1.. highlightlang:: c
2
3.. _sequence:
4
5Sequence Protocol
6=================
7
8
9.. c:function:: int PySequence_Check(PyObject *o)
10
11   Return ``1`` if the object provides sequence protocol, and ``0`` otherwise.
12   Note that it returns ``1`` for Python classes with a :meth:`__getitem__`
13   method unless they are :class:`dict` subclasses since in general case it
14   is impossible to determine what the type of keys it supports.  This
15   function always succeeds.
16
17
18.. c:function:: Py_ssize_t PySequence_Size(PyObject *o)
19               Py_ssize_t PySequence_Length(PyObject *o)
20
21   .. index:: builtin: len
22
23   Returns the number of objects in sequence *o* on success, and ``-1`` on
24   failure.  This is equivalent to the Python expression ``len(o)``.
25
26
27.. c:function:: PyObject* PySequence_Concat(PyObject *o1, PyObject *o2)
28
29   Return the concatenation of *o1* and *o2* on success, and *NULL* on failure.
30   This is the equivalent of the Python expression ``o1 + o2``.
31
32
33.. c:function:: PyObject* PySequence_Repeat(PyObject *o, Py_ssize_t count)
34
35   Return the result of repeating sequence object *o* *count* times, or *NULL* on
36   failure.  This is the equivalent of the Python expression ``o * count``.
37
38
39.. c:function:: PyObject* PySequence_InPlaceConcat(PyObject *o1, PyObject *o2)
40
41   Return the concatenation of *o1* and *o2* on success, and *NULL* on failure.
42   The operation is done *in-place* when *o1* supports it.  This is the equivalent
43   of the Python expression ``o1 += o2``.
44
45
46.. c:function:: PyObject* PySequence_InPlaceRepeat(PyObject *o, Py_ssize_t count)
47
48   Return the result of repeating sequence object *o* *count* times, or *NULL* on
49   failure.  The operation is done *in-place* when *o* supports it.  This is the
50   equivalent of the Python expression ``o *= count``.
51
52
53.. c:function:: PyObject* PySequence_GetItem(PyObject *o, Py_ssize_t i)
54
55   Return the *i*\ th element of *o*, or *NULL* on failure. This is the equivalent of
56   the Python expression ``o[i]``.
57
58
59.. c:function:: PyObject* PySequence_GetSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2)
60
61   Return the slice of sequence object *o* between *i1* and *i2*, or *NULL* on
62   failure. This is the equivalent of the Python expression ``o[i1:i2]``.
63
64
65.. c:function:: int PySequence_SetItem(PyObject *o, Py_ssize_t i, PyObject *v)
66
67   Assign object *v* to the *i*\ th element of *o*.  Raise an exception
68   and return ``-1`` on failure; return ``0`` on success.  This
69   is the equivalent of the Python statement ``o[i] = v``.  This function *does
70   not* steal a reference to *v*.
71
72   If *v* is *NULL*, the element is deleted, however this feature is
73   deprecated in favour of using :c:func:`PySequence_DelItem`.
74
75
76.. c:function:: int PySequence_DelItem(PyObject *o, Py_ssize_t i)
77
78   Delete the *i*\ th element of object *o*.  Returns ``-1`` on failure.  This is the
79   equivalent of the Python statement ``del o[i]``.
80
81
82.. c:function:: int PySequence_SetSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2, PyObject *v)
83
84   Assign the sequence object *v* to the slice in sequence object *o* from *i1* to
85   *i2*.  This is the equivalent of the Python statement ``o[i1:i2] = v``.
86
87
88.. c:function:: int PySequence_DelSlice(PyObject *o, Py_ssize_t i1, Py_ssize_t i2)
89
90   Delete the slice in sequence object *o* from *i1* to *i2*.  Returns ``-1`` on
91   failure.  This is the equivalent of the Python statement ``del o[i1:i2]``.
92
93
94.. c:function:: Py_ssize_t PySequence_Count(PyObject *o, PyObject *value)
95
96   Return the number of occurrences of *value* in *o*, that is, return the number
97   of keys for which ``o[key] == value``.  On failure, return ``-1``.  This is
98   equivalent to the Python expression ``o.count(value)``.
99
100
101.. c:function:: int PySequence_Contains(PyObject *o, PyObject *value)
102
103   Determine if *o* contains *value*.  If an item in *o* is equal to *value*,
104   return ``1``, otherwise return ``0``. On error, return ``-1``.  This is
105   equivalent to the Python expression ``value in o``.
106
107
108.. c:function:: Py_ssize_t PySequence_Index(PyObject *o, PyObject *value)
109
110   Return the first index *i* for which ``o[i] == value``.  On error, return
111   ``-1``.    This is equivalent to the Python expression ``o.index(value)``.
112
113
114.. c:function:: PyObject* PySequence_List(PyObject *o)
115
116   Return a list object with the same contents as the sequence or iterable *o*,
117   or *NULL* on failure.  The returned list is guaranteed to be new.  This is
118   equivalent to the Python expression ``list(o)``.
119
120
121.. c:function:: PyObject* PySequence_Tuple(PyObject *o)
122
123   .. index:: builtin: tuple
124
125   Return a tuple object with the same contents as the sequence or iterable *o*,
126   or *NULL* on failure.  If *o* is a tuple, a new reference will be returned,
127   otherwise a tuple will be constructed with the appropriate contents.  This is
128   equivalent to the Python expression ``tuple(o)``.
129
130
131.. c:function:: PyObject* PySequence_Fast(PyObject *o, const char *m)
132
133   Return the sequence or iterable *o* as a list, unless it is already a tuple or list, in
134   which case *o* is returned.  Use :c:func:`PySequence_Fast_GET_ITEM` to access
135   the members of the result.  Returns *NULL* on failure.  If the object is not
136   a sequence or iterable, raises :exc:`TypeError` with *m* as the message text.
137
138
139.. c:function:: Py_ssize_t PySequence_Fast_GET_SIZE(PyObject *o)
140
141   Returns the length of *o*, assuming that *o* was returned by
142   :c:func:`PySequence_Fast` and that *o* is not *NULL*.  The size can also be
143   gotten by calling :c:func:`PySequence_Size` on *o*, but
144   :c:func:`PySequence_Fast_GET_SIZE` is faster because it can assume *o* is a list
145   or tuple.
146
147
148.. c:function:: PyObject* PySequence_Fast_GET_ITEM(PyObject *o, Py_ssize_t i)
149
150   Return the *i*\ th element of *o*, assuming that *o* was returned by
151   :c:func:`PySequence_Fast`, *o* is not *NULL*, and that *i* is within bounds.
152
153
154.. c:function:: PyObject** PySequence_Fast_ITEMS(PyObject *o)
155
156   Return the underlying array of PyObject pointers.  Assumes that *o* was returned
157   by :c:func:`PySequence_Fast` and *o* is not *NULL*.
158
159   Note, if a list gets resized, the reallocation may relocate the items array.
160   So, only use the underlying array pointer in contexts where the sequence
161   cannot change.
162
163
164.. c:function:: PyObject* PySequence_ITEM(PyObject *o, Py_ssize_t i)
165
166   Return the *i*\ th element of *o* or *NULL* on failure. Macro form of
167   :c:func:`PySequence_GetItem` but without checking that
168   :c:func:`PySequence_Check` on *o* is true and without adjustment for negative
169   indices.
170