How to write a builtin plugin

Builtin plugin uses rspack_macros to help you avoid writing boilerplate code, you can use cargo-expand or rust-analyzer expand macro to checkout the expanded code, and for developing/testing these macro, you can starts with rspack_macros_test.

A simple example:

#![allow(unused)]
fn main() {
use rspack_hook::{plugin, plugin_hook};
use rspack_core::{Plugin, PluginContext, ApplyContext, CompilerOptions};
use rspack_core::CompilerCompilation;
use rspack_error::Result;

// define the plugin
#[plugin]
pub struct MyPlugin {
  options: MyPluginOptions
}

// define the plugin hook
#[plugin_hook(CompilerCompilation for MuPlugin)]
async fn compilation(&self, compilation: &mut Compilation) -> Result<()> {
  // do something...
}

// implement apply method for the plugin
impl Plugin for MyPlugin {
  fn apply(&self, ctx: PluginContext<&mut ApplyContext>, _options: &mut CompilerOptions) -> Result<()> {
    ctx.context.compiler_hooks.tap(compilation::new(self))
    Ok(())
  }
}
}

And here is an example.

If the hook you need is not defined yet, you can define it by rspack_hook::define_hook, compiler.hooks.assetEmitted for example:

#![allow(unused)]
fn main() {
// this will allow you define hook's arguments without limit
define_hook!(CompilerShouldEmit: AsyncSeriesBail(compilation: &mut Compilation) -> bool);
//           ------------------  --------------- -----------------------------  -------
//           hook name           exec kind       hook arguments                 return value (Result<Option<bool>>)

#[derive(Debug, Default)]
pub struct CompilerHooks {
  // ...
  // and add it here
  pub asset_emitted: CompilerAssetEmittedHook,
}
}

There are 5 kinds of exec kind:

• AsyncSeries, return value is Result<()>
• AsyncSeriesBail, return value is Result<Option<T>>
• AsyncParallel, return value is Result<()>
• SyncSeries, return value is Result<()>
• SyncSeriesBail, return value is Result<Option<T>>