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/* Copyright (c) 1997-2024
Ewgenij Gawrilow, Michael Joswig, and the polymake team
Technische Universität Berlin, Germany
https://polymake.org
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 2, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
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.
--------------------------------------------------------------------------------
*/
#pragma once
namespace polymake { namespace matroid {
namespace operations {
using namespace polymake::operations;
template <typename SetRef>
struct contains {
typedef typename pm::deref<SetRef>::type set_type;
typedef set_type argument_type;
typedef bool result_type;
typedef typename pm::deref<SetRef>::type::element_type element_type;
element_type elem;
contains(element_type e = element_type()) : elem(e) {}
result_type operator() (typename pm::function_argument<SetRef>::const_type set) const
{
return set.contains(elem);
}
};
template <typename Scalar>
struct dropshift {
typedef typename pm::deref<Scalar>::type scalar_type;
scalar_type elem;
public:
typedef scalar_type argument_type;
typedef scalar_type result_type;
dropshift(scalar_type e = scalar_type()) : elem(e) {}
result_type operator() (argument_type value) const
{
return value < elem ? value : value-1;
}
};
}
template <typename Container>
auto
select_k(const Container& sets, const Int k,
std::enable_if_t<pm::isomorphic_to_container_of<Container, Set<Int>>::value, std::nullptr_t> = nullptr)
{
return pm::SelectedSubset<const Container&, operations::contains<Set<Int>>>(sets, operations::contains<Set<Int>>(k));
}
template <typename Container>
auto
select_not_k(const Container& sets, const Int k,
std::enable_if_t<pm::isomorphic_to_container_of<Container, Set<Int>>::value, std::nullptr_t> = nullptr)
{
return pm::SelectedSubset<const Container&, operations::composed11<operations::contains<Set<Int>>, std::logical_not<bool>>>(sets, operations::composed11<operations::contains<Set<Int>>, std::logical_not<bool>>(operations::contains<Set<Int>>(k), std::logical_not<bool>()));
}
template <typename Container>
auto drop_shift(const Container& sets, const Int k)
{
return attach_operation(
attach_operation(sets, pm::operations::construct_unary2_with_arg< pm::SelectedSubset, operations::fix2<Int, operations::ne> >(operations::fix2<Int, operations::ne>(k))),
pm::operations::construct_unary2_with_arg<pm::TransformedContainer, operations::dropshift<Int>>(operations::dropshift<Int>(k)));
}
template <typename Container>
Array<Set<Int>>
shift_elements(const Container& sets, const Int n)
{
return Array<Set<Int>>{ attach_operation(sets,
pm::operations::construct_unary2_with_arg<pm::TransformedContainer,
operations::fix2<Int, operations::add> >(operations::fix2<Int, operations::add>(n))) };
}
}}
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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