Filter.h

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/*  YAP - Yet another PWA toolkit
    Copyright 2015, Technische Universitaet Muenchen,
    Authors: Daniel Greenwald, Johannes Rauch

    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/>.
 */


#ifndef yap__Filter_h
#define yap__Filter_h

#include "fwd/Filter.h"

#include "Exceptions.h"

#include <memory>
#include <set>

namespace yap {


template <typename container>
typename container::value_type lone_elt(container& C)
{
    if (C.size() != 1)
        throw yap::exceptions::Exception("Container size not 1 (" + std::to_string(C.size())+ ")", "lone_elt");
    return *C.begin();
}

template <typename container>
typename container::value_type lone_elt(container&& C)
{
    if (C.size() != 1)
        throw yap::exceptions::Exception("Container size not 1 (" + std::to_string(C.size()) + ")", "lone_elt");
    return *C.begin();
}

template <typename T, typename Last, typename ... UnaryPredicates>
std::set<std::shared_ptr<T> > filter(const std::set<std::shared_ptr<T> >& S, Last p, UnaryPredicates ... P)
{
    auto s = filter<T, UnaryPredicates...>(S, P...);
    for (auto it = s.begin(); it != s.end(); ) {
        if (p(**it))
            ++it;
        else
            it = s.erase(it);
    }
    return s;
}

// does nothing, needed to terminate above variadic template
template <typename T>
const std::set<std::shared_ptr<T> >& filter(const std::set<std::shared_ptr<T> >& S)
{ return S; }

// end of defgroup filters

}

#endif