| // Copyright (c) 2001-2007 Joel de Guzman |
| // Copyright (c) 2001-2009 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) && (_MSC_VER >= 1020) |
| #pragma once // MS compatible compilers support #pragma once |
| #endif |
| |
| #include <boost/spirit/home/support/component.hpp> |
| #include <boost/spirit/home/support/attribute_of.hpp> |
| #include <boost/spirit/home/support/attribute_transform.hpp> |
| #include <boost/mpl/assert.hpp> |
| #include <boost/optional.hpp> |
| |
| namespace boost { namespace spirit { namespace karma |
| { |
| namespace detail |
| { |
| template <typename Parameter> |
| inline bool |
| optional_is_valid(boost::optional<Parameter> const& opt) |
| { |
| return opt; |
| } |
| |
| template <typename Parameter> |
| inline bool |
| optional_is_valid(Parameter const& opt) |
| { |
| return true; |
| } |
| |
| inline bool |
| optional_is_valid(unused_type) |
| { |
| return true; |
| } |
| |
| template <typename Parameter> |
| inline Parameter const& |
| optional_get(boost::optional<Parameter> const& opt) |
| { |
| return get(opt); |
| } |
| |
| template <typename Parameter> |
| inline Parameter const& |
| optional_get(Parameter const& opt) |
| { |
| return opt; |
| } |
| |
| inline unused_type |
| optional_get(unused_type) |
| { |
| return unused; |
| } |
| } |
| |
| struct optional |
| { |
| template <typename T> |
| struct build_attribute_container |
| { |
| typedef boost::optional<T> type; |
| }; |
| |
| template <typename Component, typename Context, typename Iterator> |
| struct attribute : |
| build_container<optional, Component, Iterator, Context> |
| { |
| }; |
| |
| template <typename Component, typename OutputIterator, |
| typename Context, typename Delimiter, typename Parameter> |
| static bool |
| generate(Component const& component, OutputIterator& sink, |
| Context& ctx, Delimiter const& d, Parameter const& param) |
| { |
| typedef typename |
| result_of::subject<Component>::type::director |
| director; |
| |
| if (detail::optional_is_valid(param)) |
| { |
| director::generate(subject(component), sink, ctx, d, |
| detail::optional_get(param)); |
| } |
| return true; |
| } |
| |
| template <typename Component, typename Context> |
| static std::string what(Component const& component, Context const& ctx) |
| { |
| std::string result = "optional["; |
| |
| typedef typename |
| spirit::result_of::subject<Component>::type::director |
| director; |
| |
| result += director::what(spirit::subject(component), ctx); |
| result += "]"; |
| return result; |
| } |
| }; |
| |
| }}} |
| |
| #endif |