/*=============================================================================
    Copyright (c) 2001-2014 Joel de Guzman

    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_X3_GUARD_FERBRUARY_02_2013_0649PM)
#define BOOST_SPIRIT_X3_GUARD_FERBRUARY_02_2013_0649PM

#include <boost/spirit/home/x3/support/context.hpp>
#include <boost/spirit/home/x3/directive/expect.hpp>

namespace boost {
namespace spirit {
namespace x3 {
enum class error_handler_result
{
    fail
    , retry
    , accept
    , rethrow
};

template <typename Subject, typename Handler>
struct guard : unary_parser<Subject, guard<Subject, Handler>>
{
    typedef unary_parser<Subject, guard<Subject, Handler>> base_type;
    static bool const is_pass_through_unary = true;

    constexpr
    guard(Subject const& subject, Handler handler)
        : base_type(subject), handler(handler) {}

    template <typename Iterator, typename Context
              , typename RuleContext, typename Attribute>
    bool
    parse(Iterator& first, Iterator const& last
          , Context const& context, RuleContext& rcontext, Attribute& attr) const
    {
        for (;;)
        {
            try
            {
                Iterator i = first;
                bool r = this->subject.parse(i, last, context, rcontext, attr);

                if (r)
                {
                    first = i;
                }

                return r;
            }

            catch (expectation_failure<Iterator> const& x)
            {
                switch (handler(first, last, x, context))
                {
                case error_handler_result::fail:
                    return false;

                case error_handler_result::retry:
                    continue;

                case error_handler_result::accept:
                    return true;

                case error_handler_result::rethrow:
                    throw;
                }
            }
        }

        return false;
    }

    Handler handler;
};
}
}
}

#endif
