[Boost-commit] svn:boost r75384 - sandbox/variadic_templates/sandbox/stepper/boost/array_stepper

Subject: [Boost-commit] svn:boost r75384 - sandbox/variadic_templates/sandbox/stepper/boost/array_stepper
From: cppljevans_at_[hidden]
Date: 2011-11-07 10:02:30

Author: cppljevans
Date: 2011-11-07 10:02:29 EST (Mon, 07 Nov 2011)
New Revision: 75384
URL: http://svn.boost.org/trac/boost/changeset/75384

Log:
Added files for new #includes of length_strides_offset.hpp

Added:
   sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/indices_at_offset.hpp   (contents, props changed)
   sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/offset_at_indices.hpp   (contents, props changed)

Added: sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/indices_at_offset.hpp
==============================================================================
--- (empty file)
+++ sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/indices_at_offset.hpp	2011-11-07 10:02:29 EST (Mon, 07 Nov 2011)
@@ -0,0 +1,134 @@
+#ifndef BOOST_ARRAY_STEPPER_INDICES_AT_OFFSET_HPP_INCLUDED
+#define BOOST_ARRAY_STEPPER_INDICES_AT_OFFSET_HPP_INCLUDED
+#include <numeric>
+#include <boost/iterator/transform_iterator.hpp>
+
+namespace boost
+{
+namespace array_stepper
+{
+    template
+    < typename Index
+    , typename LengthStride
+    , typename GetLengthStride
+    , typename Offset
+    >
+    struct 
+  index_at_offset
+    /**@brief
+     *  Functor used by indexs_at_offset.
+     */
+    {
+          Offset
+        my_offset
+          /**@brief
+           *  offset in multitimensional array.
+           *  from beginning of array.
+           */
+          ;
+          GetLengthStride
+        my_get_length_stride
+          /**@brief
+           *  offset in multitimensional array.
+           *  from beginning of array.
+           */
+          ;
+        index_at_offset( Offset a_offset, GetLengthStride a_get_length_stride)
+          : my_offset(a_offset)
+          , my_get_length_stride(a_get_length_stride)
+          {}
+            typedef 
+          Index
+        result_type
+          /**@brief
+           *  required by make_transform_iterator
+           *  used in indexs_at_offset.
+           */
+          ;
+          result_type
+        operator()( LengthStride const& ls)const
+          /**@brief
+           *  this is equation (5.7) in @reference
+           *  for an axis described by ls.
+           */
+          { 
+              result_type div_v=my_offset/my_get_length_stride.stride(ls);
+              result_type index_v=div_v%my_get_length_stride.length(ls);
+              return index_v;
+          }
+    };
+    
+    template
+    < typename Indices
+    , typename LengthStrideIter
+    , typename GetLengthStride
+    , typename Offset
+    >
+    Indices
+  indices_at_offset 
+    ( LengthStrideIter first_ls
+    , LengthStrideIter last_ls
+    , GetLengthStride get_length_stride 
+      //provides length and stride funcitons to access lengths
+      //and strides of elements in LengthStrideIter.
+    , Offset offset0
+    )
+    /**@brief
+     *  Returns the indices corresponding to offset0
+     *  in array with length and strides given by
+     *  first_ls...last_ls.
+     *
+     *  This corresponds to equation (5.7) in @reference
+     *  for each axis.
+     *  
+     **@reference:
+     *  _An APL Compiler_
+     *  Timothy Budd
+     *  Springer-Verlag, 1988
+     */
+    {
+        std::size_t const
+      size=last_ls-first_ls
+        ;
+        Indices 
+      indices(size)
+        ;
+          typedef
+        index_at_offset
+        < typename Indices::value_type
+        , typename LengthStrideIter::value_type
+        , GetLengthStride
+        , Offset
+        >
+      iao_t
+        ;
+          typedef 
+        transform_iterator
+        < iao_t
+        , LengthStrideIter
+        > 
+      xiter_t
+        ;
+        iao_t
+      iao_v(offset0,get_length_stride)
+        ;
+        xiter_t
+      beg_index( first_ls, iao_v)
+        ;
+        xiter_t 
+      end_index( last_ls, iao_v)
+        ;
+        typename Indices::iterator 
+      beg_is=indices.begin()
+        ;
+        std::copy
+          ( beg_index
+          , end_index
+          , beg_is
+          );
+        return indices;
+    }
+         
+}//exit array_stepper namespace
+}//exit boost namespace
+#endif

Added: sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/offset_at_indices.hpp
==============================================================================
--- (empty file)
+++ sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/offset_at_indices.hpp	2011-11-07 10:02:29 EST (Mon, 07 Nov 2011)
@@ -0,0 +1,55 @@
+#ifndef BOOST_ARRAY_STEPPER_OFFSET_AT_INDICES_HPP_INCLUDED
+#define BOOST_ARRAY_STEPPER_OFFSET_AT_INDICES_HPP_INCLUDED
+#include <numeric>
+#include <boost/iterator/transform_iterator.hpp>
+
+namespace boost
+{
+namespace array_stepper
+{
+    template
+    < typename StrideIter
+    , typename GetStride
+    , typename IndexIter
+    , typename Offset
+    >
+    Offset
+  offset_at_indices 
+    ( IndexIter first_index
+    , IndexIter last_index
+    , StrideIter first_stride
+    , GetStride get_stride //functor returning strides in StrideIter
+    , Offset offset0=Offset(0)
+    )
+    /**@brief
+     *  Returns offset corresponding to the indices
+     *  in array with strides given by
+     *  first_stride...(first_stride+(last_index-first_index).
+     *
+     *  This corresponds to equation (5.2) of the @reference.
+     *  
+     **@reference:
+     *  _An APL Compiler_
+     *  Timothy Budd
+     *  Springer-Verlag, 1988
+     */
+    {
+          transform_iterator
+          < GetStride
+          , StrideIter
+          > 
+        beg_s
+          ( first_stride
+          , get_stride
+          );
+        return std::inner_product
+          ( first_index
+          , last_index
+          , beg_s
+          , offset0
+          );
+    }
+         
+}//exit array_stepper namespace
+}//exit boost namespace
+#endif