Subject: [Boost-commit] svn:boost r52608 - sandbox/SOC/2009/fusion/mini-fusion
From: mr.chr.schmidt_at_[hidden]
Date: 2009-04-26 13:55:21
Author: cschmidt
Date: 2009-04-26 13:55:21 EDT (Sun, 26 Apr 2009)
New Revision: 52608
URL: http://svn.boost.org/trac/boost/changeset/52608
Log:
more comments on concepts
Text files modified:
sandbox/SOC/2009/fusion/mini-fusion/concepts.hpp | 31 ++++++++++++++++++-------------
1 files changed, 18 insertions(+), 13 deletions(-)
Modified: sandbox/SOC/2009/fusion/mini-fusion/concepts.hpp
==============================================================================
--- sandbox/SOC/2009/fusion/mini-fusion/concepts.hpp (original)
+++ sandbox/SOC/2009/fusion/mini-fusion/concepts.hpp 2009-04-26 13:55:21 EDT (Sun, 26 Apr 2009)
@@ -18,16 +18,18 @@
template<class Iterator,class IntegralConstant>
typename result_of::advance_c<Iterator,IntegralConstant::value>::type advance_c_test(const Iterator& iterator,IntegralConstant)
{
- return advance_c<IntegralConstant::value>(iterator);
+ return advance_c<0>(iterator);
}
}
+ //Fusion-iterators are defined through a set of (meta-)functions rather than their own public interface.
+ //That means we need to instantiate these functions in our concept with fitting arguments to check if
+ //the specified type models a valid fusion iterator.
auto concept ForwardIterator<class Iterator,
- class OtherIterator=Iterator,
- int IntegralConstant=0> :
+ class OtherIterator=Iterator> :
std::CopyConstructible<Iterator>//, std::HasEqualTo<Iterator,Iterator>, std::HasNotEqualTo<Iterator,Iterator>
{
- //The iterator must have the same tag (e.g. vector_iterator_tag), otherwise operations on them wont make any sense!
+ //The iterators must have the same tag (e.g. vector_iterator_tag), otherwise operations on them wont make any sense!
typename tag=typename Iterator::tag;
typename otheriterator_tag=typename OtherIterator::tag;
requires std::SameType<tag,otheriterator_tag>;
@@ -35,22 +37,25 @@
//TODO: The sequence of the underlying iterators should be the same
//The sequence is not publically exposed though.
+ //advance_c<0> should work on all iterators.
//the computed types of the metafunctions should not exposed publically
//therefore the detail prefix
- typename detail_next_type=typename result_of::next<Iterator>::type;
- detail_next_type next(const Iterator&);
-
- typename detail_advance_c_type=typename result_of::advance_c<Iterator,IntegralConstant>::type;
- //detail_advance_c_type advance_c<IntegralConstant>(const Iterator&); is not valid in a concept!
- detail_advance_c_type advance_c_test(const Iterator&,mpl::int_<IntegralConstant>);
+ typename detail_advance_c_type=typename result_of::advance_c<Iterator,0>::type;
+ //detail_advance_c_type advance_c<0>(const Iterator&); is not valid in a concept!
+ detail_advance_c_type advance_c_test(const Iterator&);
typename detail_distance_type=typename result_of::distance<Iterator,OtherIterator>::type;
//requires boost::mpl::concepts::Integral<detail_distance_type>;
detail_distance_type distance(const Iterator&,const OtherIterator&);
- //These operations are only valid for non-end iterators. This concept should
- //be valid for all iterator types, even the end ones, though. What to do?
- //A different concept for non-end iterators?
+ //The following (meta-)functions are only valid for non-end iterators. Instantiating
+ //these functions with end-iterators might fail and therefore end-iterators could not be
+ //accepted by this concept.
+ //What to do? A different concept for non-end iterators?
+
+ //typename detail_next_type=typename result_of::next<Iterator>::type;
+ //detail_next_type next(const Iterator&);
+
//typename detail_deref_type=typename result_of::deref<Iterator>::type;
//detail_deref_type deref(const Iterator&);