You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and dots ('.'), can be up to 35 characters long. Letters must be lowercase.
105 lines
3.7 KiB
105 lines
3.7 KiB
// 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) |
|
|
|
#if !defined(SPIRIT_KARMA_OPTIONAL_MARCH_31_2007_0852AM) |
|
#define SPIRIT_KARMA_OPTIONAL_MARCH_31_2007_0852AM |
|
|
|
#if defined(_MSC_VER) |
|
#pragma once |
|
#endif |
|
|
|
#include <boost/spirit/home/karma/domain.hpp> |
|
#include <boost/spirit/home/karma/generator.hpp> |
|
#include <boost/spirit/home/karma/meta_compiler.hpp> |
|
#include <boost/spirit/home/support/info.hpp> |
|
#include <boost/spirit/home/support/unused.hpp> |
|
#include <boost/spirit/home/karma/detail/attributes.hpp> |
|
#include <boost/spirit/home/support/container.hpp> |
|
#include <boost/spirit/home/support/has_semantic_action.hpp> |
|
#include <boost/spirit/home/support/handles_container.hpp> |
|
#include <boost/mpl/assert.hpp> |
|
#include <boost/optional.hpp> |
|
#include <boost/type_traits/is_convertible.hpp> |
|
|
|
namespace boost { namespace spirit |
|
{ |
|
/////////////////////////////////////////////////////////////////////////// |
|
// Enablers |
|
/////////////////////////////////////////////////////////////////////////// |
|
template <> |
|
struct use_operator<karma::domain, proto::tag::negate> // enables -g |
|
: mpl::true_ {}; |
|
|
|
}} |
|
|
|
/////////////////////////////////////////////////////////////////////////////// |
|
namespace boost { namespace spirit { namespace karma |
|
{ |
|
/////////////////////////////////////////////////////////////////////////// |
|
template <typename Subject> |
|
struct optional : unary_generator<optional<Subject> > |
|
{ |
|
typedef Subject subject_type; |
|
typedef typename subject_type::properties properties; |
|
|
|
// 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. |
|
template <typename Context, typename Iterator = unused_type> |
|
struct attribute |
|
: traits::build_optional< |
|
typename traits::attribute_of<Subject, Context, Iterator>::type |
|
> |
|
{}; |
|
|
|
optional(Subject const& subject) |
|
: subject(subject) {} |
|
|
|
template < |
|
typename OutputIterator, typename Context, typename Delimiter |
|
, typename Attribute> |
|
bool generate(OutputIterator& sink, Context& ctx |
|
, Delimiter const& d, Attribute const& attr) const |
|
{ |
|
if (traits::has_optional_value(attr)) |
|
subject.generate(sink, ctx, d, traits::optional_value(attr)); |
|
return sink_is_good(sink); |
|
} |
|
|
|
template <typename Context> |
|
info what(Context& context) const |
|
{ |
|
return info("optional", subject.what(context)); |
|
} |
|
|
|
Subject subject; |
|
}; |
|
|
|
/////////////////////////////////////////////////////////////////////////// |
|
// Generator 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<karma::optional<Subject> > |
|
: unary_has_semantic_action<Subject> {}; |
|
|
|
/////////////////////////////////////////////////////////////////////////// |
|
template <typename Subject, typename Attribute, typename Context |
|
, typename Iterator> |
|
struct handles_container<karma::optional<Subject>, Attribute, Context |
|
, Iterator> |
|
: mpl::true_ {}; |
|
}}} |
|
|
|
#endif
|
|
|