//********************************************************
// The following code example is taken from the book
//  C++20 - The Complete Guide
//  by Nicolai M. Josuttis (www.josuttis.com)
//  http://www.cppstd20.com
//
// The code is licensed under a
//  Creative Commons Attribution 4.0 International License
//  http://creativecommons.org/licenses/by/4.0/
//********************************************************


#include <iostream>
#include <string>
#include <array>
#include <cassert>
#include "asstring.hpp"

// function template to export a compile-time string to runtime:
template<int MaxSize>
consteval auto toRuntimeString(std::string s)
{
  // ensure the size of the exported array is large enough:
  assert(s.size() <= MaxSize);

  // create a compile-time array and copy all characters into it: 
  std::array<char, MaxSize+1> arr{};  // ensure all elems are initialized
  for (int i = 0; i < s.size(); ++i) {
    arr[i] = s[i];
  }

  // return the compile-time array and the string size:
  return std::pair{arr, s.size()};
}

// function to import an exported compile-time string at runtime:
std::string fromComptimeString(const auto& dataAndSize)
{
  // init string with exported array of chars and size:
  return std::string{dataAndSize.first.data(),
                     dataAndSize.second};
}

// test the functions:
consteval auto comptimeMaxStr()
{
  std::string s = "max int is " + asString(std::numeric_limits<int>::max())
                  + " (" + asString(std::numeric_limits<int>::digits + 1)
                  + " bits)";

  return toRuntimeString<100>(s);
}

int main()
{
  std::string s = fromComptimeString(comptimeMaxStr());
  std::cout << s << '\n';
}