cisen / rapidus

JavaScript engine implemented in Rust

Rapidus

JavaScript engine implemented in Rust, now aiming at ES5.

Big thanks to boa.

Rapidus on WASM

On this page, you can try rapidus compiled into WASM on your browser. How amazing, isn't it?

The compiled rapidus on the above page is some commits behind this branch.

Features

• Small
• Partly support for Tracing-JIT compiling
• REPL

Building from Source

Building on Linux

1. Install Rust

Run the command below and follow the onscreen instructions.

curl https://sh.rustup.rs -sSf | sh

2. Use Rust Nightly

rustup override set nightly

3. Install dependencies

• LLVM 6.0
• (Other packages as necessary...)

# e.g. Ubuntu or Debian
apt-get install llvm-6.0

4. Test

cargo test

• If the compilation failed because of LLVM-related errors, the following command may help.

ln -sf /usr/bin/llvm-config-6.0 /usr/bin/llvm-config

5. Build

cargo run --release

6. Run

cargo run --release examples/XXX.js

7. multilined-aware REPL

$ cargo run
> function fact(n) {
... if (n < 2) {     <- recognize multilined input
... return n
... } else {
... return n * fact(n-1)
... }
... }                <- recognize the end of input
undefined
> fact(10)
3628800

8. Debug mode (tracing bytecode execution)

   use --trace option.

$ cargo run -- --trace
> function fibo(x) { if (x<2) return 1; return fibo(x-1)+fibo(x-2)}
00020m 00000 Return                    <empty>
undefined
> fibo(3)
00009m 00000 PushInt8 3                <empty>
00015m 00002 GetValue 'fibo'           3.0
00066m 00007 Call 1                    Function
--> call function
  module_id:0 func_id:0
00007m 00000 GetValue 'x'              <empty>
00001m 00005 PushInt8 2                3.0
00013m 00007 Lt                        2.0

...

00001m 00007 Lt                        2.0
00000m 00008 JmpIfFalse 00016          true
00000m 00013 PushInt8 1                <empty>
00167m 00015 Return                    1.0
<-- return value(1.0)
  module_id:0 func_id:2
00001m 00052 Add                       1.0
00044m 00053 Return                    3.0
<-- return value(3.0)
  module_id:0 func_id:0
00000m 00012 Return                    3.0
3
> 
   |     |     |                        | 
   |     |     |                        \- value at the top of exec stack
   |     |     \-------------------------- instruction
   |     \-------------------------------- program counter
   \-------------------------------------- execution time per inst. (in microsecs)

Building on other platforms

I don't know.

• tips: If you are using macOS, you cannot use llvm installed with brew. You should use macports or docker instead. Now it works!

Use DLLs written in Rust

THIS FEATURE IS EXPERIMENTAL

1. Make a cargo project in the directory rapidus' directory is located

$ cargo new hello --lib
$ ls
rapidus hello

2. Edit Cargo.toml

$ cd hello
$ <YOUR EDITOR> Cargo.toml

# Add the followings to Cargo.toml

[dependencies]
rapidus = { path = "../rapidus" }
# other dependencies if you want...

[lib]
name = "hello"
crate_type = ["cdylib"] # try 'dylib' if it doesn't work.

3. Edit src/lib.rs

$ <YOUR EDITOR> src/lib.rs

// src/lib.rs

#[macro_use]
extern crate rapidus;
use rapidus::{
   gc,
   vm::{callobj::CallObject, error::RuntimeError, value::*, vm::VM},
};

#[no_mangle]
fn initialize(vm: &mut VM, _: &Vec<Value>, _: CallObjectRef) -> Result<(), RuntimeError> {
    // make_object!() is useful
    let module_exports = make_object!(
        greet:   Value::default_builtin_function(greet),
        message: Value::String("hello".to_string())
    );

    vm.set_return_value(module_exports); // We have to return module.exports

    Ok(())
}

#[no_mangle]
fn greet(vm: &mut VM, _: &Vec<Value>, _: CallObjectRef) -> Result<(), RuntimeError> {
    println!("Hello World from Rust DLL!");

    vm.set_return_value(Value::Undefined); // Remember to return a value you want

    Ok(())
}

4. Let's build

$ cargo build # --release as necessary

5. Copy the generated DLL to rapidus' directory

$ cp ./target/debug/libhello.(so|dll|dylib) ../rapidus
$ cd ../rapidus
$ ls
libhello.(so|dll|dylib) etc...

6. You're ready to use it from rapidus. Let's try from REPL.

$ cargo run
> var mod = require('hello')
> mod.greet()
Hello World from Rust DLL!
> mod.message
'hello'

7. Now everything can be possible from Rust!