Line data    Source code

       1             : // SPDX-License-Identifier: BSD-3-Clause
       2             : // Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
       3             : /// @file
       4             : /// @author Simon Heybrock
       5             : #pragma once
       6             : 
       7             : #include <boost/container/small_vector.hpp>
       8             : 
       9             : #include "scipp-core_export.h"
      10             : #include "scipp/common/index.h"
      11             : #include "scipp/core/dimensions.h"
      12             : 
      13             : namespace scipp::core {
      14             : 
      15             : /// Container for strides in memory.
      16             : ///
      17             : /// Given a contiguous buffer in memory viewed as a multi-dimensional array,
      18             : /// `strides[d]` is the distance in memory between consecutive array elements
      19             : /// in dimension `d`.
      20             : /// @see scipp::flat_index_from_strides
      21             : ///
      22             : /// Strides objects do not store information on the dimensions.
      23             : /// They should therefore be accompanied by an instance of Dimensions.
      24             : /// The storage order in Strides is arbitrary but should be the same as in
      25             : /// Dimensions, i.e. the slowest moving index should be first.
      26             : class SCIPP_CORE_EXPORT Strides {
      27             : public:
      28    13645600 :   Strides() = default;
      29             :   explicit Strides(const scipp::span<const scipp::index> &strides);
      30             :   Strides(std::initializer_list<scipp::index> strides);
      31             :   explicit Strides(const Dimensions &dims);
      32             : 
      33             :   bool operator==(const Strides &other) const noexcept;
      34             :   bool operator!=(const Strides &other) const noexcept;
      35             : 
      36     6330736 :   [[nodiscard]] scipp::index size() const noexcept { return m_strides.size(); }
      37             : 
      38             :   void push_back(const scipp::index i);
      39             :   void clear();
      40             :   void resize(const scipp::index size);
      41             : 
      42    11538832 :   scipp::index operator[](const scipp::index i) const {
      43    23077664 :     return m_strides.at(i);
      44             :   }
      45             : 
      46     5603176 :   scipp::index &operator[](const scipp::index i) { return m_strides.at(i); }
      47             : 
      48      851810 :   [[nodiscard]] auto begin() const { return m_strides.begin(); }
      49             :   [[nodiscard]] auto begin() { return m_strides.begin(); }
      50             :   [[nodiscard]] auto end() const { return m_strides.end(); }
      51             :   [[nodiscard]] auto end() { return m_strides.end(); }
      52             : 
      53             :   void erase(scipp::index i);
      54             : 
      55             : private:
      56             :   boost::container::small_vector<scipp::index, NDIM_STACK> m_strides;
      57             : };
      58             : 
      59             : Strides SCIPP_CORE_EXPORT transpose(const Strides &strides, Dimensions from,
      60             :                                     scipp::span<const Dim> order);
      61             : 
      62             : } // namespace scipp::core
      63             : 
      64             : namespace scipp {
      65             : using core::Strides;
      66             : }