-// (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
-// Permission to copy, use, modify, sell and distribute this software is
-// granted provided this copyright notice appears in all copies. This software
-// is provided "as is" without express or implied warranty, and with no claim
-// as to its suitability for any purpose.
+// (C) Copyright Rani Sharoni 2003.
+// Use, modification and distribution are subject to 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).
//
-// See http://www.boost.org for most recent version including documentation.
-
+// See http://www.boost.org/libs/type_traits for most recent version including documentation.
+
#ifndef BOOST_TT_IS_BASE_AND_DERIVED_HPP_INCLUDED
#define BOOST_TT_IS_BASE_AND_DERIVED_HPP_INCLUDED
-#include "boost/type_traits/is_class.hpp"
-#include "boost/type_traits/is_convertible.hpp"
-#include "boost/type_traits/detail/ice_and.hpp"
-#include "boost/config.hpp"
+#include <boost/type_traits/intrinsics.hpp>
+#ifndef BOOST_IS_BASE_OF
+#include <boost/type_traits/is_class.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/detail/ice_and.hpp>
+#include <boost/config.hpp>
+#include <boost/static_assert.hpp>
+#endif
+#include <boost/type_traits/remove_cv.hpp>
// should be the last #include
-#include "boost/type_traits/detail/bool_trait_def.hpp"
+#include <boost/type_traits/detail/bool_trait_def.hpp>
namespace boost {
namespace detail {
-template <typename Base, typename Derived>
+#ifndef BOOST_IS_BASE_OF
+#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581)) \
+ && !BOOST_WORKAROUND(__SUNPRO_CC , <= 0x540) \
+ && !BOOST_WORKAROUND(__EDG_VERSION__, <= 243) \
+ && !BOOST_WORKAROUND(__DMC__, BOOST_TESTED_AT(0x840))
+
+ // The EDG version number is a lower estimate.
+ // It is not currently known which EDG version
+ // exactly fixes the problem.
+
+/*************************************************************************
+
+This version detects ambiguous base classes and private base classes
+correctly, and was devised by Rani Sharoni.
+
+Explanation by Terje Slettebo and Rani Sharoni.
+
+Let's take the multiple base class below as an example, and the following
+will also show why there's not a problem with private or ambiguous base
+class:
+
+struct B {};
+struct B1 : B {};
+struct B2 : B {};
+struct D : private B1, private B2 {};
+
+is_base_and_derived<B, D>::value;
+
+First, some terminology:
+
+SC - Standard conversion
+UDC - User-defined conversion
+
+A user-defined conversion sequence consists of an SC, followed by an UDC,
+followed by another SC. Either SC may be the identity conversion.
+
+When passing the default-constructed Host object to the overloaded check_sig()
+functions (initialization 8.5/14/4/3), we have several viable implicit
+conversion sequences:
+
+For "static no_type check_sig(B const volatile *, int)" we have the conversion
+sequences:
+
+C -> C const (SC - Qualification Adjustment) -> B const volatile* (UDC)
+C -> D const volatile* (UDC) -> B1 const volatile* / B2 const volatile* ->
+ B const volatile* (SC - Conversion)
+
+For "static yes_type check_sig(D const volatile *, T)" we have the conversion
+sequence:
+
+C -> D const volatile* (UDC)
+
+According to 13.3.3.1/4, in context of user-defined conversion only the
+standard conversion sequence is considered when selecting the best viable
+function, so it only considers up to the user-defined conversion. For the
+first function this means choosing between C -> C const and C -> C, and it
+chooses the latter, because it's a proper subset (13.3.3.2/3/2) of the
+former. Therefore, we have:
+
+C -> D const volatile* (UDC) -> B1 const volatile* / B2 const volatile* ->
+ B const volatile* (SC - Conversion)
+C -> D const volatile* (UDC)
+
+Here, the principle of the "shortest subsequence" applies again, and it
+chooses C -> D const volatile*. This shows that it doesn't even need to
+consider the multiple paths to B, or accessibility, as that possibility is
+eliminated before it could possibly cause ambiguity or access violation.
+
+If D is not derived from B, it has to choose between C -> C const -> B const
+volatile* for the first function, and C -> D const volatile* for the second
+function, which are just as good (both requires a UDC, 13.3.3.2), had it not
+been for the fact that "static no_type check_sig(B const volatile *, int)" is
+not templated, which makes C -> C const -> B const volatile* the best choice
+(13.3.3/1/4), resulting in "no".
+
+Also, if Host::operator B const volatile* hadn't been const, the two
+conversion sequences for "static no_type check_sig(B const volatile *, int)", in
+the case where D is derived from B, would have been ambiguous.
+
+See also
+http://groups.google.com/groups?selm=df893da6.0301280859.522081f7%40posting.
+google.com and links therein.
+
+*************************************************************************/
+
+template <typename B, typename D>
+struct bd_helper
+{
+ //
+ // This VC7.1 specific workaround stops the compiler from generating
+ // an internal compiler error when compiling with /vmg (thanks to
+ // Aleksey Gurtovoy for figuring out the workaround).
+ //
+#if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+ template <typename T>
+ static type_traits::yes_type check_sig(D const volatile *, T);
+ static type_traits::no_type check_sig(B const volatile *, int);
+#else
+ static type_traits::yes_type check_sig(D const volatile *, long);
+ static type_traits::no_type check_sig(B const volatile * const&, int);
+#endif
+};
+
+template<typename B, typename D>
+struct is_base_and_derived_impl2
+{
+#if BOOST_WORKAROUND(BOOST_MSVC_FULL_VER, >= 140050000)
+#pragma warning(push)
+#pragma warning(disable:6334)
+#endif
+ //
+ // May silently do the wrong thing with incomplete types
+ // unless we trap them here:
+ //
+ BOOST_STATIC_ASSERT(sizeof(B) != 0);
+ BOOST_STATIC_ASSERT(sizeof(D) != 0);
+
+ struct Host
+ {
+#if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
+ operator B const volatile *() const;
+#else
+ operator B const volatile * const&() const;
+#endif
+ operator D const volatile *();
+ };
+
+ BOOST_STATIC_CONSTANT(bool, value =
+ sizeof(bd_helper<B,D>::check_sig(Host(), 0)) == sizeof(type_traits::yes_type));
+#if BOOST_WORKAROUND(BOOST_MSVC_FULL_VER, >= 140050000)
+#pragma warning(pop)
+#endif
+};
+
+#else
+
+//
+// broken version:
+//
+template<typename B, typename D>
+struct is_base_and_derived_impl2
+{
+ BOOST_STATIC_CONSTANT(bool, value =
+ (::boost::is_convertible<D*,B*>::value));
+};
+
+#define BOOST_BROKEN_IS_BASE_AND_DERIVED
+
+#endif
+
+template <typename B, typename D>
+struct is_base_and_derived_impl3
+{
+ BOOST_STATIC_CONSTANT(bool, value = false);
+};
+
+template <bool ic1, bool ic2, bool iss>
+struct is_base_and_derived_select
+{
+ template <class T, class U>
+ struct rebind
+ {
+ typedef is_base_and_derived_impl3<T,U> type;
+ };
+};
+
+template <>
+struct is_base_and_derived_select<true,true,false>
+{
+ template <class T, class U>
+ struct rebind
+ {
+ typedef is_base_and_derived_impl2<T,U> type;
+ };
+};
+
+template <typename B, typename D>
struct is_base_and_derived_impl
{
- BOOST_STATIC_CONSTANT(bool, value =
- (::boost::type_traits::ice_and<
- ::boost::is_convertible<Derived*,Base*>::value,
- ::boost::is_class<Derived>::value,
- ::boost::is_class<Base>::value
- >::value)
- );
+ typedef typename remove_cv<B>::type ncvB;
+ typedef typename remove_cv<D>::type ncvD;
+
+ typedef is_base_and_derived_select<
+ ::boost::is_class<B>::value,
+ ::boost::is_class<D>::value,
+ ::boost::is_same<ncvB,ncvD>::value> selector;
+ typedef typename selector::template rebind<ncvB,ncvD> binder;
+ typedef typename binder::type bound_type;
+
+ BOOST_STATIC_CONSTANT(bool, value = bound_type::value);
};
+#else
+template <typename B, typename D>
+struct is_base_and_derived_impl
+{
+ typedef typename remove_cv<B>::type ncvB;
+ typedef typename remove_cv<D>::type ncvD;
+ BOOST_STATIC_CONSTANT(bool, value = (BOOST_IS_BASE_OF(B,D) && ! ::boost::is_same<ncvB,ncvD>::value));
+};
+#endif
} // namespace detail
BOOST_TT_AUX_BOOL_TRAIT_DEF2(
BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_2(typename Base,typename Derived,is_base_and_derived,Base&,Derived&,false)
#endif
+#if BOOST_WORKAROUND(__CODEGEARC__, BOOST_TESTED_AT(0x610))
+BOOST_TT_AUX_BOOL_TRAIT_PARTIAL_SPEC2_1(typename Base,is_base_and_derived,Base,Base,false)
+#endif
+
} // namespace boost
-#include "boost/type_traits/detail/bool_trait_undef.hpp"
+#include <boost/type_traits/detail/bool_trait_undef.hpp>
#endif // BOOST_TT_IS_BASE_AND_DERIVED_HPP_INCLUDED