nodeluna

joined 9 months ago
[–] nodeluna@programming.dev 2 points 1 month ago* (last edited 1 month ago)

alright then.

I see. expected is such a great library to have regardless of the standard version. oh c++03, I'm not familiar with that standard.

I enabled support for c++11 regardless, it's kinda cool to do so

[–] nodeluna@programming.dev 2 points 1 month ago (2 children)

ikr, constexpr is pretty cool. sure, no problem. I could make it fully compatible with c++14 without c++17 extensions if u wanna use it with c++14

[–] nodeluna@programming.dev 1 points 1 month ago

what don't u get it? why did I make this? or what is the point of this type?

if you are unfamiliar with std::expected then check out https://en.cppreference.com/w/cpp/utility/expected.html

it's basically a type that let you return either a "value" or an "error" and the caller of the function has to check which did the function return. it's a modern way of handling errors in C++ that was introduced in C++23

[–] nodeluna@programming.dev 2 points 1 month ago* (last edited 1 month ago) (4 children)

because "if constexpr(...)" is a c++17 feature which i'm using it to allow usage of nl::unexpected() to return a nl::expected<nl::monostate, E> to nl::expected<T, E> in this copy constructor

template<class U>
expected(const expected<U, E>& other) : _has_value(other.has_value())   // a copy constructor  
{
        if (_has_value)
        {
                if constexpr (std::is_same<U, monostate>::value) // it checks if U == monostate
                {
                        // makes an empty instance of "T"
                }
                else if constexpr (std::is_same<U, T>::value) // it checks if U == T
                {
                        // otherwise copies "other._value" into _value
                }
                else
                {
                        static_assert(
                            not std::is_same<U, T>::value, "no available conversion between the provided value types");
                }
        }
        else
        {
                new (std::addressof(_error)) E(other.error());
        }
}

 template<class E>
 expected<monostate, E> unexpected(const E& e) // then this can covert <monostate, E> to <T, E> fine because of this copy constructor
 {                
         return expected<monostate, E>(e);
 }


// example usage

nl::expected<int, std::string> meow = nl::unexpected("error");

but i could take a different approach and make 2 copy constructor one that explicitly takes

expected(const expected<monostate, E>& other)

and another

expected(const expected& other)

I was also using "std::is_same_v" which is a c++17 feature instead "std::is_same<>::value" but i made a commit and changed it. it now compiles with c++14 but with c++17 extensions

[–] nodeluna@programming.dev 2 points 1 month ago

you can constrain functions with c++20 concepts to ensure the compiler is calling the correct function if you're that worried

[–] nodeluna@programming.dev 1 points 1 month ago* (last edited 1 month ago)

** AI GENERATED SHOWCASE THAT'S REVIEWED BY ME **

Here are some cool and advanced features of the ljson library, with short code snippets for each:

  1. Seamless Construction from C++ Containers

You can build JSON objects and arrays directly from standard containers (e.g., std::map, std::vector, std::set, etc.): C++

std::map<std::string, int> obj = {{"a", 1}, {"b", 2}};
std::vector<std::string> arr = {"x", "y", "z"};
ljson::node data;
data.insert("object", obj);
data.insert("array", arr);
  1. Initializer-List Magic (Python/JavaScript-like Syntax)
ljson::node n = {
    {"name", "Alice"},
    {"age", 30},
    {"active", true},
    {"tags", ljson::node({"dev", "cat_lover"})},
    {"profile", ljson::node({{"city", "Paris"}, {"zip", 75000}})}
};
// n is now a JSON object with nested objects and arrays!
  1. Type-Safe Value Accessors and Type Queries
if (n.at("age").is_integer())
    std::cout << "Age: " << n.at("age").as_integer() << "\n";
if (n.at("tags").is_array()) {
    for (auto& tag : *n.at("tags").as_array())
        std::cout << tag.as_string() << " ";
}
  1. Type-Safe Mutation and Assignment
n.at("name") = "Bob";      // changes value to "Bob"
n.at("age")  = 31;         // changes value to 31
n.at("active") = false;    // changes value to false
n.at("tags").push_back("gamer"); // add "gamer" to tags array
  1. Exception-Free Parsing (Error Handling Without throw)
auto result = ljson::parser::try_parse(R"({"x":1})");
if (result) {
    std::cout << "Parsed!\n";
} else {
    std::cerr << "Parse error: " << result.error().message() << "\n";
}
  1. Pretty Printing and File Output with Custom Indentation
n.dump_to_stdout({'\t', 2});         // Pretty print using tabs, 2 per indent
n.write_to_file("output.json");       // Write to file
std::string s = n.dump_to_string();   // Get pretty JSON string
  1. Operator Overloading for JSON Merge and Addition

Concatenate arrays and objects in a natural way:

ljson::node a = {1, 2, 3};
ljson::node b = {4, 5};
ljson::node c = a + b; // [1,2,3,4,5]

ljson::node obj1 = {{"x", 1}};
ljson::node obj2 = {{"y", 2}};
ljson::node obj3 = obj1 + obj2; // {"x":1,"y":2}
  1. Automatic Null Support
n.insert("nothing", ljson::null);
if (n.at("nothing").is_null())
    std::cout << "It's " << n.at("nothing").stringify() << "!\n"; // It's null!
  1. Direct Construction from Nested Initializer Lists
ljson::node arr = { 1, 2, 3, ljson::node({"nested", "array"}), ljson::null };
ljson::node obj = { {"a", 1}, {"b", ljson::node({2, 3, 4})}, {"c", ljson::node({"d", 5})} };
  1. Safe and Direct Value Setting and Mutation

You can set a node's value using .set() or assignment:

n.at("val").set(123.45);
n.at("flag") = true;
n.at("sub").insert("newkey", "newval");
  1. Full Traversal and Iteration Support
// Iterating an array
for (auto& item : *n.at("tags").as_array())
    std::cout << item.as_string() << "\n";

// Iterating an object
for (auto& [key, value] : *n.as_object())
    std::cout << key << ": " << value.stringify() << "\n";
  1. Type-Checked Try-Cast APIs

Get error info if you try an invalid conversion:

auto res = n.at("name").try_as_integer();
if (!res) std::cerr << "Not an integer: " << res.error().message() << "\n";
  1. Flexible Construction from Arbitrary Types

Any supported type (string, int, bool, null, etc.) or nested containers can be used directly in construction or insertion.

  1. Custom Indentation Everywhere
n.dump_to_stdout({' ', 8}); // 8 spaces per indent
  1. Chaining Insertions and Additions
ljson::node obj = {
    {"a", 1},
    {"b", 2}
};
obj += ljson::object_pairs{
    {"c", 3},
    {"d", 4}
};

Summary: ljson offers a modern, expressive, and type-safe C++ JSON API with C++ types, safety, and STL integration.

[–] nodeluna@programming.dev 2 points 1 month ago* (last edited 1 month ago)

thank you! if someone wants a more modern API that's kinda similar to tomlplusplus and a little nicer to use with modern error handling then my library might come in handy. my API is inspired a lot by tomlplusplus . i was trying to make a build system that uses TOML as a config file and I needed a json library so i decided to make my own as a learning experience which was great.

I'm not familiar with simdjson, but i know a little about nlohmann and I think the exception free path using ljson::expected is a nicer/safer approach. also there is convenient operator overloads in my library to add objects/array together, but nlohmann also has that i think

// accessing values in ljson
ljson::node node = ljson::parser::parse(raw_json);
std::string val = node.at("key").as_string();

// accessing values in nlohmann
nlohmann::json::json json;
raw_json >> json;
std::string val = json["key"].get<std::string>();

9
safe enum (programming.dev)
submitted 1 month ago* (last edited 1 month ago) by nodeluna@programming.dev to c/cpp@programming.dev
 

for anyone who doesn't know, this "-Werror=switch-enum" compiler option make the compiler throw an error if all of the enum values aren't explicitly handled in a "switch" statement


enum class colors {
        blue,
        red,
        purple,
}

void func(colors c)
{
        switch(c)
        {
                case colors::blue:
                        // do something
                        break;
                case colors::red:
                        // do something
                        break;
                default:
                        // do something
                        break;
        }
}


int main()
{
        func(colors::blue);
}

this code doesn't compile on clang and gcc with the option "-Werror=switch-enum" because the "colors::purple" isn't explicitly handled. be aware that it doesn't throw a compiler error for "if" statements if one of the values isn't handled

[–] nodeluna@programming.dev 1 points 1 month ago

I'm so excited for C++26

 

It's not fully finished yet, but it's getting there, and i didn't write documentation beyond the README.md and tests/test.cpp but I'd like some feedback on it.

features

  • It's a header only library that's currently < 3000 loc
  • no 3rd-party dependencies
  • support for being imported as a module
  • supports inserting std containers into json nodes
  • highly type safe, which is made possible by using concepts
  • easy-to-use object/array iterations
  • easy-to-use type casting from json value to native c++ types which is enabled by std::variant and concepts
  • exception-free parsing and value casting.
  • modern error handling using "expected" type
  • exception-free node.try_at("key") access
  • and more

edit:

documentation link: https://nodeluna.github.io/ljson

 
[–] nodeluna@programming.dev 2 points 9 months ago (1 children)

cool! thanks for letting me know, i'll try to keep an eye on it

[–] nodeluna@programming.dev 2 points 9 months ago* (last edited 9 months ago) (3 children)

very fancy and nice to use. i see

I searched for a River socket or riverctl command that would allow me to get the active workspace number, but i couldn't find a way for that currently in River. so i can't implement it for River not currently at least. unless maybe someone knows a way to get that info who could refer me to the documentation

 

it works on hyprland, sway or qtile and it uses swww to change the backgroud

aur: https://aur.archlinux.org/packages/lunawp

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