ohos-node-bindgen
Easy way to write native Node.js module using idiomatic Rust
## 兼容华为鸿蒙`ArkTS N-API`
### 如何实现兼容
在原作者伟大作品的基础上，我做了三项工作使`node-bindgen`支持华为鸿蒙`ArkTS N-API`开发
1. 将封装了[nodejs N-API](https://nodejs.org/dist/latest/docs/api/addons.html)的内部子工程`nj-sys`·替换为·包装了【鸿蒙`ArkTS N-API`】的外部依赖项[oh-napi-sys](https://gitee.com/zr233/oh-napi)。
1. 一方面，`node-bindgen`原作者的代码设计非常科学合理，所以对核心模块`*-sys crate`的替换工作很省心。
2. 另一方面，【鸿蒙`ArkTS N-API`】与`nodejs N-API`的相似度极高。所以，模块替换后的适配工作量少之又少。
2. 添加【编译条件】 — 这算是一处适配点
1. 原因：【`C`无符号长整类型`unsigned long`】在鸿蒙`armv7`架构上是`32bit`，而在鸿蒙`aarch64`与`x86_64`架构上却是`64bit`。所以，若既不搞【条件编译】又不预备多套代码，那么`rustc`就会交叉编译失败。感谢`Rust`的【条件编译】语言支持，让`Cpp`开发都哭去吧！
2. 打广告了：在该基建之上做鸿蒙`ArkTS N-API`开发的中国同胞们就不用再分心考虑这类【架构差异】的技术细节了。这些破事实在太糟心！
3. 修改包名从`node-bindgen`至`ohos-node-bindgen`。
就目前而言，【鸿蒙`ArkTS N-API`】与`nodejs N-API`大约是`95%`相似。但是，我相信随着【鸿蒙操作系统】的后续发展，`ArkTS N-API`会引入越来越多与外国同类产品（比如，`nodejs / Deno`）不同的内容。
### `ohos-node-bindgen`用法
新/旧用法差异不在代码调用，而全部集中于`Cargo.toml`工程配置中
1. 不再需要向`[build-dependencies]`配置表添加`node-bindgen = { version = "6.0", default-features = false, features = ["build"] }`依赖项了，因为【编译时链接】已完全委托给外部依赖项[oh-napi-sys](https://gitee.com/zr233/oh-napi)完成了。
2. 输出链接库的编码格式不再是`cdylib`，而是`dylib`。即，
```toml
[lib]
crate-type = ["dylib"]
```
### `ohos-node-bindgen`还不能被直接使用
起因是`ohos-node-bindgen`的间接依赖项`socket2 v0.4.10`不兼容【华为鸿蒙操作系统】（— 别急，有得解）。依赖图如下
```shell
socket2 v0.4.10
├── async-io v1.13.0
│ ├── async-std v1.12.0
│ │ └── fluvio-future v0.6.2
│ │ └── nj-core v6.0.1
│ │ └── ohos-node-bindgen v6.0.2
```
虽然依赖“血缘”关系隔了**四层**之远，但它仍会阻塞交叉编译。我亲测的解决方案：
1. 【我已做，大家不用做】我已经`fork`了[socket2@0.4.x](https://github.com/rust-lang/socket2/tree/v0.4.x)分支，并解了其对【华为鸿蒙操作系统】的兼容缺陷。所以，
2. 大家直接克隆我的[`fork`版本](https://github.com/stuartZhang/socket2/tree/v0.4.x)至本地硬盘，和切分支至`v0.4.x`
```shell
git clone git@github.com:stuartZhang/socket2.git
git checkout v0.4.x
```
3. 重写（`Override`）调用端工程的【依赖图】，以指示`Cargo`优先加载本地的`socket2:0.4.10`依赖项，而不是从`crates.io`下载。即，向`Cargo.toml`文件增补如下配置表
```toml
[dependencies]
socket2 = "0.4.10"
[patch.crates-io]
socket2 = { path = "<指向 socket2 本地克隆复本的完整路径>" }
```
然后，就能绕过线上的残次`socket2 crate`和成功交叉编译了。
## Features
- __Easy:__ Just write idiomatic Rust code, node-bindgen take care of generating Node.js FFI wrapper codes.
- __Safe:__ Node.js arguments are checked automatically based on Rust types.
- __Async:__ Support Async Rust. Async codes are translated into Node.js promises.
- __Class:__ Rust struct can be accessed using Node.js classes.
- __Stream:__ Implement Node.js stream using Rust
- __N-API:__ Use Node.js N-API, which means you don't have to recompile your module.
# Compatibility with Node.js version
This project uses the v8 of Node N-API. Please see following [compatibility](https://nodejs.org/api/n-api.html#n_api_n_api_version_matrix) matrix.
Following OS are supported:
* Linux
* MacOs
* Windows
# Why node-bindgen?
Writing native node-js requires lots of boilerplate code. Node-bindgen generates external "C" glue code from rust code, including native module registration. node-bindgen make it writing node-js module easy and fun.
# Getting started
## CLI Installation
Install nj-cli command line, which will be used to generate the native library.
```
cargo install nj-cli
```
This is a one time step.
## Configuring Cargo.toml
Add two dependencies to your projects' ```Cargo.toml```.
Add ```node-bindgen``` as a regular dependency (as below):
```
[dependencies]
node-bindgen = { version = "6.0" }
```
Then update crate type to ```dylib``` to generate node.js compatible native module:
```
[lib]
crate-type = ["dylib"]
```
Finally, add ```build.rs``` at the top of the project with following content:
```
fn main() {
ohos_node_bindgen::build::configure();
}
```
# Example
Here is a function that adds two numbers. Note that you don't need to worry about JS conversion.
```rust
use ohos_node_bindgen::derive::node_bindgen;
/// add two integer
#[ohos_node_bindgen]
fn sum(first: i32, second: i32) -> i32 {
first + second
}
```
## Building native library
To build node.js library, using ```nj-cli``` to build:
```
nj-cli build
```
This will generate Node.js module in "./dist" folder.
To build a release version:
```
nj-cli build --release
```
## Watching `./src` for Changes
While developing your native module, you may want to watch for file changes and run a command when a change occurs, for example `cargo check` or `cargo build`.
For this, we can use `nj-cli watch`.
`nj-cli watch` installs [if it does not exist] and passes arguments to [`cargo watch`](https://crates.io/crates/cargo-watch). By default, `nj-cli watch` will run `cargo check` against your `./src` files.
To see all available methods for `nj-cli watch`, run the following command:
> `nj-cli watch -- --help`
## Using in Node.js
Then in the Node.js, rust function can be invoked as normal node.js function:
```js
$ node
Welcome to Node.js v18.18.0.
Type ".help" for more information.
> let addon = require('./dist');
undefined
> addon.sum(2,3)
5
>
```
# Features
## Function name or method can be renamed instead of default mapping
```rust
#[node_bindgen(name="multiply")]
fn mul(first: i32,second: i32) -> i32 {
first * second
}
```
Rust function mul is re-mapped as ```multiply```
## Optional argument
Argument can be skipped if it is marked as optional
```rust
#[ohos_node_bindgen]
fn sum(first: i32, second: Option) -> i32 {
first + second.unwrap_or(0)
}
```
Then sum can be invoked as
```sum(10)``` or ```sum(10,20)```
## Callback
JS callback are mapped as Rust closure.
```rust
#[ohos_node_bindgen]
fn hello(first: f64, second: F) {
let msg = format!("argument is: {}", first);
second(msg);
}
```
from node:
```js
let addon = require('./dist');
addon.hello(2,function(msg){
assert.equal(msg,"argument is: 2");
console.log(msg); // print out argument is 2
});
```
Callback are supported in Async rust as well.
## Support for Async Rust
Async rust function is mapped to Node.js promise.
```rust
use std::time::Duration;
use flv_future_aio::time::sleep;
use ohos_node_bindgen::derive::node_bindgen;
#[ohos_node_bindgen]
async fn hello(arg: f64) -> f64 {
println!("sleeping");
sleep(Duration::from_secs(1)).await;
println!("woke and adding 10.0");
arg + 10.0
}
```
```js
let addon = require('./dist');
addon.hello(5).then((val) => {
console.log("future value is %s",val);
});
```
## Struct serialization
Structs, including generic structs, can have have the to-JS conversion boilerplate autogenerated.
Just apply the `node_bindgen` macro to your struct:
```rust
#[ohos_node_bindgen]
struct MyJson {
some_name: String,
a_number: i64
}
#[ohos_node_bindgen]
fn my_json() -> MyJson {
MyJson {
some_name: "John".to_owned(),
a_number: 1337
}
}
```
```js
let addon = require('./dist');
assert.deepStrictEqual(addon.my_json(), {
someName: "John",
aNumber: 1337
});
```
Note that the fields must implement
`ohos_node_bindgen::core::TryIntoJs` themselves.
Any references must also implement `Clone`.
Field names will be converted to camelCase.
## Enums
Enums will also have their JS representation autogenerated with the help of `ohos_node_bindgen`:
```rust
#[ohos_node_bindgen]
enum ErrorType {
WithMessage(String, usize),
WithFields {
val: usize
},
UnitErrorType
}
#[ohos_node_bindgen]
fn with_message() -> ErrorType {
ErrorType::WithMessage("test".to_owned(), 321)
}
#[ohos_node_bindgen]
fn with_fields() -> ErrorType {
ErrorType::WithFields {
val: 123
}
}
#[ohos_node_bindgen]
fn with_unit() -> ErrorType {
ErrorType::UnitErrorType
}
```
```js
assert.deepStrictEqual(addon.withMessage(), {
withMessage: ["test", 321n]
});
assert.deepStrictEqual(addon.withFields(), {
withFields: {
val: 123n
}
});
assert.deepStrictEqual(addon.withUnit(), "UnitErrorType")
```
Tuple variants will be converted into lists, struct variants converted to objects, and unit variants converted into strings matching the variant's name in PascalCase.
Generics and references are supported, with the same caveats as for structs.
## JavaScript class
JavaScript class is supported.
```rust
struct MyClass {
val: f64,
}
#[ohos_node_bindgen]
impl MyClass {
#[node_bindgen(constructor)]
fn new(val: f64) -> Self {
Self { val }
}
#[ohos_node_bindgen]
fn plus_one(&self) -> f64 {
self.val + 1.0
}
#[node_bindgen(getter)]
fn value(&self) -> f64 {
self.val
}
}
```
```js
let addon = require('./dist');
const assert = require('assert');
let obj = new addon.MyObject(10);
assert.equal(obj.value,10,"verify value works");
assert.equal(obj.plusOne(),11);
```
There are more features in the examples folder.
## Preparing npm packages
Node module generated with `node-bindgen` can be used directly in any node JS project, just copied `index.node` into it. But in case of direct access to a module IDE will not highlight available functions, classes etc. Usually, this is not comfortable and makes the risks of potential bugs higher as soon as the public API of the node module is changed.
To create a full-fledged npm package with TypeScript types definitions and all necessary JavaScript wrappers can be used a crate [tslink](https://crates.io/crates/tslink).
`tslink` crate generates files `*.d.ts`, `*.js` and `package.json` with a description of the npm module. Such package could be integrated into an end-project with minimal effort.
In addition, because `tslink` generates TypeScript types definitions, any changes on the native node module (`index.node`) will be highlighted by `TypeScript` compiler and it makes the risk of bugs (related to changed API or public data types) much lower.
For example,
```ignore
#[macro_use] extern crate tslink;
use tslink::tslink;
use ohos_node_bindgen::derive::node_bindgen;
struct MyScruct {
inc: i32,
}
#[tslink(class)]
#[ohos_node_bindgen]
impl MyScruct {
#[tslink(constructor)]
#[node_bindgen(constructor)]
pub fn new(inc: i32) -> Self {
Self { inc }
}
#[tslink(snake_case_naming)]
#[ohos_node_bindgen]
fn inc_my_number(&self, a: i32) -> i32 {
a + self.inc
}
}
```
Would be represented (`*.d.ts`) as
```ignore
export declare class MyStruct {
constructor(inc: number);
incMyNumber(a: number): number;
}
```
Pay your attention, call of `#[tslink]` should be always above of call `#[ohos_node_bindgen]`.
Also, please **note**, `node-bindgen` by default applies snake case naming to methods. You should use `#[tslink(snake_case_naming)]` to consider this moment (see more on [crate page](https://docs.rs/tslink/0.1.0/tslink)).
`tslink` requires a configuration in `Cargo.toml` (section `[tslink]`) of the root of your project. A configuration should include a valid path to the native node module. By default `node-bindgen` creates `index.node` in `./dist` folder of your `root`.
File: `./Cargo.toml` (in a `root` of project):
```ignore
[project]
...
[lib]
...
[tslink]
node = "./dist/index.node"
```
Full example of usage `tslink` and `node-bindgen` is [here](https://github.com/icsmw/tslink/tree/master/examples/node_bindgen).
See more API documentation on a `tslink` [crate page](https://docs.rs/tslink/0.1.0/tslink).
**Note**. The node-bindgen's developers are not responsible for the correctness of the work tslink crate. All possible issues and feature requests related to tslink should be addressed to tslink's developers.
## Contributing
If you'd like to contribute to the project, please read our [Contributing guide](CONTRIBUTING.md).
## License
This project is licensed under the [Apache license](LICENSE-APACHE).
