feat(napi/transform): support for enabling legacy decorator

napi/transform/index.d.ts

@@ -20,6 +20,19 @@ export interface CompilerAssumptions {
   setPublicClassFields?: boolean
 }
 
+export interface DecoratorOptions {
+  /**
+   * Enables experimental support for decorators, which is a version of decorators that predates the TC39 standardization process.
+   *
+   * Decorators are a language feature which hasn’t yet been fully ratified into the JavaScript specification.
+   * This means that the implementation version in TypeScript may differ from the implementation in JavaScript when it it decided by TC39.
+   *
+   * @see https://www.typescriptlang.org/tsconfig/#experimentalDecorators
+   * @default false
+   */
+  legacy?: boolean
+}
+
 export interface ErrorLabel {
   message?: string
   start: number
@@ -270,6 +283,8 @@ export interface TransformOptions {
   define?: Record<string, string>
   /** Inject Plugin */
   inject?: Record<string, string | [string, string]>
+  /** Decorator plugin */
+  decorator?: DecoratorOptions
 }
 
 export interface TransformResult {

napi/transform/src/transformer.rs

@@ -15,9 +15,8 @@ use oxc::{
     diagnostics::OxcDiagnostic,
     span::SourceType,
     transformer::{
-        DecoratorOptions, EnvOptions, HelperLoaderMode, HelperLoaderOptions,
-        InjectGlobalVariablesConfig, InjectImport, JsxRuntime, ReplaceGlobalDefinesConfig,
-        RewriteExtensionsMode,
+        EnvOptions, HelperLoaderMode, HelperLoaderOptions, InjectGlobalVariablesConfig,
+        InjectImport, JsxRuntime, ReplaceGlobalDefinesConfig, RewriteExtensionsMode,
     },
     CompilerInterface,
 };
@@ -134,6 +133,9 @@ pub struct TransformOptions {
     /// Inject Plugin
     #[napi(ts_type = "Record<string, string | [string, string]>")]
     pub inject: Option<FxHashMap<String, Either<String, Vec<String>>>>,
+
+    /// Decorator plugin
+    pub decorator: Option<DecoratorOptions>,
 }
 
 impl TryFrom<TransformOptions> for oxc::transformer::TransformOptions {
@@ -152,7 +154,10 @@ impl TryFrom<TransformOptions> for oxc::transformer::TransformOptions {
                 .typescript
                 .map(oxc::transformer::TypeScriptOptions::from)
                 .unwrap_or_default(),
-            decorator: DecoratorOptions::default(),
+            decorator: options
+                .decorator
+                .map(oxc::transformer::DecoratorOptions::from)
+                .unwrap_or_default(),
             jsx: match options.jsx {
                 Some(Either::A(s)) => {
                     if s == "preserve" {
@@ -262,6 +267,25 @@ impl From<TypeScriptOptions> for oxc::transformer::TypeScriptOptions {
     }
 }
 
+#[napi(object)]
+#[derive(Default)]
+pub struct DecoratorOptions {
+    /// Enables experimental support for decorators, which is a version of decorators that predates the TC39 standardization process.
+    ///
+    /// Decorators are a language feature which hasn’t yet been fully ratified into the JavaScript specification.
+    /// This means that the implementation version in TypeScript may differ from the implementation in JavaScript when it it decided by TC39.
+    ///
+    /// @see https://www.typescriptlang.org/tsconfig/#experimentalDecorators
+    /// @default false
+    pub legacy: Option<bool>,
+}
+
+impl From<DecoratorOptions> for oxc::transformer::DecoratorOptions {
+    fn from(options: DecoratorOptions) -> Self {
+        oxc::transformer::DecoratorOptions { legacy: options.legacy.unwrap_or_default() }
+    }
+}
+
 /// Configure how TSX and JSX are transformed.
 ///
 /// @see {@link https://babeljs.io/docs/babel-plugin-transform-react-jsx#options}

napi/transform/test/transform.test.ts

@@ -244,3 +244,33 @@ describe('inject plugin', () => {
     expect(ret.code).toEqual('import $inject_Object_assign from "foo";\nlet _ = $inject_Object_assign;\n');
   });
 });
+
+describe('legacy decorator', () => {
+  it('matches output', () => {
+    const code = `
+      export default @dce class C {
+        @dce
+        prop = 0;
+        method(@dce param) {}
+      }
+    `;
+    const ret = transform('test.tsx', code, {
+      decorator: {
+        legacy: true,
+      },
+    });
+    expect(ret.code).toMatchInlineSnapshot(`
+      "import _decorate from "@babel/runtime/helpers/decorate";
+      import _decorateParam from "@babel/runtime/helpers/decorateParam";
+      let C = class C {
+      	prop = 0;
+      	method(param) {}
+      };
+      _decorate([dce], C.prototype, "prop", void 0);
+      _decorate([_decorateParam(0, dce)], C.prototype, "method", null);
+      C = _decorate([dce], C);
+      export default C;
+      "
+    `);
+  });
+});