boost/spirit/home/karma/detail/pass_container.hpp
/*=============================================================================
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_PASS_CONTAINER_MAR_15_2009_0114PM)
#define SPIRIT_PASS_CONTAINER_MAR_15_2009_0114PM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/karma/detail/attributes.hpp>
#include <boost/spirit/home/support/container.hpp>
#include <boost/spirit/home/support/handles_container.hpp>
#include <boost/spirit/home/support/detail/hold_any.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/and.hpp>
#include <boost/mpl/or.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/repetition/repeat.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/fusion/include/deduce_sequence.hpp>
#include <boost/mpl/print.hpp>
namespace boost { namespace spirit { namespace karma { namespace detail
{
// Helper meta-function allowing to evaluate weak substitutability and
// negate the result if the predicate (Sequence) is not true
template <typename Sequence, typename Attribute, typename ValueType>
struct negate_weak_substitute_if_not
: mpl::if_<
Sequence
, typename traits::is_weak_substitute<Attribute, ValueType>::type
, typename mpl::not_<
traits::is_weak_substitute<Attribute, ValueType>
>::type>
{};
// pass_through_container: utility to check decide whether a provided
// container attribute needs to be passed through to the current component
// or of we need to split the container by passing along instances of its
// value type
// if the expected attribute of the current component is neither a Fusion
// sequence nor a container, we will pass through the provided container
// only if its value type is not compatible with the component
template <typename Container, typename ValueType, typename Attribute
, typename Sequence, typename Enable = void>
struct pass_through_container_base
: negate_weak_substitute_if_not<Sequence, ValueType, Attribute>
{};
// Specialization for fusion sequences, in this case we check whether all
// the types in the sequence are convertible to the lhs attribute.
//
// We return false if the rhs attribute itself is a fusion sequence, which
// is compatible with the LHS sequence (we want to pass through this
// attribute without it being split apart).
template <typename Container, typename ValueType, typename Attribute
, typename Sequence = mpl::true_>
struct not_compatible_element
: mpl::and_<
negate_weak_substitute_if_not<Sequence, Container, Attribute>
, negate_weak_substitute_if_not<Sequence, ValueType, Attribute> >
{};
// If the value type of the container is not a Fusion sequence, we pass
// through the container if each of the elements of the Attribute
// sequence is compatible with either the container or its value type.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence
, bool IsSequence = fusion::traits::is_sequence<ValueType>::value>
struct pass_through_container_fusion_sequence
{
typedef typename mpl::find_if<
Attribute, not_compatible_element<Container, ValueType, mpl::_1>
>::type iter;
typedef typename mpl::end<Attribute>::type end;
typedef typename is_same<iter, end>::type type;
};
// If both, the Attribute and the value type of the provided container
// are Fusion sequences, we pass the container only if the two
// sequences are not compatible.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container_fusion_sequence<
Container, ValueType, Attribute, Sequence, true>
{
typedef typename mpl::find_if<
Attribute
, not_compatible_element<Container, ValueType, mpl::_1, Sequence>
>::type iter;
typedef typename mpl::end<Attribute>::type end;
typedef typename is_same<iter, end>::type type;
};
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container_base<Container, ValueType, Attribute
, Sequence
, typename enable_if<fusion::traits::is_sequence<Attribute> >::type>
: pass_through_container_fusion_sequence<
Container, ValueType, Attribute, Sequence>
{};
// Specialization for containers
//
// If the value type of the attribute of the current component is not
// a Fusion sequence, we have to pass through the provided container if
// both are compatible.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence, typename AttributeValueType
, bool IsSequence = fusion::traits::is_sequence<AttributeValueType>::value>
struct pass_through_container_container
: mpl::or_<
traits::is_weak_substitute<Container, Attribute>
, traits::is_weak_substitute<Container, AttributeValueType> >
{};
// If the value type of the exposed container attribute is a Fusion
// sequence, we use the already existing logic for those.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence, typename AttributeValueType>
struct pass_through_container_container<
Container, ValueType, Attribute, Sequence, AttributeValueType, true>
: pass_through_container_fusion_sequence<
Container, ValueType, AttributeValueType, Sequence>
{};
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container_base<Container, ValueType, Attribute
, Sequence
, typename enable_if<traits::is_container<Attribute> >::type>
: detail::pass_through_container_container<
Container, ValueType, Attribute, Sequence
, typename traits::container_value<Attribute>::type>
{};
// Specialization for exposed optional attributes
//
// If the type embedded in the exposed optional is not a Fusion
// sequence we pass through the container attribute if it is compatible
// either to the optionals embedded type or to the containers value
// type.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence
, bool IsSequence = fusion::traits::is_sequence<Attribute>::value>
struct pass_through_container_optional
: mpl::or_<
traits::is_weak_substitute<Container, Attribute>
, traits::is_weak_substitute<ValueType, Attribute> >
{};
// If the embedded type of the exposed optional attribute is a Fusion
// sequence, we use the already existing logic for those.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container_optional<
Container, ValueType, Attribute, Sequence, true>
: pass_through_container_fusion_sequence<
Container, ValueType, Attribute, Sequence>
{};
///////////////////////////////////////////////////////////////////////////
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container
: pass_through_container_base<Container, ValueType, Attribute, Sequence>
{};
// Handle optional attributes
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container<
Container, ValueType, boost::optional<Attribute>, Sequence>
: pass_through_container_optional<
Container, ValueType, Attribute, Sequence>
{};
// If both, the containers value type and the exposed attribute type are
// optionals we are allowed to pass through the the container only if the
// embedded types of those optionals are not compatible.
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container<
Container, boost::optional<ValueType>, boost::optional<Attribute>
, Sequence>
: mpl::not_<traits::is_weak_substitute<ValueType, Attribute> >
{};
// Specialization for exposed variant attributes
//
// We pass through the container attribute if at least one of the embedded
// types in the variant requires to pass through the attribute
#define BOOST_SPIRIT_PASS_THROUGH_CONTAINER(z, N, _) \
pass_through_container<Container, ValueType, \
BOOST_PP_CAT(T, N), Sequence>::type::value || \
/***/
// make sure unused variant parameters do not affect the outcome
template <typename Container, typename ValueType, typename Sequence>
struct pass_through_container<Container, ValueType
, boost::detail::variant::void_, Sequence>
: mpl::false_
{};
template <typename Container, typename ValueType, typename Sequence
, BOOST_VARIANT_ENUM_PARAMS(typename T)>
struct pass_through_container<Container, ValueType
, boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Sequence>
: mpl::bool_<BOOST_PP_REPEAT(BOOST_VARIANT_LIMIT_TYPES
, BOOST_SPIRIT_PASS_THROUGH_CONTAINER, _) false>
{};
#undef BOOST_SPIRIT_PASS_THROUGH_CONTAINER
}}}}
///////////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit { namespace traits
{
///////////////////////////////////////////////////////////////////////////
// forwarding customization point for domain karma::domain
template <typename Container, typename ValueType, typename Attribute
, typename Sequence>
struct pass_through_container<
Container, ValueType, Attribute, Sequence, karma::domain>
: karma::detail::pass_through_container<
Container, ValueType, Attribute, Sequence>
{};
}}}
namespace boost { namespace spirit { namespace karma { namespace detail
{
///////////////////////////////////////////////////////////////////////////
// This function handles the case where the attribute (Attr) given
// to the sequence is an STL container. This is a wrapper around F.
// The function F does the actual generating.
template <typename F, typename Attr, typename Iterator, typename Sequence>
struct pass_container
{
typedef typename F::context_type context_type;
pass_container(F const& f, Iterator begin, Iterator end)
: f(f), iter(begin), end(end)
{}
bool is_at_end() const
{
return traits::compare(iter, end);
}
void next()
{
traits::next(iter);
}
// this is for the case when the current element expects an attribute
// which is taken from the next entry in the container
template <typename Component>
bool dispatch_container(Component const& component, mpl::false_) const
{
// get the next value to generate from container
if (!is_at_end() && !f(component, traits::deref(iter)))
{
// needs to return false as long as everything is ok
traits::next(iter);
return false;
}
// either no elements available any more or generation failed
return true;
}
// this is for the case when the current element is able to handle an
// attribute which is a container itself, this element will push its
// data directly into the attribute container
template <typename Component>
bool dispatch_container(Component const& component, mpl::true_) const
{
return f(component, make_iterator_range(iter, end));
}
///////////////////////////////////////////////////////////////////////
// this is for the case when the current element doesn't expect an
// attribute
template <typename Component>
bool dispatch_attribute(Component const& component, mpl::false_) const
{
return f(component, unused);
}
// the current element expects an attribute
template <typename Component>
bool dispatch_attribute(Component const& component, mpl::true_) const
{
typedef typename traits::container_value<Attr>::type value_type;
typedef typename
traits::attribute_of<Component, context_type>::type
lhs_attribute;
// this predicate detects, whether the value type of the container
// attribute is a substitute for the attribute of the current
// element
typedef mpl::and_<
traits::handles_container<Component, Attr, context_type>
, traits::pass_through_container<
Attr, value_type, lhs_attribute, Sequence, karma::domain>
> predicate;
return dispatch_container(component, predicate());
}
// Dispatches to dispatch_main depending on the attribute type
// of the Component
template <typename Component>
bool operator()(Component const& component) const
{
// we need to dispatch depending on the type of the attribute
// of the current element (component). If this is has no attribute
// we shouldn't use an element of the container but unused_type
// instead
typedef traits::not_is_unused<
typename traits::attribute_of<Component, context_type>::type
> predicate;
return dispatch_attribute(component, predicate());
}
F f;
mutable Iterator iter;
mutable Iterator end;
private:
// silence MSVC warning C4512: assignment operator could not be generated
pass_container& operator= (pass_container const&);
};
}}}}
#endif
