/* Implementation helper: a struct that looks like a tuple.

See timemodule and posixmodule for example uses.

The structseq helper is considered an internal CPython implementation

detail. Docs for modules using structseqs should call them

"named tuples" (be sure to include a space between the two

words and add a link back to the term in Docs/glossary.rst).

*/

#include "Python.h"

#include "pycore_initconfig.h" // _PyStatus_OK()

#include "pycore_modsupport.h" // _PyArg_NoPositional()

#include "pycore_object.h" // _PyObject_GC_TRACK()

#include "pycore_structseq.h" // PyStructSequence_InitType()

#include "pycore_tuple.h" // _PyTuple_FromArray()

#include "pycore_typeobject.h" // _PyStaticType_FiniBuiltin()

static const char visible_length_key[] = "n_sequence_fields";

static const char real_length_key[] = "n_fields";

static const char unnamed_fields_key[] = "n_unnamed_fields";

static const char match_args_key[] = "__match_args__";

/* Fields with this name have only a field index, not a field name.

They are only allowed for indices < n_visible_fields. */

const char * const PyStructSequence_UnnamedField = "unnamed field";

static Py_ssize_t

get_type_attr_as_size(PyTypeObject *tp, PyObject *name)

{

PyObject *v = PyDict_GetItemWithError(_PyType_GetDict(tp), name);

if (v == NULL && !PyErr_Occurred()) {

PyErr_Format(PyExc_TypeError,

"Missed attribute '%U' of type %s",

name, tp->tp_name);

return -1;

}

return PyLong_AsSsize_t(v);

}

#define VISIBLE_SIZE(op) Py_SIZE(op)

#define VISIBLE_SIZE_TP(tp) \

get_type_attr_as_size(tp, &_Py_ID(n_sequence_fields))

#define REAL_SIZE_TP(tp) \

get_type_attr_as_size(tp, &_Py_ID(n_fields))

#define REAL_SIZE(op) get_real_size((PyObject *)op)

#define UNNAMED_FIELDS_TP(tp) \

get_type_attr_as_size(tp, &_Py_ID(n_unnamed_fields))

#define UNNAMED_FIELDS(op) UNNAMED_FIELDS_TP(Py_TYPE(op))

static Py_ssize_t

get_real_size(PyObject *op)

{

// Compute the real size from the visible size (i.e., Py_SIZE()) and the

// number of non-sequence fields accounted for in tp_basicsize.

Py_ssize_t hidden = Py_TYPE(op)->tp_basicsize - offsetof(PyStructSequence, ob_item);

return Py_SIZE(op) + hidden / sizeof(PyObject *);

}

PyObject *

PyStructSequence_New(PyTypeObject *type)

{

PyStructSequence *obj;

Py_ssize_t size = REAL_SIZE_TP(type), i;

if (size < 0) {

return NULL;

}

Py_ssize_t vsize = VISIBLE_SIZE_TP(type);

if (vsize < 0) {

return NULL;

}

obj = PyObject_GC_NewVar(PyStructSequence, type, size);

if (obj == NULL)

return NULL;

/* Hack the size of the variable object, so invisible fields don't appear

to Python code. */

Py_SET_SIZE(obj, vsize);

for (i = 0; i < size; i++)

obj->ob_item[i] = NULL;

return (PyObject*)obj;

}

void

PyStructSequence_SetItem(PyObject *op, Py_ssize_t index, PyObject *value)

{

PyTupleObject *tuple = _PyTuple_CAST(op);

assert(0 <= index);

#ifndef NDEBUG

Py_ssize_t n_fields = REAL_SIZE(op);

assert(n_fields >= 0);

assert(index < n_fields);

#endif

tuple->ob_item[index] = value;

}

PyObject*

PyStructSequence_GetItem(PyObject *op, Py_ssize_t index)

{

assert(0 <= index);

#ifndef NDEBUG

Py_ssize_t n_fields = REAL_SIZE(op);

assert(n_fields >= 0);

assert(index < n_fields);

#endif

return PyTuple_GET_ITEM(op, index);

}

static int

structseq_traverse(PyObject *op, visitproc visit, void *arg)

{

PyStructSequence *obj = (PyStructSequence *)op;

if (Py_TYPE(obj)->tp_flags & Py_TPFLAGS_HEAPTYPE) {

Py_VISIT(Py_TYPE(obj));

}

Py_ssize_t i, size;

size = REAL_SIZE(obj);

for (i = 0; i < size; ++i) {

Py_VISIT(obj->ob_item[i]);

}

return 0;

}

static void

structseq_dealloc(PyObject *op)

{

PyStructSequence *obj = (PyStructSequence *)op;

Py_ssize_t i, size;

PyObject_GC_UnTrack(obj);

PyTypeObject *tp = Py_TYPE(obj);

// gh-122527: We can't use REAL_SIZE_TP() or any macros that access the

// type's dictionary here, because the dictionary may have already been

// cleared by the garbage collector.

size = REAL_SIZE(obj);

for (i = 0; i < size; ++i) {

Py_XDECREF(obj->ob_item[i]);

}

PyObject_GC_Del(obj);

if (_PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE)) {

Py_DECREF(tp);

}

}

/*[clinic input]

class structseq "PyStructSequence *" "NULL"

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=9d781c6922c77752]*/

#include "clinic/structseq.c.h"

/*[clinic input]

@classmethod

structseq.__new__ as structseq_new

sequence as arg: object

dict: object(c_default="NULL") = {}

[clinic start generated code]*/

static PyObject *

structseq_new_impl(PyTypeObject *type, PyObject *arg, PyObject *dict)

/*[clinic end generated code: output=baa082e788b171da input=90532511101aa3fb]*/

{

PyStructSequence *res = NULL;

Py_ssize_t len, min_len, max_len, i, n_unnamed_fields;

min_len = VISIBLE_SIZE_TP(type);

if (min_len < 0) {

return NULL;

}

max_len = REAL_SIZE_TP(type);

if (max_len < 0) {

return NULL;

}

n_unnamed_fields = UNNAMED_FIELDS_TP(type);

if (n_unnamed_fields < 0) {

return NULL;

}

arg = PySequence_Fast(arg, "constructor requires a sequence");

if (!arg) {

return NULL;

}

if (dict && !PyDict_Check(dict)) {

PyErr_Format(PyExc_TypeError,

"%.500s() takes a dict as second arg, if any",

type->tp_name);

Py_DECREF(arg);

return NULL;

}

len = PySequence_Fast_GET_SIZE(arg);

if (min_len != max_len) {

if (len < min_len) {

PyErr_Format(PyExc_TypeError,

"%.500s() takes an at least %zd-sequence (%zd-sequence given)",

type->tp_name, min_len, len);

Py_DECREF(arg);

return NULL;

}

if (len > max_len) {

PyErr_Format(PyExc_TypeError,

"%.500s() takes an at most %zd-sequence (%zd-sequence given)",

type->tp_name, max_len, len);

Py_DECREF(arg);

return NULL;

}

}

else {

if (len != min_len) {

PyErr_Format(PyExc_TypeError,

"%.500s() takes a %zd-sequence (%zd-sequence given)",

type->tp_name, min_len, len);

Py_DECREF(arg);

return NULL;

}

}

res = (PyStructSequence*) PyStructSequence_New(type);

if (res == NULL) {

Py_DECREF(arg);

return NULL;

}

for (i = 0; i < len; ++i) {

PyObject *v = PySequence_Fast_GET_ITEM(arg, i);

res->ob_item[i] = Py_NewRef(v);

}

Py_DECREF(arg);

if (dict != NULL && PyDict_GET_SIZE(dict) > 0) {

Py_ssize_t n_found_keys = 0;

for (i = len; i < max_len; ++i) {

PyObject *ob = NULL;

const char *name = type->tp_members[i - n_unnamed_fields].name;

if (PyDict_GetItemStringRef(dict, name, &ob) < 0) {

Py_DECREF(res);

return NULL;

}

if (ob == NULL) {

ob = Py_NewRef(Py_None);

}

else {

++n_found_keys;

}

res->ob_item[i] = ob;

}

if (PyDict_GET_SIZE(dict) > n_found_keys) {

PyErr_Format(PyExc_TypeError,

"%.500s() got duplicate or unexpected field name(s)",

type->tp_name);

Py_DECREF(res);

return NULL;

}

} else {

for (i = len; i < max_len; ++i) {

res->ob_item[i] = Py_NewRef(Py_None);

}

}

_PyObject_GC_TRACK(res);

return (PyObject*) res;

}

static PyObject *

structseq_repr(PyObject *op)

{

PyStructSequence *obj = (PyStructSequence *)op;

PyTypeObject *typ = Py_TYPE(obj);

// count 5 characters per item: "x=1, "

Py_ssize_t type_name_len = strlen(typ->tp_name);

Py_ssize_t prealloc = (type_name_len + 1

+ VISIBLE_SIZE(obj) * 5 + 1);

PyUnicodeWriter *writer = PyUnicodeWriter_Create(prealloc);

if (writer == NULL) {

return NULL;

}

// Write "typename("

if (PyUnicodeWriter_WriteUTF8(writer, typ->tp_name, type_name_len) < 0) {

goto error;

}

if (PyUnicodeWriter_WriteChar(writer, '(') < 0) {

goto error;

}

for (Py_ssize_t i=0; i < VISIBLE_SIZE(obj); i++) {

if (i > 0) {

// Write ", "

if (PyUnicodeWriter_WriteChar(writer, ',') < 0) {

goto error;

}

if (PyUnicodeWriter_WriteChar(writer, ' ') < 0) {

goto error;

}

}

// Write name

const char *name_utf8 = typ->tp_members[i].name;

if (name_utf8 == NULL) {

PyErr_Format(PyExc_SystemError,

"In structseq_repr(), member %zd name is NULL"

" for type %.500s", i, typ->tp_name);

goto error;

}

if (PyUnicodeWriter_WriteUTF8(writer, name_utf8, -1) < 0) {

goto error;

}

// Write "=" + repr(value)

if (PyUnicodeWriter_WriteChar(writer, '=') < 0) {

goto error;

}

PyObject *value = PyStructSequence_GetItem((PyObject*)obj, i);

assert(value != NULL);

if (PyUnicodeWriter_WriteRepr(writer, value) < 0) {

goto error;

}

}

if (PyUnicodeWriter_WriteChar(writer, ')') < 0) {

goto error;

}

return PyUnicodeWriter_Finish(writer);

error:

PyUnicodeWriter_Discard(writer);

return NULL;

}

static PyObject *

structseq_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))

{

PyStructSequence *self = (PyStructSequence*)op;

PyObject* tup = NULL;

PyObject* dict = NULL;

PyObject* result;

Py_ssize_t n_fields, n_visible_fields, n_unnamed_fields, i;

n_fields = REAL_SIZE(self);

if (n_fields < 0) {

return NULL;

}

n_visible_fields = VISIBLE_SIZE(self);

n_unnamed_fields = UNNAMED_FIELDS(self);

if (n_unnamed_fields < 0) {

return NULL;

}

tup = _PyTuple_FromArray(self->ob_item, n_visible_fields);

if (!tup)

goto error;

dict = PyDict_New();

if (!dict)

goto error;

for (i = n_visible_fields; i < n_fields; i++) {

const char *n = Py_TYPE(self)->tp_members[i-n_unnamed_fields].name;

if (PyDict_SetItemString(dict, n, self->ob_item[i]) < 0)

goto error;

}

result = Py_BuildValue("(O(OO))", Py_TYPE(self), tup, dict);

Py_DECREF(tup);

Py_DECREF(dict);

return result;

error:

Py_XDECREF(tup);

Py_XDECREF(dict);

return NULL;

}

static PyObject *

structseq_replace(PyObject *op, PyObject *args, PyObject *kwargs)

{

PyStructSequence *self = (PyStructSequence*)op;

PyStructSequence *result = NULL;

Py_ssize_t n_fields, n_unnamed_fields, i;

if (!_PyArg_NoPositional("__replace__", args)) {

return NULL;

}

n_fields = REAL_SIZE(self);

if (n_fields < 0) {

return NULL;

}

n_unnamed_fields = UNNAMED_FIELDS(self);

if (n_unnamed_fields < 0) {

return NULL;

}

if (n_unnamed_fields > 0) {

PyErr_Format(PyExc_TypeError,

"__replace__() is not supported for %.500s "

"because it has unnamed field(s)",

Py_TYPE(self)->tp_name);

return NULL;

}

result = (PyStructSequence *) PyStructSequence_New(Py_TYPE(self));

if (!result) {

return NULL;

}

if (kwargs != NULL) {

// We do not support types with unnamed fields, so we can iterate over

// i >= n_visible_fields case without slicing with (i - n_unnamed_fields).

for (i = 0; i < n_fields; ++i) {

PyObject *ob;

if (PyDict_PopString(kwargs, Py_TYPE(self)->tp_members[i].name,

&ob) < 0) {

goto error;

}

if (ob == NULL) {

ob = Py_NewRef(self->ob_item[i]);

}

result->ob_item[i] = ob;

}

// Check if there are any unexpected fields.

if (PyDict_GET_SIZE(kwargs) > 0) {

PyObject *names = PyDict_Keys(kwargs);

if (names) {

PyErr_Format(PyExc_TypeError, "Got unexpected field name(s): %R", names);

Py_DECREF(names);

}

goto error;

}

}

else

{

// Just create a copy of the original.

for (i = 0; i < n_fields; ++i) {

result->ob_item[i] = Py_NewRef(self->ob_item[i]);

}

}

return (PyObject *)result;

error:

Py_DECREF(result);

return NULL;

}

static PyMethodDef structseq_methods[] = {

{"__reduce__", structseq_reduce, METH_NOARGS, NULL},

{"__replace__", _PyCFunction_CAST(structseq_replace), METH_VARARGS | METH_KEYWORDS,

PyDoc_STR("__replace__($self, /, **changes)\n--\n\n"

"Return a copy of the structure with new values for the specified fields.")},

{NULL, NULL} // sentinel

};

static Py_ssize_t

count_members(PyStructSequence_Desc *desc, Py_ssize_t *n_unnamed_members) {

Py_ssize_t i;

*n_unnamed_members = 0;

for (i = 0; desc->fields[i].name != NULL; ++i) {

if (desc->fields[i].name == PyStructSequence_UnnamedField) {

(*n_unnamed_members)++;

}

}

return i;

}

static int

initialize_structseq_dict(PyStructSequence_Desc *desc, PyObject* dict,

Py_ssize_t n_members, Py_ssize_t n_unnamed_members) {

PyObject *v;

#define SET_DICT_FROM_SIZE(key, value) \

do { \

v = PyLong_FromSsize_t(value); \

if (v == NULL) { \

return -1; \

} \

if (PyDict_SetItemString(dict, key, v) < 0) { \

Py_DECREF(v); \

return -1; \

} \

Py_DECREF(v); \

} while (0)

SET_DICT_FROM_SIZE(visible_length_key, desc->n_in_sequence);

SET_DICT_FROM_SIZE(real_length_key, n_members);

SET_DICT_FROM_SIZE(unnamed_fields_key, n_unnamed_members);

// Prepare and set __match_args__

Py_ssize_t i, k;

PyObject* keys = PyTuple_New(desc->n_in_sequence);

if (keys == NULL) {

return -1;

}

for (i = k = 0; i < desc->n_in_sequence; ++i) {

if (desc->fields[i].name == PyStructSequence_UnnamedField) {

continue;

}

PyObject* new_member = PyUnicode_FromString(desc->fields[i].name);

if (new_member == NULL) {

goto error;

}

PyTuple_SET_ITEM(keys, k, new_member);

k++;

}

if (_PyTuple_Resize(&keys, k) == -1) {

goto error;

}

if (PyDict_SetItemString(dict, match_args_key, keys) < 0) {

goto error;

}

Py_DECREF(keys);

return 0;

error:

Py_DECREF(keys);

return -1;

}

static PyMemberDef *

initialize_members(PyStructSequence_Desc *desc,

Py_ssize_t n_members, Py_ssize_t n_unnamed_members)

{

PyMemberDef *members;

members = PyMem_NEW(PyMemberDef, n_members - n_unnamed_members + 1);

if (members == NULL) {

PyErr_NoMemory();

return NULL;

}

Py_ssize_t i, k;

for (i = k = 0; i < n_members; ++i) {

if (desc->fields[i].name == PyStructSequence_UnnamedField) {

continue;

}

/* The names and docstrings in these MemberDefs are statically */

/* allocated so it is expected that they'll outlive the MemberDef */

members[k].name = desc->fields[i].name;

members[k].type = _Py_T_OBJECT;

members[k].offset = offsetof(PyStructSequence, ob_item)

+ i * sizeof(PyObject*);

members[k].flags = Py_READONLY;

members[k].doc = desc->fields[i].doc;

k++;

}

members[k].name = NULL;

return members;

}

static void

initialize_static_fields(PyTypeObject *type, PyStructSequence_Desc *desc,

PyMemberDef *tp_members, Py_ssize_t n_members,

unsigned long tp_flags)

{

type->tp_name = desc->name;

// Account for hidden members in tp_basicsize because they are not

// included in the variable size.

Py_ssize_t n_hidden = n_members - desc->n_in_sequence;

type->tp_basicsize = sizeof(PyStructSequence) + (n_hidden - 1) * sizeof(PyObject *);

type->tp_itemsize = sizeof(PyObject *);

type->tp_dealloc = structseq_dealloc;

type->tp_repr = structseq_repr;

type->tp_doc = desc->doc;

type->tp_base = &PyTuple_Type;

type->tp_methods = structseq_methods;

type->tp_new = structseq_new;

type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | tp_flags;

type->tp_traverse = structseq_traverse;

type->tp_members = tp_members;

}

static int

initialize_static_type(PyTypeObject *type, PyStructSequence_Desc *desc,

Py_ssize_t n_members, Py_ssize_t n_unnamed_members) {

/* initialize_static_fields() should have been called already. */

if (PyType_Ready(type) < 0) {

return -1;

}

Py_INCREF(type);

if (initialize_structseq_dict(

desc, _PyType_GetDict(type), n_members, n_unnamed_members) < 0) {

Py_DECREF(type);

return -1;

}

return 0;

}

int

_PyStructSequence_InitBuiltinWithFlags(PyInterpreterState *interp,

PyTypeObject *type,

PyStructSequence_Desc *desc,

unsigned long tp_flags)

{

if (Py_TYPE(type) == NULL) {

Py_SET_TYPE(type, &PyType_Type);

}

Py_ssize_t n_unnamed_members;

Py_ssize_t n_members = count_members(desc, &n_unnamed_members);

PyMemberDef *members = NULL;

if ((type->tp_flags & Py_TPFLAGS_READY) == 0) {

assert(type->tp_name == NULL);

assert(type->tp_members == NULL);

assert(type->tp_base == NULL);

members = initialize_members(desc, n_members, n_unnamed_members);

if (members == NULL) {

goto error;

}

initialize_static_fields(type, desc, members, n_members, tp_flags);

_Py_SetImmortal((PyObject *)type);

}

#ifndef NDEBUG

else {

// Ensure that the type was initialized.

assert(type->tp_name != NULL);

assert(type->tp_members != NULL);

assert(type->tp_base == &PyTuple_Type);

assert((type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN));

assert(_Py_IsImmortal(type));

}

#endif

if (_PyStaticType_InitBuiltin(interp, type) < 0) {

PyErr_Format(PyExc_RuntimeError,

"Can't initialize builtin type %s",

desc->name);

goto error;

}

if (initialize_structseq_dict(

desc, _PyType_GetDict(type), n_members, n_unnamed_members) < 0)

{

goto error;

}

return 0;

error:

if (members != NULL) {

PyMem_Free(members);

}

return -1;

}

int

PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)

{

PyMemberDef *members;

Py_ssize_t n_members, n_unnamed_members;

#ifdef Py_TRACE_REFS

/* if the type object was traced, remove it first

before overwriting its storage */

PyInterpreterState *interp = _PyInterpreterState_GET();

if (_PyRefchain_IsTraced(interp, (PyObject *)type)) {

_Py_ForgetReference((PyObject *)type);

}

#endif

/* PyTypeObject has already been initialized */

if (Py_REFCNT(type) != 0) {

PyErr_BadInternalCall();

return -1;

}

n_members = count_members(desc, &n_unnamed_members);

members = initialize_members(desc, n_members, n_unnamed_members);

if (members == NULL) {

return -1;

}

initialize_static_fields(type, desc, members, n_members, 0);

if (initialize_static_type(type, desc, n_members, n_unnamed_members) < 0) {

PyMem_Free(members);

return -1;

}

return 0;

}

void

PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)

{

(void)PyStructSequence_InitType2(type, desc);

}

/* This is exposed in the internal API, not the public API.

It is only called on builtin static types, which are all

initialized via _PyStructSequence_InitBuiltinWithFlags(). */

void

_PyStructSequence_FiniBuiltin(PyInterpreterState *interp, PyTypeObject *type)

{

// Ensure that the type is initialized

assert(type->tp_name != NULL);

assert(type->tp_base == &PyTuple_Type);

assert((type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN));

assert(_Py_IsImmortal(type));

// Cannot delete a type if it still has subclasses

if (_PyType_HasSubclasses(type)) {

// XXX Shouldn't this be an error?

return;

}

_PyStaticType_FiniBuiltin(interp, type);

if (_Py_IsMainInterpreter(interp)) {

// Undo _PyStructSequence_InitBuiltinWithFlags().

type->tp_name = NULL;

PyMem_Free(type->tp_members);

type->tp_members = NULL;

type->tp_base = NULL;

}

}

PyTypeObject *

_PyStructSequence_NewType(PyStructSequence_Desc *desc, unsigned long tp_flags)

{

PyMemberDef *members;

PyTypeObject *type;

PyType_Slot slots[8];

PyType_Spec spec;

Py_ssize_t n_members, n_unnamed_members;

/* Initialize MemberDefs */

n_members = count_members(desc, &n_unnamed_members);

members = initialize_members(desc, n_members, n_unnamed_members);

if (members == NULL) {

return NULL;

}

/* Initialize Slots */

slots[0] = (PyType_Slot){Py_tp_dealloc, structseq_dealloc};

slots[1] = (PyType_Slot){Py_tp_repr, structseq_repr};

slots[2] = (PyType_Slot){Py_tp_doc, (void *)desc->doc};

slots[3] = (PyType_Slot){Py_tp_methods, structseq_methods};

slots[4] = (PyType_Slot){Py_tp_new, structseq_new};

slots[5] = (PyType_Slot){Py_tp_members, members};

slots[6] = (PyType_Slot){Py_tp_traverse, structseq_traverse};

slots[7] = (PyType_Slot){0, 0};

/* Initialize Spec */

/* The name in this PyType_Spec is statically allocated so it is */

/* expected that it'll outlive the PyType_Spec */

spec.name = desc->name;

Py_ssize_t hidden = n_members - desc->n_in_sequence;

spec.basicsize = (int)(sizeof(PyStructSequence) + (hidden - 1) * sizeof(PyObject *));

spec.itemsize = sizeof(PyObject *);

spec.flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | tp_flags;

spec.slots = slots;

type = (PyTypeObject *)PyType_FromSpecWithBases(&spec, (PyObject *)&PyTuple_Type);

PyMem_Free(members);

if (type == NULL) {

return NULL;

}

if (initialize_structseq_dict(

desc, _PyType_GetDict(type), n_members, n_unnamed_members) < 0) {

Py_DECREF(type);

return NULL;

}

return type;

}

PyTypeObject *

PyStructSequence_NewType(PyStructSequence_Desc *desc)

{

return _PyStructSequence_NewType(desc, 0);

}