Nova

Small, embeddable scripting language for Rust no_std programs.

Features:

• Supports ints, bools, static strings, while loops, if/else, function definitions
• Modules allow calling Rust code from a script (with automatic generation of bindings)
• Small binary size: <25KB without default features
• No heap allocations (except for allocation of the VmContext itself)
• The implementation limits all resources of the language (adjustable via generic parameters)

Example

Simple fibonacci example:

let mut vm: VmContext<'_, '_> = VmContext::new(
	br#"fn fib(n) {
		if n <= 1 {
			return n;
		} else {
			return fib(n - 1) + fib(n - 2);
		}
	}
	result = fib(10);
	"#,
);
vm.run().expect("Running VM with Fibonacci function");

let variable = vm.get_var(b"result").unwrap();
let result: i32 = FromEngine::from_engine(variable).unwrap();
assert_eq!(result, 55);

Module example - bindings are automatically generated by macros:

// Note: only pub attributes / functions are exposed to the script!

#[engine_module]
struct MathModule {
	// Read-only access to values; may be modified by functions
	pub CONSTANT: u32
}

#[script_module]
impl MathModule {
	// All parameter and return types must implement the FromEngine/ToEngine traits
    pub fn add(&self, a: i32, b: i32) -> i32 {
        a + b
    }
}

use nova::FromEngine;
let mut math = MathModule { CONSTANT: 41 };
let mut vm: VmContext<'_, '_> = VmContext::new(
	br#"
	import math;
	i = math.add(1, math.CONSTANT);
"#,
)
.add_module(b"math", &mut math)
.unwrap();
vm.run().unwrap();

let variable = vm.get_var(b"i").unwrap();
let result: i32 = FromEngine::from_engine(variable).unwrap();
assert_eq!(result, 42);

Installation

Add this to your Cargo.toml file:

nova = { git = "ssh://git@github.com/xarantolus/nova-lang.git", default-features = false }

If you want to print errors returned from the interpreter, enable the detailed_errors (or just remove default-features = false).

Fuzzing

Any kind of panic is considered a bug, so we try to find things via fuzzing.

You can install fuzzing tools with this command:

cargo install cargo-fuzz grcov

Run fuzzing:

make fuzz