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// Copyright (c) 2001-2011 Hartmut Kaiser
// Copyright (c) 2001-2011 Joel de Guzman
//
// 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_ALTERNATIVE_MAR_01_2007_1124AM)
#define SPIRIT_KARMA_ALTERNATIVE_MAR_01_2007_1124AM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/karma/domain.hpp>
#include <boost/spirit/home/karma/directive/buffer.hpp>
#include <boost/spirit/home/support/unused.hpp>
#include <boost/spirit/home/support/utree/utree_traits_fwd.hpp>
#include <boost/spirit/home/karma/detail/attributes.hpp>
#include <boost/spirit/home/support/detail/hold_any.hpp>
#include <boost/spirit/home/karma/detail/output_iterator.hpp>
#include <boost/spirit/home/support/container.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/variant.hpp>
#include <boost/detail/workaround.hpp>
///////////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit { namespace karma { namespace detail
{
///////////////////////////////////////////////////////////////////////////
// execute a generator if the given Attribute type is compatible
///////////////////////////////////////////////////////////////////////////
// this gets instantiated if the Attribute type is _not_ compatible with
// the generator
template <typename Component, typename Attribute, typename Expected
, typename Enable = void>
struct alternative_generate
{
template <typename OutputIterator, typename Context, typename Delimiter>
static bool
call(Component const&, OutputIterator&, Context&, Delimiter const&
, Attribute const&, bool& failed)
{
failed = true;
return false;
}
};
template <typename Component>
struct alternative_generate<Component, unused_type, unused_type>
{
template <typename OutputIterator, typename Context, typename Delimiter>
static bool
call(Component const& component, OutputIterator& sink, Context& ctx
, Delimiter const& d, unused_type, bool&)
{
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
#endif
// return true if any of the generators succeed
return component.generate(sink, ctx, d, unused);
}
};
// this gets instantiated if there is no Attribute given for the
// alternative generator
template <typename Component, typename Expected>
struct alternative_generate<Component, unused_type, Expected>
: alternative_generate<Component, unused_type, unused_type> {};
// this gets instantiated if the generator does not expect to receive an
// Attribute (the generator is self contained).
template <typename Component, typename Attribute>
struct alternative_generate<Component, Attribute, unused_type>
: alternative_generate<Component, unused_type, unused_type> {};
// this gets instantiated if the Attribute type is compatible to the
// generator
template <typename Component, typename Attribute, typename Expected>
struct alternative_generate<Component, Attribute, Expected
, typename enable_if<
traits::compute_compatible_component<Expected, Attribute, karma::domain> >::type>
{
template <typename OutputIterator, typename Context, typename Delimiter>
static bool
call(Component const& component, OutputIterator& sink
, Context& ctx, Delimiter const& d, Attribute const& attr, bool&)
{
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
#endif
return call(component, sink, ctx, d, attr
, spirit::traits::not_is_variant<Attribute, karma::domain>());
}
template <typename OutputIterator, typename Context, typename Delimiter>
static bool
call(Component const& component, OutputIterator& sink
, Context& ctx, Delimiter const& d, Attribute const& attr, mpl::true_)
{
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
#endif
return component.generate(sink, ctx, d, attr);
}
template <typename OutputIterator, typename Context, typename Delimiter>
static bool
call(Component const& component, OutputIterator& sink
, Context& ctx, Delimiter const& d, Attribute const& attr, mpl::false_)
{
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
component; // suppresses warning: C4100: 'component' : unreferenced formal parameter
#endif
typedef
traits::compute_compatible_component<Expected, Attribute, domain>
component_type;
// if we got passed an empty optional, just fail generation
if (!traits::has_optional_value(attr))
return false;
// make sure, the content of the passed variant matches our
// expectations
typename traits::optional_attribute<Attribute>::type attr_ =
traits::optional_value(attr);
if (!component_type::is_compatible(spirit::traits::which(attr_)))
return false;
// returns true if any of the generators succeed
typedef typename component_type::compatible_type compatible_type;
return component.generate(sink, ctx, d
, boost::get<compatible_type>(attr_));
}
};
///////////////////////////////////////////////////////////////////////////
// alternative_generate_function: a functor supplied to fusion::any which
// will be executed for every generator in a given alternative generator
// expression
///////////////////////////////////////////////////////////////////////////
template <typename OutputIterator, typename Context, typename Delimiter,
typename Attribute, typename Strict>
struct alternative_generate_function
{
alternative_generate_function(OutputIterator& sink_, Context& ctx_
, Delimiter const& d, Attribute const& attr_)
: sink(sink_), ctx(ctx_), delim(d), attr(attr_) {}
template <typename Component>
bool operator()(Component const& component)
{
typedef
typename traits::attribute_of<Component, Context>::type
expected_type;
typedef
alternative_generate<Component, Attribute, expected_type>
generate;
// wrap the given output iterator avoid output as long as one
// component fails
detail::enable_buffering<OutputIterator> buffering(sink);
bool r = false;
bool failed = false; // will be ignored
{
detail::disable_counting<OutputIterator> nocounting(sink);
r = generate::call(component, sink, ctx, delim, attr, failed);
}
if (r)
buffering.buffer_copy();
return r;
}
// avoid double buffering
template <typename Component>
bool operator()(buffer_directive<Component> const& component)
{
typedef typename
traits::attribute_of<Component, Context>::type
expected_type;
typedef alternative_generate<
buffer_directive<Component>, Attribute, expected_type>
generate;
bool failed = false; // will be ignored
return generate::call(component, sink, ctx, delim, attr, failed);
}
OutputIterator& sink;
Context& ctx;
Delimiter const& delim;
Attribute const& attr;
private:
// silence MSVC warning C4512: assignment operator could not be generated
alternative_generate_function& operator= (alternative_generate_function const&);
};
// specialization for strict alternatives
template <typename OutputIterator, typename Context, typename Delimiter,
typename Attribute>
struct alternative_generate_function<
OutputIterator, Context, Delimiter, Attribute, mpl::true_>
{
alternative_generate_function(OutputIterator& sink_, Context& ctx_
, Delimiter const& d, Attribute const& attr_)
: sink(sink_), ctx(ctx_), delim(d), attr(attr_), failed(false) {}
template <typename Component>
bool operator()(Component const& component)
{
typedef
typename traits::attribute_of<Component, Context>::type
expected_type;
typedef
alternative_generate<Component, Attribute, expected_type>
generate;
if (failed)
return false; // give up when already failed
// wrap the given output iterator avoid output as long as one
// component fails
detail::enable_buffering<OutputIterator> buffering(sink);
bool r = false;
{
detail::disable_counting<OutputIterator> nocounting(sink);
r = generate::call(component, sink, ctx, delim, attr, failed);
}
if (r && !failed)
{
buffering.buffer_copy();
return true;
}
return false;
}
OutputIterator& sink;
Context& ctx;
Delimiter const& delim;
Attribute const& attr;
bool failed;
private:
// silence MSVC warning C4512: assignment operator could not be generated
alternative_generate_function& operator= (alternative_generate_function const&);
};
}}}}
#endif
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