boost/spirit/home/qi/detail/pass_container.hpp
/*=============================================================================
Copyright (c) 2001-2011 Joel de Guzman
Copyright (c) 2001-2011 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_PASS_CONTAINER_JANUARY_06_2009_0802PM)
#define SPIRIT_PASS_CONTAINER_JANUARY_06_2009_0802PM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/qi/detail/attributes.hpp>
#include <boost/spirit/home/support/container.hpp>
#include <boost/spirit/home/support/handles_container.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/mpl/bool.hpp>
namespace boost { namespace spirit { namespace qi { namespace detail
{
// has_same_elements: utility to check if the RHS attribute
// is an STL container and that its value_type is convertible
// to the LHS.
template <typename LHS, typename RHSAttribute
, bool IsContainer = traits::is_container<RHSAttribute>::value>
struct has_same_elements : mpl::false_ {};
template <typename LHS, typename RHSAttribute>
struct has_same_elements<LHS, RHSAttribute, true>
: is_convertible<typename RHSAttribute::value_type, LHS> {};
template <typename LHS, typename T>
struct has_same_elements<LHS, optional<T>, true>
: has_same_elements<LHS, T> {};
#define BOOST_SPIRIT_IS_CONVERTIBLE(z, N, data) \
has_same_elements<LHS, BOOST_PP_CAT(T, N)>::value || \
/***/
// Note: variants are treated as containers if one of the held types is a
// container (see support/container.hpp).
template <typename LHS, BOOST_VARIANT_ENUM_PARAMS(typename T)>
struct has_same_elements<
LHS, boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, true>
: mpl::bool_<BOOST_PP_REPEAT(BOOST_VARIANT_LIMIT_TYPES
, BOOST_SPIRIT_IS_CONVERTIBLE, _) false> {};
#undef BOOST_SPIRIT_IS_CONVERTIBLE
// This function handles the case where the attribute (Attr) given
// the sequence is an STL container. This is a wrapper around F.
// The function F does the actual parsing.
template <typename F, typename Attr>
struct pass_container
{
typedef typename F::context_type context_type;
typedef typename F::iterator_type iterator_type;
pass_container(F const& f, Attr& attr)
: f(f), attr(attr) {}
// this is for the case when the current element exposes an attribute
// which is pushed back onto the container
template <typename Component>
bool dispatch_attribute_element(Component const& component, mpl::false_) const
{
// synthesized attribute needs to be default constructed
typename traits::container_value<Attr>::type val =
typename traits::container_value<Attr>::type();
iterator_type save = f.first;
bool r = f(component, val);
if (!r)
{
// push the parsed value into our attribute
r = !traits::push_back(attr, val);
if (r)
f.first = save;
}
return r;
}
// this is for the case when the current element expects an attribute
// which is a container itself, this element will push its data
// directly into the attribute container
template <typename Component>
bool dispatch_attribute_element(Component const& component, mpl::true_) const
{
return f(component, attr);
}
// This handles the distinction between elements in a sequence expecting
// containers themselves and elements expecting non-containers as their
// attribute. Note: is_container treats optional<T>, where T is a
// container as a container as well.
template <typename Component>
bool dispatch_attribute(Component const& component, mpl::true_) const
{
typedef typename traits::attribute_of<
Component, context_type, iterator_type>::type attribute_type;
typedef mpl::and_<
traits::is_container<attribute_type>
, traits::handles_container<Component, Attr, context_type
, iterator_type>
> predicate;
return dispatch_attribute_element(component, predicate());
}
// 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);
}
// This handles the case where the attribute of the component
// is not an STL container or its element is not convertible
// to the target attribute's (Attr) value_type.
template <typename Component>
bool dispatch_main(Component const& component, mpl::false_) const
{
// we need to dispatch again depending on the type of the attribute
// of the current element (component). If this is has no attribute
// we shouldn't push an element into the container.
typedef traits::not_is_unused<
typename traits::attribute_of<
Component, context_type, iterator_type
>::type
> predicate;
return dispatch_attribute(component, predicate());
}
// This handles the case where the attribute of the component is
// an STL container *and* its value_type is convertible to the
// target attribute's (Attr) value_type.
template <typename Component>
bool dispatch_main(Component const& component, mpl::true_) const
{
return f(component, attr);
}
// Dispatches to dispatch_main depending on the attribute type
// of the Component
template <typename Component>
bool operator()(Component const& component) const
{
typedef typename traits::container_value<Attr>::type lhs;
typedef typename traits::attribute_of<
Component, context_type, iterator_type>::type
rhs_attribute;
typedef mpl::and_<
has_same_elements<lhs, rhs_attribute>
, traits::handles_container<Component, Attr, context_type
, iterator_type>
> predicate;
return dispatch_main(component, predicate());
}
F f;
Attr& attr;
private:
// silence MSVC warning C4512: assignment operator could not be generated
pass_container& operator= (pass_container const&);
};
// Utility function to make a pass_container
template <typename F, typename Attr>
pass_container<F, Attr>
inline make_pass_container(F const& f, Attr& attr)
{
return pass_container<F, Attr>(f, attr);
}
}}}}
#endif
