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// -*- c++ -*-
/*
* Copyright (c) 2010-2012, Jim Bosch
* All rights reserved.
*
* ndarray is distributed under a simple BSD-like license;
* see the LICENSE file that should be present in the root
* of the source distribution, or alternately available at:
* https://github.com/ndarray/ndarray
*/
#ifndef NDARRAY_views_h_INCLUDED
#define NDARRAY_views_h_INCLUDED
/**
* \file ndarray/views.h @brief Public interface for arbitrary views into arrays.
*/
#include <boost/fusion/include/push_back.hpp>
#include <boost/fusion/include/vector.hpp>
#include <boost/fusion/include/make_vector.hpp>
#include <boost/fusion/include/mpl.hpp>
#include "ndarray_fwd.h"
namespace ndarray {
namespace index {
/**
* @brief Simple structure defining a noncontiguous range of indices.
*/
struct Slice {
Size start;
Size stop;
Offset step;
Slice(Size start_, Size stop_, Offset step_) : start(start_), stop(stop_), step(step_) {}
Size computeSize() const { return (step > 1) ? (stop - start + 1) / step : stop - start; }
};
/**
* @brief Simple structure defining a contiguous range of indices.
*/
struct Range {
Size start;
Size stop;
Range(Size start_, Size stop_) : start(start_), stop(stop_) {}
};
/**
* @brief Empty structure marking a view of an entire dimension.
*/
struct Full {};
/**
* @brief Structure marking a single element of a dimension.
*/
struct Scalar {
Size n;
explicit Scalar(Size n_) : n(n_) {}
};
} // namespace index
/**
* @brief A template meta-sequence that defines an arbitrary view into an unspecified array.
*
* A View is constructed from a call to the global view() function
* and subsequent chained calls to operator().
*/
template <typename Seq_ = boost::fusion::vector<> >
struct View {
typedef Seq_ Sequence; ///< A boost::fusion sequence type
Sequence _seq; ///< A boost::fusion sequence of index objects.
explicit View(Sequence seq) : _seq(seq) {}
template <typename OtherSequence>
explicit View(OtherSequence const & other) : _seq(other) {}
template <typename OtherSequence>
View(View<OtherSequence> const & other) : _seq(other._seq) {}
/// @brief The View that results from chaining an full dimension index <b><tt>()</tt></b> to this.
typedef View<typename boost::fusion::result_of::push_back<Sequence const,index::Full>::type> Full;
/// @brief The View that results from chaining a range <b><tt>(start,stop)</tt></b> to this.
typedef View<typename boost::fusion::result_of::push_back<Sequence const,index::Range>::type> Range;
/// @brief The View that results from chaining a slice <b><tt>(start,stop,step)</tt></b> to this.
typedef View<typename boost::fusion::result_of::push_back<Sequence const,index::Slice>::type> Slice;
/// @brief The View that results from chaining a scalar <b><tt>(n)</tt></b> to this.
typedef View<typename boost::fusion::result_of::push_back<Sequence const,index::Scalar>::type> Scalar;
/// @brief Chain the full next dimension to this.
Full operator()() const { return Full(boost::fusion::push_back(_seq, index::Full())); }
/// @brief Chain a contiguous range of the next dimension to this.
Range operator()(Size start, Size stop) const {
return Range(boost::fusion::push_back(_seq, index::Range(start, stop)));
}
/// @brief Chain a noncontiguous slice of the next dimension to this.
Slice operator()(Size start, Size stop, Offset step) const {
return Slice(boost::fusion::push_back(_seq, index::Slice(start, stop, step)));
}
/// @brief Chain a single element of the next dimension to this.
Scalar operator()(Size n) const {
return Scalar(boost::fusion::push_back(_seq, index::Scalar(n)));
}
};
/// @addtogroup ndarrayMainGroup
/// @{
/** @brief Start a view definition that includes the entire first dimension. */
inline View< boost::fusion::vector1<index::Full> > view() {
return View< boost::fusion::vector1<index::Full> >(
boost::fusion::make_vector(index::Full())
);
}
/** @brief Start a view definition that selects a contiguous range in the first dimension. */
inline View< boost::fusion::vector1<index::Range> > view(Size start, Size stop) {
return View< boost::fusion::vector1<index::Range> >(
boost::fusion::make_vector(index::Range(start, stop))
);
}
/** @brief Start a view definition that selects a noncontiguous slice of the first dimension. */
inline View< boost::fusion::vector1<index::Slice> > view(Size start, Size stop, Offset step) {
return View< boost::fusion::vector1<index::Slice> >(
boost::fusion::make_vector(index::Slice(start, stop, step))
);
}
/** @brief Start a view definition that selects single element from the first dimension. */
inline View< boost::fusion::vector1<index::Scalar> > view(Size n) {
return View< boost::fusion::vector1<index::Scalar> >(
boost::fusion::make_vector(index::Scalar(n))
);
}
/// @}
} // namespace ndarray
#endif // !NDARRAY_views_h_INCLUDED