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// (C) Copyright David Abrahams 2002. Permission to copy, use, modify,
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// sell and distribute this software is granted provided this
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// copyright notice appears in all copies. This software is provided
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// "as is" without express or implied warranty, and with no claim as
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// to its suitability for any purpose.
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// std::iterator_traits<>::iterator_category
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// std::iterator_traits<>::difference_type
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// ...for all compilers and iterators
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// Additionally, if X is a pointer
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// std::iterator_traits<X>::pointer
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// Otherwise, if partial specialization is supported or X is not a pointer
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// std::iterator_traits<X>::value_type
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// std::iterator_traits<X>::pointer
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// std::iterator_traits<X>::reference
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// See http://www.boost.org for most recent version including documentation.
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// 04 Mar 2001 - More attempted fixes for Intel C++ (David Abrahams)
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// 03 Mar 2001 - Put all implementation into namespace
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// boost::detail::iterator_traits_. Some progress made on fixes
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// for Intel compiler. (David Abrahams)
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// 02 Mar 2001 - Changed BOOST_MSVC to BOOST_MSVC_STD_ITERATOR in a few
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// places. (Jeremy Siek)
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// 19 Feb 2001 - Improved workarounds for stock MSVC6; use yes_type and
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// no_type from type_traits.hpp; stopped trying to remove_cv
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// before detecting is_pointer, in honor of the new type_traits
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// semantics. (David Abrahams)
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// 13 Feb 2001 - Make it work with nearly all standard-conforming iterators
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// under raw VC6. The one category remaining which will fail is
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// that of iterators derived from std::iterator but not
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// boost::iterator and which redefine difference_type.
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// 11 Feb 2001 - Clean away code which can never be used (David Abrahams)
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// 09 Feb 2001 - Always have a definition for each traits member, even if it
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// can't be properly deduced. These will be incomplete types in
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// some cases (undefined<void>), but it helps suppress MSVC errors
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// elsewhere (David Abrahams)
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// 07 Feb 2001 - Support for more of the traits members where possible, making
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// this useful as a replacement for std::iterator_traits<T> when
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// used as a default template parameter.
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// 06 Feb 2001 - Removed useless #includes of standard library headers
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#ifndef ITERATOR_DWA122600_HPP_
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# define ITERATOR_DWA122600_HPP_
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# include <boost/config.hpp>
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# include <boost/type_traits/remove_const.hpp>
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# include <boost/type_traits/detail/yes_no_type.hpp>
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# include <boost/type_traits/is_pointer.hpp>
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# include <boost/type_traits/is_base_and_derived.hpp>
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# include <boost/mpl/if.hpp>
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# include <boost/mpl/aux_/has_xxx.hpp>
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// should be the last #include
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#include "boost/type_traits/detail/bool_trait_def.hpp"
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// STLPort 4.0 and betas have a bug when debugging is enabled and there is no
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// partial specialization: instead of an iterator_category typedef, the standard
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// container iterators have _Iterator_category.
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// Also, whether debugging is enabled or not, there is a broken specialization
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// of std::iterator<output_iterator_tag,void,void,void,void> which has no
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// typedefs but iterator_category.
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# if defined(__SGI_STL_PORT)
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# if (__SGI_STL_PORT <= 0x410) && !defined(__STL_CLASS_PARTIAL_SPECIALIZATION) && defined(__STL_DEBUG)
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# define BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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# define BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
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# endif // STLPort <= 4.1b4 && no partial specialization
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namespace boost { namespace detail {
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BOOST_MPL_HAS_XXX_TRAIT_DEF(value_type)
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BOOST_MPL_HAS_XXX_TRAIT_DEF(reference)
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BOOST_MPL_HAS_XXX_TRAIT_DEF(pointer)
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BOOST_MPL_HAS_XXX_TRAIT_DEF(difference_type)
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BOOST_MPL_HAS_XXX_TRAIT_DEF(iterator_category)
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# if !defined(BOOST_NO_STD_ITERATOR_TRAITS) \
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&& !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
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&& !defined(BOOST_MSVC_STD_ITERATOR)
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// Define a new template so it can be specialized
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template <class Iterator>
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struct iterator_traits
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: std::iterator_traits<Iterator>
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# elif !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
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&& !defined(BOOST_MSVC_STD_ITERATOR)
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// Rogue Wave Standard Library fools itself into thinking partial
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// specialization is missing on some platforms (e.g. Sun), so fails to
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// supply iterator_traits!
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template <class Iterator>
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struct iterator_traits
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typedef typename Iterator::value_type value_type;
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typedef typename Iterator::reference reference;
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typedef typename Iterator::pointer pointer;
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typedef typename Iterator::difference_type difference_type;
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typedef typename Iterator::iterator_category iterator_category;
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struct iterator_traits<T*>
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typedef T value_type;
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typedef T& reference;
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typedef std::ptrdiff_t difference_type;
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typedef std::random_access_iterator_tag iterator_category;
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struct iterator_traits<T const*>
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typedef T value_type;
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typedef T const& reference;
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typedef T const* pointer;
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typedef std::ptrdiff_t difference_type;
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typedef std::random_access_iterator_tag iterator_category;
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// is_mutable_iterator --
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// A metafunction returning true iff T is a mutable iterator type
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// with a nested value_type. Will only work portably with iterators
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// whose operator* returns a reference, but that seems to be OK for
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// the iterators supplied by Dinkumware. Some input iterators may
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// compile-time if they arrive here, and if the compiler is strict
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// about not taking the address of an rvalue.
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// This one detects ordinary mutable iterators - the result of
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// operator* is convertible to the value_type.
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type_traits::yes_type is_mutable_iterator_helper(T const*, BOOST_DEDUCED_TYPENAME T::value_type*);
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// This one detects output iterators such as ostream_iterator which
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// return references to themselves.
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type_traits::yes_type is_mutable_iterator_helper(T const*, T const*);
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type_traits::no_type is_mutable_iterator_helper(...);
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struct is_mutable_iterator_impl
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BOOST_STATIC_CONSTANT(bool, value = sizeof(
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detail::is_mutable_iterator_helper((T*)0, &*t))
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== sizeof(type_traits::yes_type)
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BOOST_TT_AUX_BOOL_TRAIT_DEF1(
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is_mutable_iterator,T,::boost::detail::is_mutable_iterator_impl<T>::value)
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// is_full_iterator_traits --
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// A metafunction returning true iff T has all the requisite nested
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// types to satisfy the requirements for a fully-conforming
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// iterator_traits implementation.
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struct is_full_iterator_traits_impl
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has_value_type<T>::value
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& has_reference<T>::value
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& has_pointer<T>::value
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& has_difference_type<T>::value
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& has_iterator_category<T>::value
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BOOST_TT_AUX_BOOL_TRAIT_DEF1(
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is_full_iterator_traits,T,::boost::detail::is_full_iterator_traits_impl<T>::value)
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# ifdef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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BOOST_MPL_HAS_XXX_TRAIT_DEF(_Iterator_category)
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// is_stlport_40_debug_iterator --
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// A metafunction returning true iff T has all the requisite nested
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// types to satisfy the requirements of an STLPort 4.0 debug iterator
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// iterator_traits implementation.
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struct is_stlport_40_debug_iterator_impl
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has_value_type<T>::value
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& has_reference<T>::value
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& has_pointer<T>::value
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& has_difference_type<T>::value
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& has__Iterator_category<T>::value
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BOOST_TT_AUX_BOOL_TRAIT_DEF1(
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is_stlport_40_debug_iterator,T,::boost::detail::is_stlport_40_debug_iterator_impl<T>::value)
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struct stlport_40_debug_iterator_traits
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typedef typename T::value_type value_type;
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typedef typename T::reference reference;
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typedef typename T::pointer pointer;
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typedef typename T::difference_type difference_type;
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typedef typename T::_Iterator_category iterator_category;
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# endif // BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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template <class T> struct pointer_iterator_traits;
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# ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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struct pointer_iterator_traits<T*>
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typedef remove_const<T>::type value_type;
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typedef T& reference;
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typedef std::random_access_iterator_tag iterator_category;
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typedef std::ptrdiff_t difference_type;
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struct must_manually_specialize_boost_detail_iterator_traits;
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struct pointer_iterator_traits
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typedef std::random_access_iterator_tag iterator_category;
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typedef std::ptrdiff_t difference_type;
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// Makes MSVC6 happy under some circumstances
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typedef must_manually_specialize_boost_detail_iterator_traits<T> value_type;
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typedef must_manually_specialize_boost_detail_iterator_traits<T> reference;
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// Use this as a base class in manual iterator_traits specializations
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// for pointer types. T should be the value_type. CV should be the
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// cv-qualified value_type to which */& is added in order to produce
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// pointer/reference.
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template <class T, class CV = T>
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struct ptr_iter_traits
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typedef T value_type;
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typedef CV& reference;
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typedef std::random_access_iterator_tag iterator_category;
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typedef std::ptrdiff_t difference_type;
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# endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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// We'll sort iterator types into one of these classifications, from which we
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// can determine the difference_type, pointer, reference, and value_type
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template <class Iterator>
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struct standard_iterator_traits
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typedef typename Iterator::difference_type difference_type;
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typedef typename Iterator::value_type value_type;
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typedef typename Iterator::pointer pointer;
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typedef typename Iterator::reference reference;
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typedef typename Iterator::iterator_category iterator_category;
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template <class Iterator>
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struct msvc_stdlib_mutable_traits
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: std::iterator_traits<Iterator>
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typedef typename std::iterator_traits<Iterator>::distance_type difference_type;
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typedef value_type* pointer;
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typedef value_type& reference;
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template <class Iterator>
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struct msvc_stdlib_const_traits
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: std::iterator_traits<Iterator>
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typedef typename std::iterator_traits<Iterator>::distance_type difference_type;
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typedef const value_type* pointer;
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typedef const value_type& reference;
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# ifdef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
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template <class Iterator>
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struct is_bad_output_iterator
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: is_base_and_derived<
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std::iterator<std::output_iterator_tag,void,void,void,void>
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struct bad_output_iterator_traits
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typedef void value_type;
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typedef void difference_type;
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typedef std::output_iterator_tag iterator_category;
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typedef void pointer;
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typedef void reference;
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// If we're looking at an MSVC6 (old Dinkumware) ``standard''
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// iterator, this will generate an appropriate traits class.
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template <class Iterator>
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struct msvc_stdlib_iterator_traits
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is_mutable_iterator<Iterator>
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, msvc_stdlib_mutable_traits<Iterator>
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, msvc_stdlib_const_traits<Iterator>
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template <class Iterator>
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struct non_pointer_iterator_traits
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// if the iterator contains all the right nested types...
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is_full_iterator_traits<Iterator>
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// Use a standard iterator_traits implementation
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, standard_iterator_traits<Iterator>
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# ifdef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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// Check for STLPort 4.0 broken _Iterator_category type
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is_stlport_40_debug_iterator<Iterator>
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, stlport_40_debug_iterator_traits<Iterator>
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// Otherwise, assume it's a Dinkum iterator
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, msvc_stdlib_iterator_traits<Iterator>
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# ifdef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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template <class Iterator>
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struct iterator_traits_aux
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, pointer_iterator_traits<Iterator>
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, non_pointer_iterator_traits<Iterator>
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template <class Iterator>
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struct iterator_traits
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// Explicit forwarding from base class needed to keep MSVC6 happy
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// under some circumstances.
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# ifdef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
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is_bad_output_iterator<Iterator>
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, bad_output_iterator_traits
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, iterator_traits_aux<Iterator>
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typedef iterator_traits_aux<Iterator> base;
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typedef typename base::value_type value_type;
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typedef typename base::pointer pointer;
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typedef typename base::reference reference;
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typedef typename base::difference_type difference_type;
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typedef typename base::iterator_category iterator_category;
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// This specialization cuts off ETI (Early Template Instantiation) for MSVC.
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template <> struct iterator_traits<int>{};
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namespace iterator_traits_
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template <class Iterator, class Difference>
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struct distance_select
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static Difference execute(Iterator i1, const Iterator i2, ...)
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typename Difference result = 0;
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static Difference execute(Iterator i1, const Iterator i2, std::random_access_iterator_tag*)
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} // namespace boost::detail::iterator_traits_
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template <class Iterator>
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inline typename iterator_traits<Iterator>::difference_type
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distance(Iterator first, Iterator last)
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typedef typename iterator_traits<Iterator>::difference_type diff_t;
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typedef typename ::boost::detail::iterator_traits<Iterator>::iterator_category iterator_category;
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return iterator_traits_::distance_select<Iterator,diff_t>::execute(
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first, last, (iterator_category*)0);
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# endif // workarounds
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}} // namespace boost::detail
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# undef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
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# undef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
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#endif // ITERATOR_DWA122600_HPP_
added
removed
boost/boost/detail/iterator.hpp
