| .. Algorithms/Concepts//Inserter |
| |
| Inserter |
| ======== |
| |
| Description |
| ----------- |
| |
| An |Inserter| is a compile-time substitute for STL |Output Iterator|. |
| Under the hood, it's simply a type holding |
| two entities: a *state* and an *operation*. When passed to a |
| |transformation algorithm|, the inserter's binary operation is |
| invoked for every element that would normally be written into the |
| output iterator, with the element itself (as the second |
| argument) and the result of the previous operation's invocation |--| or, |
| for the very first element, the inserter's initial state. |
| |
| Technically, instead of taking a single inserter parameter, |
| |transformation algorithms| could accept the state and the "output" |
| operation separately. Grouping these in a single parameter entity, |
| however, brings the algorithms semantically and syntactically closer to |
| their STL counterparts, significantly simplifying many of the common |
| use cases. |
| |
| |
| Valid expressions |
| ----------------- |
| |
| |In the following table...| ``in`` is a model of |Inserter|. |
| |
| +-----------------------+-------------------------------+ |
| | Expression | Type | |
| +=======================+===============================+ |
| | ``in::state`` | Any type | |
| +-----------------------+-------------------------------+ |
| | ``in::operation`` | Binary |Lambda Expression| | |
| +-----------------------+-------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| +-----------------------+-------------------------------------------+ |
| | Expression | Semantics | |
| +=======================+===========================================+ |
| | ``in::state`` | The inserter's initial state. | |
| +-----------------------+-------------------------------------------+ |
| | ``in::operation`` | The inserter's "output" operation. | |
| +-----------------------+-------------------------------------------+ |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| typedef transform< |
| range_c<int,0,10> |
| , plus<_1,_1> |
| , back_inserter< vector0<> > |
| >::type result; |
| |
| |
| Models |
| ------ |
| |
| * |[inserter]| |
| * |front_inserter| |
| * |back_inserter| |
| |
| See also |
| -------- |
| |
| |Algorithms|, |Transformation Algorithms|, |[inserter]|, |front_inserter|, |back_inserter| |
| |
| |
| .. 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) |
