cpython/Objects/structseq.c at b17f60574f836522c02e5724c23af193e5c064bf · python/cpython · GitHub

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/* 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_tuple.h" // _PyTuple_FromArray()

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

#include "structmember.h" // PyMemberDef

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

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

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(tp->tp_dict, 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) REAL_SIZE_TP(Py_TYPE(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))

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 i, PyObject* v)

{

PyStructSequence_SET_ITEM(op, i, v);

}

PyObject*

PyStructSequence_GetItem(PyObject* op, Py_ssize_t i)

{

return PyStructSequence_GET_ITEM(op, i);

}

static int

structseq_traverse(PyStructSequence *obj, visitproc visit, void *arg)

{

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(PyStructSequence *obj)

{

Py_ssize_t i, size;

PyObject_GC_UnTrack(obj);

PyTypeObject *tp = Py_TYPE(obj);

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]*/

{

PyObject *ob;

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);

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

if (dict == NULL) {

ob = Py_None;

}

else {

ob = _PyDict_GetItemStringWithError(dict,

type->tp_members[i-n_unnamed_fields].name);

if (ob == NULL) {

if (PyErr_Occurred()) {

Py_DECREF(res);

return NULL;

}

ob = Py_None;

}

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

}

_PyObject_GC_TRACK(res);

return (PyObject*) res;

}

static PyObject *

structseq_repr(PyStructSequence *obj)

{

PyTypeObject *typ = Py_TYPE(obj);

_PyUnicodeWriter writer;

/* Write "typename(" */

PyObject *type_name = PyUnicode_DecodeUTF8(typ->tp_name,

strlen(typ->tp_name),

NULL);

if (type_name == NULL) {

return NULL;

}

_PyUnicodeWriter_Init(&writer);

writer.overallocate = 1;

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

writer.min_length = (PyUnicode_GET_LENGTH(type_name) + 1

+ VISIBLE_SIZE(obj) * 5 + 1);

if (_PyUnicodeWriter_WriteStr(&writer, type_name) < 0) {

Py_DECREF(type_name);

goto error;

}

Py_DECREF(type_name);

if (_PyUnicodeWriter_WriteChar(&writer, '(') < 0) {

goto error;

}

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

if (i > 0) {

/* Write ", " */

if (_PyUnicodeWriter_WriteASCIIString(&writer, ", ", 2) < 0) {

goto error;

}

/* Write "name=repr" */

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;

}

PyObject *name = PyUnicode_DecodeUTF8(name_utf8, strlen(name_utf8), NULL);

if (name == NULL) {

goto error;

}

if (_PyUnicodeWriter_WriteStr(&writer, name) < 0) {

Py_DECREF(name);

goto error;

}

Py_DECREF(name);

if (_PyUnicodeWriter_WriteChar(&writer, '=') < 0) {

goto error;

}

PyObject *value = PyStructSequence_GET_ITEM(obj, i);

assert(value != NULL);

PyObject *repr = PyObject_Repr(value);

if (repr == NULL) {

goto error;

}

if (_PyUnicodeWriter_WriteStr(&writer, repr) < 0) {

Py_DECREF(repr);

goto error;

}

Py_DECREF(repr);

}

if (_PyUnicodeWriter_WriteChar(&writer, ')') < 0) {

goto error;

}

return _PyUnicodeWriter_Finish(&writer);

error:

_PyUnicodeWriter_Dealloc(&writer);

return NULL;

}

static PyObject *

structseq_reduce(PyStructSequence* self, PyObject *Py_UNUSED(ignored))

{

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 PyMethodDef structseq_methods[] = {

{"__reduce__", (PyCFunction)structseq_reduce, METH_NOARGS, NULL},

{NULL, NULL}

};

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 *pn_members, Py_ssize_t *pn_unnamed_members)

{

PyMemberDef *members;

Py_ssize_t n_members, n_unnamed_members;

n_members = count_members(desc, &n_unnamed_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 = T_OBJECT;

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

+ i * sizeof(PyObject*);

members[k].flags = READONLY;

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

k++;

}

members[k].name = NULL;

*pn_members = n_members;

*pn_unnamed_members = n_unnamed_members;

return members;

}

static void

initialize_static_fields(PyTypeObject *type, PyStructSequence_Desc *desc,

PyMemberDef *tp_members, unsigned long tp_flags)

{

type->tp_name = desc->name;

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

type->tp_itemsize = sizeof(PyObject *);

type->tp_dealloc = (destructor)structseq_dealloc;

type->tp_repr = (reprfunc)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 = (traverseproc) 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, type->tp_dict, n_members, n_unnamed_members) < 0) {

Py_DECREF(type);

return -1;

}

return 0;

}

int

_PyStructSequence_InitBuiltinWithFlags(PyTypeObject *type,

PyStructSequence_Desc *desc,

unsigned long tp_flags)

{

if (type->tp_flags & Py_TPFLAGS_READY) {

if (_PyStaticType_InitBuiltin(type) < 0) {

goto failed_init_builtin;

}

return 0;

}

PyMemberDef *members;

Py_ssize_t n_members, n_unnamed_members;

members = initialize_members(desc, &n_members, &n_unnamed_members);

if (members == NULL) {

return -1;

}

initialize_static_fields(type, desc, members, tp_flags);

Py_INCREF(type); // XXX It should be immortal.

if (_PyStaticType_InitBuiltin(type) < 0) {

PyMem_Free(members);

goto failed_init_builtin;

}

if (initialize_structseq_dict(

desc, type->tp_dict, n_members, n_unnamed_members) < 0) {

PyMem_Free(members);

return -1;

}

return 0;

failed_init_builtin:

PyErr_Format(PyExc_RuntimeError,

"Can't initialize builtin type %s",

desc->name);

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 chained, unchain it first

before overwriting its storage */

if (type->ob_base.ob_base._ob_next) {

_Py_ForgetReference((PyObject *)type);

}

#endif

/* PyTypeObject has already been initialized */

if (Py_REFCNT(type) != 0) {

PyErr_BadInternalCall();

return -1;

}

members = initialize_members(desc, &n_members, &n_unnamed_members);

if (members == NULL) {

return -1;

}

initialize_static_fields(type, desc, 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);

}

void

_PyStructSequence_FiniType(PyTypeObject *type)

{

// Ensure that the type is initialized

assert(type->tp_name != NULL);

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

// Cannot delete a type if it still has subclasses

if (_PyType_HasSubclasses(type)) {

return;

}

// Undo PyStructSequence_NewType()

type->tp_name = NULL;

PyMem_Free(type->tp_members);

_PyStaticType_Dealloc(type);

assert(Py_REFCNT(type) == 1);

// Undo Py_INCREF(type) of _PyStructSequence_InitType().

// Don't use Py_DECREF(): static type must not be deallocated

Py_SET_REFCNT(type, 0);

#ifdef Py_REF_DEBUG

_Py_DecRefTotal(_PyInterpreterState_GET());

#endif

// Make sure that _PyStructSequence_InitType() will initialize

// the type again

assert(Py_REFCNT(type) == 0);

assert(type->tp_name == 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 */

members = initialize_members(desc, &n_members, &n_unnamed_members);

if (members == NULL) {

return NULL;

}

/* Initialize Slots */

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

slots[1] = (PyType_Slot){Py_tp_repr, (reprfunc)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, (traverseproc)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;

spec.basicsize = sizeof(PyStructSequence) - 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, type->tp_dict, n_members, n_unnamed_members) < 0) {

Py_DECREF(type);

return NULL;

}

return type;

}

PyTypeObject *

PyStructSequence_NewType(PyStructSequence_Desc *desc)

{

return _PyStructSequence_NewType(desc, 0);

}

cpython/Objects/structseq.c at b17f60574f836522c02e5724c23af193e5c064bf · python/cpython · GitHub

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