// charset.hpp
// Copyright (c) 2005-2018 Ben Hanson (http://www.benhanson.net/)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file licence_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef LEXERTL_CHARSET_HPP
#define LEXERTL_CHARSET_HPP

#include <algorithm>
#include <iterator>
#include <set>
#include "../string_token.hpp"

namespace lexertl
{
namespace detail
{
template<typename char_type, typename id_type>
struct basic_charset
{
    using token = basic_string_token<char_type>;
    using index_set = std::set<id_type>;

    token _token;
    index_set _index_set;

    basic_charset() :
        _token(),
        _index_set()
    {
    }

    basic_charset(const token &token_, const id_type index_) :
        _token(token_),
        _index_set()
    {
        _index_set.insert(index_);
    }

    bool empty() const
    {
        return _token.empty() && _index_set.empty();
    }

    void intersect(basic_charset &rhs_, basic_charset &overlap_)
    {
        _token.intersect(rhs_._token, overlap_._token);

        if (!overlap_._token.empty())
        {
            std::merge(_index_set.begin(), _index_set.end(),
                rhs_._index_set.begin(), rhs_._index_set.end(),
                std::inserter(overlap_._index_set,
                overlap_._index_set.end()));

            if (_token.empty())
            {
                _index_set.clear();
            }

            if (rhs_._token.empty())
            {
                rhs_._index_set.clear();
            }
        }
    }
};
}
}

#endif