class Stream
{
public:
    Stream();

    [...]

    StreamIterator iter()
    {
        return StreamIterator(this);
    }

private:
    class impl;
    std::unique_ptr<impl> pimpl;
};

class StreamFilter
{
public:
    StreamFilter();

    [...]

private:
    class impl;
    std::shared_ptr<impl> pimpl;
};

class StreamIterator
{
public:
    StreamIterator(Stream* streamToFilter);

    [...]

    void addFilter(StreamFilter* filter);
    void removeFilter(StreamFilter* filter);

    [...]

private:
    class impl;
    std::unique_ptr<impl> pimpl;
};

StreamIterator iter = stream.iter();
iter.addFilter(new FilterByOffset([...with parameters...]));
for (auto item : iter)
{
    [...doing something with filtered items...]
}

class StreamIterator
{
public:
    StreamIterator(Stream* streamToFilter);

    [...]

    iterator begin();
    iterator end();

    const_iterator cbegin();
    const_iterator cend();

    [...]

    void addFilter(StreamFilter* filter);
    void removeFilter(StreamFilter* filter);

    [...]

private:
    class impl;
    std::unique_ptr<impl> pimpl;
};