examples/rust/hello/src/lib.rs

extern crate serde;
extern crate serde_json;

use core::ffi::{c_char, c_int, CStr};
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
struct Person {
    name: String,
    age: u8,
}

fn print_args(argc: c_int, argv: *mut *mut c_char) {
    if argv.is_null() {
        return;
    }

    for i in 1..argc {
        let arg = unsafe { *argv.add(i as usize) };
        if arg.is_null() {
            continue;
        }

        let arg = unsafe { CStr::from_ptr(arg) }.to_string_lossy();
        println!("{}: {}", i, arg);
    }
}

// Function hello_rust_cargo without mangling
#[no_mangle]
pub extern "C" fn hello_rust_cargo_main(argc: c_int, argv: *mut *mut c_char) -> c_int {
    print_args(argc, argv);

    #[cfg(feature = "sim")]
    println!("On simulator");

    let john = Person {
        name: "John".to_string(),
        age: 30,
    };

    let json_str = serde_json::to_string(&john).unwrap();
    println!("{}", json_str);

    let jane = Person {
        name: "Jane".to_string(),
        age: 25,
    };

    let json_str_jane = serde_json::to_string(&jane).unwrap();
    println!("{}", json_str_jane);

    let json_data = r#"
        {
            "name": "Alice",
            "age": 28
        }"#;

    let alice: Person = serde_json::from_str(json_data).unwrap();
    println!("Deserialized: {} is {} years old", alice.name, alice.age);

    let pretty_json_str = serde_json::to_string_pretty(&alice).unwrap();
    println!("Pretty JSON:\n{}", pretty_json_str);

    tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(async {
            println!("Hello world from tokio!");
        });
    0
}