cpython/Objects/funcobject.c

/* Function object implementation */

#include "Python.h"
#include "compile.h"
#include "eval.h"
#include "structmember.h"

PyObject *
PyFunction_New(PyObject *code, PyObject *globals)
{
	PyFunctionObject *op = PyObject_GC_New(PyFunctionObject,
					    &PyFunction_Type);
	if (op != NULL) {
		PyObject *doc;
		PyObject *consts;
		op->func_weakreflist = NULL;
		Py_INCREF(code);
		op->func_code = code;
		Py_INCREF(globals);
		op->func_globals = globals;
		op->func_name = ((PyCodeObject *)code)->co_name;
		Py_INCREF(op->func_name);
		op->func_defaults = NULL; /* No default arguments */
		op->func_closure = NULL;
		consts = ((PyCodeObject *)code)->co_consts;
		if (PyTuple_Size(consts) >= 1) {
			doc = PyTuple_GetItem(consts, 0);
			if (!PyString_Check(doc) && !PyUnicode_Check(doc))
				doc = Py_None;
		}
		else
			doc = Py_None;
		Py_INCREF(doc);
		op->func_doc = doc;
		op->func_dict = NULL;
	}
	else
		return NULL;
	_PyObject_GC_TRACK(op);
	return (PyObject *)op;
}

PyObject *
PyFunction_GetCode(PyObject *op)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	return ((PyFunctionObject *) op) -> func_code;
}

PyObject *
PyFunction_GetGlobals(PyObject *op)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	return ((PyFunctionObject *) op) -> func_globals;
}

PyObject *
PyFunction_GetDefaults(PyObject *op)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	return ((PyFunctionObject *) op) -> func_defaults;
}

int
PyFunction_SetDefaults(PyObject *op, PyObject *defaults)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return -1;
	}
	if (defaults == Py_None)
		defaults = NULL;
	else if (PyTuple_Check(defaults)) {
		Py_XINCREF(defaults);
	}
	else {
		PyErr_SetString(PyExc_SystemError, "non-tuple default args");
		return -1;
	}
	Py_XDECREF(((PyFunctionObject *) op) -> func_defaults);
	((PyFunctionObject *) op) -> func_defaults = defaults;
	return 0;
}

PyObject *
PyFunction_GetClosure(PyObject *op)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	return ((PyFunctionObject *) op) -> func_closure;
}

int
PyFunction_SetClosure(PyObject *op, PyObject *closure)
{
	if (!PyFunction_Check(op)) {
		PyErr_BadInternalCall();
		return -1;
	}
	if (closure == Py_None)
		closure = NULL;
	else if (PyTuple_Check(closure)) {
		Py_XINCREF(closure);
	}
	else {
		PyErr_SetString(PyExc_SystemError, "non-tuple closure");
		return -1;
	}
	Py_XDECREF(((PyFunctionObject *) op) -> func_closure);
	((PyFunctionObject *) op) -> func_closure = closure;
	return 0;
}

/* Methods */

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

static struct memberlist func_memberlist[] = {
        {"func_code",     T_OBJECT,     OFF(func_code)},
        {"func_globals",  T_OBJECT,     OFF(func_globals),      READONLY},
        {"func_name",     T_OBJECT,     OFF(func_name),         READONLY},
        {"__name__",      T_OBJECT,     OFF(func_name),         READONLY},
        {"func_closure",  T_OBJECT,     OFF(func_closure),      READONLY},
        {"func_defaults", T_OBJECT,     OFF(func_defaults)},
        {"func_doc",      T_OBJECT,     OFF(func_doc)},
        {"__doc__",       T_OBJECT,     OFF(func_doc)},
        {"func_dict",     T_OBJECT,     OFF(func_dict)},
        {"__dict__",      T_OBJECT,     OFF(func_dict)},
        {NULL}  /* Sentinel */
};

static PyObject *
func_getattro(PyObject *op, PyObject *name)
{
	char *sname = PyString_AsString(name);
	
	if (sname[0] != '_' && PyEval_GetRestricted()) {
		PyErr_SetString(PyExc_RuntimeError,
		  "function attributes not accessible in restricted mode");
		return NULL;
	}
	/* If func_dict is being accessed but no attribute has been set
	 * yet, then initialize it to the empty dictionary.
	 */
	if ((!strcmp(sname, "func_dict") || !strcmp(sname, "__dict__"))
	     && ((PyFunctionObject*)op)->func_dict == NULL)
	{
		PyFunctionObject* funcop = (PyFunctionObject*)op;
		
		funcop->func_dict = PyDict_New();
		if (funcop->func_dict == NULL)
			return NULL;
	}
	return PyObject_GenericGetAttr(op, name);
}

static int
func_setattro(PyObject *op, PyObject *name, PyObject *value)
{
	char *sname = PyString_AsString(name);

	if (PyEval_GetRestricted()) {
		PyErr_SetString(PyExc_RuntimeError,
		  "function attributes not settable in restricted mode");
		return -1;
	}
	if (strcmp(sname, "func_code") == 0) {
		/* not legal to del f.func_code or to set it to anything
		 * other than a code object.
		 */
		if (value == NULL || !PyCode_Check(value)) {
			PyErr_SetString(
				PyExc_TypeError,
				"func_code must be set to a code object");
			return -1;
		}
	}
	else if (strcmp(sname, "func_defaults") == 0) {
		/* legal to del f.func_defaults.  Can only set
		 * func_defaults to NULL or a tuple.
		 */
		if (value == Py_None)
			value = NULL;
		if (value != NULL && !PyTuple_Check(value)) {
			PyErr_SetString(
				PyExc_TypeError,
				"func_defaults must be set to a tuple object");
			return -1;
		}
	}
	else if (!strcmp(sname, "func_dict") || !strcmp(sname, "__dict__")) {
		/* It is illegal to del f.func_dict.  Can only set
		 * func_dict to a dictionary.
		 */
		if (value == NULL) {
			PyErr_SetString(
				PyExc_TypeError,
				"function's dictionary may not be deleted");
			return -1;
		}
		if (!PyDict_Check(value)) {
			PyErr_SetString(
				PyExc_TypeError,
				"setting function's dictionary to a non-dict");
			return -1;
		}
	}
	return PyObject_GenericSetAttr(op, name, value);
}

static void
func_dealloc(PyFunctionObject *op)
{
	_PyObject_GC_UNTRACK(op);
	PyObject_ClearWeakRefs((PyObject *) op);
	Py_DECREF(op->func_code);
	Py_DECREF(op->func_globals);
	Py_DECREF(op->func_name);
	Py_XDECREF(op->func_defaults);
	Py_XDECREF(op->func_doc);
	Py_XDECREF(op->func_dict);
	Py_XDECREF(op->func_closure);
	PyObject_GC_Del(op);
}

static PyObject*
func_repr(PyFunctionObject *op)
{
	if (op->func_name == Py_None)
		return PyString_FromFormat("<anonymous function at %p>", op);
	return PyString_FromFormat("<function %s at %p>",
				   PyString_AsString(op->func_name),
				   op);
}

static int
func_traverse(PyFunctionObject *f, visitproc visit, void *arg)
{
	int err;
	if (f->func_code) {
		err = visit(f->func_code, arg);
		if (err)
			return err;
	}
	if (f->func_globals) {
		err = visit(f->func_globals, arg);
		if (err)
			return err;
	}
	if (f->func_defaults) {
		err = visit(f->func_defaults, arg);
		if (err)
			return err;
	}
	if (f->func_doc) {
		err = visit(f->func_doc, arg);
		if (err)
			return err;
	}
	if (f->func_name) {
		err = visit(f->func_name, arg);
		if (err)
			return err;
	}
	if (f->func_dict) {
		err = visit(f->func_dict, arg);
		if (err)
			return err;
	}
	if (f->func_closure) {
		err = visit(f->func_closure, arg);
		if (err)
			return err;
	}
	return 0;
}

static PyObject *
function_call(PyObject *func, PyObject *arg, PyObject *kw)
{
	PyObject *result;
	PyObject *argdefs;
	PyObject **d, **k;
	int nk, nd;

	argdefs = PyFunction_GET_DEFAULTS(func);
	if (argdefs != NULL && PyTuple_Check(argdefs)) {
		d = &PyTuple_GET_ITEM((PyTupleObject *)argdefs, 0);
		nd = PyTuple_Size(argdefs);
	}
	else {
		d = NULL;
		nd = 0;
	}

	if (kw != NULL && PyDict_Check(kw)) {
		int pos, i;
		nk = PyDict_Size(kw);
		k = PyMem_NEW(PyObject *, 2*nk);
		if (k == NULL) {
			PyErr_NoMemory();
			Py_DECREF(arg);
			return NULL;
		}
		pos = i = 0;
		while (PyDict_Next(kw, &pos, &k[i], &k[i+1]))
			i += 2;
		nk = i/2;
		/* XXX This is broken if the caller deletes dict items! */
	}
	else {
		k = NULL;
		nk = 0;
	}

	result = PyEval_EvalCodeEx(
		(PyCodeObject *)PyFunction_GET_CODE(func),
		PyFunction_GET_GLOBALS(func), (PyObject *)NULL,
		&PyTuple_GET_ITEM(arg, 0), PyTuple_Size(arg),
		k, nk, d, nd,
		PyFunction_GET_CLOSURE(func));

	if (k != NULL)
		PyMem_DEL(k);

	return result;
}

/* Bind a function to an object */
static PyObject *
func_descr_get(PyObject *func, PyObject *obj, PyObject *type)
{
	if (obj == Py_None)
		obj = NULL;
	return PyMethod_New(func, obj, type);
}

PyTypeObject PyFunction_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"function",
	sizeof(PyFunctionObject),
	0,
	(destructor)func_dealloc,		/* tp_dealloc */
	0,					/* tp_print */
	0,					/* tp_getattr */
	0,					/* tp_setattr */
	0,					/* tp_compare */
	(reprfunc)func_repr,			/* tp_repr */
	0,					/* tp_as_number */
	0,					/* tp_as_sequence */
	0,					/* tp_as_mapping */
	0,					/* tp_hash */
	function_call,				/* tp_call */
	0,					/* tp_str */
	func_getattro,				/* tp_getattro */
	func_setattro,				/* tp_setattro */
	0,					/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
	0,					/* tp_doc */
	(traverseproc)func_traverse,		/* tp_traverse */
	0,					/* tp_clear */
	0,					/* tp_richcompare */
	offsetof(PyFunctionObject, func_weakreflist), /* tp_weaklistoffset */
	0,					/* tp_iter */
	0,					/* tp_iternext */
	0,					/* tp_methods */
	func_memberlist,			/* tp_members */
	0,					/* tp_getset */
	0,					/* tp_base */
	0,					/* tp_dict */
	func_descr_get,				/* tp_descr_get */
	0,					/* tp_descr_set */
	offsetof(PyFunctionObject, func_dict),	/* tp_dictoffset */
};


/* Class method object */

/* A class method receives the class as implicit first argument,
   just like an instance method receives the instance.
   To declare a class method, use this idiom:

     class C:
         def f(cls, arg1, arg2, ...): ...
	 f = classmethod(f)
   
   It can be called either on the class (e.g. C.f()) or on an instance
   (e.g. C().f()); the instance is ignored except for its class.
   If a class method is called for a derived class, the derived class
   object is passed as the implied first argument.

   Class methods are different than C++ or Java static methods.
   If you want those, see static methods below.
*/

typedef struct {
	PyObject_HEAD
	PyObject *cm_callable;
} classmethod;

static void
cm_dealloc(classmethod *cm)
{
	Py_XDECREF(cm->cm_callable);
	PyObject_DEL(cm);
}

static PyObject *
cm_descr_get(PyObject *self, PyObject *obj, PyObject *type)
{
	classmethod *cm = (classmethod *)self;

	if (cm->cm_callable == NULL) {
		PyErr_SetString(PyExc_RuntimeError,
				"uninitialized classmethod object");
		return NULL;
	}
 	return PyMethod_New(cm->cm_callable,
			    type, (PyObject *)(type->ob_type));
}

static int
cm_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	classmethod *cm = (classmethod *)self;
	PyObject *callable;

	if (!PyArg_ParseTuple(args, "O:callable", &callable))
		return -1;
	Py_INCREF(callable);
	cm->cm_callable = callable;
	return 0;
}

PyTypeObject PyClassMethod_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"classmethod",
	sizeof(classmethod),
	0,
	(destructor)cm_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 */
	PyObject_GenericGetAttr,		/* tp_getattro */
	0,					/* tp_setattro */
	0,					/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	0,					/* 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 */
	cm_descr_get,				/* tp_descr_get */
	0,					/* tp_descr_set */
	0,					/* tp_dictoffset */
	cm_init,				/* tp_init */
	PyType_GenericAlloc,			/* tp_alloc */
	PyType_GenericNew,			/* tp_new */
};

PyObject *
PyClassMethod_New(PyObject *callable)
{
	classmethod *cm = (classmethod *)
		PyType_GenericAlloc(&PyClassMethod_Type, 0);
	if (cm != NULL) {
		Py_INCREF(callable);
		cm->cm_callable = callable;
	}
	return (PyObject *)cm;
}


/* Static method object */

/* A static method does not receive an implicit first argument.
   To declare a static method, use this idiom:

     class C:
         def f(arg1, arg2, ...): ...
	 f = staticmethod(f)

   It can be called either on the class (e.g. C.f()) or on an instance
   (e.g. C().f()); the instance is ignored except for its class.

   Static methods in Python are similar to those found in Java or C++.
   For a more advanced concept, see class methods above.
*/

typedef struct {
	PyObject_HEAD
	PyObject *sm_callable;
} staticmethod;

static void
sm_dealloc(staticmethod *sm)
{
	Py_XDECREF(sm->sm_callable);
	PyObject_DEL(sm);
}

static PyObject *
sm_descr_get(PyObject *self, PyObject *obj, PyObject *type)
{
	staticmethod *sm = (staticmethod *)self;

	if (sm->sm_callable == NULL) {
		PyErr_SetString(PyExc_RuntimeError,
				"uninitialized staticmethod object");
		return NULL;
	}
	Py_INCREF(sm->sm_callable);
	return sm->sm_callable;
}

static int
sm_init(PyObject *self, PyObject *args, PyObject *kwds)
{
	staticmethod *sm = (staticmethod *)self;
	PyObject *callable;

	if (!PyArg_ParseTuple(args, "O:callable", &callable))
		return -1;
	Py_INCREF(callable);
	sm->sm_callable = callable;
	return 0;
}

PyTypeObject PyStaticMethod_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"staticmethod",
	sizeof(staticmethod),
	0,
	(destructor)sm_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 */
	PyObject_GenericGetAttr,		/* tp_getattro */
	0,					/* tp_setattro */
	0,					/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	0,					/* 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 */
	sm_descr_get,				/* tp_descr_get */
	0,					/* tp_descr_set */
	0,					/* tp_dictoffset */
	sm_init,				/* tp_init */
	PyType_GenericAlloc,			/* tp_alloc */
	PyType_GenericNew,			/* tp_new */
};

PyObject *
PyStaticMethod_New(PyObject *callable)
{
	staticmethod *sm = (staticmethod *)
		PyType_GenericAlloc(&PyStaticMethod_Type, 0);
	if (sm != NULL) {
		Py_INCREF(callable);
		sm->sm_callable = callable;
	}
	return (PyObject *)sm;
}