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added new iterator category support to iterator adaptors

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[SVN r609]
This commit is contained in:
Jeremy Siek
2002-10-23 22:55:53 +00:00
parent 73e3961cd5
commit 26f5ac9a55
2 changed files with 63 additions and 28 deletions
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64
include/boost/iterator/iterator_adaptors.hpp
View File

@@ -3,25 +3,24 @@
#include <boost/utility.hpp> // for prior
#include <boost/iterator.hpp>
#include <boost/iterator/iterator_categories.hpp>
namespace boost {
template <class Final, class V, class R, class P, class C, class D>
template <class Final, class V, class R, class P, class RC, class TC, class D>
struct repository
: iterator<C, V, D, P, R>
: iterator<typename cvt_iterator_category<RC, TC>::type, V, D, P, R>
{
typedef Final type;
typedef V value_type;
typedef R reference;
typedef C iterator_category;
typedef D difference_type;
typedef Final final;
typedef RC return_category;
typedef TC traversal_category;
};
template <class Base>
struct downcastable : Base
{
typedef typename Base::type final_t;
typedef typename Base::final final_t;
public:
final_t& downcast() { return static_cast<final_t&>(*this); }
const final_t& downcast() const { return static_cast<const final_t&>(*this); }
@@ -80,16 +79,20 @@ struct iterator_arith : B { };
template <class Base>
typename Base::final operator+(
iterator_arith<Base> i, typename Base::distance n)
const iterator_arith<Base>& i, // pass by ref, not value to avoid slicing -JGS
typename Base::difference_type n)
{
return i.downcast() += n;
typename Base::final tmp(i.downcast());
return tmp += n;
}
template <class Base>
typename Base::final operator+(
typename Base::distance n, iterator_arith<Base> i)
typename Base::difference_type n,
const iterator_arith<Base>& i) // pass by ref, not value to avoid slicing -JGS
{
return i.downcast() += n;
typename Base::final tmp(i.downcast());
return tmp += n;
}
template <class Base1, class Base2>
@@ -102,17 +105,17 @@ typename Base1::difference_type operator-(
template <class Final
, class V, class R, class P, class C, class D
, class V, class R, class P, class RC, class TC, class D
, class B = iterator_arith<
iterator_comparisons<
downcastable<repository<Final, V, R, P, C, D> > > >
iterator_comparisons<
downcastable<repository<Final, V, R, P, RC, TC, D> > > >
>
struct iterator_adaptor : B
struct iterator_adaptor : B, new_iterator_base
{
typedef V value_type;
typedef R reference;
typedef P pointer;
typedef C iterator_category;
typedef typename B::iterator_category iterator_category;
typedef D difference_type;
reference operator*() const
@@ -135,14 +138,25 @@ struct iterator_adaptor : B
Final operator-(difference_type x) const
{ Final result(downcast()); return result -= x; }
template <class Final2, class V2, class R2, class P2>
bool equal(iterator_adaptor<Final2,V2,R2,P2,C,D> const& x) const
template <class Final2, class V2, class R2, class P2, class B2>
bool equal(iterator_adaptor<Final2,V2,R2,P2,RC,TC,D,B2> const& x) const
{
return this->downcast().base() == x.downcast().base();
}
void advance(difference_type n)
{
this->downcast().base() += n;
}
void increment() { ++this->downcast().base(); }
void decrement() { --this->downcast().base(); }
template <class Final2, class B2, class V2, class R2, class P2>
difference_type
distance_from(const iterator_adaptor<Final2,V2,R2,P2,RC,TC,D,B2>& y) const
{
return y.downcast().base() - this->downcast().base();//?
}
private:
using B::downcast;
@@ -150,13 +164,13 @@ struct iterator_adaptor : B
template <class Base,
class V, class R, class P, class C, class D>
class V, class R, class P, class RC, class TC, class D>
struct reverse_iterator
: iterator_adaptor<
reverse_iterator<Base, V, R, P, C, D>, V, R, P, C, D
reverse_iterator<Base, V, R, P, RC, TC, D>, V, R, P, RC, TC, D
>
{
typedef iterator_adaptor<reverse_iterator<Base, V, R, P, C, D>, V, R, P, C, D> super;
typedef iterator_adaptor<reverse_iterator<Base, V, R, P, RC, TC, D>, V, R, P, RC, TC, D> super;
// friend class super;
// hmm, I don't like the next two lines
@@ -171,7 +185,7 @@ struct reverse_iterator
Base const& base() const { return m_base; }
template <class B2, class V2, class R2, class P2>
reverse_iterator(const reverse_iterator<B2,V2,R2,P2,C,D>& y)
reverse_iterator(const reverse_iterator<B2,V2,R2,P2,RC,TC,D>& y)
: m_base(y.m_base) { }
@@ -186,7 +200,7 @@ struct reverse_iterator
template <class B2, class V2, class R2, class P2>
typename super::difference_type
distance_from(const reverse_iterator<B2,V2,R2,P2,C,D>& y) const
distance_from(const reverse_iterator<B2,V2,R2,P2,RC,TC,D>& y) const
{
return m_base - y.m_base;
}
@@ -195,8 +209,6 @@ struct reverse_iterator
};
} // namespace boost

27
include/boost/iterator/iterator_categories.hpp
View File

@@ -12,6 +12,8 @@
#include <boost/type_traits/cv_traits.hpp>
#include <boost/pending/ct_if.hpp>
#include <boost/detail/iterator.hpp>
#include <boost/mpl/if.hpp>
#include <iterator>
namespace boost {
@@ -106,10 +108,10 @@ namespace boost {
bidirectional_traversal_tag,
typename ct_if<
is_convertible<Category*, std::forward_iterator_tag*>::value,
forward_traversal_tag,
forward_traversal_tag,
typename ct_if<
is_convertible<Category*, std::input_iterator_tag*>::value,
input_traversal_tag,
input_traversal_tag,
output_traversal_tag
>::type
>::type
@@ -187,6 +189,27 @@ namespace boost {
#endif
template <class RC, class TC>
struct cvt_iterator_category {
typedef
typename mpl::if_c<(is_convertible<RC*, mutable_lvalue_iterator_tag*>::value
|| is_convertible<RC*, constant_lvalue_iterator_tag*>::value),
typename mpl::if_c<is_convertible<TC*, random_access_traversal_tag*>::value,
std::random_access_iterator_tag,
typename mpl::if_c<is_convertible<TC*, bidirectional_traversal_tag*>::value,
std::bidirectional_iterator_tag,
typename mpl::if_c<is_convertible<TC*, forward_traversal_tag*>::value,
std::forward_iterator_tag,
boost::error_iterator_tag>::type >::type >::type,
typename mpl::if_c<(is_convertible<RC*, readable_iterator_tag*>::value
&& is_convertible<TC*, input_traversal_tag*>::value),
std::input_iterator_tag,
typename mpl::if_c<(is_convertible<RC*, writable_iterator_tag*>::value
&& is_convertible<TC*, output_traversal_tag*>::value),
std::output_iterator_tag,
boost::error_iterator_tag>::type>::type >::type type;
};
} // namespace boost
#endif // BOOST_ITERATOR_CATEGORIES_HPP