| // 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_OMIT_JUL_20_2009_1008AM) |
| #define SPIRIT_KARMA_OMIT_JUL_20_2009_1008AM |
| |
| #if defined(_MSC_VER) |
| #pragma once |
| #endif |
| |
| #include <boost/spirit/home/karma/meta_compiler.hpp> |
| #include <boost/spirit/home/karma/generator.hpp> |
| #include <boost/spirit/home/karma/domain.hpp> |
| #include <boost/spirit/home/support/unused.hpp> |
| #include <boost/spirit/home/support/info.hpp> |
| #include <boost/spirit/home/support/common_terminals.hpp> |
| #include <boost/spirit/home/karma/detail/attributes.hpp> |
| |
| namespace boost { namespace spirit |
| { |
| /////////////////////////////////////////////////////////////////////////// |
| // Enablers |
| /////////////////////////////////////////////////////////////////////////// |
| template <> |
| struct use_directive<karma::domain, tag::omit> // enables omit |
| : mpl::true_ {}; |
| |
| template <> |
| struct use_directive<karma::domain, tag::skip> // enables skip |
| : mpl::true_ {}; |
| }} |
| |
| namespace boost { namespace spirit { namespace karma |
| { |
| using spirit::omit; |
| using spirit::omit_type; |
| using spirit::skip; |
| using spirit::skip_type; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // omit_directive consumes the attribute of subject generator without |
| // generating anything |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Subject, bool Execute> |
| struct omit_directive : unary_generator<omit_directive<Subject, Execute> > |
| { |
| typedef Subject subject_type; |
| |
| typedef mpl::int_< |
| generator_properties::disabling | subject_type::properties::value |
| > properties; |
| |
| omit_directive(Subject const& subject) |
| : subject(subject) {} |
| |
| template <typename Context, typename Iterator = unused_type> |
| struct attribute |
| : traits::attribute_of<subject_type, Context, Iterator> |
| {}; |
| |
| template <typename OutputIterator, typename Context, typename Delimiter |
| , typename Attribute> |
| bool generate(OutputIterator& sink, Context& ctx, Delimiter const& d |
| , Attribute const& attr) const |
| { |
| // We need to actually compile the output operation as we don't |
| // have any other means to verify, whether the passed attribute is |
| // compatible with the subject. |
| |
| // omit[] will execute the code, while skip[] doesn't execute it |
| if (Execute) { |
| // wrap the given output iterator to avoid output |
| detail::disable_output<OutputIterator> disable(sink); |
| subject.generate(sink, ctx, d, attr); |
| } |
| return true; |
| } |
| |
| template <typename Context> |
| info what(Context& context) const |
| { |
| return info(Execute ? "omit" : "skip", subject.what(context)); |
| } |
| |
| Subject subject; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Generator generators: make_xxx function (objects) |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Subject, typename Modifiers> |
| struct make_directive<tag::omit, Subject, Modifiers> |
| { |
| typedef omit_directive<Subject, true> result_type; |
| result_type operator()(unused_type, Subject const& subject |
| , unused_type) const |
| { |
| return result_type(subject); |
| } |
| }; |
| |
| template <typename Subject, typename Modifiers> |
| struct make_directive<tag::skip, Subject, Modifiers> |
| { |
| typedef omit_directive<Subject, false> 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, bool Execute> |
| struct has_semantic_action<karma::omit_directive<Subject, Execute> > |
| : unary_has_semantic_action<Subject> {}; |
| }}} |
| |
| #endif |