python容器-floatobject
2020-07-22 本文已影响0人
dalewong
float定义:
floatobject.h
#ifndef Py_LIMITED_API
typedef struct {
PyObject_HEAD
double ob_fval;
} PyFloatObject;
#endif
从中我们可以看到PyFloatObject是由HEAD和double的ob_fval值组成，
我们再查看HEAD的内容
/* PyObject_HEAD defines the initial segment of every PyObject. */
#define PyObject_HEAD PyObject ob_base;
这里指向了PyObject这个结构体
/* Nothing is actually declared to be a PyObject, but every pointer to
* a Python object can be cast to a PyObject*. This is inheritance built
* by hand. Similarly every pointer to a variable-size Python object can,
* in addition, be cast to PyVarObject*.
*/
typedef struct _object {
_PyObject_HEAD_EXTRA
Py_ssize_t ob_refcnt;
struct _typeobject *ob_type;
} PyObject;
okay,我们看到Pyobject的组成，是由一个head_extra和obrefcnt和指向另一个结构体的_typeobeject组成
head_extra
#define _PyObject_HEAD_EXTRA \
struct _object *_ob_next; \
struct _object *_ob_prev;
python活跃对象的双向链表
#define _PyObject_EXTRA_INIT 0, 0
define PyObject_HEAD_INIT(type) \
{ _PyObject_EXTRA_INIT \
1, type },
#define PyVarObject_HEAD_INIT(type, size) \
{ PyObject_HEAD_INIT(type) size },
根据类型来初始化PyObject
typedef struct _object {
_PyObject_HEAD_EXTRA
Py_ssize_t ob_refcnt;
struct _typeobject *ob_type;
} PyObject;
/* Cast argument to PyObject* type. */
#define _PyObject_CAST(op) ((PyObject*)(op))
typedef struct {
PyObject ob_base;
Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;
这里可以看到定长对象初始化引用计数1，边长对象增加了ob_size来记录了边长对象的元素的大小[如list, int]
ob_refcnt是python的引用计数 继续查看_typeobject
typedef struct _typeobject {
PyObject_VAR_HEAD
const char *tp_name; /* For printing, in format "<module>.<name>" */
Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
/* Methods to implement standard operations */
destructor tp_dealloc;
Py_ssize_t tp_vectorcall_offset;
getattrfunc tp_getattr;
setattrfunc tp_setattr;
PyAsyncMethods *tp_as_async; /* formerly known as tp_compare (Python 2)
or tp_reserved (Python 3) */
reprfunc tp_repr;
/* Method suites for standard classes */
PyNumberMethods *tp_as_number;
PySequenceMethods *tp_as_sequence;
PyMappingMethods *tp_as_mapping;
/* More standard operations (here for binary compatibility) */
hashfunc tp_hash;
ternaryfunc tp_call;
reprfunc tp_str;
getattrofunc tp_getattro;
setattrofunc tp_setattro;
/* Functions to access object as input/output buffer */
PyBufferProcs *tp_as_buffer;
/* Flags to define presence of optional/expanded features */
unsigned long tp_flags;
const char *tp_doc; /* Documentation string */
/* Assigned meaning in release 2.0 */
/* call function for all accessible objects */
traverseproc tp_traverse;
/* delete references to contained objects */
inquiry tp_clear;
/* Assigned meaning in release 2.1 */
/* rich comparisons */
richcmpfunc tp_richcompare;
/* weak reference enabler */
Py_ssize_t tp_weaklistoffset;
/* Iterators */
getiterfunc tp_iter;
iternextfunc tp_iternext;
/* Attribute descriptor and subclassing stuff */
struct PyMethodDef *tp_methods;
struct PyMemberDef *tp_members;
struct PyGetSetDef *tp_getset;
struct _typeobject *tp_base;
PyObject *tp_dict;
descrgetfunc tp_descr_get;
descrsetfunc tp_descr_set;
Py_ssize_t tp_dictoffset;
initproc tp_init;
allocfunc tp_alloc;
newfunc tp_new;
freefunc tp_free; /* Low-level free-memory routine */
inquiry tp_is_gc; /* For PyObject_IS_GC */
PyObject *tp_bases;
PyObject *tp_mro; /* method resolution order */
PyObject *tp_cache;
PyObject *tp_subclasses;
PyObject *tp_weaklist;
destructor tp_del;
/* Type attribute cache version tag. Added in version 2.6 */
unsigned int tp_version_tag;
destructor tp_finalize;
vectorcallfunc tp_vectorcall;
/* bpo-37250: kept for backwards compatibility in CPython 3.8 only */
Py_DEPRECATED(3.8) int (*tp_print)(PyObject *, FILE *, int);
#ifdef COUNT_ALLOCS
/* these must be last and never explicitly initialized */
Py_ssize_t tp_allocs;
Py_ssize_t tp_frees;
Py_ssize_t tp_maxalloc;
struct _typeobject *tp_prev;
struct _typeobject *tp_next;
#endif
} PyTypeObject;
_typeobject
- PyObject_VAR_HEAD：
typedef struct {
PyObject ob_base;
Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;
这里有趣的是typeobject指向了pyobject
值得注意的是tp_call, 当初始化float(3.14)的时候，调用的是tp_call
那tp_call是如何生成对应的float对象的呢
PyTypeObject PyType_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"type", /* tp_name */
sizeof(PyHeapTypeObject), /* tp_basicsize */
sizeof(PyMemberDef), /* tp_itemsize */
(destructor)type_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
(reprfunc)type_repr, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
(ternaryfunc)type_call, /* tp_call */
0, /* tp_str */
(getattrofunc)type_getattro, /* tp_getattro */
(setattrofunc)type_setattro, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
Py_TPFLAGS_BASETYPE | Py_TPFLAGS_TYPE_SUBCLASS, /* tp_flags */
type_doc, /* tp_doc */
(traverseproc)type_traverse, /* tp_traverse */
(inquiry)type_clear, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyTypeObject, tp_weaklist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
type_methods, /* tp_methods */
type_members, /* tp_members */
type_getsets, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
offsetof(PyTypeObject, tp_dict), /* tp_dictoffset */
type_init, /* tp_init */
0, /* tp_alloc */
type_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
(inquiry)type_is_gc, /* tp_is_gc */
};
查看typeobject.c中的定义的PyType_Type
这里type_call指向了tp_call
static PyObject *
type_call(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
PyObject *obj;
if (type->tp_new == NULL) {
PyErr_Format(PyExc_TypeError,
"cannot create '%.100s' instances",
type->tp_name);
return NULL;
}
#ifdef Py_DEBUG
/* type_call() 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());
#endif
obj = type->tp_new(type, args, kwds);
obj = _Py_CheckFunctionResult((PyObject*)type, obj, NULL);
if (obj == NULL)
return NULL;
/* Ugly exception: when the call was type(something),
don't call tp_init on the result. */
if (type == &PyType_Type &&
PyTuple_Check(args) && PyTuple_GET_SIZE(args) == 1 &&
(kwds == NULL ||
(PyDict_Check(kwds) && PyDict_GET_SIZE(kwds) == 0)))
return obj;
/* If the returned object is not an instance of type,
it won't be initialized. */
if (!PyType_IsSubtype(Py_TYPE(obj), type))
return obj;
type = Py_TYPE(obj);
if (type->tp_init != NULL) {
int res = type->tp_init(obj, args, kwds);
if (res < 0) {
assert(PyErr_Occurred());
Py_DECREF(obj);
obj = NULL;
}
else {
assert(!PyErr_Occurred());
}
}
return obj;
}
调用type->tp_new生成object对象
Py_TYPE(obj)把对象转换成type(指向自己的type)
PyTypeObject PyFloat_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"float",
sizeof(PyFloatObject),
0,
(destructor)float_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
(reprfunc)float_repr, /* tp_repr */
&float_as_number, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
(hashfunc)float_hash, /* 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 */
float_new__doc__, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
float_richcompare, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
float_methods, /* tp_methods */
0, /* tp_members */
float_getset, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
float_new, /* tp_new */
};
如上则是PyFloat_Type的定义
初始化了tp_type为"float", 注意这时候tp_base为0
PyStatus
_PyTypes_Init(void)
{
#define INIT_TYPE(TYPE, NAME) \
do { \
if (PyType_Ready(TYPE) < 0) { \
return _PyStatus_ERR("Can't initialize " NAME " type"); \
} \
} while (0)
INIT_TYPE(&PyBaseObject_Type, "object");
INIT_TYPE(&PyType_Type, "type");
INIT_TYPE(&_PyWeakref_RefType, "weakref");
INIT_TYPE(&_PyWeakref_CallableProxyType, "callable weakref proxy");
INIT_TYPE(&_PyWeakref_ProxyType, "weakref proxy");
INIT_TYPE(&PyLong_Type, "int");
INIT_TYPE(&PyBool_Type, "bool");
INIT_TYPE(&PyByteArray_Type, "bytearray");
INIT_TYPE(&PyBytes_Type, "str");
INIT_TYPE(&PyList_Type, "list");
INIT_TYPE(&_PyNone_Type, "None");
INIT_TYPE(&_PyNotImplemented_Type, "NotImplemented");
INIT_TYPE(&PyTraceBack_Type, "traceback");
INIT_TYPE(&PySuper_Type, "super");
INIT_TYPE(&PyRange_Type, "range");
INIT_TYPE(&PyDict_Type, "dict");
INIT_TYPE(&PyDictKeys_Type, "dict keys");
INIT_TYPE(&PyDictValues_Type, "dict values");
INIT_TYPE(&PyDictItems_Type, "dict items");
INIT_TYPE(&PyDictRevIterKey_Type, "reversed dict keys");
INIT_TYPE(&PyDictRevIterValue_Type, "reversed dict values");
INIT_TYPE(&PyDictRevIterItem_Type, "reversed dict items");
INIT_TYPE(&PyODict_Type, "OrderedDict");
INIT_TYPE(&PyODictKeys_Type, "odict_keys");
INIT_TYPE(&PyODictItems_Type, "odict_items");
INIT_TYPE(&PyODictValues_Type, "odict_values");
INIT_TYPE(&PyODictIter_Type, "odict_keyiterator");
INIT_TYPE(&PySet_Type, "set");
INIT_TYPE(&PyUnicode_Type, "str");
INIT_TYPE(&PySlice_Type, "slice");
INIT_TYPE(&PyStaticMethod_Type, "static method");
INIT_TYPE(&PyComplex_Type, "complex");
INIT_TYPE(&PyFloat_Type, "float");
INIT_TYPE(&PyFrozenSet_Type, "frozenset");
INIT_TYPE(&PyProperty_Type, "property");
INIT_TYPE(&_PyManagedBuffer_Type, "managed buffer");
INIT_TYPE(&PyMemoryView_Type, "memoryview");
INIT_TYPE(&PyTuple_Type, "tuple");
INIT_TYPE(&PyEnum_Type, "enumerate");
INIT_TYPE(&PyReversed_Type, "reversed");
INIT_TYPE(&PyStdPrinter_Type, "StdPrinter");
INIT_TYPE(&PyCode_Type, "code");
INIT_TYPE(&PyFrame_Type, "frame");
INIT_TYPE(&PyCFunction_Type, "builtin function");
INIT_TYPE(&PyMethod_Type, "method");
INIT_TYPE(&PyFunction_Type, "function");
INIT_TYPE(&PyDictProxy_Type, "dict proxy");
INIT_TYPE(&PyGen_Type, "generator");
INIT_TYPE(&PyGetSetDescr_Type, "get-set descriptor");
INIT_TYPE(&PyWrapperDescr_Type, "wrapper");
INIT_TYPE(&_PyMethodWrapper_Type, "method wrapper");
INIT_TYPE(&PyEllipsis_Type, "ellipsis");
INIT_TYPE(&PyMemberDescr_Type, "member descriptor");
INIT_TYPE(&_PyNamespace_Type, "namespace");
INIT_TYPE(&PyCapsule_Type, "capsule");
INIT_TYPE(&PyLongRangeIter_Type, "long range iterator");
INIT_TYPE(&PyCell_Type, "cell");
INIT_TYPE(&PyInstanceMethod_Type, "instance method");
INIT_TYPE(&PyClassMethodDescr_Type, "class method descr");
INIT_TYPE(&PyMethodDescr_Type, "method descr");
INIT_TYPE(&PyCallIter_Type, "call iter");
INIT_TYPE(&PySeqIter_Type, "sequence iterator");
INIT_TYPE(&PyPickleBuffer_Type, "pickle.PickleBuffer");
INIT_TYPE(&PyCoro_Type, "coroutine");
INIT_TYPE(&_PyCoroWrapper_Type, "coroutine wrapper");
INIT_TYPE(&_PyInterpreterID_Type, "interpreter ID");
return _PyStatus_OK();
#undef INIT_TYPE
}
这时候在object.c进行初始化操作，调用typeobject.c中的PyType_Ready
int
PyType_Ready(PyTypeObject *type)
{
// ...
base = type->tp_base;
if (base == NULL && type != &PyBaseObject_Type) {
base = type->tp_base = &PyBaseObject_Type;
Py_INCREF(base);
}
// ...
}
在typeobject中把Float_Type的base设置为type->tp_base.
PyTypeObject PyBaseObject_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"object", /* tp_name */
sizeof(PyObject), /* tp_basicsize */
0, /* tp_itemsize */
object_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
object_repr, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
(hashfunc)_Py_HashPointer, /* tp_hash */
0, /* tp_call */
object_str, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
PyObject_GenericSetAttr, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
object_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
object_richcompare, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
object_methods, /* tp_methods */
0, /* tp_members */
object_getsets, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
object_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
object_new, /* tp_new */
PyObject_Del, /* tp_free */
};
为什么要这么初始化呢，是因为所有的base都要有一个终点，否则就没有办法完成了。
接着继续查看float_as_number装载了tp_as_number: 数字操作符，tp_as_sequence: 序列操作, tp_as_mapping: 映射操作,
因为float只有数字操作，所以tp_as_sequence和tp_as_mapping都为0
static PyNumberMethods float_as_number = {
float_add, /* nb_add */
float_sub, /* nb_subtract */
float_mul, /* nb_multiply */
float_rem, /* nb_remainder */
float_divmod, /* nb_divmod */
float_pow, /* nb_power */
(unaryfunc)float_neg, /* nb_negative */
float_float, /* nb_positive */
(unaryfunc)float_abs, /* nb_absolute */
(inquiry)float_bool, /* nb_bool */
0, /* nb_invert */
0, /* nb_lshift */
0, /* nb_rshift */
0, /* nb_and */
0, /* nb_xor */
0, /* nb_or */
float___trunc___impl, /* nb_int */
0, /* nb_reserved */
float_float, /* nb_float */
0, /* nb_inplace_add */
0, /* nb_inplace_subtract */
0, /* nb_inplace_multiply */
0, /* nb_inplace_remainder */
0, /* nb_inplace_power */
0, /* nb_inplace_lshift */
0, /* nb_inplace_rshift */
0, /* nb_inplace_and */
0, /* nb_inplace_xor */
0, /* nb_inplace_or */
float_floor_div, /* nb_floor_divide */
float_div, /* nb_true_divide */
0, /* nb_inplace_floor_divide */
0, /* nb_inplace_true_divide */
};
以上则是float_as_number，数字操作的函数
回到之前的函数, tp_init生成结果 查看floatobject.c.h
static PyObject *
float_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
{
PyObject *return_value = NULL;
PyObject *x = _PyLong_Zero;
if ((type == &PyFloat_Type) &&
!_PyArg_NoKeywords("float", kwargs)) {
goto exit;
}
if (!_PyArg_CheckPositional("float", PyTuple_GET_SIZE(args), 0, 1)) {
goto exit;
}
if (PyTuple_GET_SIZE(args) < 1) {
goto skip_optional;
}
x = PyTuple_GET_ITEM(args, 0);
skip_optional:
return_value = float_new_impl(type, x);
exit:
return return_value;
}
调用float_new_impl, 我们进一步查看
static PyObject *
float_new_impl(PyTypeObject *type, PyObject *x)
/*[clinic end generated code: output=ccf1e8dc460ba6ba input=540ee77c204ff87a]*/
{
if (type != &PyFloat_Type)
return float_subtype_new(type, x); /* Wimp out */
/* If it's a string, but not a string subclass, use
PyFloat_FromString. */
if (PyUnicode_CheckExact(x))
return PyFloat_FromString(x);
return PyNumber_Float(x);
}
调用float_dubtype_new
static PyObject *
float_subtype_new(PyTypeObject *type, PyObject *x)
{
PyObject *tmp, *newobj;
assert(PyType_IsSubtype(type, &PyFloat_Type));
tmp = float_new_impl(&PyFloat_Type, x);
if (tmp == NULL)
return NULL;
assert(PyFloat_Check(tmp));
newobj = type->tp_alloc(type, 0);
if (newobj == NULL) {
Py_DECREF(tmp);
return NULL;
}
((PyFloatObject *)newobj)->ob_fval = ((PyFloatObject *)tmp)->ob_fval;
Py_DECREF(tmp);
return newobj;
}
这里给float对象分配内存
回到floatobject.c，最后再给float对象ob_fval赋值
float(3.14) = PyObject *float_new(float_type, 3.14)
由于float是常量存在，查看floatobject.c中定义的PyFloat_Type,
这里的tp_init是0，因为float是常数所以不需要额外操作
最终我们可以得出Python的blue print的大致模型了:
PyFloat_Type
pyobject_head ---------> PyObject
_typeobject------------> PyType_Type
|tp_base
tp_base --------------------------------------> PyBaseObject_Type
