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Produce operator-> proxy objects for InputIterators

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Added static assertions to do some basic concept checks

Renamed single-type generators -> xxx_generator
Renamed const/nonconst iterator generators -> xxx_pair_generator

Added make_transform_iterator(iter, function)

The existence of boost::detail::iterator_traits allowed many
template arguments to be defaulted. Some arguments had to be
moved to accomplish it.


[SVN r8994]
This commit is contained in:
Dave Abrahams
2001-02-07 05:15:42 +00:00
parent d17e8dae9b
commit 07482538ed
1 changed files with 137 additions and 82 deletions
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201
include/boost/iterator_adaptors.hpp
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@ -11,7 +11,23 @@
// to its suitability for any purpose. // to its suitability for any purpose.
// //
// Revision History: // Revision History:
// 04 Feb 2001 MWERKS bug workaround
// 06 Feb 2001
// Produce operator-> proxy objects for InputIterators
//
// Added static assertions to do some basic concept checks
//
// Renamed single-type generators -> xxx_generator
// Renamed const/nonconst iterator generators -> xxx_pair_generator
//
// Added make_transform_iterator(iter, function)
//
// The existence of boost::detail::iterator_traits allowed many
// template arguments to be defaulted. Some arguments had to be
// moved to accomplish it.
//
// 04 Feb 2001 MWERKS bug workaround, concept checking for proper
// reference types (David Abrahams)
#ifndef BOOST_ITERATOR_ADAPTOR_DWA053000_HPP_ #ifndef BOOST_ITERATOR_ADAPTOR_DWA053000_HPP_
# define BOOST_ITERATOR_ADAPTOR_DWA053000_HPP_ # define BOOST_ITERATOR_ADAPTOR_DWA053000_HPP_
@ -21,6 +37,10 @@
# include <boost/compressed_pair.hpp> # include <boost/compressed_pair.hpp>
# include <boost/concept_check.hpp> # include <boost/concept_check.hpp>
# include <boost/type.hpp> # include <boost/type.hpp>
# include <boost/static_assert.hpp>
# include <boost/type_traits.hpp>
# include <boost/detail/iterator.hpp>
# include <boost/detail/select_type.hpp>
// I was having some problems with VC6. I couldn't tell whether our hack for // I was having some problems with VC6. I couldn't tell whether our hack for
// stock GCC was causing problems so I needed an easy way to turn it on and // stock GCC was causing problems so I needed an easy way to turn it on and
@ -241,11 +261,6 @@ namespace detail {
// Dummy versions for iterators that don't support various operators // Dummy versions for iterators that don't support various operators
template <class Iter> template <class Iter>
inline typename Iter::pointer inline typename Iter::pointer
operator_arrow(const Iter&, std::input_iterator_tag) {
return typename Iter::pointer();
}
template <class Iter>
inline typename Iter::pointer
operator_arrow(const Iter&, std::output_iterator_tag) { operator_arrow(const Iter&, std::output_iterator_tag) {
return typename Iter::pointer(); return typename Iter::pointer();
} }
@ -262,12 +277,49 @@ namespace detail {
#endif #endif
// Real versions // Real versions
// operator->() needs special support for input iterators to strictly meet the
// standard's requirements. If *i is not a reference type, we must still
// produce a (constant) lvalue to which a pointer can be formed. We do that by
// returning an instantiation of this special proxy class template.
template <class T>
struct operator_arrow_proxy
{
operator_arrow_proxy(const T& x) : m_value(x) {}
const T* operator->() const { return &m_value; }
T m_value;
};
template <class Iter>
inline operator_arrow_proxy<typename Iter::value_type>
operator_arrow(const Iter& i, std::input_iterator_tag) {
return operator_arrow_proxy<typename Iter::value_type>(*i);
}
template <class Iter> template <class Iter>
inline typename Iter::pointer inline typename Iter::pointer
operator_arrow(const Iter& i, std::forward_iterator_tag) { operator_arrow(const Iter& i, std::forward_iterator_tag) {
return &(*i); return &(*i);
} }
template <class Traits>
struct operator_arrow_result_generator
{
typedef typename Traits::iterator_category category;
typedef operator_arrow_proxy<typename Traits::value_type> proxy;
typedef typename Traits::pointer pointer;
typedef typename boost::detail::if_true<(
boost::is_convertible<category,std::input_iterator_tag>::value
& !boost::is_convertible<category,std::forward_iterator_tag>::value
)>::template
then<
proxy,
// else
pointer
>::type type;
};
template <class Iter, class Diff> template <class Iter, class Diff>
inline void inline void
advance_impl(Iter& i, Diff n, std::random_access_iterator_tag) { advance_impl(Iter& i, Diff n, std::random_access_iterator_tag) {
@ -322,6 +374,15 @@ public:
typedef typename Traits::iterator_category iterator_category; typedef typename Traits::iterator_category iterator_category;
typedef Iterator iterator_type; typedef Iterator iterator_type;
// Iterators should satisfy one of the known categories
BOOST_STATIC_ASSERT((boost::is_convertible<iterator_category,std::input_iterator_tag>::value
|| boost::is_convertible<iterator_category,std::output_iterator_tag>::value));
// Iterators >= ForwardIterator must produce real references.
BOOST_STATIC_ASSERT((!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));
iterator_adaptor() { } iterator_adaptor() { }
iterator_adaptor(const Iterator& it, const Policies& p = Policies()) iterator_adaptor(const Iterator& it, const Policies& p = Policies())
@ -353,7 +414,8 @@ public:
# pragma warning( disable : 4284 ) # pragma warning( disable : 4284 )
#endif #endif
pointer operator->() const typename boost::detail::operator_arrow_result_generator<Traits>::type
operator->() const
{ return detail::operator_arrow(*this, iterator_category()); } { return detail::operator_arrow(*this, iterator_category()); }
#ifdef _MSC_VER #ifdef _MSC_VER
@ -478,7 +540,7 @@ operator!=(const iterator_adaptor<Iterator1,Policies,Traits1>& x,
#endif #endif
//============================================================================= //=============================================================================
// iterator_adaptors - A type generator that simplifies creating // iterator_adaptor_pair_generator - A type generator that simplifies creating
// mutable/const pairs of iterator adaptors. // mutable/const pairs of iterator adaptors.
template <class Iterator, class ConstIterator, template <class Iterator, class ConstIterator,
@ -490,7 +552,7 @@ template <class Iterator, class ConstIterator,
class ConstTraits = std::iterator_traits<ConstIterator>, class ConstTraits = std::iterator_traits<ConstIterator>,
#endif #endif
class Policies = default_iterator_policies> class Policies = default_iterator_policies>
class iterator_adaptors class iterator_adaptor_pair_generator
{ {
public: public:
typedef iterator_adaptor<Iterator, Policies, Traits> iterator; typedef iterator_adaptor<Iterator, Policies, Traits> iterator;
@ -529,21 +591,26 @@ struct transform_iterator_traits {
template <class AdaptableUnaryFunction, template <class AdaptableUnaryFunction,
class Iterator, class Iterator,
#ifndef BOOST_NO_STD_ITERATOR_TRAITS class Traits = boost::detail::iterator_traits<Iterator>
class Traits = std::iterator_traits<Iterator>
#else
class Traits
#endif
> >
struct transform_iterator struct transform_iterator_generator
{ {
typedef transform_iterator_traits<AdaptableUnaryFunction,Traits> typedef transform_iterator_traits<AdaptableUnaryFunction,Traits>
TransTraits; transform_traits;
typedef iterator_adaptor<Iterator, typedef iterator_adaptor<Iterator,
transform_iterator_policies<AdaptableUnaryFunction>, TransTraits> transform_iterator_policies<AdaptableUnaryFunction>, transform_traits>
type; type;
}; };
template <class AdaptableUnaryFunction, class Iterator>
typename transform_iterator_generator<AdaptableUnaryFunction,Iterator>::type
make_transform_iterator(
const Iterator& base,
const AdaptableUnaryFunction& f = AdaptableUnaryFunction())
{
typedef typename transform_iterator_generator<AdaptableUnaryFunction,Iterator>::type result_t;
return result_t(base, f);
}
//============================================================================= //=============================================================================
// Indirect Iterators Adaptor // Indirect Iterators Adaptor
@ -567,14 +634,15 @@ struct indirect_iterator_policies : public default_iterator_policies
{ return **x; } { return **x; }
}; };
template <class OuterIterator, class InnerIterator, template <class OuterIterator,
#ifdef BOOST_NO_STD_ITERATOR_TRAITS #ifdef BOOST_NO_STD_ITERATOR_TRAITS
class OuterTraits, class InnerIterator,
class InnerTraits class InnerTraits,
#else #else
class OuterTraits = std::iterator_traits<OuterIterator>, class InnerIterator = typename std::iterator_traits<OuterIterator>::value_type,
class InnerTraits = std::iterator_traits<InnerIterator> class InnerTraits = std::iterator_traits<InnerIterator>,
#endif #endif
class OuterTraits = boost::detail::iterator_traits<OuterIterator>
> >
struct indirect_traits struct indirect_traits
{ {
@ -586,49 +654,49 @@ struct indirect_traits
}; };
template <class OuterIterator, // Mutable or Immutable, does not matter template <class OuterIterator, // Mutable or Immutable, does not matter
#ifdef BOOST_NO_STD_ITERATOR_TRAITS
class InnerIterator, // Mutable -> mutable indirect iterator class InnerIterator, // Mutable -> mutable indirect iterator
// Immutable -> immutable indirect iterator // Immutable -> immutable indirect iterator
#ifdef BOOST_NO_STD_ITERATOR_TRAITS class InnerTraits,
class OuterTraits,
class InnerTraits
#else #else
class OuterTraits = std::iterator_traits<OuterIterator>, class InnerIterator = typename std::iterator_traits<OuterIterator>::value_type,
class InnerTraits = std::iterator_traits<InnerIterator> class InnerTraits = std::iterator_traits<InnerIterator>,
#endif #endif
class OuterTraits = boost::detail::iterator_traits<OuterIterator>
> >
struct indirect_iterator struct indirect_iterator_generator
{ {
typedef iterator_adaptor<OuterIterator, typedef iterator_adaptor<OuterIterator,
indirect_iterator_policies, indirect_iterator_policies,
indirect_traits<OuterIterator, InnerIterator, indirect_traits<OuterIterator, InnerIterator,
OuterTraits, InnerTraits> InnerTraits, OuterTraits>
> type; > type;
}; };
template <class OuterIterator, // Mutable or Immutable, does not matter template <class OuterIterator, // Mutable or Immutable, does not matter
class InnerIterator, // Mutable
class ConstInnerIterator, // Immutable class ConstInnerIterator, // Immutable
#ifdef BOOST_NO_STD_ITERATOR_TRAITS #ifdef BOOST_NO_STD_ITERATOR_TRAITS
class OuterTraits, class ConstInnerTraits,
class InnerIterator, // Mutable
class InnerTraits, class InnerTraits,
class ConstInnerTraits
#else #else
class OuterTraits = std::iterator_traits<OuterIterator>, class ConstInnerTraits = std::iterator_traits<ConstInnerIterator>,
class InnerIterator = typename std::iterator_traits<OuterIterator>::value_type,
class InnerTraits = std::iterator_traits<InnerIterator>, class InnerTraits = std::iterator_traits<InnerIterator>,
class ConstInnerTraits = std::iterator_traits<ConstInnerIterator>
#endif #endif
class OuterTraits = boost::detail::iterator_traits<OuterIterator>
> >
struct indirect_iterators struct indirect_iterator_pair_generator
{ {
typedef iterator_adaptors<OuterIterator, OuterIterator, typedef iterator_adaptor_pair_generator<OuterIterator, OuterIterator,
indirect_traits<OuterIterator, InnerIterator, indirect_traits<OuterIterator, InnerIterator,
OuterTraits, InnerTraits>, InnerTraits, OuterTraits>,
indirect_traits<OuterIterator, ConstInnerIterator, indirect_traits<OuterIterator, ConstInnerIterator,
OuterTraits, ConstInnerTraits>, ConstInnerTraits, OuterTraits>,
indirect_iterator_policies indirect_iterator_policies
> Adaptors; > pair_generator;
typedef typename Adaptors::iterator iterator; typedef typename pair_generator::iterator iterator;
typedef typename Adaptors::const_iterator const_iterator; typedef typename pair_generator::const_iterator const_iterator;
}; };
@ -674,7 +742,7 @@ template <class Iterator,
class Traits class Traits
#endif #endif
> >
struct reverse_iterator struct reverse_iterator_generator
{ {
typedef iterator_adaptor<Iterator, reverse_iterator_policies, typedef iterator_adaptor<Iterator, reverse_iterator_policies,
Traits> type; Traits> type;
@ -687,7 +755,7 @@ template <class ConstIterator,
class ConstTraits class ConstTraits
#endif #endif
> >
struct const_reverse_iterator struct const_reverse_iterator_generator
{ {
typedef iterator_adaptor<ConstIterator, reverse_iterator_policies, typedef iterator_adaptor<ConstIterator, reverse_iterator_policies,
ConstTraits> type; ConstTraits> type;
@ -702,12 +770,12 @@ template <class Iterator, class ConstIterator,
class ConstTraits class ConstTraits
#endif #endif
> >
struct reverse_iterators struct reverse_iterator_pair_generator
{ {
typedef iterator_adaptors<Iterator,ConstIterator,Traits,ConstTraits, typedef iterator_adaptor_pair_generator<Iterator,ConstIterator,Traits,ConstTraits,
reverse_iterator_policies> Adaptor; reverse_iterator_policies> pair_generator;
typedef typename Adaptor::iterator iterator; typedef typename pair_generator::iterator iterator;
typedef typename Adaptor::const_iterator const_iterator; typedef typename pair_generator::const_iterator const_iterator;
}; };
//============================================================================= //=============================================================================
@ -746,13 +814,9 @@ struct const_projection_iterator_traits {
}; };
template <class AdaptableUnaryFunction, class Iterator, template <class AdaptableUnaryFunction, class Iterator,
#ifndef BOOST_NO_STD_ITERATOR_TRAITS class Traits = boost::detail::iterator_traits<Iterator>
class Traits = std::iterator_traits<Iterator>
#else
class Traits
#endif
> >
struct projection_iterator { struct projection_iterator_generator {
typedef projection_iterator_traits<AdaptableUnaryFunction, Traits> typedef projection_iterator_traits<AdaptableUnaryFunction, Traits>
Projection_Traits; Projection_Traits;
typedef iterator_adaptor<Iterator, typedef iterator_adaptor<Iterator,
@ -761,13 +825,9 @@ struct projection_iterator {
}; };
template <class AdaptableUnaryFunction, class Iterator, template <class AdaptableUnaryFunction, class Iterator,
#ifndef BOOST_NO_STD_ITERATOR_TRAITS class Traits = boost::detail::iterator_traits<Iterator>
class Traits = std::iterator_traits<Iterator>
#else
class Traits
#endif
> >
struct const_projection_iterator { struct const_projection_iterator_generator {
typedef const_projection_iterator_traits<AdaptableUnaryFunction, typedef const_projection_iterator_traits<AdaptableUnaryFunction,
Traits> Projection_Traits; Traits> Projection_Traits;
typedef iterator_adaptor<Iterator, typedef iterator_adaptor<Iterator,
@ -776,24 +836,19 @@ struct const_projection_iterator {
}; };
template <class AdaptableUnaryFunction, class Iterator, class ConstIterator, template <class AdaptableUnaryFunction, class Iterator, class ConstIterator,
#ifndef BOOST_NO_STD_ITERATOR_TRAITS class Traits = boost::detail::iterator_traits<Iterator>,
class Traits = std::iterator_traits<Iterator>, class ConstTraits = boost::detail::iterator_traits<ConstIterator>
class ConstTraits = std::iterator_traits<ConstIterator>
#else
class Traits,
class ConstTraits
#endif
> >
struct projection_iterators { struct projection_iterator_pair_generator {
typedef projection_iterator_traits<AdaptableUnaryFunction, Traits> typedef projection_iterator_traits<AdaptableUnaryFunction, Traits>
Projection_Traits; Projection_Traits;
typedef const_projection_iterator_traits<AdaptableUnaryFunction, typedef const_projection_iterator_traits<AdaptableUnaryFunction,
ConstTraits> Const_Projection_Traits; ConstTraits> Const_Projection_Traits;
typedef iterator_adaptors<Iterator, ConstIterator, typedef iterator_adaptor_pair_generator<Iterator, ConstIterator,
Projection_Traits, Const_Projection_Traits, Projection_Traits, Const_Projection_Traits,
projection_iterator_policies<AdaptableUnaryFunction> > Adaptors; projection_iterator_policies<AdaptableUnaryFunction> > pair_generator;
typedef typename Adaptors::iterator iterator; typedef typename pair_generator::iterator iterator;
typedef typename Adaptors::const_iterator const_iterator; typedef typename pair_generator::const_iterator const_iterator;
}; };
//============================================================================= //=============================================================================
@ -835,7 +890,7 @@ struct projection_iterators {
class Traits class Traits
#endif #endif
> >
class filter_iterator { class filter_iterator_generator {
typedef filter_iterator_policies<Predicate, Iterator> Policies; typedef filter_iterator_policies<Predicate, Iterator> Policies;
public: public:
typedef iterator_adaptor<Iterator, Policies, Traits> type; typedef iterator_adaptor<Iterator, Policies, Traits> type;