| .. Sequences/Views//zip_view |
| |
| zip_view |
| ======== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename Sequences |
| > |
| struct zip_view |
| { |
| // |unspecified| |
| // |...| |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Provides a "zipped" view onto several sequences; that is, represents several |
| sequences as a single sequence of elements each of which, in turn, |
| is a sequence of the corresponding ``Sequences``\ ' elements. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/zip_view.hpp> |
| |
| |
| |
| Model of |
| -------- |
| |
| * |Forward Sequence| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-----------------------------------+-------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================================+===============================+ |
| | ``Sequences`` | A |Forward Sequence| of | Sequences to be "zipped". | |
| | | |Forward Sequence|\ s | | |
| +---------------+-----------------------------------+-------------------------------+ |
| |
| Expression semantics |
| -------------------- |
| |
| |Semantics disclaimer...| |Forward Sequence|. |
| |
| In the following table, ``v`` is an instance of ``zip_view``, ``seq`` a |Forward Sequence| of ``n`` |
| |Forward Sequence|\ s. |
| |
| +-------------------------------+-----------------------------------------------------------+ |
| | Expression | Semantics | |
| +===============================+===========================================================+ |
| | .. parsed-literal:: | A lazy |Forward Sequence| ``v`` such that for each ``i`` | |
| | | in |begin/end<v>| and for each ``j`` in | |
| | zip_view<seq> | [``begin<seq>::type``, ``end<seq>::type``) | |
| | zip_view<seq>::type | ``deref<i>::type`` is identical to | |
| | | ``transform< deref<j>::type, deref<_1> >::type``. | |
| +-------------------------------+-----------------------------------------------------------+ |
| | ``size<v>::type`` | The size of ``v``; ``size<v>::value`` is equal to | |
| | | :: | |
| | | | |
| | | deref< min_element< | |
| | | transform_view< seq, size<_1> > | |
| | | >::type >::type::value; | |
| | | | |
| | | linear complexity; see |Forward Sequence|. | |
| +-------------------------------+-----------------------------------------------------------+ |
| |
| |
| Example |
| ------- |
| |
| Element-wise sum of three vectors. |
| |
| .. parsed-literal:: |
| |
| typedef vector_c<int,1,2,3,4,5> v1; |
| typedef vector_c<int,5,4,3,2,1> v2; |
| typedef vector_c<int,1,1,1,1,1> v3; |
| |
| typedef transform_view< |
| zip_view< vector<v1,v2,v3> > |
| , unpack_args< plus<_1,_2,_3> > |
| > sum; |
| |
| BOOST_MPL_ASSERT(( equal< sum, vector_c<int,7,7,7,7,7> > )); |
| |
| |
| See also |
| -------- |
| |
| |Sequences|, |Views|, |filter_view|, |transform_view|, |joint_view|, |single_view|, |iterator_range| |
| |
| |
| .. 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) |
