1.. Sequences/Concepts//Bidirectional Sequence |20
2
3Bidirectional Sequence
4======================
5
6Description
7-----------
8
9A |Bidirectional Sequence| is a |Forward Sequence| whose iterators model
10|Bidirectional Iterator|.
11
12Refinement of
13-------------
14
15|Forward Sequence|
16
17
18Expression requirements
19-----------------------
20
21In addition to the requirements defined in |Forward Sequence|,
22for any |Bidirectional Sequence| ``s`` the following must be met:
23
24+---------------------------+-----------------------------------+---------------------------+
25| Expression                | Type                              | Complexity                |
26+===========================+===================================+===========================+
27| ``begin<s>::type``        | |Bidirectional Iterator|          | Amortized constant time   |
28+---------------------------+-----------------------------------+---------------------------+
29| ``end<s>::type``          | |Bidirectional Iterator|          | Amortized constant time   |
30+---------------------------+-----------------------------------+---------------------------+
31| ``back<s>::type``         | Any type                          | Amortized constant time   |
32+---------------------------+-----------------------------------+---------------------------+
33
34
35Expression semantics
36--------------------
37
38|Semantics disclaimer...| |Forward Sequence|.
39
40+---------------------------+-----------------------------------------------------------------------+
41| Expression                | Semantics                                                             |
42+===========================+=======================================================================+
43| ``back<s>::type``         | The last element in the sequence; see |back|.                         |
44+---------------------------+-----------------------------------------------------------------------+
45
46
47Models
48------
49
50* |vector|
51* |range_c|
52
53
54See also
55--------
56
57|Sequences|, |Forward Sequence|, |Random Access Sequence|, |Bidirectional Iterator|, |begin| / |end|, |back|
58
59
60.. copyright:: Copyright �  2001-2009 Aleksey Gurtovoy and David Abrahams
61   Distributed under the Boost Software License, Version 1.0. (See accompanying
62   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
63