feat(napi): implement get_js_function

crates/backend/src/codegen/fn.rs

@@ -300,10 +300,7 @@ impl NapiFn {
       let module_register_name = get_register_ident(&name_str);
       let intermediate_ident = get_intermediate_ident(&name_str);
       let js_mod_ident = js_mod_to_token_stream(self.js_mod.as_ref());
-      let cb_name = Ident::new(
-        &format!("__register__fn__{}_callback__", name_str),
-        Span::call_site(),
-      );
+      let cb_name = Ident::new(&format!("{}_js_function", name_str), Span::call_site());
       quote! {
         #[allow(non_snake_case)]
         #[allow(clippy::all)]
@@ -322,7 +319,7 @@ impl NapiFn {
             "Failed to register function `{}`",
             #name_str,
           )?;
-
+          napi::bindgen_prelude::register_js_function(#js_name, env, #cb_name, Some(#intermediate_ident));
           Ok(fn_ptr)
         }
 

crates/napi/src/bindgen_runtime/module_register.rs

@@ -6,7 +6,9 @@ use std::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
 
 use lazy_static::lazy_static;
 
-use crate::{check_status, check_status_or_throw, sys, JsError, Property, Result};
+use crate::{
+  check_status, check_status_or_throw, sys, JsError, JsFunction, Property, Result, Value, ValueType,
+};
 
 pub type ExportRegisterCallback = unsafe fn(sys::napi_env) -> Result<sys::napi_value>;
 pub type ModuleExportsCallback =
@@ -82,12 +84,18 @@ type ModuleClassProperty = PersistedSingleThreadHashMap<
   HashMap<Option<&'static str>, (&'static str, Vec<Property>)>,
 >;
 
+type FnRegisterMap = PersistedSingleThreadHashMap<
+  ExportRegisterCallback,
+  (sys::napi_env, sys::napi_callback, &'static str),
+>;
+
 unsafe impl<K, V> Send for PersistedSingleThreadHashMap<K, V> {}
 unsafe impl<K, V> Sync for PersistedSingleThreadHashMap<K, V> {}
 
 lazy_static! {
   static ref MODULE_REGISTER_CALLBACK: ModuleRegisterCallback = Default::default();
   static ref MODULE_CLASS_PROPERTIES: ModuleClassProperty = Default::default();
+  static ref FN_REGISTER_MAP: FnRegisterMap = Default::default();
 }
 
 #[cfg(feature = "compat-mode")]
@@ -103,6 +111,7 @@ thread_local! {
   >> = Default::default();
 }
 
+#[doc(hidden)]
 pub fn get_class_constructor(js_name: &'static str) -> Option<sys::napi_ref> {
   REGISTERED_CLASSES.with(|registered_classes| {
     let classes = registered_classes.borrow();
@@ -110,12 +119,14 @@ pub fn get_class_constructor(js_name: &'static str) -> Option<sys::napi_ref> {
   })
 }
 
+#[doc(hidden)]
 #[cfg(feature = "compat-mode")]
 // compatibility for #[module_exports]
 pub fn register_module_exports(callback: ModuleExportsCallback) {
   MODULE_EXPORTS.push(callback);
 }
 
+#[doc(hidden)]
 pub fn register_module_export(
   js_mod: Option<&'static str>,
   name: &'static str,
@@ -124,6 +135,17 @@ pub fn register_module_export(
   MODULE_REGISTER_CALLBACK.push((js_mod, (name, cb)));
 }
 
+#[doc(hidden)]
+pub fn register_js_function(
+  name: &'static str,
+  env: sys::napi_env,
+  cb: ExportRegisterCallback,
+  c_fn: sys::napi_callback,
+) {
+  FN_REGISTER_MAP.borrow_mut().insert(cb, (env, c_fn, name));
+}
+
+#[doc(hidden)]
 pub fn register_class(
   rust_name: &'static str,
   js_mod: Option<&'static str>,
@@ -138,6 +160,40 @@ pub fn register_class(
   val.1.extend(props.into_iter());
 }
 
+#[inline]
+pub fn get_js_function(raw_fn: ExportRegisterCallback) -> Result<JsFunction> {
+  FN_REGISTER_MAP
+    .borrow_mut()
+    .get(&raw_fn)
+    .and_then(|(env, cb, name)| {
+      let mut function = ptr::null_mut();
+      let name_len = name.len() - 1;
+      let fn_name = unsafe { CStr::from_bytes_with_nul_unchecked(name.as_bytes()) };
+      check_status!(unsafe {
+        sys::napi_create_function(
+          *env,
+          fn_name.as_ptr(),
+          name_len,
+          *cb,
+          ptr::null_mut(),
+          &mut function,
+        )
+      })
+      .ok()?;
+      Some(JsFunction(Value {
+        env: *env,
+        value: function,
+        value_type: ValueType::Function,
+      }))
+    })
+    .ok_or_else(|| {
+      crate::Error::new(
+        crate::Status::InvalidArg,
+        "JavaScript function does not exists".to_owned(),
+      )
+    })
+}
+
 #[no_mangle]
 unsafe extern "C" fn napi_register_module_v1(
   env: sys::napi_env,
@@ -191,17 +247,13 @@ unsafe extern "C" fn napi_register_module_v1(
         let js_name = unsafe { CStr::from_bytes_with_nul_unchecked(name.as_bytes()) };
         unsafe {
           if let Err(e) = callback(env).and_then(|v| {
+            let exported_object = if exports_js_mod.is_null() {
+              exports
+            } else {
+              exports_js_mod
+            };
             check_status!(
-              sys::napi_set_named_property(
-                env,
-                if exports_js_mod.is_null() {
-                  exports
-                } else {
-                  exports_js_mod
-                },
-                js_name.as_ptr(),
-                v
-              ),
+              sys::napi_set_named_property(env, exported_object, js_name.as_ptr(), v),
               "Failed to register export `{}`",
               name,
             )

examples/napi/__test__/typegen.spec.ts.md

@@ -38,6 +38,7 @@ Generated by [AVA](https://avajs.dev).
     export function optionOnly(callback: (arg0?: string | undefined | null) => void): void␊
     /** napi = { version = 2, features = ["serde-json"] } */␊
     export function readFile(callback: (arg0: Error | undefined, arg1?: string | undefined | null) => void): void␊
+    export function returnJsFunction(): (...args: any[]) => any␊
     export function eitherStringOrNumber(input: string | number): number␊
     export function returnEither(input: number): string | number␊
     export function either3(input: string | number | boolean): number␊

examples/napi/__test__/values.spec.ts

@@ -77,6 +77,7 @@ import {
   JsClassForEither,
   receiveMutClassOrNumber,
   getStrFromObject,
+  returnJsFunction,
 } from '../'
 
 test('export const', (t) => {
@@ -193,6 +194,16 @@ test('callback', (t) => {
   })
 })
 
+test('return function', (t) => {
+  return new Promise<void>((resolve) => {
+    returnJsFunction()((err: Error | undefined, content: string) => {
+      t.is(err, undefined)
+      t.is(content, 'hello world')
+      resolve()
+    })
+  })
+})
+
 test('object', (t) => {
   t.deepEqual(listObjKeys({ name: 'John Doe', age: 20 }), ['name', 'age'])
   t.deepEqual(createObj(), { test: 1 })

examples/napi/index.d.ts

@@ -28,6 +28,7 @@ export function optionStartEnd(callback: (arg0: string | undefined | null, arg1:
 export function optionOnly(callback: (arg0?: string | undefined | null) => void): void
 /** napi = { version = 2, features = ["serde-json"] } */
 export function readFile(callback: (arg0: Error | undefined, arg1?: string | undefined | null) => void): void
+export function returnJsFunction(): (...args: any[]) => any
 export function eitherStringOrNumber(input: string | number): number
 export function returnEither(input: number): string | number
 export function either3(input: string | number | boolean): number

examples/napi/src/callback.rs

@@ -1,6 +1,7 @@
-use napi::bindgen_prelude::*;
 use std::env;
 
+use napi::bindgen_prelude::*;
+
 #[napi]
 fn get_cwd<T: Fn(String) -> Result<()>>(callback: T) {
   callback(env::current_dir().unwrap().to_string_lossy().to_string()).unwrap();
@@ -40,3 +41,8 @@ fn read_file_content() -> Result<String> {
   // serde_json::from_str(&s)?;
   Ok("hello world".to_string())
 }
+
+#[napi]
+fn return_js_function() -> Result<JsFunction> {
+  get_js_function(read_file_js_function)
+}