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Diffstat (limited to 'src/Coxeter_triangulation/include/gudhi/Permutahedral_representation/Ordered_set_partition_iterator.h')
-rw-r--r-- | src/Coxeter_triangulation/include/gudhi/Permutahedral_representation/Ordered_set_partition_iterator.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/src/Coxeter_triangulation/include/gudhi/Permutahedral_representation/Ordered_set_partition_iterator.h b/src/Coxeter_triangulation/include/gudhi/Permutahedral_representation/Ordered_set_partition_iterator.h new file mode 100644 index 00000000..866079fa --- /dev/null +++ b/src/Coxeter_triangulation/include/gudhi/Permutahedral_representation/Ordered_set_partition_iterator.h @@ -0,0 +1,93 @@ +/* This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT. + * See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details. + * Author(s): Siargey Kachanovich + * + * Copyright (C) 2019 Inria + * + * Modification(s): + * - YYYY/MM Author: Description of the modification + */ + +#ifndef PERMUTAHEDRAL_REPRESENTATION_ORDERED_SET_PARTITION_ITERATOR_H_ +#define PERMUTAHEDRAL_REPRESENTATION_ORDERED_SET_PARTITION_ITERATOR_H_ + +#include <vector> +#include <limits> + +#include <gudhi/Permutahedral_representation/Permutation_iterator.h> +#include <gudhi/Permutahedral_representation/Set_partition_iterator.h> + +#include <boost/range/iterator_range.hpp> + +namespace Gudhi { + +namespace coxeter_triangulation { + +typedef unsigned uint; + +/** \brief Class that represents an ordered set partition of a set {0,...,n-1} in k parts as + * a pair of an unordered set partition given in lexicographic order and + * a permutation of the parts. + */ +struct Ordered_set_partition { + Set_partition_iterator s_it_; + Permutation_iterator p_it_; + + // Ordered_set_partition(const Set_partition_iterator& s_it, const Permutation_iterator& p_it) + // : s_it_(s_it), p_it_(p_it) {} + + const std::vector<uint> operator[](const uint& i) const { return (*s_it_)[(*p_it_)[i]]; } + + std::size_t size() const { return s_it_->size(); } +}; + +/** \brief Class that allows the user to generate set partitions of a set {0,...,n-1} in k parts. + * + */ +class Ordered_set_partition_iterator + : public boost::iterator_facade<Ordered_set_partition_iterator, Ordered_set_partition const, + boost::forward_traversal_tag> { + using value_t = Ordered_set_partition; + + private: + friend class boost::iterator_core_access; + + bool equal(Ordered_set_partition_iterator const& other) const { return (is_end_ && other.is_end_); } + + value_t const& dereference() const { return value_; } + + void increment() { + if (++value_.p_it_ == p_end_) { + if (++value_.s_it_ == s_end_) { + is_end_ = true; + return; + } else + value_.p_it_.reinitialize(); + } + } + + public: + Ordered_set_partition_iterator(const uint& n, const uint& k) + : value_({Set_partition_iterator(n, k), Permutation_iterator(k)}), is_end_(n == 0) {} + + // Used for the creating an end iterator + Ordered_set_partition_iterator() : is_end_(true) {} + + void reinitialize() { + is_end_ = false; + value_.p_it_.reinitialize(); + value_.s_it_.reinitialize(); + } + + private: + Set_partition_iterator s_end_; // Set partition iterator and the corresponding end iterator + Permutation_iterator p_end_; // Permutation iterator and the corresponding end iterator + value_t value_; // the dereference value + bool is_end_; // is true when the current permutation is the final one +}; + +} // namespace coxeter_triangulation + +} // namespace Gudhi + +#endif |