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turbonss/cxxmph/hollow_iterator.h

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#ifndef __CXXMPH_HOLLOW_ITERATOR_H__
#define __CXXMPH_HOLLOW_ITERATOR_H__
#include <vector>
namespace cxxmph {
template <typename container_type, typename presence_type, typename iterator_type>
struct hollow_iterator_base
: public std::iterator<std::forward_iterator_tag,
typename container_type::value_type> {
typedef presence_type presence;
typedef container_type container;
typedef iterator_type iterator;
typedef hollow_iterator_base<container, presence, iterator>& self_reference;
typedef typename iterator::reference reference;
typedef typename iterator::pointer pointer;
hollow_iterator_base(container* c, presence* p, iterator it)
: c_(c), p_(p), it_(it) { if (c_) find_present(); }
self_reference operator++() {
++it_; find_present();
}
reference operator*() { return *it_; }
pointer operator->() { return &(*it_); }
// TODO find syntax to make this less permissible at compile time
template <class T>
bool operator==(const T& rhs) { return rhs.it_ == this->it_; }
template <class T>
bool operator!=(const T& rhs) { return rhs.it_ != this->it_; }
public: // TODO find syntax to make this friend of const iterator
void find_present() {
while (it_ != c_->end() && !((*p_)[it_-c_->begin()])) ++it_;
}
container* c_;
presence* p_;
iterator it_;
};
template <typename container_type>
struct hollow_iterator : public hollow_iterator_base<
container_type, std::vector<bool>, typename container_type::iterator> {
typedef hollow_iterator_base<
container_type, std::vector<bool>, typename container_type::iterator> parent_class;
hollow_iterator() : parent_class(NULL, NULL, typename container_type::iterator()) { }
hollow_iterator(typename parent_class::container* c,
typename parent_class::presence* p,
typename parent_class::iterator it)
: parent_class(c, p, it) { }
};
template <typename container_type>
struct hollow_const_iterator : public hollow_iterator_base<
const container_type, const std::vector<bool>, typename container_type::const_iterator> {
typedef hollow_iterator_base<
const container_type, const std::vector<bool>, typename container_type::const_iterator> parent_class;
typedef hollow_const_iterator<container_type> self_type;
typedef hollow_iterator<container_type> non_const_type;
hollow_const_iterator(non_const_type rhs) : parent_class(rhs.c_, rhs.p_, typename container_type::const_iterator(rhs.it_)) { }
hollow_const_iterator() : parent_class(NULL, NULL, typename container_type::iterator()) { }
hollow_const_iterator(const typename parent_class::container* c,
const typename parent_class::presence* p,
typename parent_class::iterator it)
: parent_class(c, p, it) { }
};
} // namespace cxxmph
#endif // __CXXMPH_HOLLOW_ITERATOR_H__