| .. Sequences/Concepts//Random Access Sequence |30 |
| |
| Random Access Sequence |
| ====================== |
| |
| Description |
| ----------- |
| |
| A |Random Access Sequence| is a |Bidirectional Sequence| whose iterators model |
| |Random Access Iterator|. A random access sequence guarantees amortized constant |
| time access to an arbitrary sequence element. |
| |
| Refinement of |
| ------------- |
| |
| |Bidirectional Sequence| |
| |
| |
| Expression requirements |
| ----------------------- |
| |
| In addition to the requirements defined in |Bidirectional Sequence|, |
| for any |Random Access Sequence| ``s`` the following must be met: |
| |
| +---------------------------+-----------------------------------+---------------------------+ |
| | Expression | Type | Complexity | |
| +===========================+===================================+===========================+ |
| | ``begin<s>::type`` | |Random Access Iterator| | Amortized constant time | |
| +---------------------------+-----------------------------------+---------------------------+ |
| | ``end<s>::type`` | |Random Access Iterator| | Amortized constant time | |
| +---------------------------+-----------------------------------+---------------------------+ |
| | ``at<s,n>::type`` | Any type | Amortized constant time | |
| +---------------------------+-----------------------------------+---------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| Semantics of an expression is defined only where it differs from, or is not |
| defined in |Bidirectional Sequence|. |
| |
| +---------------------------+-----------------------------------------------------------------------+ |
| | Expression | Semantics | |
| +===========================+=======================================================================+ |
| | ``at<s,n>::type`` | The ``n``\ th element from the beginning of the sequence; see |at|. | |
| +---------------------------+-----------------------------------------------------------------------+ |
| |
| |
| Models |
| ------ |
| |
| * |vector| |
| * |range_c| |
| |
| |
| See also |
| -------- |
| |
| |Sequences|, |Bidirectional Sequence|, |Extensible Sequence|, |Random Access Iterator|, |
| |begin| / |end|, |at| |
| |
| |
| .. copyright:: Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
