| // Copyright (c) 2001-2010 Joel de Guzman |
| // Copyright (c) 2001-2010 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/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> {}; |
| |
| }}} |
| |
| #endif |