Method alloc

example/http/server/fast/fields_alloc.hpp:65–75

    }

    void*
    alloc(std::size_t n)
    {
        auto last = p_ + n;
        if(last >= end())
            BOOST_THROW_EXCEPTION(std::bad_alloc{});
        ++count_;
        auto p = p_;
        p_ = last;
        return p;
    }

    void
    dealloc()