| .. Algorithms/Iteration Algorithms//accumulate |10 |
| |
| accumulate |
| ========== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename Sequence |
| , typename State |
| , typename ForwardOp |
| > |
| struct accumulate |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Returns the result of the successive application of binary ``ForwardOp`` to the |
| result of the previous ``ForwardOp`` invocation (``State`` if it's the first call) |
| and every element of the sequence in the range |begin/end<Sequence>| in order. |
| |Note:| ``accumulate`` is a synonym for |fold| |-- end note| |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/accumulate.hpp> |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===============================+===================================================+ |
| | ``Sequence`` | |Forward Sequence| | A sequence to iterate. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | ``State`` | Any type | The initial state for the first ``ForwardOp`` | |
| | | | application. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | ``ForwardOp`` | Binary |Lambda Expression| | The operation to be executed on forward | |
| | | | traversal. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any |Forward Sequence| ``s``, binary |Lambda Expression| ``op``, and arbitrary type ``state``: |
| |
| |
| .. parsed-literal:: |
| |
| typedef accumulate<s,state,op>::type t; |
| |
| :Return type: |
| A type. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef fold<s,state,op>::type t; |
| |
| |
| |
| Complexity |
| ---------- |
| |
| Linear. Exactly ``size<s>::value`` applications of ``op``. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| typedef vector<long,float,short,double,float,long,long double> types; |
| typedef accumulate< |
| types |
| , int_<0> |
| , if_< is_float<_2>,next<_1>,_1 > |
| >::type number_of_floats; |
| |
| BOOST_MPL_ASSERT_RELATION( number_of_floats::value, ==, 4 ); |
| |
| |
| See also |
| -------- |
| |
| |Algorithms|, |fold|, |reverse_fold|, |iter_fold|, |reverse_iter_fold|, |copy|, |copy_if| |
| |
| |
| .. 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) |
