Iterators.h

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#pragma once
 
#include <functional>
#include <utility>
 
namespace ogdf {
namespace internal {
namespace gcm {
 
namespace datastructure {
template<typename Iterator>
class FilterIterator {
protected:
    Iterator m_begin;
    Iterator m_cur;
    Iterator m_end;
    const std::function<bool(const typename Iterator::T)> m_predicate;
 
public:
    using T = typename Iterator::T;
 
    FilterIterator(Iterator begin, Iterator end,
            const std::function<bool(const typename Iterator::T)>& _predicate)
        : m_begin(std::move(begin))
        , m_cur(m_begin)
        , m_end(std::move(end))
        , m_predicate(std::move(_predicate)) {
        if (m_cur != m_end && !m_predicate(*m_cur)) {
            ++(*this);
        }
        // nothing to do
    }
 
    FilterIterator<Iterator>& operator--() {
        do {
            --m_cur;
        } while (m_cur != m_begin && !m_predicate(*m_cur));
        return *this;
    }
 
    FilterIterator<Iterator>& operator++() {
        do {
            ++m_cur;
        } while (m_cur != m_end && !m_predicate(*m_cur));
        return *this;
    }
 
    bool operator==(const FilterIterator<Iterator>& b) const { return m_cur == b.m_cur; }
 
    bool operator!=(const FilterIterator<Iterator>& b) const { return m_cur != b.m_cur; }
 
    T operator*() {
        if (m_cur != m_end && !m_predicate(*m_cur)) {
            ++(*this);
        }
        return *m_cur;
    }
};
 
template<typename Iterator>
class IteratorRange {
private:
    Iterator m_begin;
    Iterator m_end;
 
public:
    IteratorRange(Iterator begin, Iterator end) : m_begin(begin), m_end(end) { }
 
    Iterator begin() { return m_begin; }
 
    Iterator end() { return m_end; }
};
 
 
}
 
}
}
}