Chris@16: //  Copyright (c) 2001-2011 Hartmut Kaiser
Chris@16: //  Copyright (c) 2001-2011 Joel de Guzman
Chris@16: //
Chris@16: //  Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #if !defined(SPIRIT_KARMA_ALTERNATIVE_MAR_01_2007_1124AM)
Chris@16: #define SPIRIT_KARMA_ALTERNATIVE_MAR_01_2007_1124AM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/home/karma/domain.hpp>
Chris@16: #include <boost/spirit/home/karma/directive/buffer.hpp>
Chris@16: #include <boost/spirit/home/support/unused.hpp>
Chris@16: #include <boost/spirit/home/support/utree/utree_traits_fwd.hpp>
Chris@16: #include <boost/spirit/home/karma/detail/attributes.hpp>
Chris@16: #include <boost/spirit/home/support/detail/hold_any.hpp>
Chris@16: #include <boost/spirit/home/karma/detail/output_iterator.hpp>
Chris@16: #include <boost/spirit/home/support/container.hpp>
Chris@16: #include <boost/utility/enable_if.hpp>
Chris@16: #include <boost/variant.hpp>
Chris@16: #include <boost/detail/workaround.hpp>
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost { namespace spirit { namespace karma { namespace detail
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //  execute a generator if the given Attribute type is compatible
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16:     //  this gets instantiated if the Attribute type is _not_ compatible with
Chris@16:     //  the generator
Chris@16:     template <typename Component, typename Attribute, typename Expected
Chris@16:       , typename Enable = void>
Chris@16:     struct alternative_generate
Chris@16:     {
Chris@16:         template <typename OutputIterator, typename Context, typename Delimiter>
Chris@16:         static bool
Chris@16:         call(Component const&, OutputIterator&, Context&, Delimiter const&
Chris@16:           , Attribute const&, bool& failed)
Chris@16:         {
Chris@16:             failed = true;
Chris@16:             return false;
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Component>
Chris@16:     struct alternative_generate<Component, unused_type, unused_type>
Chris@16:     {
Chris@16:         template <typename OutputIterator, typename Context, typename Delimiter>
Chris@16:         static bool
Chris@16:         call(Component const& component, OutputIterator& sink, Context& ctx
Chris@16:           , Delimiter const& d, unused_type, bool&)
Chris@16:         {
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
Chris@16:             component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
Chris@16: #endif
Chris@16:             // return true if any of the generators succeed
Chris@16:             return component.generate(sink, ctx, d, unused);
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     //  this gets instantiated if there is no Attribute given for the
Chris@16:     //  alternative generator
Chris@16:     template <typename Component, typename Expected>
Chris@16:     struct alternative_generate<Component, unused_type, Expected>
Chris@16:       : alternative_generate<Component, unused_type, unused_type> {};
Chris@16: 
Chris@16:     //  this gets instantiated if the generator does not expect to receive an
Chris@16:     //  Attribute (the generator is self contained).
Chris@16:     template <typename Component, typename Attribute>
Chris@16:     struct alternative_generate<Component, Attribute, unused_type>
Chris@16:       : alternative_generate<Component, unused_type, unused_type> {};
Chris@16: 
Chris@16:     //  this gets instantiated if the Attribute type is compatible to the
Chris@16:     //  generator
Chris@16:     template <typename Component, typename Attribute, typename Expected>
Chris@16:     struct alternative_generate<Component, Attribute, Expected
Chris@16:       , typename enable_if<
Chris@16:             traits::compute_compatible_component<Expected, Attribute, karma::domain> >::type>
Chris@16:     {
Chris@16:         template <typename OutputIterator, typename Context, typename Delimiter>
Chris@16:         static bool
Chris@16:         call(Component const& component, OutputIterator& sink
Chris@16:           , Context& ctx, Delimiter const& d, Attribute const& attr, bool&)
Chris@16:         {
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
Chris@16:             component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
Chris@16: #endif
Chris@16:             return call(component, sink, ctx, d, attr
Chris@16:               , spirit::traits::not_is_variant<Attribute, karma::domain>());
Chris@16:         }
Chris@16: 
Chris@16:         template <typename OutputIterator, typename Context, typename Delimiter>
Chris@16:         static bool
Chris@16:         call(Component const& component, OutputIterator& sink
Chris@16:           , Context& ctx, Delimiter const& d, Attribute const& attr, mpl::true_)
Chris@16:         {
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
Chris@16:             component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
Chris@16: #endif
Chris@16:             return component.generate(sink, ctx, d, attr);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename OutputIterator, typename Context, typename Delimiter>
Chris@16:         static bool
Chris@16:         call(Component const& component, OutputIterator& sink
Chris@16:           , Context& ctx, Delimiter const& d, Attribute const& attr, mpl::false_)
Chris@16:         {
Chris@16: #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
Chris@16:             component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
Chris@16: #endif
Chris@16:             typedef
Chris@16:                 traits::compute_compatible_component<Expected, Attribute, domain>
Chris@16:             component_type;
Chris@16: 
Chris@16:             // if we got passed an empty optional, just fail generation
Chris@16:             if (!traits::has_optional_value(attr))
Chris@16:                 return false;
Chris@16: 
Chris@16:             // make sure, the content of the passed variant matches our
Chris@16:             // expectations
Chris@16:             typename traits::optional_attribute<Attribute>::type attr_ = 
Chris@16:                 traits::optional_value(attr);
Chris@16:             if (!component_type::is_compatible(spirit::traits::which(attr_)))
Chris@16:                 return false;
Chris@16: 
Chris@16:             // returns true if any of the generators succeed
Chris@16:             typedef typename component_type::compatible_type compatible_type;
Chris@16:             return component.generate(sink, ctx, d
Chris@16:               , boost::get<compatible_type>(attr_));
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //  alternative_generate_function: a functor supplied to fusion::any which
Chris@16:     //  will be executed for every generator in a given alternative generator
Chris@16:     //  expression
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename OutputIterator, typename Context, typename Delimiter,
Chris@16:         typename Attribute, typename Strict>
Chris@16:     struct alternative_generate_function
Chris@16:     {
Chris@16:         alternative_generate_function(OutputIterator& sink_, Context& ctx_
Chris@16:               , Delimiter const& d, Attribute const& attr_)
Chris@16:           : sink(sink_), ctx(ctx_), delim(d), attr(attr_) {}
Chris@16: 
Chris@16:         template <typename Component>
Chris@16:         bool operator()(Component const& component)
Chris@16:         {
Chris@16:             typedef
Chris@16:                 typename traits::attribute_of<Component, Context>::type
Chris@16:             expected_type;
Chris@16:             typedef
Chris@16:                 alternative_generate<Component, Attribute, expected_type>
Chris@16:             generate;
Chris@16: 
Chris@16:             // wrap the given output iterator avoid output as long as one
Chris@16:             // component fails
Chris@16:             detail::enable_buffering<OutputIterator> buffering(sink);
Chris@16:             bool r = false;
Chris@16:             bool failed = false;    // will be ignored
Chris@16:             {
Chris@16:                 detail::disable_counting<OutputIterator> nocounting(sink);
Chris@16:                 r = generate::call(component, sink, ctx, delim, attr, failed);
Chris@16:             }
Chris@16:             if (r) 
Chris@16:                 buffering.buffer_copy();
Chris@16:             return r;
Chris@16:         }
Chris@16: 
Chris@16:         // avoid double buffering
Chris@16:         template <typename Component>
Chris@16:         bool operator()(buffer_directive<Component> const& component)
Chris@16:         {
Chris@16:             typedef typename 
Chris@16:                 traits::attribute_of<Component, Context>::type
Chris@16:             expected_type;
Chris@16:             typedef alternative_generate<
Chris@16:                 buffer_directive<Component>, Attribute, expected_type>
Chris@16:             generate;
Chris@16: 
Chris@16:             bool failed = false;    // will be ignored
Chris@16:             return generate::call(component, sink, ctx, delim, attr, failed);
Chris@16:         }
Chris@16: 
Chris@16:         OutputIterator& sink;
Chris@16:         Context& ctx;
Chris@16:         Delimiter const& delim;
Chris@16:         Attribute const& attr;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         alternative_generate_function& operator= (alternative_generate_function const&);
Chris@16:     };
Chris@16: 
Chris@16:     // specialization for strict alternatives
Chris@16:     template <typename OutputIterator, typename Context, typename Delimiter,
Chris@16:         typename Attribute>
Chris@16:     struct alternative_generate_function<
Chris@16:         OutputIterator, Context, Delimiter, Attribute, mpl::true_>
Chris@16:     {
Chris@16:         alternative_generate_function(OutputIterator& sink_, Context& ctx_
Chris@16:               , Delimiter const& d, Attribute const& attr_)
Chris@16:           : sink(sink_), ctx(ctx_), delim(d), attr(attr_), failed(false) {}
Chris@16: 
Chris@16:         template <typename Component>
Chris@16:         bool operator()(Component const& component)
Chris@16:         {
Chris@16:             typedef
Chris@16:                 typename traits::attribute_of<Component, Context>::type
Chris@16:             expected_type;
Chris@16:             typedef
Chris@16:                 alternative_generate<Component, Attribute, expected_type>
Chris@16:             generate;
Chris@16: 
Chris@16:             if (failed)
Chris@16:                 return false;     // give up when already failed
Chris@16: 
Chris@16:             // wrap the given output iterator avoid output as long as one
Chris@16:             // component fails
Chris@16:             detail::enable_buffering<OutputIterator> buffering(sink);
Chris@16:             bool r = false;
Chris@16:             {
Chris@16:                 detail::disable_counting<OutputIterator> nocounting(sink);
Chris@16:                 r = generate::call(component, sink, ctx, delim, attr, failed);
Chris@16:             }
Chris@16:             if (r && !failed) 
Chris@16:             {
Chris@16:                 buffering.buffer_copy();
Chris@16:                 return true;
Chris@16:             }
Chris@16:             return false;
Chris@16:         }
Chris@16: 
Chris@16:         OutputIterator& sink;
Chris@16:         Context& ctx;
Chris@16:         Delimiter const& delim;
Chris@16:         Attribute const& attr;
Chris@16:         bool failed;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         alternative_generate_function& operator= (alternative_generate_function const&);
Chris@16:     };
Chris@16: }}}}
Chris@16: 
Chris@16: #endif