boost/iterator/filter_iterator.hpp
// (C) Copyright David Abrahams 2002.
// (C) Copyright Jeremy Siek 2002.
// (C) Copyright Thomas Witt 2002.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_FILTER_ITERATOR_23022003THW_HPP
#define BOOST_FILTER_ITERATOR_23022003THW_HPP
#include <boost/iterator.hpp>
#include <boost/iterator/iterator_adaptor.hpp>
#include <boost/iterator/iterator_categories.hpp>
#include <boost/type_traits/is_class.hpp>
#include <boost/static_assert.hpp>
namespace boost {
namespace iterators {
template <class Predicate, class Iterator>
class filter_iterator;
namespace detail
{
template <class Predicate, class Iterator>
struct filter_iterator_base
{
typedef iterator_adaptor<
filter_iterator<Predicate, Iterator>
, Iterator
, use_default
, typename mpl::if_<
is_convertible<
typename iterator_traversal<Iterator>::type
, random_access_traversal_tag
>
, bidirectional_traversal_tag
, use_default
>::type
> type;
};
}
template <class Predicate, class Iterator>
class filter_iterator
: public detail::filter_iterator_base<Predicate, Iterator>::type
{
typedef typename detail::filter_iterator_base<
Predicate, Iterator
>::type super_t;
friend class iterator_core_access;
public:
filter_iterator() { }
filter_iterator(Predicate f, Iterator x, Iterator end_ = Iterator())
: super_t(x), m_predicate(f), m_end(end_)
{
satisfy_predicate();
}
filter_iterator(Iterator x, Iterator end_ = Iterator())
: super_t(x), m_predicate(), m_end(end_)
{
// Pro8 is a little too aggressive about instantiating the
// body of this function.
#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
// Don't allow use of this constructor if Predicate is a
// function pointer type, since it will be 0.
BOOST_STATIC_ASSERT(is_class<Predicate>::value);
#endif
satisfy_predicate();
}
template<class OtherIterator>
filter_iterator(
filter_iterator<Predicate, OtherIterator> const& t
, typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
)
: super_t(t.base()), m_predicate(t.predicate()), m_end(t.end()) {}
Predicate predicate() const { return m_predicate; }
Iterator end() const { return m_end; }
private:
void increment()
{
++(this->base_reference());
satisfy_predicate();
}
void decrement()
{
while(!this->m_predicate(*--(this->base_reference()))){};
}
void satisfy_predicate()
{
while (this->base() != this->m_end && !this->m_predicate(*this->base()))
++(this->base_reference());
}
// Probably should be the initial base class so it can be
// optimized away via EBO if it is an empty class.
Predicate m_predicate;
Iterator m_end;
};
template <class Predicate, class Iterator>
inline filter_iterator<Predicate,Iterator>
make_filter_iterator(Predicate f, Iterator x, Iterator end = Iterator())
{
return filter_iterator<Predicate,Iterator>(f,x,end);
}
template <class Predicate, class Iterator>
inline filter_iterator<Predicate,Iterator>
make_filter_iterator(
typename iterators::enable_if<
is_class<Predicate>
, Iterator
>::type x
, Iterator end = Iterator())
{
return filter_iterator<Predicate,Iterator>(x,end);
}
} // namespace iterators
using iterators::filter_iterator;
using iterators::make_filter_iterator;
} // namespace boost
#endif // BOOST_FILTER_ITERATOR_23022003THW_HPP