//********************************************************
// The following code example is taken from the book
//  C++23 - The Complete Guide
//  by Nicolai M. Josuttis (www.josuttis.com)
//  https://www.cppstd23.com
//
// The code is licensed under a
//  Creative Commons Attribution 4.0 International License
//  https://creativecommons.org/licenses/by/4.0/
//********************************************************


#include <print>
#include <vector>
#include <cmath>
#include <ranges>

int main()
{
  std::vector coll{1, 2, 3, 4};
  coll.reserve(100);
  auto allEvenOrOdd = [] (auto x, auto y) { 
    return std::abs(x % 2) == std::abs(y % 2); 
  };

  // initialize views:
  auto v1 = coll | std::views::chunk_by(std::less{});
  auto v2 = coll | std::views::chunk_by(allEvenOrOdd);

  // apply views:
  std::println("coll:       {} =>", coll);
  std::println("  less:     {}", v1);
  std::println("  even/odd: {}\n", v2);

  // modify underlying range:
  coll.insert(coll.begin(), -1);

  // apply views again:
  std::println("modified:   {} =>", coll);
  std::println("  less:     {}", v1);
  std::println("  even/odd: {}\n", v2);

  // create new views and apply them:
  auto coll2 = coll;
  auto v3 = coll | std::views::chunk_by(std::less{});
  auto v4 = coll | std::views::chunk_by(allEvenOrOdd);
  std::println("new views:  {} =>", coll);
  std::println("  less:     {}", v3);
  std::println("  even/odd: {}\n", v4);
}