boost/spirit/home/qi/directive/hold.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)
=============================================================================*/
#if !defined(SPIRIT_HOLD_FEBRUARY_6_2010_0917AM)
#define SPIRIT_HOLD_FEBRUARY_6_2010_0917AM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/qi/meta_compiler.hpp>
#include <boost/spirit/home/qi/skip_over.hpp>
#include <boost/spirit/home/qi/parser.hpp>
#include <boost/spirit/home/support/attributes.hpp>
#include <boost/spirit/home/support/info.hpp>
#include <boost/spirit/home/support/common_terminals.hpp>
#include <boost/spirit/home/support/unused.hpp>
#include <boost/spirit/home/support/has_semantic_action.hpp>
#include <boost/spirit/home/support/handles_container.hpp>
namespace boost { namespace spirit
{
///////////////////////////////////////////////////////////////////////////
// Enablers
///////////////////////////////////////////////////////////////////////////
template <>
struct use_directive<qi::domain, tag::hold> // enables hold
: mpl::true_ {};
}}
namespace boost { namespace spirit { namespace qi
{
#ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
using spirit::hold;
#endif
using spirit::hold_type;
template <typename Subject>
struct hold_directive : unary_parser<hold_directive<Subject> >
{
typedef Subject subject_type;
hold_directive(Subject const& subject_)
: subject(subject_) {}
template <typename Context, typename Iterator>
struct attribute
{
typedef typename
traits::attribute_of<subject_type, Context, Iterator>::type
type;
};
template <typename Iterator, typename Context
, typename Skipper, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, Context& context, Skipper const& skipper, Attribute& attr_) const
{
Attribute copy(attr_);
if (subject.parse(first, last, context, skipper, copy))
{
traits::swap_impl(copy, attr_);
return true;
}
return false;
}
template <typename Context>
info what(Context& context) const
{
return info("hold", subject.what(context));
}
Subject subject;
};
///////////////////////////////////////////////////////////////////////////
// Parser generators: make_xxx function (objects)
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename Modifiers>
struct make_directive<tag::hold, Subject, Modifiers>
{
typedef hold_directive<Subject> result_type;
result_type operator()(unused_type, Subject const& subject, unused_type) const
{
return result_type(subject);
}
};
}}}
namespace boost { namespace spirit { namespace traits
{
///////////////////////////////////////////////////////////////////////////
template <typename Subject>
struct has_semantic_action<qi::hold_directive<Subject> >
: unary_has_semantic_action<Subject> {};
///////////////////////////////////////////////////////////////////////////
template <typename Subject, typename Attribute, typename Context
, typename Iterator>
struct handles_container<qi::hold_directive<Subject>, Attribute
, Context, Iterator>
: unary_handles_container<Subject, Attribute, Context, Iterator> {};
}}}
#endif