138 lines
4.9 KiB
C++
138 lines
4.9 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2001-2011 Joel de Guzman
|
|
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)
|
|
=============================================================================*/
|
|
#ifndef BOOST_SPIRIT_QI_OPERATOR_OPTIONAL_HPP
|
|
#define BOOST_SPIRIT_QI_OPERATOR_OPTIONAL_HPP
|
|
|
|
#if defined(_MSC_VER)
|
|
#pragma once
|
|
#endif
|
|
|
|
#include <boost/spirit/home/support/unused.hpp>
|
|
#include <boost/spirit/home/qi/detail/attributes.hpp>
|
|
#include <boost/spirit/home/support/has_semantic_action.hpp>
|
|
#include <boost/spirit/home/support/handles_container.hpp>
|
|
#include <boost/spirit/home/support/info.hpp>
|
|
#include <boost/spirit/home/support/container.hpp>
|
|
#include <boost/spirit/home/qi/parser.hpp>
|
|
#include <boost/spirit/home/qi/meta_compiler.hpp>
|
|
#include <boost/spirit/home/qi/detail/assign_to.hpp>
|
|
#include <boost/optional.hpp>
|
|
#include <boost/proto/operators.hpp>
|
|
#include <boost/proto/tags.hpp>
|
|
#include <vector>
|
|
|
|
namespace boost { namespace spirit
|
|
{
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Enablers
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <>
|
|
struct use_operator<qi::domain, proto::tag::negate> // enables -p
|
|
: mpl::true_ {};
|
|
}}
|
|
|
|
namespace boost { namespace spirit { namespace qi
|
|
{
|
|
template <typename Subject>
|
|
struct optional : unary_parser<optional<Subject> >
|
|
{
|
|
typedef Subject subject_type;
|
|
|
|
template <typename Context, typename Iterator>
|
|
struct attribute
|
|
{
|
|
// Build a boost::optional from the subject's attribute. Note
|
|
// that boost::optional may return unused_type if the
|
|
// subject's attribute is an unused_type.
|
|
typedef typename
|
|
traits::build_optional<
|
|
typename traits::
|
|
attribute_of<Subject, Context, Iterator>::type
|
|
>::type
|
|
type;
|
|
};
|
|
|
|
optional(Subject const& subject_)
|
|
: subject(subject_) {}
|
|
|
|
template <typename Iterator, typename Context
|
|
, typename Skipper, typename Attribute>
|
|
bool parse_impl(Iterator& first, Iterator const& last
|
|
, Context& context, Skipper const& skipper
|
|
, Attribute& attr_, mpl::false_) const
|
|
{
|
|
// create a local value if Attribute is not unused_type
|
|
typename spirit::result_of::optional_value<Attribute>::type val =
|
|
typename spirit::result_of::optional_value<Attribute>::type();
|
|
|
|
if (subject.parse(first, last, context, skipper, val))
|
|
{
|
|
// assign the parsed value into our attribute
|
|
spirit::traits::assign_to(val, attr_);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
template <typename Iterator, typename Context
|
|
, typename Skipper, typename Attribute>
|
|
bool parse_impl(Iterator& first, Iterator const& last
|
|
, Context& context, Skipper const& skipper
|
|
, Attribute& attr_, mpl::true_) const
|
|
{
|
|
subject.parse(first, last, context, skipper, attr_);
|
|
return true;
|
|
}
|
|
|
|
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 typename spirit::result_of::optional_value<Attribute>::type
|
|
attribute_type;
|
|
|
|
return parse_impl(first, last, context, skipper, attr_
|
|
, traits::is_container<attribute_type>());
|
|
}
|
|
|
|
template <typename Context>
|
|
info what(Context& context) const
|
|
{
|
|
return info("optional", subject.what(context));
|
|
}
|
|
|
|
Subject subject;
|
|
};
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Parser generators: make_xxx function (objects)
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename Elements, typename Modifiers>
|
|
struct make_composite<proto::tag::negate, Elements, Modifiers>
|
|
: make_unary_composite<Elements, optional>
|
|
{};
|
|
}}}
|
|
|
|
namespace boost { namespace spirit { namespace traits
|
|
{
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename Subject>
|
|
struct has_semantic_action<qi::optional<Subject> >
|
|
: unary_has_semantic_action<Subject> {};
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
template <typename Subject, typename Attribute, typename Context
|
|
, typename Iterator>
|
|
struct handles_container<qi::optional<Subject>, Attribute
|
|
, Context, Iterator>
|
|
: mpl::true_ {};
|
|
}}}
|
|
|
|
#endif
|