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field_map.hh
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/**
* @file field_map.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 26 Sep 2017
*
* @brief just and indirection to include all iterables defined for fields
*
* Copyright © 2017 Till Junge
*
* µSpectre 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, or (at
* your option) any later version.
*
* µSpectre 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 GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "common/field_map_tensor.hh"
#include "common/field_map_matrixlike.hh"
#include "common/field_map_scalar.hh"
#include <sstream>
#include <stdexcept>
#include <type_traits>
#ifndef FIELD_MAP_H
#define FIELD_MAP_H
namespace muSpectre {
/**
* allows to iterate over raw data as if it were a FieldMap. This is
* particularly useful when interacting with external solvers, such
* as scipy and Eigen
* @param EigenMap needs to be statically sized a Eigen::Map<XXX>
*/
template <class EigenMap>
class RawFieldMap
{
public:
/**
* determining the constness of the mapped array required in order
* to formulate the constructors const-correctly
*/
constexpr static bool IsConst{
std::is_const<
std::remove_pointer_t<typename EigenMap::PointerArgType>>::value};
// short-hand for the basic scalar type
using T = typename EigenMap::Scalar;
// raw pointer type to store
using T_ptr = std::conditional_t<IsConst,
const T*,
T*>;
// input array (~field) type to be mapped
using FieldVec_t = std::conditional_t<IsConst,
const Eigen::VectorXd,
Eigen::VectorXd>;
//! Default constructor
RawFieldMap() = delete;
//! constructor from a *contiguous* array
RawFieldMap(Eigen::Map<FieldVec_t> vec):
data{vec.data()}, nb_pixels{vec.size()/NbComponents}
{
if (vec.size() % NbComponents != 0) {
std::stringstream err{};
err << "The vector size of " << vec.size()
<< " is not an integer multiple of the size of value_type, which "
<< "is " << NbComponents << ".";
throw std::runtime_error(err.str());
}
}
//! constructor from a *contiguous* array
RawFieldMap(Eigen::Ref<FieldVec_t> vec):
data{vec.data()}, nb_pixels{vec.size()/NbComponents}
{
if (vec.size() % NbComponents != 0) {
std::stringstream err{};
err << "The vector size of " << vec.size()
<< " is not an integer multiple of the size of value_type, which "
<< "is " << NbComponents << ".";
throw std::runtime_error(err.str());
}
}
//! Copy constructor
RawFieldMap(const RawFieldMap &other) = delete;
//! Move constructor
RawFieldMap(RawFieldMap &&other) = default;
//! Destructor
virtual ~RawFieldMap() = default;
//! Copy assignment operator
RawFieldMap& operator=(const RawFieldMap &other) = delete;
//! Move assignment operator
RawFieldMap& operator=(RawFieldMap &&other) = delete;
//! returns number of EigenMaps stored within the array
size_t size() const {return this->nb_pixels;}
//! forward declaration of iterator type
class iterator;
//! returns an iterator to the first element
iterator begin() { return iterator{this->data, 0};}
//! returns an iterator past the last element
iterator end() {return iterator{this->data, this->size()};}
protected:
//! statically known size of the mapped type
constexpr static size_t NbComponents{EigenMap::SizeAtCompileTime};
//! raw data pointer (ugly, I know)
T_ptr data;
//! number of EigenMaps stored within the array
size_t nb_pixels;
private:
};
/**
* Small iterator class to be used with the RawFieldMap
*/
template <class EigenMap>
class RawFieldMap<EigenMap>::iterator
{
public:
//! short hand for the raw field map's type
using Parent = RawFieldMap<EigenMap>;
//! the map needs to be friend in order to access the protected constructor
friend Parent;
//! stl compliance
using value_type = EigenMap;
//! stl compliance
using iterator_category = std::forward_iterator_tag;
//! Default constructor
iterator() = delete;
//! Copy constructor
iterator(const iterator &other) = default;
//! Move constructor
iterator(iterator &&other) = default;
//! Destructor
virtual ~iterator() = default;
//! Copy assignment operator
iterator& operator=(const iterator &other) = default;
//! Move assignment operator
iterator& operator=(iterator &&other) = default;
//! pre-increment
inline iterator & operator++() {
++this->index;
return *this;
}
//! dereference
inline value_type operator *() {
return EigenMap(raw_map + Parent::NbComponents*index);
}
//! inequality
inline bool operator != (const iterator & other) const {
return this->index != other.index;
}
//! equality
inline bool operator == (const iterator & other) const {
return this->index == other.index;
}
protected:
//! protected constructor
iterator (Parent::T_ptr raw_map, size_t start):
raw_map{raw_map}, index{start} {}
//! raw data
Parent::T_ptr raw_map;
//! currently pointed-to element
size_t index;
private:
};
} // muSpectre
#endif /* FIELD_MAP_H */

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