Let's see how we can implement a simple pipe operator so that we can write the following:
auto numbers = std::vector<int>{1, 3, 5, 7, 9};
auto seven = 7;
bool has_seven = numbers | contains(seven);
The contains function used with a pipeable syntax has two arguments: numbers and seven. As the left argument, numbers could be anything; we need the overload to contain something unique on the right side.
So, we create a struct named ContainsProxy, which holds onto the right argument; this way, the overloaded pipe operator can recognize the overload:
template <typename T>struct ContainsProxy { const T& value_; };template <typename Range, typename T>auto operator|(const Range& r, const ContainsProxy<T>& proxy) { const auto& v ...
