Subject: [Boost-commit] svn:boost r62683 - trunk/boost/tuple/detail
From: steven_at_[hidden]
Date: 2010-06-09 14:28:18
Author: steven_watanabe
Date: 2010-06-09 14:28:16 EDT (Wed, 09 Jun 2010)
New Revision: 62683
URL: http://svn.boost.org/trac/boost/changeset/62683
Log:
Reimplement boost::tuples::element and boost::tuples::get to make better use of memoization. Fixes #2130
Text files modified:
trunk/boost/tuple/detail/tuple_basic.hpp | 138 ++++++++++-----------------------------
1 files changed, 37 insertions(+), 101 deletions(-)
Modified: trunk/boost/tuple/detail/tuple_basic.hpp
==============================================================================
--- trunk/boost/tuple/detail/tuple_basic.hpp (original)
+++ trunk/boost/tuple/detail/tuple_basic.hpp 2010-06-09 14:28:16 EDT (Wed, 09 Jun 2010)
@@ -86,45 +86,28 @@
template<class T>
class generate_error;
-// - cons getters --------------------------------------------------------
-// called: get_class<N>::get<RETURN_TYPE>(aTuple)
-
-template< int N >
-struct get_class {
- template<class RET, class HT, class TT >
- inline static RET get(const cons<HT, TT>& t)
- {
-#if BOOST_WORKAROUND(__IBMCPP__,==600)
- // vacpp 6.0 is not very consistent regarding the member template keyword
- // Here it generates an error when the template keyword is used.
- return get_class<N-1>::get<RET>(t.tail);
-#else
- return get_class<N-1>::BOOST_NESTED_TEMPLATE get<RET>(t.tail);
-#endif
- }
- template<class RET, class HT, class TT >
- inline static RET get(cons<HT, TT>& t)
- {
-#if BOOST_WORKAROUND(__IBMCPP__,==600)
- return get_class<N-1>::get<RET>(t.tail);
-#else
- return get_class<N-1>::BOOST_NESTED_TEMPLATE get<RET>(t.tail);
-#endif
- }
+template<int N>
+struct drop_front {
+ template<class Tuple>
+ struct apply {
+ typedef BOOST_DEDUCED_TYPENAME drop_front<N-1>::BOOST_NESTED_TEMPLATE
+ apply<Tuple> next;
+ typedef BOOST_DEDUCED_TYPENAME next::type::tail_type type;
+ static const type& call(const Tuple& tup) {
+ return next::call(tup).tail;
+ }
+ };
};
template<>
-struct get_class<0> {
- template<class RET, class HT, class TT>
- inline static RET get(const cons<HT, TT>& t)
- {
- return t.head;
- }
- template<class RET, class HT, class TT>
- inline static RET get(cons<HT, TT>& t)
- {
- return t.head;
- }
+struct drop_front<0> {
+ template<class Tuple>
+ struct apply {
+ typedef Tuple type;
+ static const type& call(const Tuple& tup) {
+ return tup;
+ }
+ };
};
} // end of namespace detail
@@ -140,41 +123,23 @@
template<int N, class T>
struct element
{
-private:
- typedef typename T::tail_type Next;
-public:
- typedef typename element<N-1, Next>::type type;
-};
-template<class T>
-struct element<0,T>
-{
- typedef typename T::head_type type;
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<T>::type::head_type type;
};
template<int N, class T>
struct element<N, const T>
{
private:
- typedef typename T::tail_type Next;
- typedef typename element<N-1, Next>::type unqualified_type;
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<T>::type::head_type unqualified_type;
public:
#if BOOST_WORKAROUND(__BORLANDC__,<0x600)
typedef const unqualified_type type;
#else
- typedef typename boost::add_const<unqualified_type>::type type;
-#endif
-
-};
-template<class T>
-struct element<0,const T>
-{
-#if BOOST_WORKAROUND(__BORLANDC__,<0x600)
- typedef const typename T::head_type type;
-#else
- typedef typename boost::add_const<typename T::head_type>::type type;
+ typedef BOOST_DEDUCED_TYPENAME boost::add_const<unqualified_type>::type type;
#endif
};
-
#else // def BOOST_NO_CV_SPECIALIZATIONS
namespace detail {
@@ -182,31 +147,16 @@
template<int N, class T, bool IsConst>
struct element_impl
{
-private:
- typedef typename T::tail_type Next;
-public:
- typedef typename element_impl<N-1, Next, IsConst>::type type;
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<T>::type::head_type type;
};
template<int N, class T>
struct element_impl<N, T, true /* IsConst */>
{
-private:
- typedef typename T::tail_type Next;
-public:
- typedef const typename element_impl<N-1, Next, true>::type type;
-};
-
-template<class T>
-struct element_impl<0, T, false /* IsConst */>
-{
- typedef typename T::head_type type;
-};
-
-template<class T>
-struct element_impl<0, T, true /* IsConst */>
-{
- typedef const typename T::head_type type;
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<T>::type::head_type unqualified_type;
+ typedef const unqualified_type type;
};
} // end of namespace detail
@@ -258,17 +208,10 @@
typename element<N, cons<HT, TT> >::type
>::non_const_type
get(cons<HT, TT>& c BOOST_APPEND_EXPLICIT_TEMPLATE_NON_TYPE(int, N)) {
-#if BOOST_WORKAROUND(__IBMCPP__,==600 )
- return detail::get_class<N>::
-#else
- return detail::get_class<N>::BOOST_NESTED_TEMPLATE
-#endif
- get<
- typename access_traits<
- typename element<N, cons<HT, TT> >::type
- >::non_const_type,
- HT,TT
- >(c);
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<cons<HT, TT> > impl;
+ typedef BOOST_DEDUCED_TYPENAME impl::type cons_element;
+ return const_cast<cons_element&>(impl::call(c)).head;
}
// get function for const cons-lists, returns a const reference to
@@ -279,17 +222,10 @@
typename element<N, cons<HT, TT> >::type
>::const_type
get(const cons<HT, TT>& c BOOST_APPEND_EXPLICIT_TEMPLATE_NON_TYPE(int, N)) {
-#if BOOST_WORKAROUND(__IBMCPP__,==600)
- return detail::get_class<N>::
-#else
- return detail::get_class<N>::BOOST_NESTED_TEMPLATE
-#endif
- get<
- typename access_traits<
- typename element<N, cons<HT, TT> >::type
- >::const_type,
- HT,TT
- >(c);
+ typedef BOOST_DEDUCED_TYPENAME detail::drop_front<N>::BOOST_NESTED_TEMPLATE
+ apply<cons<HT, TT> > impl;
+ typedef BOOST_DEDUCED_TYPENAME impl::type cons_element;
+ return impl::call(c).head;
}
// -- the cons template --------------------------------------------------