utility.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2015  Virginia Tech
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Justus Calvin
 *  Department of Chemistry, Virginia Tech
 *
 *  untility.h
 *  Jun 1, 2015
 *
 */

#ifndef TILEDARRAY_TENSOR_UTILITY_H__INCLUDED
#define TILEDARRAY_TENSOR_UTILITY_H__INCLUDED

#include <TiledArray/utility.h>
#include <TiledArray/range.h>
#include <TiledArray/block_range.h>
#include <TiledArray/size_array.h>
#include <TiledArray/tensor/type_traits.h>

namespace TiledArray {
  namespace detail {


    template <typename T,
        typename std::enable_if<is_contiguous_tensor<T>::value>::type* = nullptr>
    inline auto clone_range(const T& tensor)
    { return tensor.range(); }


    template <typename T,
        typename std::enable_if<! is_contiguous_tensor<T>::value>::type* = nullptr>
    inline Range clone_range(const T& tensor) {
      return Range(tensor.range().lobound(), tensor.range().upbound());
    }


    template <typename Range>
    inline bool is_congruent(const Range& r1, const Range& r2){
      return r1 == r2;
    }


    template <>
    inline bool is_congruent(const BlockRange& r1, const BlockRange& r2){
      return (r1.rank() == r2.rank()) &&
             std::equal(r1.extent_data(),
                        r1.extent_data() + r1.rank(), r2.extent_data());
    }


    template <typename Range>
    inline bool is_congruent(const BlockRange& r1, const Range& r2){
      return (r1.rank() == r2.rank()) &&
             std::equal(r1.extent_data(),
                        r1.extent_data() + r1.rank(), r2.extent_data());
    }


    template <typename Range>
    inline bool is_congruent(const Range& r1, const BlockRange& r2){
      return is_congruent(r2,r1);
    }


    template <typename T1, typename T2,
        typename std::enable_if<! (is_shifted<T1>::value
            || is_shifted<T2>::value)>::type* = nullptr>
    inline bool is_range_congruent(const T1& tensor1, const T2& tensor2) {
      return is_congruent(tensor1.range(), tensor2.range());
    }


    template <typename T1, typename T2,
        typename std::enable_if<! (is_shifted<T1>::value
            || is_shifted<T2>::value)>::type* = nullptr>
    inline bool is_range_congruent(const T1& tensor1, const T2& tensor2,
        const Permutation& perm)
    {
      return is_congruent(tensor1.range(), perm*tensor2.range());
    }


    template <typename T1, typename T2,
        typename std::enable_if<is_shifted<T1>::value
            || is_shifted<T2>::value>::type* = nullptr>
    inline bool is_range_congruent(const T1& tensor1, const T2& tensor2) {
      const auto rank1 = tensor1.range().rank();
      const auto rank2 = tensor2.range().rank();
      const auto* const extent1 = tensor1.range().extent_data();
      const auto* const extent2 = tensor2.range().extent_data();
      return (rank1 == rank2) && std::equal(extent1, extent1 + rank1, extent2);
    }



    template <typename T>
    inline constexpr bool
    is_range_set_congruent(const Permutation& perm, const T& tensor) {
      return true;
    }


    template <typename T1, typename T2, typename... Ts>
    inline bool is_range_set_congruent(const Permutation& perm,
        const T1& tensor1, const T2& tensor2, const Ts&... tensors)
    {
      return is_range_congruent(tensor1, tensor2, perm)
          && is_range_set_congruent(perm, tensor1, tensors...);
    }



    template <typename T>
    inline constexpr bool is_range_set_congruent(const T& tensor) {
      return true;
    }


    template <typename T1, typename T2, typename... Ts>
    inline bool is_range_set_congruent(const T1& tensor1, const T2& tensor2,
        const Ts&... tensors)
    {
      return is_range_congruent(tensor1, tensor2)
          && is_range_set_congruent(tensor1, tensors...);
    }



    template <typename T>
    inline typename T::size_type inner_size_helper(const T& tensor) {
      const auto* MADNESS_RESTRICT const stride = tensor.range().stride_data();
      const auto* MADNESS_RESTRICT const size = tensor.range().extent_data();

      int i = int(tensor.range().rank()) - 1;
      auto volume = size[i];

      for(--i; i >= 0; --i) {
        const auto stride_i = stride[i];
        const auto size_i = size[i];

        if(volume != stride_i)
          break;
        volume *= size_i;
      }

      return volume;
    }


    template <typename T1, typename T2>
    inline typename T1::size_type
    inner_size_helper(const T1& tensor1, const T2& tensor2) {
      TA_ASSERT(is_range_congruent(tensor1, tensor2));
      const auto* MADNESS_RESTRICT const size1   = tensor1.range().extent_data();
      const auto* MADNESS_RESTRICT const stride1 = tensor1.range().stride_data();
      const auto* MADNESS_RESTRICT const size2   = tensor2.range().extent_data();
      const auto* MADNESS_RESTRICT const stride2 = tensor2.range().stride_data();

      int i = int(tensor1.range().rank()) - 1;
      auto volume1 = size1[i];
      auto volume2 = size2[i];

      for(--i; i >= 0; --i) {
        const auto stride1_i = stride1[i];
        const auto stride2_i = stride2[i];
        const auto size1_i = size1[i];
        const auto size2_i = size2[i];

        if((volume1 != stride1_i) || (volume2 != stride2_i))
          break;
        volume1 *= size1_i;
        volume2 *= size2_i;
      }

      return volume1;
    }


    template <typename T1, typename T2,
        typename std::enable_if<! is_contiguous_tensor<T1>::value
                 && is_contiguous_tensor<T2>::value>::type* = nullptr>
    inline typename T1::size_type inner_size(const T1& tensor1, const T2&) {
      return inner_size_helper(tensor1);
    }



    template <typename T1, typename T2,
        typename std::enable_if<is_contiguous_tensor<T1>::value
                 && ! is_contiguous_tensor<T2>::value>::type* = nullptr>
    inline typename T1::size_type inner_size(const T1&, const T2& tensor2) {
      return inner_size_helper(tensor2);
    }


    template <typename T1, typename T2,
        typename std::enable_if<! is_contiguous_tensor<T1>::value
                 && ! is_contiguous_tensor<T2>::value>::type* = nullptr>
    inline typename T1::size_type inner_size(const T1& tensor1, const T2& tensor2) {
      return inner_size_helper(tensor1, tensor2);
    }



    template <typename T,
        typename std::enable_if<! is_contiguous_tensor<T>::value>::type* = nullptr>
    inline typename T::size_type inner_size(const T& tensor) {
      return inner_size_helper(tensor);
    }



    inline constexpr bool empty() {  return true; }


    template <typename T1, typename... Ts>
    inline bool empty(const T1& tensor1, const Ts&... tensors) {
      return tensor1.empty() && empty(tensors...);
    }

  }  // namespace detail
} // namespace TiledArray

#endif // TILEDARRAY_TENSOR_UTILITY_H__INCLUDED