//  Copyright (c) 2001-2011 Hartmut Kaiser
//
//  Distributed under the Boost Software License, Version 1.0. (See accompanying
//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#if !defined(BOOST_SPIRIT_ITERATOR_SPLIT_FUNCTOR_INPUT_POLICY_JAN_16_2008_0448M)
#define BOOST_SPIRIT_ITERATOR_SPLIT_FUNCTOR_INPUT_POLICY_JAN_16_2008_0448M

#include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
#include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
#include <boost/assert.hpp>

namespace boost {
namespace spirit {
namespace iterator_policies {
namespace is_valid_test_ {
template <typename Token>
inline bool
token_is_valid(Token const&)
{
    return true;
}
}

///////////////////////////////////////////////////////////////////////////
//  class functor_input
//  Implementation of the InputPolicy used by multi_pass
//  functor_input gets tokens from a functor
//
//  Note: the functor must have a typedef for result_type
//        It also must have a static variable of type result_type defined
//        to represent EOF that is called eof.
//
///////////////////////////////////////////////////////////////////////////
struct functor_input
{
    ///////////////////////////////////////////////////////////////////////
    template <typename Functor>
  class unique : public detail::default_input_policy
    {
        private:
        typedef typename Functor::result_type result_type;

        protected:
        unique() {}
        explicit
        unique(Functor const& x) : ftor(x) {}

        void
        swap(unique& x)
        {
            boost::swap(ftor, x.ftor);
        }

public:
        typedef result_type value_type;
        typedef std::ptrdiff_t difference_type;
        typedef std::ptrdiff_t distance_type;
        typedef result_type* pointer;
        typedef result_type& reference;

public:
        // get the next token
        template <typename MultiPass>
        static typename MultiPass::reference
        get_input(MultiPass& mp)
        {
            value_type& curtok = mp.shared()->curtok;

            if (!input_is_valid(mp, curtok))
            {
                curtok = mp.ftor();
            }

            return curtok;
        }

        template <typename MultiPass>
        static void
        advance_input(MultiPass& mp)
        {
            // if mp.shared is NULL then this instance of the multi_pass
            // represents a end iterator
            BOOST_ASSERT(0 != mp.shared());
            mp.shared()->curtok = mp.ftor();
        }

        // test, whether we reached the end of the underlying stream
        template <typename MultiPass>
        static bool
        input_at_eof(MultiPass const& mp)
        {
            return mp.shared()->curtok == mp.ftor.eof;
        }

        template <typename MultiPass>
        static bool
        input_is_valid(MultiPass const&, value_type const& t)
        {
            using namespace is_valid_test_;
            return token_is_valid(t);
        }

        Functor&
        get_functor() const
        {
            return ftor;
        }

protected:
        mutable Functor ftor;
    };

    ///////////////////////////////////////////////////////////////////////
    template <typename Functor>
    struct shared
    {
        explicit
        shared(Functor const&) : curtok(0) {}

        typename Functor::result_type curtok;
    };
};

}
}
}

#endif
