Neat! Could you expand on why someone might prefer to use this instead of other json parsing libs such as nlohmann or simdjson?
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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>();
** 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:
- 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);
- 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!
- 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() << " ";
}
- 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
- 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";
}
- 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
- 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}
- 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!
- 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})} };
- 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");
- 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";
- 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";
- Flexible Construction from Arbitrary Types
Any supported type (string, int, bool, null, etc.) or nested containers can be used directly in construction or insertion.
- Custom Indentation Everywhere
n.dump_to_stdout({' ', 8}); // 8 spaces per indent
- 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.