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Moved concept checks into a separate class, which makes MSVC better at dealing with them

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[SVN r12255]
This commit is contained in:
Dave Abrahams 2002-01-09 12:14:16 +00:00
parent ebcb4d861a
commit 57251d58cc
1 changed files with 96 additions and 83 deletions
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51
include/boost/iterator_adaptors.hpp
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@ -12,6 +12,9 @@
// //
// Revision History: // Revision History:
// 08 Jan 2001 David Abrahams
// Moved concept checks into a separate class, which makes MSVC
// better at dealing with them.
// 07 Jan 2001 David Abrahams // 07 Jan 2001 David Abrahams
// Choose proxy for operator->() only if the reference type is not a reference. // Choose proxy for operator->() only if the reference type is not a reference.
// Updated workarounds for __MWERKS__ == 0x2406 // Updated workarounds for __MWERKS__ == 0x2406
@ -727,6 +730,29 @@ namespace detail {
difference_type, pointer, reference> type; difference_type, pointer, reference> type;
}; };
// This is really a partial concept check for iterators. Should it
// be moved or done differently?
template <class Category, class Value, class Difference, class Pointer, class Reference>
struct validator
{
BOOST_STATIC_CONSTANT(
bool, is_input_or_output_iter
= (boost::is_convertible<Category*,std::input_iterator_tag*>::value
| boost::is_convertible<Category*,std::output_iterator_tag*>::value));
// Iterators should satisfy one of the known categories
BOOST_STATIC_ASSERT(is_input_or_output_iter);
// Iterators >= ForwardIterator must produce real references
// as required by the C++ standard requirements in Table 74.
BOOST_STATIC_CONSTANT(
bool, forward_iter_with_real_reference
= ((!boost::is_convertible<Category*,std::forward_iterator_tag*>::value)
| boost::is_same<Reference,Value&>::value
| boost::is_same<Reference,typename add_const<Value>::type&>::value));
BOOST_STATIC_ASSERT(forward_iter_with_real_reference);
};
} // namespace detail } // namespace detail
@ -738,8 +764,6 @@ namespace detail {
# define BOOST_ARG_DEPENDENT_TYPENAME # define BOOST_ARG_DEPENDENT_TYPENAME
# endif # endif
template <class T> struct undefined;
//============================================================================ //============================================================================
//iterator_adaptor - Adapts a generic piece of data as an iterator. Adaptation //iterator_adaptor - Adapts a generic piece of data as an iterator. Adaptation
// is especially easy if the data being adapted is itself an iterator // is especially easy if the data being adapted is itself an iterator
@ -800,25 +824,14 @@ struct iterator_adaptor :
typedef Policies policies_type; typedef Policies policies_type;
private: private:
BOOST_STATIC_CONSTANT(bool, is_input_or_output_iter typedef detail::validator<
= (boost::is_convertible<iterator_category*,std::input_iterator_tag*>::value iterator_category,value_type,difference_type,pointer,reference
| boost::is_convertible<iterator_category*,std::output_iterator_tag*>::value)); > concept_check;
// Iterators should satisfy one of the known categories
BOOST_STATIC_ASSERT(is_input_or_output_iter);
// Iterators >= ForwardIterator must produce real references
// as required by the C++ standard requirements in Table 74.
BOOST_STATIC_CONSTANT(bool, forward_iter_with_real_reference
= ((!boost::is_convertible<iterator_category*,std::forward_iterator_tag*>::value)
| boost::is_same<reference,value_type&>::value
| boost::is_same<reference,const value_type&>::value));
// This check gives incorrect results in iter_traits_gen_test.cpp
BOOST_STATIC_ASSERT(forward_iter_with_real_reference);
public: public:
iterator_adaptor() { } iterator_adaptor()
{
}
explicit explicit
iterator_adaptor(const Base& it, const Policies& p = Policies()) iterator_adaptor(const Base& it, const Policies& p = Policies())