Implement << operator for std basic_ostream and etl string_view

[mike919192]

I recently wanted to print the contents of etl::string_view to std::cout and I realized that there is not yet an overload for the << operator. I decided to experiment with adding the function overload and all seems to be working.

I put the function overload and unit test behind ETL_USING_STL macro. It will not be including in no stl configs. For the unit test I am using std::stringstream variants, but I have also tested with std::cout.

If this is acceptable I would think that the same could be done for etl::string. Let me know of any comments. Thanks

[jwellbelove]

It would probably be better to create overloads of std::ostream << operator for etl::ibasic_string and etl::basic_string_view.

[mike919192]

Sorry I'm not sure what you mean by the comment. std::ostream is a typedef for std::basic_ostream<char>. I implemented the template function so that it can be used with char / wchar_t / etc. That way the function can be used with whatever char type the stream supports.

The definition for the function I added:

template <typename T>
std::basic_ostream<T, std::char_traits<T> > &operator<<(std::basic_ostream<T, std::char_traits<T> > &os, 
                                                        etl::basic_string_view<T, etl::char_traits<T> > text)

[jwellbelove]

Sorry, my mistake.
I've been a bit busy recently and given the pull request my full attention!

[jwellbelove]

Add the overload for etl::ibasic_string<T> and I'll merge the pull request.

[mike919192]

No problem. I will add the same overload for etl::ibasic_string later today.

[mike919192]

Add the overload for etl::ibasic_string<T> and I'll merge the pull request.

It's implemented and I think I have all the tests covered. Let me know if anything is missing.