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added filter iterator

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[SVN r8735]
This commit is contained in:
Jeremy Siek
2001-01-23 19:09:30 +00:00
parent c948483ec1
commit 9a4b0b576d
1 changed files with 52 additions and 3 deletions
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55
include/boost/pending/iterator_adaptors.hpp
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@ -130,6 +130,10 @@ struct default_iterator_policies
// and thought they were non-const. Also, Sun C++ does not like static
// function templates.
template <class Iterator>
void initialize(Iterator&)
{ }
template <class Reference, class Iterator>
Reference dereference(type<Reference>, const Iterator& x) const
{ return *x; }
@ -317,13 +321,16 @@ public:
iterator_adaptor() { }
iterator_adaptor(const Iterator& iter, const Policies& p = Policies())
: m_iter_p(iter, p) {}
iterator_adaptor(const Iterator& it, const Policies& p = Policies())
: m_iter_p(it, p) {
policies().initialize(iter());
}
template <class OtherIter, class OtherTraits>
iterator_adaptor (const iterator_adaptor<OtherIter, Policies,
OtherTraits>& src)
: m_iter_p(src.iter(), src.policies()) {
policies().initialize(iter());
}
reference operator*() const {
@ -617,7 +624,7 @@ struct indirect_iterators
//=============================================================================
// Reverse Iterators Adaptor
struct reverse_iterator_policies
struct reverse_iterator_policies : public default_iterator_policies
{
template <class Reference, class Iterator>
Reference dereference(type<Reference>, const Iterator& x) const
@ -778,6 +785,48 @@ struct projection_iterators {
typedef typename Adaptors::const_iterator const_iterator;
};
//=============================================================================
// Filter Iterator Adaptor
template <class Predicate, class Iterator>
class filter_iterator_policies : public default_iterator_policies {
public:
filter_iterator_policies() { }
filter_iterator_policies(const Predicate& p, const Iterator& end)
: m_predicate(p), m_end(end) { }
void initialize(Iterator& x) {
advance(x);
}
void increment(Iterator& x) {
++x;
advance(x);
}
private:
void advance(Iterator& iter)
{
while (m_end != iter && !m_predicate(*iter))
++iter;
}
Predicate m_predicate;
Iterator m_end;
};
template <class Predicate, class Iterator,
#ifndef BOOST_NO_STD_ITERATOR_TRAITS
class Traits = std::iterator_traits<Iterator>
#else
class Traits
#endif
>
class filter_iterator {
typedef filter_iterator_policies<Predicate, Iterator> Policies;
public:
typedef iterator_adaptor<Iterator, Policies, Traits> type;
};
} // namespace boost
#endif