Boost C++ Libraries

boost/spirit/home/qi/operator/sequential_or.hpp

/*=============================================================================
    Copyright (c) 2001-2011 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)
=============================================================================*/
#ifndef BOOST_SPIRIT_QI_OPERATOR_SEQUENTIAL_OR_HPP
#define BOOST_SPIRIT_QI_OPERATOR_SEQUENTIAL_OR_HPP

#if defined(_MSC_VER)
#pragma once
#endif

#include <boost/spirit/home/qi/meta_compiler.hpp>
#include <boost/spirit/home/qi/detail/pass_function.hpp>
#include <boost/spirit/home/qi/detail/attributes.hpp>
#include <boost/spirit/home/support/detail/what_function.hpp>
#include <boost/spirit/home/support/algorithm/any_if_ns_so.hpp>
#include <boost/spirit/home/support/handles_container.hpp>
#include <boost/fusion/include/as_vector.hpp>
#include <boost/fusion/include/for_each.hpp>
#include <boost/proto/operators.hpp>
#include <boost/proto/tags.hpp>

namespace boost { namespace spirit
{
    ///////////////////////////////////////////////////////////////////////////
    // Enablers
    ///////////////////////////////////////////////////////////////////////////
    template <>
    struct use_operator<qi::domain, proto::tag::logical_or> // enables ||
      : mpl::true_ {};

    template <>
    struct flatten_tree<qi::domain, proto::tag::logical_or> // flattens ||
      : mpl::true_ {};
}}

namespace boost { namespace spirit { namespace qi
{
    template <typename Elements>
    struct sequential_or : nary_parser<sequential_or<Elements> >
    {
        template <typename Context, typename Iterator>
        struct attribute
        {
            // Put all the element attributes in a tuple,
            // wrapping each element in a boost::optional
            typedef typename traits::build_attribute_sequence<
                Elements, Context, traits::sequential_or_attribute_transform
              , Iterator, qi::domain
            >::type all_attributes;

            // Now, build a fusion vector over the attributes. Note
            // that build_fusion_vector 1) removes all unused attributes
            // and 2) may return unused_type if all elements have
            // unused_type(s).
            typedef typename
                traits::build_fusion_vector<all_attributes>::type
            type;
        };

        sequential_or(Elements const& elements_)
          : elements(elements_) {}

        template <typename Iterator, typename Context
          , typename Skipper, typename Attribute>
        bool parse(Iterator& first, Iterator const& last
          , Context& context, Skipper const& skipper
          , Attribute& attr_) const
        {
            typedef traits::attribute_not_unused<Context, Iterator> predicate;
            detail::pass_function<Iterator, Context, Skipper>
                f(first, last, context, skipper);

            // wrap the attribute in a tuple if it is not a tuple
            typename traits::wrap_if_not_tuple<Attribute>::type attr_local(attr_);

            // return true if *any* of the parsers succeed
            // (we use the non-short-circuiting and strict order version:
            // any_if_ns_so to force all the elements to be tested and
            // in the defined order: first is first, last is last)
            return spirit::any_if_ns_so(elements, attr_local, f, predicate());
        }

        template <typename Context>
        info what(Context& context) const
        {
            info result("sequential-or");
            fusion::for_each(elements,
                spirit::detail::what_function<Context>(result, context));
            return result;
        }

        Elements elements;
    };

    ///////////////////////////////////////////////////////////////////////////
    // Parser generators: make_xxx function (objects)
    ///////////////////////////////////////////////////////////////////////////
    template <typename Elements, typename Modifiers>
    struct make_composite<proto::tag::logical_or, Elements, Modifiers>
      : make_nary_composite<Elements, sequential_or>
    {};
}}}

namespace boost { namespace spirit { namespace traits
{
    ///////////////////////////////////////////////////////////////////////////
    // We specialize this for sequential_or (see support/attributes.hpp).
    // For sequential_or, we only wrap the attribute in a tuple IFF
    // it is not already a fusion tuple.
    template <typename Elements, typename Attribute>
    struct pass_attribute<qi::sequential_or<Elements>, Attribute>
      : wrap_if_not_tuple<Attribute> {};

    ///////////////////////////////////////////////////////////////////////////
    template <typename Elements>
    struct has_semantic_action<qi::sequential_or<Elements> >
      : nary_has_semantic_action<Elements> {};

    ///////////////////////////////////////////////////////////////////////////
    template <typename Elements, typename Attribute, typename Context
      , typename Iterator>
    struct handles_container<qi::sequential_or<Elements>, Attribute, Context
      , Iterator>
      : nary_handles_container<Elements, Attribute, Context, Iterator> {};
}}}

#endif