Subject: [Boost-commit] svn:boost r52931 - trunk/boost/spirit/home/support
From: hartmut.kaiser_at_[hidden]
Date: 2009-05-11 22:50:42
Author: hkaiser
Date: 2009-05-11 22:50:42 EDT (Mon, 11 May 2009)
New Revision: 52931
URL: http://svn.boost.org/trac/boost/changeset/52931
Log:
Spirit: fixing a problem during attribute type calculation for qi alternatives
Text files modified:
trunk/boost/spirit/home/support/attributes.hpp | 31 ++++++++++++++++++++++++-------
1 files changed, 24 insertions(+), 7 deletions(-)
Modified: trunk/boost/spirit/home/support/attributes.hpp
==============================================================================
--- trunk/boost/spirit/home/support/attributes.hpp (original)
+++ trunk/boost/spirit/home/support/attributes.hpp 2009-05-11 22:50:42 EDT (Mon, 11 May 2009)
@@ -23,6 +23,7 @@
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/end.hpp>
+#include <boost/mpl/equal_to.hpp>
#include <boost/mpl/find_if.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/variant.hpp>
@@ -255,15 +256,17 @@
filter_unused_attributes<Sequence>::type
filtered_attributes;
+ typedef has_no_unused<Sequence> has_no_unused_type;
+
// If the original attribute list does not contain any unused
// attributes, it is used, otherwise a single unused_type is
// pushed to the front of the list. This is to make sure that if
// there is an unused_type in the list, it is the first one.
typedef typename
mpl::eval_if<
- has_no_unused<Sequence>,
- mpl::identity<Sequence>,
- fusion::result_of::push_front<filtered_attributes, unused_type>
+ has_no_unused_type
+ , mpl::identity<Sequence>
+ , fusion::result_of::push_front<filtered_attributes, unused_type>
>::type
attribute_sequence;
@@ -278,13 +281,27 @@
>::type
new_sequence;
+ // If there is only an unused_type and one other type in the list of
+ // types we strip off the variant. IOTW, we collapse single element
+ // variants, variant<unused_type, T> to T.
+ typedef typename
+ mpl::eval_if<
+ mpl::and_<
+ mpl::equal_to<mpl::size<new_sequence>, mpl::int_<2> >
+ , mpl::not_<has_no_unused_type> >
+ , fusion::result_of::pop_front<new_sequence>
+ , mpl::identity<new_sequence>
+ >::type
+ shortened_type;
+
// If there is only one type in the list of types we strip off the
- // variant. IOTW, collapse single element variants, variant<T> to T.
+ // variant as well. IOTW, we collapse single element variants,
+ // variant<T> to T.
typedef typename
mpl::eval_if<
- mpl::equal_to<mpl::size<new_sequence>, mpl::int_<1> >,
- mpl::deref<mpl::front<attribute_sequence> >,
- spirit::detail::as_variant<new_sequence>
+ mpl::equal_to<mpl::size<shortened_type>, mpl::int_<1> >,
+ mpl::front<shortened_type>,
+ spirit::detail::as_variant<shortened_type>
>::type
type;
};