Line data    Source code

       1             : /* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
       2             :    Copyright (c) 2025 The plumed team
       3             :    (see the PEOPLE file at the root of the distribution for a list of names)
       4             : 
       5             :    See http://www.plumed.org for more information.
       6             : 
       7             :    This file is part of plumed, version 2.
       8             : 
       9             :    plumed is free software: you can redistribute it and/or modify
      10             :    it under the terms of the GNU Lesser General Public License as published by
      11             :    the Free Software Foundation, either version 3 of the License, or
      12             :    (at your option) any later version.
      13             : 
      14             :    plumed is distributed in the hope that it will be useful,
      15             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      16             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      17             :    GNU Lesser General Public License for more details.
      18             : 
      19             :    You should have received a copy of the GNU Lesser General Public License
      20             :    along with plumed.  If not, see <http://www.gnu.org/licenses/>.
      21             : +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
      22             : #ifndef __PLUMED_tools_View2D_h
      23             : #define __PLUMED_tools_View2D_h
      24             : #include <limits>
      25             : #include <type_traits>
      26             : 
      27             : #include "View.h"
      28             : 
      29             : namespace PLMD {
      30             : 
      31             : /**A not-owning view for accessing array witha  2D interface
      32             : 
      33             : The main idea is to have something that works like the mdspan from c++23.
      34             : 
      35             : Views are CHEAP to copy (pointer and an integer), so it is better to pass
      36             : them as values
      37             : 
      38             : 
      39             : 
      40             : @todo  ctors from std::array and from iterators to parallel the span implementatio
      41             : */
      42             : template <typename T, std::size_t N= helpers::dynamic_extent, std::size_t M= helpers::dynamic_extent>
      43             : class View2D {
      44             : public:
      45             :   using value_type      = T;
      46             :   using element_type    = View<value_type,M>;
      47             :   using pointer         = value_type*;
      48             :   using iterator        = pointer;
      49             :   using const_iterator  = const pointer;
      50             :   using reference       = value_type&;
      51             :   using const_reference = const value_type&;
      52             : private:
      53             :   pointer ptr_;
      54             :   std::size_t sizeN_{N};
      55             :   std::size_t sizeM_{M};
      56             : public:
      57             : 
      58             :   ///constructor for fixed size View2D
      59             :   template <size_t N_ = N, size_t M_ = M,
      60             :             typename = std::enable_if_t<N_ != helpers::dynamic_extent && M_ != helpers::dynamic_extent>>
      61             :   explicit View2D(pointer p) noexcept : ptr_(p) {}
      62             : 
      63             :   ///constructor for a View2D with known second dimension at compile time
      64             :   template <size_t N_ = N, size_t M_ = M,
      65             :             typename = std::enable_if_t<N_ == helpers::dynamic_extent && M_ != helpers::dynamic_extent>>
      66     4500403 :   View2D(pointer p, size_t NN) noexcept: ptr_(p), sizeN_(NN) {}
      67             : 
      68             :   ///constructor for a View2D with all dimension known at run time
      69             :   template <size_t N_ = N, size_t M_ = M,
      70             :             typename = std::enable_if_t<N_ == helpers::dynamic_extent && M_ == helpers::dynamic_extent>>
      71    94436940 :   View2D(pointer p, size_t NN, size_t MM) noexcept : ptr_(p), sizeN_(NN), sizeM_(MM) {}
      72             : 
      73             :   View2D(const View2D&) noexcept =default;
      74             :   View2D(View2D&&) noexcept =default;
      75             :   View2D&operator =(const View2D&) noexcept =default;
      76             :   View2D&operator =(View2D&&) noexcept =default;
      77             : 
      78             :   ///returns the size of the first dimension
      79             :   constexpr size_t size() const noexcept {
      80     2191521 :     return sizeN_;
      81             :   }
      82             : 
      83             :   ///returns the View to the i-th row
      84             :   constexpr element_type operator[](size_t i) noexcept {
      85   887659911 :     return element_type{ptr_ + i * sizeM_,sizeM_};
      86             :   }
      87             : 
      88             :   ///returns the reference i-th element
      89             :   constexpr const element_type operator[](size_t i) const noexcept {
      90   928112229 :     return element_type{ptr_ + i * sizeM_, sizeM_};
      91             :   }
      92             : 
      93             :   ///return the pointer to the data
      94             :   constexpr pointer data() const noexcept {
      95             :     return ptr_;
      96             :   }
      97             : };
      98             : 
      99             : } // namespace PLMD
     100             : #endif // __PLUMED_tools_View2D_h