m_ml = ml;
    Py_XINCREF(self);
    op->m_self = self;
    Py_XINCREF(module);
    op->m_module = module;
    _PyObject_GC_TRACK(op);
    return (PyObject *)op;
}

PyCFunction
PyCFunction_GetFunction(PyObject *op)
{
    if (!PyCFunction_Check(op)) {
        PyErr_BadInternalCall();
        return NULL;
    }
    return ((PyCFunctionObject *)op) -> m_ml -> ml_meth;
}

PyObject *
PyCFunction_GetSelf(PyObject *op)
{
    if (!PyCFunction_Check(op)) {
        PyErr_BadInternalCall();
        return NULL;
    }
    return ((PyCFunctionObject *)op) -> m_self;
}

int
PyCFunction_GetFlags(PyObject *op)
{
    if (!PyCFunction_Check(op)) {
        PyErr_BadInternalCall();
        return -1;
    }
    return ((PyCFunctionObject *)op) -> m_ml -> ml_flags;
}

PyObject *
PyCFunction_Call(PyObject *func, PyObject *arg, PyObject *kw)
{
    PyCFunctionObject* f = (PyCFunctionObject*)func;
    PyCFunction meth = PyCFunction_GET_FUNCTION(func);
    PyObject *self = PyCFunction_GET_SELF(func);
    Py_ssize_t size;

    switch (PyCFunction_GET_FLAGS(func) & ~(METH_CLASS | METH_STATIC | METH_COEXIST)) {
    case METH_VARARGS:
        if (kw == NULL || PyDict_Size(kw) == 0)
            return (*meth)(self, arg);
        break;
    case METH_VARARGS | METH_KEYWORDS:
    case METH_OLDARGS | METH_KEYWORDS:
        return (*(PyCFunctionWithKeywords)meth)(self, arg, kw);
    case METH_NOARGS:
        if (kw == NULL || PyDict_Size(kw) == 0) {
            size = PyTuple_GET_SIZE(arg);
            if (size == 0)
                return (*meth)(self, NULL);
            PyErr_Format(PyExc_TypeError,
                "%.200s() takes no arguments (%zd given)",
                f->m_ml->ml_name, size);
            return NULL;
        }
        break;
    case METH_O:
        if (kw == NULL || PyDict_Size(kw) == 0) {
            size = PyTuple_GET_SIZE(arg);
            if (size == 1)
                return (*meth)(self, PyTuple_GET_ITEM(arg, 0));
            PyErr_Format(PyExc_TypeError,
                "%.200s() takes exactly one argument (%zd given)",
                f->m_ml->ml_name, size);
            return NULL;
        }
        break;
    case METH_OLDARGS:
        /* the really old style */
        if (kw == NULL || PyDict_Size(kw) == 0) {
            size = PyTuple_GET_SIZE(arg);
            if (size == 1)
                arg = PyTuple_GET_ITEM(arg, 0);
            else if (size == 0)
                arg = NULL;
            return (*meth)(self, arg);
        }
        break;
    default:
        PyErr_BadInternalCall();
        return NULL;
    }
    PyErr_Format(PyExc_TypeError, "%.200s() takes no keyword arguments",
                 f->m_ml->ml_name);
    return NULL;
}

/* Methods (the standard built-in methods, that is) */

static void
meth_dealloc(PyCFunctionObject *m)
{
    _PyObject_GC_UNTRACK(m);
    Py_XDECREF(m->m_self);
    Py_XDECREF(m->m_module);
    if (numfree < PyCFunction_MAXFREELIST) {
        m->m_self = (PyObject *)free_list;
        free_list = m;
        numfree++;
    }
    else {
        PyObject_GC_Del(m);
    }
}

static PyObject *
meth_get__doc__(PyCFunctionObject *m, void *closure)
{
    const char *doc = m->m_ml->ml_doc;

    if (doc != NULL)
        return PyString_FromString(doc);
    Py_INCREF(Py_None);
    return Py_None;
}

static PyObject *
meth_get__name__(PyCFunctionObject *m, void *closure)
{
    return PyString_FromString(m->m_ml->ml_name);
}

static int
meth_traverse(PyCFunctionObject *m, visitproc visit, void *arg)
{
    Py_VISIT(m->m_self);
    Py_VISIT(m->m_module);
    return 0;
}

static PyObject *
meth_get__self__(PyCFunctionObject *m, void *closure)
{
    PyObject *self;
    if (PyEval_GetRestricted()) {
        PyErr_SetString(PyExc_RuntimeError,
            "method.__self__ not accessible in restricted mode");
        return NULL;
    }
    self = m->m_self;
    if (self == NULL)
        self = Py_None;
    Py_INCREF(self);
    return self;
}

static PyGetSetDef meth_getsets [] = {
    {"__doc__",  (getter)meth_get__doc__,  NULL, NULL},
    {"__name__", (getter)meth_get__name__, NULL, NULL},
    {"__self__", (getter)meth_get__self__, NULL, NULL},
    {0}
};

#define OFF(x) offsetof(PyCFunctionObject, x)

static PyMemberDef meth_members[] = {
    {"__module__",    T_OBJECT,     OFF(m_module), PY_WRITE_RESTRICTED},
    {NULL}
};

static PyObject *
meth_repr(PyCFunctionObject *m)
{
    if (m->m_self == NULL)
        return PyString_FromFormat("<built-in function %s>",
                                   m->m_ml->ml_name);
    return PyString_FromFormat("<built-in method %s of %s object at %p>",
                               m->m_ml->ml_name,
                               m->m_self->ob_type->tp_name,
                               m->m_self);
}

static int
meth_compare(PyCFunctionObject *a, PyCFunctionObject *b)
{
    if (a->m_self != b->m_self)
        return (a->m_self < b->m_self) ? -1 : 1;
    if (a->m_ml->ml_meth == b->m_ml->ml_meth)
        return 0;
    if (strcmp(a->m_ml->ml_name, b->m_ml->ml_name) < 0)
        return -1;
    else
        return 1;
}

static PyObject *
meth_richcompare(PyObject *self, PyObject *other, int op)
{
    PyCFunctionObject *a, *b;
    PyObject *res;
    int eq;

    if (op != Py_EQ && op != Py_NE) {
        /* Py3K warning if comparison isn't == or !=.  */
        if (PyErr_WarnPy3k("builtin_function_or_method order "
                           "comparisons not supported in 3.x", 1) < 0) {
            return NULL;
        }

        Py_INCREF(Py_NotImplemented);
        return Py_NotImplemented;
    }
    else if (!PyCFunction_Check(self) || !PyCFunction_Check(other)) {
        Py_INCREF(Py_NotImplemented);
        return Py_NotImplemented;
    }
    a = (PyCFunctionObject *)self;
    b = (PyCFunctionObject *)other;
    eq = a->m_self == b->m_self;
    if (eq)
        eq = a->m_ml->ml_meth == b->m_ml->ml_meth;
    if (op == Py_EQ)
        res = eq ? Py_True : Py_False;
    else
        res = eq ? Py_False : Py_True;
    Py_INCREF(res);
    return res;
}

static long
meth_hash(PyCFunctionObject *a)
{
    long x,y;
    if (a->m_self == NULL)
        x = 0;
    else {
        x = PyObject_Hash(a->m_self);
        if (x == -1)
            return -1;
    }
    y = _Py_HashPointer((void*)(a->m_ml->ml_meth));
    if (y == -1)
        return -1;
    x ^= y;
    if (x == -1)
        x = -2;
    return x;
}


PyTypeObject PyCFunction_Type = {
    PyVarObject_HEAD_INIT(&PyType_Type, 0)
    "builtin_function_or_method",
    sizeof(PyCFunctionObject),
    0,
    (destructor)meth_dealloc,                   /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    (cmpfunc)meth_compare,                      /* tp_compare */
    (reprfunc)meth_repr,                        /* tp_repr */
    0,                                          /* tp_as_number */
    0,                                          /* tp_as_sequence */
    0,                                          /* tp_as_mapping */
    (hashfunc)meth_hash,                        /* tp_hash */
    PyCFunction_Call,                           /* tp_call */
    0,                                          /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
    0,                                          /* tp_doc */
    (traverseproc)meth_traverse,                /* tp_traverse */
    0,                                          /* tp_clear */
    meth_richcompare,                                           /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    0,                                          /* tp_iter */
    0,                                          /* tp_iternext */
    0,                                          /* tp_methods */
    meth_members,                               /* tp_members */
    meth_getsets,                               /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
};

/* List all methods in a chain -- helper for findmethodinchain */

static PyObject *
listmethodchain(PyMethodChain *chain)
{
    PyMethodChain *c;
    PyMethodDef *ml;
    int i, n;
    PyObject *v;

    n = 0;
    for (c = chain; c != NULL; c = c->link) {
        for (ml = c->methods; ml->ml_name != NULL; ml++)
            n++;
    }
    v = PyList_New(n);
    if (v == NULL)
        return NULL;
    i = 0;
    for (c = chain; c != NULL; c = c->link) {
        for (ml = c->methods; ml->ml_name != NULL; ml++) {
            PyList_SetItem(v, i, PyString_FromString(ml->ml_name));
            i++;
        }
    }
    if (PyErr_Occurred()) {
        Py_DECREF(v);
        return NULL;
    }
    PyList_Sort(v);
    return v;
}

/* Find a method in a method chain */

PyObject *
Py_FindMethodInChain(PyMethodChain *chain, PyObject *self, const char *name)
{
    if (name[0] == '_' && name[1] == '_') {
        if (strcmp(name, "__methods__") == 0) {
            if (PyErr_WarnPy3k("__methods__ not supported in 3.x",
                               1) < 0)
                return NULL;
            return listmethodchain(chain);
        }
        if (strcmp(name, "__doc__") == 0) {
            const char *doc = self->ob_type->tp_doc;
            if (doc != NULL)
                return PyString_FromString(doc);
        }
    }
    while (chain != NULL) {
        PyMethodDef *ml = chain->methods;
        for (; ml->ml_name != NULL; ml++) {
            if (name[0] == ml->ml_name[0] &&
                strcmp(name+1, ml->ml_name+1) == 0)
                /* XXX */
                return PyCFunction_New(ml, self);
        }
        chain = chain->link;
    }
    PyErr_SetString(PyExc_AttributeError, name);
    return NULL;
}

/* Find a method in a single method list */

PyObject *
Py_FindMethod(PyMethodDef *methods, PyObject *self, const char *name)
{
    PyMethodChain chain;
    chain.methods = methods;
    chain.link = NULL;
    return Py_FindMethodInChain(&chain, self, name);
}

/* Clear out the free list */

int
PyCFunction_ClearFreeList(void)
{
    int freelist_size = numfree;

    while (free_list) {
        PyCFunctionObject *v = free_list;
        free_list = (PyCFunctionObject *)(v->m_self);
        PyObject_GC_Del(v);
        numfree--;
    }
    assert(numfree == 0);
    return freelist_size;
}

void
PyCFunction_Fini(void)
{
    (void)PyCFunction_ClearFreeList();
}

/* PyCFunction_New() is now just a macro that calls PyCFunction_NewEx(),
   but it's part of the API so we need to keep a function around that
   existing C extensions can call.
*/

#undef PyCFunction_New
PyAPI_FUNC(PyObject *) PyCFunction_New(PyMethodDef *, PyObject *);

PyObject *
PyCFunction_New(PyMethodDef *ml, PyObject *self)
{
    return PyCFunction_NewEx(ml, self, NULL);
}