feat(napi): allow return self as this

crates/backend/src/codegen/fn.rs

@@ -245,6 +245,8 @@ impl NapiFn {
     let js_name = &self.js_name;
 
     if let Some(ty) = &self.ret {
+      let ty_string = ty.into_token_stream().to_string();
+      let is_return_self = ty_string == "& Self" || ty_string == "&mut Self";
       if self.kind == FnKind::Constructor {
         if self.is_ret_result {
           quote! { cb.construct(#js_name, #ret?) }
@@ -263,19 +265,27 @@ impl NapiFn {
             <#ty as napi::bindgen_prelude::ToNapiValue>::to_napi_value(env, #ret)
           }
         } else {
-          quote! {
-            match #ret {
-              Ok(value) => napi::bindgen_prelude::ToNapiValue::to_napi_value(env, value),
-              Err(err) => {
-                napi::bindgen_prelude::JsError::from(err).throw_into(env);
-                Ok(std::ptr::null_mut())
-              },
+          if is_return_self {
+            quote! { #ret.map(|_| cb.this) }
+          } else {
+            quote! {
+              match #ret {
+                Ok(value) => napi::bindgen_prelude::ToNapiValue::to_napi_value(env, value),
+                Err(err) => {
+                  napi::bindgen_prelude::JsError::from(err).throw_into(env);
+                  Ok(std::ptr::null_mut())
+                },
+              }
             }
           }
         }
       } else {
-        quote! {
-          <#ty as napi::bindgen_prelude::ToNapiValue>::to_napi_value(env, #ret)
+        if is_return_self {
+          quote! { Ok(cb.this) }
+        } else {
+          quote! {
+            <#ty as napi::bindgen_prelude::ToNapiValue>::to_napi_value(env, #ret)
+          }
         }
       }
     } else {

crates/backend/src/typegen/fn.rs

@@ -112,6 +112,8 @@ impl NapiFn {
           let (ts_type, _) = ty_to_ts_type(ret, true);
           if ts_type == "undefined" {
             "void".to_owned()
+          } else if ts_type == "Self" {
+            "this".to_owned()
           } else {
             ts_type
           }

crates/napi/src/bindgen_runtime/callback_info.rs

@@ -12,7 +12,7 @@ pub static ___CALL_FROM_FACTORY: AtomicBool = AtomicBool::new(false);
 
 pub struct CallbackInfo<const N: usize> {
   env: sys::napi_env,
-  this: sys::napi_value,
+  pub this: sys::napi_value,
   pub args: [sys::napi_value; N],
 }
 

crates/napi/src/bindgen_runtime/js_values/array.rs

@@ -123,8 +123,8 @@ impl Array {
     T: ToNapiValue,
   {
     let mut arr = Array::new(env.0, value.len() as u32)?;
-    value.into_iter().try_for_each(|val| {
-      arr.insert(val)?;
+    value.into_iter().enumerate().try_for_each(|(index, val)| {
+      arr.set(index as u32, val)?;
       Ok::<(), Error>(())
     })?;
     Ok(arr)