boost/spirit/home/qi/detail/assign_to.hpp
/*=============================================================================
Copyright (c) 2001-2011 Joel de Guzman
Copyright (c) 2001-2011 Hartmut Kaiser
http://spirit.sourceforge.net/
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(BOOST_SPIRIT_ASSIGN_TO_APR_16_2006_0812PM)
#define BOOST_SPIRIT_ASSIGN_TO_APR_16_2006_0812PM
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/qi/detail/construct.hpp>
#include <boost/spirit/home/support/unused.hpp>
#include <boost/spirit/home/qi/detail/attributes.hpp>
#include <boost/spirit/home/support/container.hpp>
#include <boost/fusion/include/copy.hpp>
#include <boost/fusion/adapted/struct/detail/extension.hpp>
#include <boost/ref.hpp>
#include <boost/range/range_fwd.hpp>
namespace boost { namespace spirit { namespace traits
{
///////////////////////////////////////////////////////////////////////////
// This file contains assignment utilities. The utilities provided also
// accept spirit's unused_type; all no-ops. Compiler optimization will
// easily strip these away.
///////////////////////////////////////////////////////////////////////////
namespace detail
{
template <typename T>
struct is_iter_range : mpl::false_ {};
template <typename I>
struct is_iter_range<boost::iterator_range<I> > : mpl::true_ {};
template <typename C>
struct is_container_of_ranges
: is_iter_range<typename C::value_type> {};
}
template <typename Attribute, typename Iterator, typename Enable>
struct assign_to_attribute_from_iterators
{
// Common case
static void
call(Iterator const& first, Iterator const& last, Attribute& attr, mpl::false_)
{
if (traits::is_empty(attr))
attr = Attribute(first, last);
else {
for (Iterator i = first; i != last; ++i)
push_back(attr, *i);
}
}
// If Attribute is a container with value_type==iterator_range<T> just push the
// iterator_range into it
static void
call(Iterator const& first, Iterator const& last, Attribute& attr, mpl::true_)
{
typename Attribute::value_type rng(first, last);
push_back(attr, rng);
}
static void
call(Iterator const& first, Iterator const& last, Attribute& attr)
{
call(first, last, attr, detail::is_container_of_ranges<Attribute>());
}
};
template <typename Attribute, typename Iterator>
struct assign_to_attribute_from_iterators<
reference_wrapper<Attribute>, Iterator>
{
static void
call(Iterator const& first, Iterator const& last
, reference_wrapper<Attribute> attr)
{
if (traits::is_empty(attr))
attr = Attribute(first, last);
else {
for (Iterator i = first; i != last; ++i)
push_back(attr, *i);
}
}
};
template <typename Attribute, typename Iterator>
struct assign_to_attribute_from_iterators<
boost::optional<Attribute>, Iterator>
{
static void
call(Iterator const& first, Iterator const& last
, boost::optional<Attribute>& attr)
{
Attribute val;
assign_to(first, last, val);
attr = val;
}
};
template <typename Iterator>
struct assign_to_attribute_from_iterators<
iterator_range<Iterator>, Iterator>
{
static void
call(Iterator const& first, Iterator const& last
, iterator_range<Iterator>& attr)
{
attr = iterator_range<Iterator>(first, last);
}
};
template <typename Iterator, typename Attribute>
inline void
assign_to(Iterator const& first, Iterator const& last, Attribute& attr)
{
assign_to_attribute_from_iterators<Attribute, Iterator>::
call(first, last, attr);
}
template <typename Iterator>
inline void
assign_to(Iterator const&, Iterator const&, unused_type)
{
}
///////////////////////////////////////////////////////////////////////////
template <typename T, typename Attribute>
void assign_to(T const& val, Attribute& attr);
template <typename Attribute, typename T, typename Enable>
struct assign_to_attribute_from_value
{
typedef typename traits::one_element_sequence<Attribute>::type
is_one_element_sequence;
typedef typename mpl::eval_if<
is_one_element_sequence
, fusion::result_of::at_c<Attribute, 0>
, mpl::identity<Attribute&>
>::type type;
template <typename T_>
static void
call(T_ const& val, Attribute& attr, mpl::false_)
{
attr = static_cast<Attribute>(val);
}
// This handles the case where the attribute is a single element fusion
// sequence. We silently assign to the only element and treat it as the
// attribute to parse the results into.
template <typename T_>
static void
call(T_ const& val, Attribute& attr, mpl::true_)
{
typedef typename fusion::result_of::value_at_c<Attribute, 0>::type
element_type;
fusion::at_c<0>(attr) = static_cast<element_type>(val);
}
static void
call(T const& val, Attribute& attr)
{
call(val, attr, is_one_element_sequence());
}
};
template <typename Attribute>
struct assign_to_attribute_from_value<Attribute, Attribute>
{
static void
call(Attribute const& val, Attribute& attr)
{
attr = val;
}
};
template <typename Attribute, typename T>
struct assign_to_attribute_from_value<Attribute, reference_wrapper<T>
, typename disable_if<is_same<Attribute, reference_wrapper<T> > >::type>
{
static void
call(reference_wrapper<T> const& val, Attribute& attr)
{
assign_to(val.get(), attr);
}
};
template <typename Attribute, typename T>
struct assign_to_attribute_from_value<Attribute, boost::optional<T>
, typename disable_if<is_same<Attribute, boost::optional<T> > >::type>
{
static void
call(boost::optional<T> const& val, Attribute& attr)
{
assign_to(val.get(), attr);
}
};
template <typename Attribute, int N, bool Const, typename T>
struct assign_to_attribute_from_value<fusion::extension::adt_attribute_proxy<Attribute, N, Const>, T>
{
static void
call(T const& val, typename fusion::extension::adt_attribute_proxy<Attribute, N, Const>& attr)
{
attr = val;
}
};
namespace detail
{
template <typename A, typename B>
struct is_same_size_sequence
: mpl::bool_<fusion::result_of::size<A>::value
== fusion::result_of::size<B>::value>
{};
}
template <typename Attribute, typename T>
struct assign_to_attribute_from_value<Attribute, T,
mpl::and_<
fusion::traits::is_sequence<Attribute>,
fusion::traits::is_sequence<T>,
detail::is_same_size_sequence<Attribute, T>
>
>
{
static void
call(T const& val, Attribute& attr)
{
fusion::copy(val, attr);
}
};
///////////////////////////////////////////////////////////////////////////
template <typename Attribute, typename T, typename Enable>
struct assign_to_container_from_value
{
// T is not a container and not a string
template <typename T_>
static void call(T_ const& val, Attribute& attr, mpl::false_, mpl::false_)
{
traits::push_back(attr, val);
}
// T is a container (but not a string), and T is convertible to the
// value_type of the Attribute container
template <typename T_>
static void
append_to_container_not_string(T_ const& val, Attribute& attr, mpl::true_)
{
traits::push_back(attr, val);
}
// T is a container (but not a string), generic overload
template <typename T_>
static void
append_to_container_not_string(T_ const& val, Attribute& attr, mpl::false_)
{
typedef typename traits::container_iterator<T_ const>::type
iterator_type;
iterator_type end = traits::end(val);
for (iterator_type i = traits::begin(val); i != end; traits::next(i))
traits::push_back(attr, traits::deref(i));
}
// T is a container (but not a string)
template <typename T_>
static void call(T_ const& val, Attribute& attr, mpl::true_, mpl::false_)
{
typedef typename container_value<Attribute>::type value_type;
typedef typename is_convertible<T, value_type>::type is_value_type;
append_to_container_not_string(val, attr, is_value_type());
}
///////////////////////////////////////////////////////////////////////
// T is a string
template <typename Iterator>
static void append_to_string(Attribute& attr, Iterator begin, Iterator end)
{
for (Iterator i = begin; i != end; ++i)
traits::push_back(attr, *i);
}
// T is string, but not convertible to value_type of container
template <typename T_>
static void append_to_container(T_ const& val, Attribute& attr, mpl::false_)
{
typedef typename char_type_of<T_>::type char_type;
append_to_string(attr, traits::get_begin<char_type>(val)
, traits::get_end<char_type>(val));
}
// T is string, and convertible to value_type of container
template <typename T_>
static void append_to_container(T_ const& val, Attribute& attr, mpl::true_)
{
traits::push_back(attr, val);
}
template <typename T_, typename Pred>
static void call(T_ const& val, Attribute& attr, Pred, mpl::true_)
{
typedef typename container_value<Attribute>::type value_type;
typedef typename is_convertible<T, value_type>::type is_value_type;
append_to_container(val, attr, is_value_type());
}
///////////////////////////////////////////////////////////////////////
static void call(T const& val, Attribute& attr)
{
typedef typename traits::is_container<T>::type is_container;
typedef typename traits::is_string<T>::type is_string;
call(val, attr, is_container(), is_string());
}
};
template <typename Attribute>
struct assign_to_container_from_value<Attribute, Attribute>
{
static void
call(Attribute const& val, Attribute& attr)
{
attr = val;
}
};
template <typename Attribute, typename T>
struct assign_to_container_from_value<Attribute, boost::optional<T>
, typename disable_if<is_same<Attribute, boost::optional<T> > >::type>
{
static void
call(boost::optional<T> const& val, Attribute& attr)
{
assign_to(val.get(), attr);
}
};
template <typename Attribute, typename T>
struct assign_to_container_from_value<Attribute, reference_wrapper<T>
, typename disable_if<is_same<Attribute, reference_wrapper<T> > >::type>
{
static void
call(reference_wrapper<T> const& val, Attribute& attr)
{
assign_to(val.get(), attr);
}
};
///////////////////////////////////////////////////////////////////////////
namespace detail
{
// overload for non-container attributes
template <typename T, typename Attribute>
inline void
assign_to(T const& val, Attribute& attr, mpl::false_)
{
assign_to_attribute_from_value<Attribute, T>::call(val, attr);
}
// overload for containers (but not for variants or optionals
// holding containers)
template <typename T, typename Attribute>
inline void
assign_to(T const& val, Attribute& attr, mpl::true_)
{
assign_to_container_from_value<Attribute, T>::call(val, attr);
}
}
template <typename T, typename Attribute>
inline void
assign_to(T const& val, Attribute& attr)
{
typedef typename mpl::and_<
traits::is_container<Attribute>
, traits::not_is_variant<Attribute>
, traits::not_is_optional<Attribute>
>::type is_not_wrapped_container;
detail::assign_to(val, attr, is_not_wrapped_container());
}
template <typename T>
inline void
assign_to(T const&, unused_type)
{
}
}}}
#endif
