I’m writing filter and map algorithms using boost::range library:
template <class Range> struct Converter
{
Converter(const Range& p_range) : m_range(p_range) {}
template<class OutContainer> operator OutContainer() const
{
return {m_range.begin(), m_range.end()};
}
private:
Range m_range;
};
template<class Range> Converter<Range> convert(const Range& p_range) { return {p_range}; }
template<class Range, class Fun> auto map(Range&& p_range, Fun&& p_fun)
{
return convert(p_range | boost::adaptors::transformed(p_fun));
}
template<class Range, class Pred> auto filter(Range&& p_range, Pred&& p_pred)
{
return convert(p_range | boost::adaptors::filtered(p_pred));
}
Right now I can use them like this:
std::vector<int> l_in = {1, 2, 3, 4, 5};
std::vector<int> l_tmp_out = filter(l_in, [](int p){ return p < 4; });
std::vector<int> l_out = map(l_tmp_out, [](int p){ return p + 5; });
I would also like to write code this way:
map(filter(l_in, [](int p){ return p < 4; }), [](int p){ return p + 5; });
Unfortunately my Converter class does not compose with boost::range algorithms so this example does not compile. I'm looking for a proper way to change that.
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