一个用于常量和非常量迭代器的类。有可能吗?

我正在为我的科学软件实现一个带有类似STL的3D网格控件接口的自定义容器。这是关于这个容器的迭代器类的第二个问题。谢谢你帮我 the first

我的问题是 "How do you avoid code duplication when implementing const and non-const iterators?" . 我只是想问是否可以提供 无模板解决方案

迭代器类如下所示:

class spGridIterator {
public:
    typedef forward_iterator_tag iterator_category;
    typedef spGridNode value_type;
    typedef int difference_type;
    typedef spGridNode* pointer;
    typedef spGridNode& reference;

    spGridIterator();
    spGridIterator(spGrid* gr, int index);
    spGridIterator(const spGridIterator& orig);
    virtual ~spGridIterator();

    // STL-ные операторы итератора
    bool operator == ( const spGridIterator& hs ) const {
        return (m_grid == hs.m_grid) && (m_idx == hs.m_idx);
    }

    bool operator != ( const spGridIterator& hs ) const {
        return (m_grid != hs.m_grid) || (m_idx != hs.m_idx);
    }

    // non-const operators
    spGridIterator& operator++();
    spGridIterator& operator++(int);

    reference operator*() const;
    pointer operator->() const { return &(operator*()); }

private:
    spGrid* m_grid;
    int m_idx;
};

还有一个实现。。。

spGridIterator::spGridIterator(spGrid* gr, int index) {
    m_grid = gr;
    m_idx  = index;
}

spGridIterator& spGridIterator::operator++()
{
    int last = m_grid->numpoints;

    if (m_idx < last) {
        m_idx++;
    }
    return *this;
}

spGridIterator& spGridIterator::operator++(int) {
    return operator++();
}

spGridIterator::reference spGridIterator::operator*() const {
    return ( m_grid->GetNode(m_idx) );
}

doctor dobbs article 关于自定义迭代器实现。他们建议实现一个迭代器类模板,并为 value_type .

有没有第三种,也许是“有点老套”的,单类无模板的解决方案?可能提供转换运算符或 operator++() ?

谢谢, 伊利亚