Example 1: CETL C++20 Polyfill Header

Full example for cetl/pf20/cetlpf.hpp

#include "cetl/pf20/cetlpf.hpp"
#include <iostream>
#include <string>
#include <algorithm>
#include <type_traits>
 
#include <gtest/gtest.h>
 
TEST(example_01_polyfill_20, span_static)
{
std::string            greeting{"Hello Dynamic World."};
 
// the cetl/pf20/cetlpf.hpp header will automatically define cetl::span
// based on the C++ standard available to the compiler. If < 20 then
// it will be the CETL version, if >= 20 then it will be the std version.
cetl::span<const char> dynamic{greeting.c_str(), 13};
auto                   print = [](const char c) { std::cout << c; };
 
// Print just the characters in the span...
std::for_each(dynamic.begin(), dynamic.end(), print);
std::cout << std::endl;
 
// or...
std::string substring{dynamic.begin(), dynamic.end()};
std::cout << substring << std::endl;
}
 
#include "cetl/pf20/span.hpp"
 
namespace
{
//Define these in a header or something...
constexpr std::size_t my_dynamic_extent = cetl::pf20::dynamic_extent;
 
template <typename T, std::size_t Extent = my_dynamic_extent>
using my_span = cetl::pf20::span<T, Extent>;

}// namespace
 
TEST(example_01_polyfill_20, example_01_polyfill_20_span_dynamic)
{
std::string         greeting{"Hello Dynamic World."};
 
// now use my_span instead of cetl::span and you only have one place
// to change to std::span when you upgrade your compiler.
my_span<const char> dynamic{greeting.c_str(), 13};
auto                print = [](const char c) { std::cout << c; };
 
// Print just the characters in the span...
std::for_each(dynamic.begin(), dynamic.end(), print);
std::cout << std::endl;
 
// or...
std::string substring{dynamic.begin(), dynamic.end()};
std::cout << substring << std::endl;

}