/* Generic object operations; and implementation of None */

#include "Python.h"

#include "pycore_call.h" // _PyObject_CallNoArgs()

#include "pycore_ceval.h" // _Py_EnterRecursiveCallTstate()

#include "pycore_context.h" // _PyContextTokenMissing_Type

#include "pycore_descrobject.h" // _PyMethodWrapper_Type

#include "pycore_dict.h" // _PyObject_MakeDictFromInstanceAttributes()

#include "pycore_floatobject.h" // _PyFloat_DebugMallocStats()

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

#include "pycore_hashtable.h" // _Py_hashtable_new()

#include "pycore_memoryobject.h" // _PyManagedBuffer_Type

#include "pycore_namespace.h" // _PyNamespace_Type

#include "pycore_object.h" // PyAPI_DATA() _Py_SwappedOp definition

#include "pycore_optimizer.h" // _PyUOpExecutor_Type, _PyUOpOptimizer_Type, ...

#include "pycore_pyerrors.h" // _PyErr_Occurred()

#include "pycore_pymem.h" // _PyMem_IsPtrFreed()

#include "pycore_pystate.h" // _PyThreadState_GET()

#include "pycore_symtable.h" // PySTEntry_Type

#include "pycore_typeobject.h" // _PyBufferWrapper_Type

#include "pycore_typevarobject.h" // _PyTypeAlias_Type, _Py_initialize_generic

#include "pycore_unionobject.h" // _PyUnion_Type

#include "interpreteridobject.h" // _PyInterpreterID_Type

#ifdef Py_LIMITED_API

// Prevent recursive call _Py_IncRef() <=> Py_INCREF()

# error "Py_LIMITED_API macro must not be defined"

#endif

/* Defined in tracemalloc.c */

extern void _PyMem_DumpTraceback(int fd, const void *ptr);

int

_PyObject_CheckConsistency(PyObject *op, int check_content)

{

#define CHECK(expr) \

do { if (!(expr)) { _PyObject_ASSERT_FAILED_MSG(op, Py_STRINGIFY(expr)); } } while (0)

CHECK(!_PyObject_IsFreed(op));

CHECK(Py_REFCNT(op) >= 1);

_PyType_CheckConsistency(Py_TYPE(op));

if (PyUnicode_Check(op)) {

_PyUnicode_CheckConsistency(op, check_content);

}

else if (PyDict_Check(op)) {

_PyDict_CheckConsistency(op, check_content);

}

return 1;

#undef CHECK

}

#ifdef Py_REF_DEBUG

/* We keep the legacy symbol around for backward compatibility. */

Py_ssize_t _Py_RefTotal;

static inline Py_ssize_t

get_legacy_reftotal(void)

{

return _Py_RefTotal;

}

#endif

#ifdef Py_REF_DEBUG

# define REFTOTAL(interp) \

interp->object_state.reftotal

static inline void

reftotal_increment(PyInterpreterState *interp)

{

REFTOTAL(interp)++;

}

static inline void

reftotal_decrement(PyInterpreterState *interp)

{

REFTOTAL(interp)--;

}

static inline void

reftotal_add(PyInterpreterState *interp, Py_ssize_t n)

{

REFTOTAL(interp) += n;

}

static inline Py_ssize_t get_global_reftotal(_PyRuntimeState *);

/* We preserve the number of refs leaked during runtime finalization,

so they can be reported if the runtime is initialized again. */

// XXX We don't lose any information by dropping this,

// so we should consider doing so.

static Py_ssize_t last_final_reftotal = 0;

void

_Py_FinalizeRefTotal(_PyRuntimeState *runtime)

{

last_final_reftotal = get_global_reftotal(runtime);

runtime->object_state.interpreter_leaks = 0;

}

void

_PyInterpreterState_FinalizeRefTotal(PyInterpreterState *interp)

{

interp->runtime->object_state.interpreter_leaks += REFTOTAL(interp);

REFTOTAL(interp) = 0;

}

static inline Py_ssize_t

get_reftotal(PyInterpreterState *interp)

{

/* For a single interpreter, we ignore the legacy _Py_RefTotal,

since we can't determine which interpreter updated it. */

return REFTOTAL(interp);

}

static inline Py_ssize_t

get_global_reftotal(_PyRuntimeState *runtime)

{

Py_ssize_t total = 0;

/* Add up the total from each interpreter. */

HEAD_LOCK(&_PyRuntime);

PyInterpreterState *interp = PyInterpreterState_Head();

for (; interp != NULL; interp = PyInterpreterState_Next(interp)) {

total += REFTOTAL(interp);

}

HEAD_UNLOCK(&_PyRuntime);

/* Add in the updated value from the legacy _Py_RefTotal. */

total += get_legacy_reftotal();

total += last_final_reftotal;

total += runtime->object_state.interpreter_leaks;

return total;

}

#undef REFTOTAL

void

_PyDebug_PrintTotalRefs(void) {

_PyRuntimeState *runtime = &_PyRuntime;

fprintf(stderr,

"[%zd refs, %zd blocks]\n",

get_global_reftotal(runtime), _Py_GetGlobalAllocatedBlocks());

/* It may be helpful to also print the "legacy" reftotal separately.

Likewise for the total for each interpreter. */

}

#endif /* Py_REF_DEBUG */

/* Object allocation routines used by NEWOBJ and NEWVAROBJ macros.

These are used by the individual routines for object creation.

Do not call them otherwise, they do not initialize the object! */

#ifdef Py_TRACE_REFS

#define REFCHAIN(interp) interp->object_state.refchain

#define REFCHAIN_VALUE ((void*)(uintptr_t)1)

bool

_PyRefchain_IsTraced(PyInterpreterState *interp, PyObject *obj)

{

return (_Py_hashtable_get(REFCHAIN(interp), obj) == REFCHAIN_VALUE);

}

static void

_PyRefchain_Trace(PyInterpreterState *interp, PyObject *obj)

{

if (_Py_hashtable_set(REFCHAIN(interp), obj, REFCHAIN_VALUE) < 0) {

// Use a fatal error because _Py_NewReference() cannot report

// the error to the caller.

Py_FatalError("_Py_hashtable_set() memory allocation failed");

}

}

static void

_PyRefchain_Remove(PyInterpreterState *interp, PyObject *obj)

{

void *value = _Py_hashtable_steal(REFCHAIN(interp), obj);

#ifndef NDEBUG

assert(value == REFCHAIN_VALUE);

#else

(void)value;

#endif

}

/* Add an object to the refchain hash table.

*

* Note that objects are normally added to the list by PyObject_Init()

* indirectly. Not all objects are initialized that way, though; exceptions

* include statically allocated type objects, and statically allocated

* singletons (like Py_True and Py_None). */

void

_Py_AddToAllObjects(PyObject *op)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (!_PyRefchain_IsTraced(interp, op)) {

_PyRefchain_Trace(interp, op);

}

}

#endif /* Py_TRACE_REFS */

#ifdef Py_REF_DEBUG

/* Log a fatal error; doesn't return. */

void

_Py_NegativeRefcount(const char *filename, int lineno, PyObject *op)

{

_PyObject_AssertFailed(op, NULL, "object has negative ref count",

filename, lineno, __func__);

}

/* This is used strictly by Py_INCREF(). */

void

_Py_INCREF_IncRefTotal(void)

{

reftotal_increment(_PyInterpreterState_GET());

}

/* This is used strictly by Py_DECREF(). */

void

_Py_DECREF_DecRefTotal(void)

{

reftotal_decrement(_PyInterpreterState_GET());

}

void

_Py_IncRefTotal(PyInterpreterState *interp)

{

reftotal_increment(interp);

}

void

_Py_DecRefTotal(PyInterpreterState *interp)

{

reftotal_decrement(interp);

}

void

_Py_AddRefTotal(PyInterpreterState *interp, Py_ssize_t n)

{

reftotal_add(interp, n);

}

/* This includes the legacy total

and any carried over from the last runtime init/fini cycle. */

Py_ssize_t

_Py_GetGlobalRefTotal(void)

{

return get_global_reftotal(&_PyRuntime);

}

Py_ssize_t

_Py_GetLegacyRefTotal(void)

{

return get_legacy_reftotal();

}

Py_ssize_t

_PyInterpreterState_GetRefTotal(PyInterpreterState *interp)

{

return get_reftotal(interp);

}

#endif /* Py_REF_DEBUG */

void

Py_IncRef(PyObject *o)

{

Py_XINCREF(o);

}

void

Py_DecRef(PyObject *o)

{

Py_XDECREF(o);

}

void

_Py_IncRef(PyObject *o)

{

Py_INCREF(o);

}

void

_Py_DecRef(PyObject *o)

{

Py_DECREF(o);

}

#ifdef Py_NOGIL

static inline int

is_shared_refcnt_dead(Py_ssize_t shared)

{

#if SIZEOF_SIZE_T == 8

return shared == (Py_ssize_t)0xDDDDDDDDDDDDDDDD;

#else

return shared == (Py_ssize_t)0xDDDDDDDD;

#endif

}

void

_Py_DecRefSharedDebug(PyObject *o, const char *filename, int lineno)

{

// Should we queue the object for the owning thread to merge?

int should_queue;

Py_ssize_t new_shared;

Py_ssize_t shared = _Py_atomic_load_ssize_relaxed(&o->ob_ref_shared);

do {

should_queue = (shared == 0 || shared == _Py_REF_MAYBE_WEAKREF);

if (should_queue) {

// If the object had refcount zero, not queued, and not merged,

// then we enqueue the object to be merged by the owning thread.

// In this case, we don't subtract one from the reference count

// because the queue holds a reference.

new_shared = _Py_REF_QUEUED;

}

else {

// Otherwise, subtract one from the reference count. This might

// be negative!

new_shared = shared - (1 << _Py_REF_SHARED_SHIFT);

}

#ifdef Py_REF_DEBUG

if ((_Py_REF_IS_MERGED(new_shared) && new_shared < 0) ||

is_shared_refcnt_dead(shared))

{

_Py_NegativeRefcount(filename, lineno, o);

}

#endif

} while (!_Py_atomic_compare_exchange_ssize(&o->ob_ref_shared,

&shared, new_shared));

if (should_queue) {

// TODO: the inter-thread queue is not yet implemented. For now,

// we just merge the refcount here.

Py_ssize_t refcount = _Py_ExplicitMergeRefcount(o, -1);

if (refcount == 0) {

_Py_Dealloc(o);

}

}

else if (new_shared == _Py_REF_MERGED) {

// refcount is zero AND merged

_Py_Dealloc(o);

}

}

void

_Py_DecRefShared(PyObject *o)

{

_Py_DecRefSharedDebug(o, NULL, 0);

}

void

_Py_MergeZeroLocalRefcount(PyObject *op)

{

assert(op->ob_ref_local == 0);

_Py_atomic_store_uintptr_relaxed(&op->ob_tid, 0);

Py_ssize_t shared = _Py_atomic_load_ssize_relaxed(&op->ob_ref_shared);

if (shared == 0) {

// Fast-path: shared refcount is zero (including flags)

_Py_Dealloc(op);

return;

}

// Slow-path: atomically set the flags (low two bits) to _Py_REF_MERGED.

Py_ssize_t new_shared;

do {

new_shared = (shared & ~_Py_REF_SHARED_FLAG_MASK) | _Py_REF_MERGED;

} while (!_Py_atomic_compare_exchange_ssize(&op->ob_ref_shared,

&shared, new_shared));

if (new_shared == _Py_REF_MERGED) {

// i.e., the shared refcount is zero (only the flags are set) so we

// deallocate the object.

_Py_Dealloc(op);

}

}

Py_ssize_t

_Py_ExplicitMergeRefcount(PyObject *op, Py_ssize_t extra)

{

assert(!_Py_IsImmortal(op));

Py_ssize_t refcnt;

Py_ssize_t new_shared;

Py_ssize_t shared = _Py_atomic_load_ssize_relaxed(&op->ob_ref_shared);

do {

refcnt = Py_ARITHMETIC_RIGHT_SHIFT(Py_ssize_t, shared, _Py_REF_SHARED_SHIFT);

if (_Py_REF_IS_MERGED(shared)) {

return refcnt;

}

refcnt += (Py_ssize_t)op->ob_ref_local;

refcnt += extra;

new_shared = _Py_REF_SHARED(refcnt, _Py_REF_MERGED);

} while (!_Py_atomic_compare_exchange_ssize(&op->ob_ref_shared,

&shared, new_shared));

_Py_atomic_store_uint32_relaxed(&op->ob_ref_local, 0);

_Py_atomic_store_uintptr_relaxed(&op->ob_tid, 0);

return refcnt;

}

#endif

/**************************************/

PyObject *

PyObject_Init(PyObject *op, PyTypeObject *tp)

{

if (op == NULL) {

return PyErr_NoMemory();

}

_PyObject_Init(op, tp);

return op;

}

PyVarObject *

PyObject_InitVar(PyVarObject *op, PyTypeObject *tp, Py_ssize_t size)

{

if (op == NULL) {

return (PyVarObject *) PyErr_NoMemory();

}

_PyObject_InitVar(op, tp, size);

return op;

}

PyObject *

_PyObject_New(PyTypeObject *tp)

{

PyObject *op = (PyObject *) PyObject_Malloc(_PyObject_SIZE(tp));

if (op == NULL) {

return PyErr_NoMemory();

}

_PyObject_Init(op, tp);

return op;

}

PyVarObject *

_PyObject_NewVar(PyTypeObject *tp, Py_ssize_t nitems)

{

PyVarObject *op;

const size_t size = _PyObject_VAR_SIZE(tp, nitems);

op = (PyVarObject *) PyObject_Malloc(size);

if (op == NULL) {

return (PyVarObject *)PyErr_NoMemory();

}

_PyObject_InitVar(op, tp, nitems);

return op;

}

void

PyObject_CallFinalizer(PyObject *self)

{

PyTypeObject *tp = Py_TYPE(self);

if (tp->tp_finalize == NULL)

return;

/* tp_finalize should only be called once. */

if (_PyType_IS_GC(tp) && _PyGC_FINALIZED(self))

return;

tp->tp_finalize(self);

if (_PyType_IS_GC(tp)) {

_PyGC_SET_FINALIZED(self);

}

}

int

PyObject_CallFinalizerFromDealloc(PyObject *self)

{

if (Py_REFCNT(self) != 0) {

_PyObject_ASSERT_FAILED_MSG(self,

"PyObject_CallFinalizerFromDealloc called "

"on object with a non-zero refcount");

}

/* Temporarily resurrect the object. */

Py_SET_REFCNT(self, 1);

PyObject_CallFinalizer(self);

_PyObject_ASSERT_WITH_MSG(self,

Py_REFCNT(self) > 0,

"refcount is too small");

/* Undo the temporary resurrection; can't use DECREF here, it would

* cause a recursive call. */

Py_SET_REFCNT(self, Py_REFCNT(self) - 1);

if (Py_REFCNT(self) == 0) {

return 0; /* this is the normal path out */

}

/* tp_finalize resurrected it! Make it look like the original Py_DECREF

* never happened. */

Py_ssize_t refcnt = Py_REFCNT(self);

_Py_NewReferenceNoTotal(self);

Py_SET_REFCNT(self, refcnt);

_PyObject_ASSERT(self,

(!_PyType_IS_GC(Py_TYPE(self))

|| _PyObject_GC_IS_TRACKED(self)));

return -1;

}

int

PyObject_Print(PyObject *op, FILE *fp, int flags)

{

int ret = 0;

if (PyErr_CheckSignals())

return -1;

#ifdef USE_STACKCHECK

if (PyOS_CheckStack()) {

PyErr_SetString(PyExc_MemoryError, "stack overflow");

return -1;

}

#endif

clearerr(fp); /* Clear any previous error condition */

if (op == NULL) {

Py_BEGIN_ALLOW_THREADS

fprintf(fp, "<nil>");

Py_END_ALLOW_THREADS

}

else {

if (Py_REFCNT(op) <= 0) {

Py_BEGIN_ALLOW_THREADS

fprintf(fp, "<refcnt %zd at %p>", Py_REFCNT(op), (void *)op);

Py_END_ALLOW_THREADS

}

else {

PyObject *s;

if (flags & Py_PRINT_RAW)

s = PyObject_Str(op);

else

s = PyObject_Repr(op);

if (s == NULL) {

ret = -1;

}

else {

assert(PyUnicode_Check(s));

const char *t;

Py_ssize_t len;

t = PyUnicode_AsUTF8AndSize(s, &len);

if (t == NULL) {

ret = -1;

}

else {

fwrite(t, 1, len, fp);

}

Py_DECREF(s);

}

}

}

if (ret == 0) {

if (ferror(fp)) {

PyErr_SetFromErrno(PyExc_OSError);

clearerr(fp);

ret = -1;

}

}

return ret;

}

/* For debugging convenience. Set a breakpoint here and call it from your DLL */

void

_Py_BreakPoint(void)

{

}

/* Heuristic checking if the object memory is uninitialized or deallocated.

Rely on the debug hooks on Python memory allocators:

see _PyMem_IsPtrFreed().

The function can be used to prevent segmentation fault on dereferencing

pointers like 0xDDDDDDDDDDDDDDDD. */

int

_PyObject_IsFreed(PyObject *op)

{

if (_PyMem_IsPtrFreed(op) || _PyMem_IsPtrFreed(Py_TYPE(op))) {

return 1;

}

return 0;

}

/* For debugging convenience. See Misc/gdbinit for some useful gdb hooks */

void

_PyObject_Dump(PyObject* op)

{

if (_PyObject_IsFreed(op)) {

/* It seems like the object memory has been freed:

don't access it to prevent a segmentation fault. */

fprintf(stderr, "<object at %p is freed>\n", op);

fflush(stderr);

return;

}

/* first, write fields which are the least likely to crash */

fprintf(stderr, "object address : %p\n", (void *)op);

fprintf(stderr, "object refcount : %zd\n", Py_REFCNT(op));

fflush(stderr);

PyTypeObject *type = Py_TYPE(op);

fprintf(stderr, "object type : %p\n", type);

fprintf(stderr, "object type name: %s\n",

type==NULL ? "NULL" : type->tp_name);

/* the most dangerous part */

fprintf(stderr, "object repr : ");

fflush(stderr);

PyGILState_STATE gil = PyGILState_Ensure();

PyObject *exc = PyErr_GetRaisedException();

(void)PyObject_Print(op, stderr, 0);

fflush(stderr);

PyErr_SetRaisedException(exc);

PyGILState_Release(gil);

fprintf(stderr, "\n");

fflush(stderr);

}

PyObject *

PyObject_Repr(PyObject *v)

{

PyObject *res;

if (PyErr_CheckSignals())

return NULL;

#ifdef USE_STACKCHECK

if (PyOS_CheckStack()) {

PyErr_SetString(PyExc_MemoryError, "stack overflow");

return NULL;

}

#endif

if (v == NULL)

return PyUnicode_FromString("<NULL>");

if (Py_TYPE(v)->tp_repr == NULL)

return PyUnicode_FromFormat("<%s object at %p>",

Py_TYPE(v)->tp_name, v);

PyThreadState *tstate = _PyThreadState_GET();

#ifdef Py_DEBUG

/* PyObject_Repr() must not be called with an exception set,

because it can clear it (directly or indirectly) and so the

caller loses its exception */

assert(!_PyErr_Occurred(tstate));

#endif

/* It is possible for a type to have a tp_repr representation that loops

infinitely. */

if (_Py_EnterRecursiveCallTstate(tstate,

" while getting the repr of an object")) {

return NULL;

}

res = (*Py_TYPE(v)->tp_repr)(v);

_Py_LeaveRecursiveCallTstate(tstate);

if (res == NULL) {

return NULL;

}

if (!PyUnicode_Check(res)) {

_PyErr_Format(tstate, PyExc_TypeError,

"__repr__ returned non-string (type %.200s)",

Py_TYPE(res)->tp_name);

Py_DECREF(res);

return NULL;

}

return res;

}

PyObject *

PyObject_Str(PyObject *v)

{

PyObject *res;

if (PyErr_CheckSignals())

return NULL;

#ifdef USE_STACKCHECK

if (PyOS_CheckStack()) {

PyErr_SetString(PyExc_MemoryError, "stack overflow");

return NULL;

}

#endif

if (v == NULL)

return PyUnicode_FromString("<NULL>");

if (PyUnicode_CheckExact(v)) {

return Py_NewRef(v);

}

if (Py_TYPE(v)->tp_str == NULL)

return PyObject_Repr(v);

PyThreadState *tstate = _PyThreadState_GET();

#ifdef Py_DEBUG

/* PyObject_Str() must not be called with an exception set,

because it can clear it (directly or indirectly) and so the

caller loses its exception */

assert(!_PyErr_Occurred(tstate));

#endif

/* It is possible for a type to have a tp_str representation that loops

infinitely. */

if (_Py_EnterRecursiveCallTstate(tstate, " while getting the str of an object")) {

return NULL;

}

res = (*Py_TYPE(v)->tp_str)(v);

_Py_LeaveRecursiveCallTstate(tstate);

if (res == NULL) {

return NULL;

}

if (!PyUnicode_Check(res)) {

_PyErr_Format(tstate, PyExc_TypeError,

"__str__ returned non-string (type %.200s)",

Py_TYPE(res)->tp_name);

Py_DECREF(res);

return NULL;

}

assert(_PyUnicode_CheckConsistency(res, 1));

return res;

}

PyObject *

PyObject_ASCII(PyObject *v)

{

PyObject *repr, *ascii, *res;

repr = PyObject_Repr(v);

if (repr == NULL)

return NULL;

if (PyUnicode_IS_ASCII(repr))

return repr;

/* repr is guaranteed to be a PyUnicode object by PyObject_Repr */

ascii = _PyUnicode_AsASCIIString(repr, "backslashreplace");

Py_DECREF(repr);

if (ascii == NULL)

return NULL;

res = PyUnicode_DecodeASCII(

PyBytes_AS_STRING(ascii),

PyBytes_GET_SIZE(ascii),

NULL);

Py_DECREF(ascii);

return res;

}

PyObject *

PyObject_Bytes(PyObject *v)

{

PyObject *result, *func;

if (v == NULL)

return PyBytes_FromString("<NULL>");

if (PyBytes_CheckExact(v)) {

return Py_NewRef(v);

}

func = _PyObject_LookupSpecial(v, &_Py_ID(__bytes__));

if (func != NULL) {

result = _PyObject_CallNoArgs(func);

Py_DECREF(func);

if (result == NULL)

return NULL;

if (!PyBytes_Check(result)) {

PyErr_Format(PyExc_TypeError,

"__bytes__ returned non-bytes (type %.200s)",

Py_TYPE(result)->tp_name);

Py_DECREF(result);

return NULL;

}

return result;

}

else if (PyErr_Occurred())

return NULL;

return PyBytes_FromObject(v);

}

/*

def _PyObject_FunctionStr(x):

try:

qualname = x.__qualname__

except AttributeError:

return str(x)

try:

mod = x.__module__

if mod is not None and mod != 'builtins':

return f"{x.__module__}.{qualname}()"

except AttributeError:

pass

return qualname

*/

PyObject *

_PyObject_FunctionStr(PyObject *x)

{

assert(!PyErr_Occurred());

PyObject *qualname;

int ret = PyObject_GetOptionalAttr(x, &_Py_ID(__qualname__), &qualname);

if (qualname == NULL) {

if (ret < 0) {

return NULL;

}

return PyObject_Str(x);

}

PyObject *module;

PyObject *result = NULL;

ret = PyObject_GetOptionalAttr(x, &_Py_ID(__module__), &module);

if (module != NULL && module != Py_None) {

ret = PyObject_RichCompareBool(module, &_Py_ID(builtins), Py_NE);

if (ret < 0) {

// error

goto done;

}

if (ret > 0) {

result = PyUnicode_FromFormat("%S.%S()", module, qualname);

goto done;

}

}

else if (ret < 0) {

goto done;

}

result = PyUnicode_FromFormat("%S()", qualname);

done:

Py_DECREF(qualname);

Py_XDECREF(module);

return result;

}

/* For Python 3.0.1 and later, the old three-way comparison has been

completely removed in favour of rich comparisons. PyObject_Compare() and

PyObject_Cmp() are gone, and the builtin cmp function no longer exists.

The old tp_compare slot has been renamed to tp_as_async, and should no

longer be used. Use tp_richcompare instead.

See (*) below for practical amendments.

tp_richcompare gets called with a first argument of the appropriate type

and a second object of an arbitrary type. We never do any kind of

coercion.

The tp_richcompare slot should return an object, as follows:

NULL if an exception occurred

NotImplemented if the requested comparison is not implemented

any other false value if the requested comparison is false

any other true value if the requested comparison is true

The PyObject_RichCompare[Bool]() wrappers raise TypeError when they get

NotImplemented.

(*) Practical amendments:

- If rich comparison returns NotImplemented, == and != are decided by

comparing the object pointer (i.e. falling back to the base object

implementation).

*/

/* Map rich comparison operators to their swapped version, e.g. LT <--> GT */

int _Py_SwappedOp[] = {Py_GT, Py_GE, Py_EQ, Py_NE, Py_LT, Py_LE};

static const char * const opstrings[] = {"<", "<=", "==", "!=", ">", ">="};

/* Perform a rich comparison, raising TypeError when the requested comparison

operator is not supported. */

static PyObject *

do_richcompare(PyThreadState *tstate, PyObject *v, PyObject *w, int op)

{

richcmpfunc f;

PyObject *res;

int checked_reverse_op = 0;

if (!Py_IS_TYPE(v, Py_TYPE(w)) &&

PyType_IsSubtype(Py_TYPE(w), Py_TYPE(v)) &&

(f = Py_TYPE(w)->tp_richcompare) != NULL) {

checked_reverse_op = 1;

res = (*f)(w, v, _Py_SwappedOp[op]);

if (res != Py_NotImplemented)

return res;

Py_DECREF(res);

}

if ((f = Py_TYPE(v)->tp_richcompare) != NULL) {

res = (*f)(v, w, op);

if (res != Py_NotImplemented)

return res;

Py_DECREF(res);

}

if (!checked_reverse_op && (f = Py_TYPE(w)->tp_richcompare) != NULL) {

res = (*f)(w, v, _Py_SwappedOp[op]);

if (res != Py_NotImplemented)

return res;

Py_DECREF(res);

}

/* If neither object implements it, provide a sensible default

for == and !=, but raise an exception for ordering. */

switch (op) {

case Py_EQ:

res = (v == w) ? Py_True : Py_False;

break;

case Py_NE:

res = (v != w) ? Py_True : Py_False;

break;

default:

_PyErr_Format(tstate, PyExc_TypeError,

"'%s' not supported between instances of '%.100s' and '%.100s'",

opstrings[op],

Py_TYPE(v)->tp_name,

Py_TYPE(w)->tp_name);

return NULL;

}

return Py_NewRef(res);

}

/* Perform a rich comparison with object result. This wraps do_richcompare()

with a check for NULL arguments and a recursion check. */

PyObject *

PyObject_RichCompare(PyObject *v, PyObject *w, int op)

{

PyThreadState *tstate = _PyThreadState_GET();

assert(Py_LT <= op && op <= Py_GE);

if (v == NULL || w == NULL) {

if (!_PyErr_Occurred(tstate)) {

PyErr_BadInternalCall();

}

return NULL;

}

if (_Py_EnterRecursiveCallTstate(tstate, " in comparison")) {

return NULL;

}

PyObject *res = do_richcompare(tstate, v, w, op);

_Py_LeaveRecursiveCallTstate(tstate);

return res;

}

/* Perform a rich comparison with integer result. This wraps

PyObject_RichCompare(), returning -1 for error, 0 for false, 1 for true. */

int

PyObject_RichCompareBool(PyObject *v, PyObject *w, int op)

{

PyObject *res;

int ok;

/* Quick result when objects are the same.

Guarantees that identity implies equality. */

if (v == w) {

if (op == Py_EQ)

return 1;

else if (op == Py_NE)

return 0;

}

res = PyObject_RichCompare(v, w, op);

if (res == NULL)

return -1;

if (PyBool_Check(res))

ok = (res == Py_True);

else

ok = PyObject_IsTrue(res);

Py_DECREF(res);

return ok;

}

Py_hash_t

PyObject_HashNotImplemented(PyObject *v)

{

PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",

Py_TYPE(v)->tp_name);

return -1;

}

Py_hash_t

PyObject_Hash(PyObject *v)

{

PyTypeObject *tp = Py_TYPE(v);

if (tp->tp_hash != NULL)

return (*tp->tp_hash)(v);

/* To keep to the general practice that inheriting

* solely from object in C code should work without

* an explicit call to PyType_Ready, we implicitly call