std::map<Key,T,Compare,Allocator>:: map

#include <iomanip>
#include <iostream>
#include <map>
#include <string>
template<typename Key, typename Value, typename Cmp>
std::ostream& operator<<(std::ostream& os, const std::map<Key, Value, Cmp>& map)
{
    os << "{ ";
    for (auto comma{map.size()}; const auto& p : map)
        os << '\'' << p.primero << "' es " << p.second << (--comma ? ", " : " ");
    return os << "}\n";
}
struct Point
{
    double x, y;
    friend std::ostream& operator<<(std::ostream& os, Point pt)
    {
        return os << '(' << pt.x << ", " << pt.y << ')';
    }
};
struct PointCmp
{
    bool operator()(const Point& lhs, const Point& rhs) const
    {
        return lhs.x < rhs.x; // NB: y se ignora intencionalmente
    }
};
int main()
{
    // (1) Constructor predeterminado
    std::map<std::string, int> map1;
    map1["algo"] = 69;
    map1["anything"] = 199;
    map1["esa cosa"] = 50;
    std::cout << "map1 = " << map1;
    // (4) Constructor de rango
    std::map<std::string, int> iter(map1.find("anything"), map1.end());
    std::cout << "\niter = " << iter;
    std::cout << "map1 = " << map1;
    // (6) Constructor de copia
    std::map<std::string, int> copied(map1);
    std::cout << "\ncopied = " << copied;
    std::cout << "map1 = " << map1;
    // (8) Constructor de movimiento
    std::map<std::string, int> moved{std::move(map1)};
    std::cout << "\nmoved = " << moved;
    std::cout << "map1 = " << map1;
    // (10) Constructor de lista de inicializadores
    const std::map<std::string, int> init
    {
        {"this", 100},
        {"puede", 100},
        {"ser", 100},
        {"const", 100}
    };
    std::cout << "\ninit = " << init;
    std::cout << "\nClase Key personalizada opción 1:\n";
    // Usar una estructura de comparación
    std::map<Point, double, PointCmp> mag =
    {
        {{5, -12}, 13},
        {{3, 4}, 5},
        {{-8, -15}, 17}
    };
    std::cout << "mag = " << mag << '\n';
    std::cout << "Opción 2 de clase de clave personalizada:\n";
    // Usar una lambda de comparación
    // Esta lambda ordena puntos según sus magnitudes, donde
    // estas magnitudes se toman de la variable local mag.
    auto cmpLambda = [&mag](const Point& lhs, const Point& rhs)
    {
        return mag[lhs] < mag[rhs];
    };
    // También podrías usar una lambda que no dependa de variables locales, así:
    // auto cmpLambda = [](const Point& lhs, const Point& rhs){ return lhs.y < rhs.y; };
    std::map<Point, double, decltype(cmpLambda)> magy(cmpLambda);
    // Varias formas de insertar elementos:
    magy.insert(std::pair<Point, double>({5, -12}, 13));
    magy.insert({{3, 4}, 5});
    magy.insert({Point{-8.0, -15.0}, 17});    
    std::cout << "magy = " << magy << '\n';
    std::cout << "Construcción desde un rango:\n";
    using PS = std::pair<const std::string, int>;
    const auto rg = {PS{"uno", 1}, {"uno", 101}, {"dos", 2}, {"tres", 3}};
#if __cpp_lib_containers_ranges
    std::map<std::string, int> nums(std::from_range, rg); // sobrecarga (12)
#else
    std::map<std::string, int> nums(rg.begin(), rg.end()); // recurrir a (4)
#endif
    std::cout << "nums = " << nums << '\n';
}