Optional try catch binding (#422)

swc_ecma_parser:
 - Add test for optional try catch binding
 
swc_ecma_transforms:
 - Implement optional catch binding (#411)

README.md

@@ -25,8 +25,6 @@
    </a>
 </p>
 
-
-
 <h2 align="center">Supporting swc</h2>
 
 <p align="center">
@@ -38,7 +36,6 @@
    </a>
 </p>
 
-
 swc is a community-driven project, and is maintained by a group of [volunteers](https://opencollective.com/swc#team). If you'd like to help support the future of the project, please consider:
 
 - Giving developer time on the project. (Message us on [Slack](https://swc-org.slack.com/) for guidance!)
@@ -69,7 +66,6 @@ Become a sponsor and get your logo on our README on Github with a link to your s
 <a href="https://opencollective.com/swc/backer/8/website?requireActive=false" target="_blank"><img src="https://opencollective.com/swc/backer/8/avatar.svg?requireActive=false"></a>
 <a href="https://opencollective.com/swc/backer/9/website?requireActive=false" target="_blank"><img src="https://opencollective.com/swc/backer/9/avatar.svg?requireActive=false"></a>
 
-
 # Documentation
 
 Check out the documentation [in the website](https://swc-project.github.io/docs/installation).
@@ -77,22 +73,27 @@ Check out the documentation [in the website](https://swc-project.github.io/docs/
 # Features
 
 ## Parsers
- - [x] es2019
- - [x] jsx
- - [x] typescript
+
+- [x] es2019
+- [x] jsx
+- [x] typescript
 
 ## Transforms
+
 New generation javascript to old-days javascript.
 
- - es3
+- es3
+
   - [x] member-expression-literals
   - [x] property-literals
   - [x] reserved-words
 
- - es5
+- es5
+
   - [ ] property-mutators
 
- - es2015
+- es2015
+
   - [x] arrow-functions
   - [x] block-scoped-functions
   - [x] block-scoping
@@ -115,21 +116,24 @@ New generation javascript to old-days javascript.
   - [x] typeof-symbol
   - [ ] unicode-regex
 
- - es2016
+- es2016
+
   - [x] exponentiation-operator
 
- - es2017
+- es2017
+
   - [x] async-to-generator
 
- - es2018
+- es2018
+
   - [ ] async-generator-functions
   - [ ] dotall-regex
   - [x] object-rest-spread
     - [ ] Using symbol as a key
-    - [ ] optional-catch-binding
+  - [x] optional-catch-binding
   - [ ] unicode-property-regex
 
-  - react
+- react
   - [x] jsx
 
 # Performance
@@ -137,16 +141,15 @@ New generation javascript to old-days javascript.
 The lower bound of the speedup compared to babel is **16**. The benchmarks were run on Macbook pro, dual core, 2.3GHz Intel Core i5, 16 GB ram
 
 |                    |               performance               |
-| ------------------------ |:--------------------------------------:|
+| ------------------ | :-------------------------------------: |
 | swc (es3)          |  610 ops/sec ±1.76% (82 runs sampled)   |
 | swc (es2015)       |  682 ops/sec ±0.63% (88 runs sampled)   |
 | swc (es2016)       | 1,659 ops/sec ±4.32% (79 runs sampled)  |
 | swc (es2017)       | 1,384 ops/sec ±7.24% (82 runs sampled)  |
-| swc (es2018)             | 1,765 ops/sec ±11.78% (82 runs sampled)|
+| swc (es2018)       | 1,765 ops/sec ±11.78% (82 runs sampled) |
 | swc-optimize (es3) |  535 ops/sec ±1.01% (83 runs sampled)   |
 | babel              | 42.12 ops/sec ±6.27% (55 runs sampled)  |
 
-
 ## Contributing
 
 See [CONTRIBUTING.md](CONTRIBUTING.md). You may also find the architecture
@@ -159,8 +162,6 @@ and the Apache License (Version 2.0).
 
 See LICENSE-APACHE and LICENSE-MIT for details.
 
-
-
-[babel]:https://github.com/babel/babel
-[closure compiler]:https://github.com/google/closure-compiler
-[rust]:https://www.rust-lang.org
+[babel]: https://github.com/babel/babel
+[closure compiler]: https://github.com/google/closure-compiler
+[rust]: https://www.rust-lang.org

ecmascript/parser/src/parser/stmt/mod.rs

@@ -1347,4 +1347,20 @@ export default function waitUntil(callback, options = {}) {
         );
     }
 
+    #[test]
+    fn issue_411() {
+        test_parser(
+            "try {
+} catch {}",
+            Syntax::Es(EsConfig {
+                ..Default::default()
+            }),
+            |p| {
+                p.parse_module().map_err(|mut e| {
+                    e.emit();
+                    ()
+                })
+            },
+        );
+    }
 }

ecmascript/transforms/src/compat/es2018/mod.rs

@@ -1,9 +1,12 @@
-pub use self::object_rest_spread::object_rest_spread;
-
+pub use self::{
+    object_rest_spread::object_rest_spread, optional_catch_binding::optional_catch_binding,
+};
 use crate::pass::Pass;
+use ast::Module;
 
 mod object_rest_spread;
+mod optional_catch_binding;
 
 pub fn es2018() -> impl Pass {
-    object_rest_spread()
+    chain_at!(Module, object_rest_spread(), optional_catch_binding())
 }

ecmascript/transforms/src/compat/es2018/optional_catch_binding.rs

@@ -0,0 +1,35 @@
+use crate::pass::Pass;
+use ast::*;
+use swc_common::Fold;
+
+struct OptionalCatchBinding;
+
+pub fn optional_catch_binding() -> impl Pass {
+    OptionalCatchBinding
+}
+
+impl Fold<CatchClause> for OptionalCatchBinding {
+    fn fold(&mut self, cc: CatchClause) -> CatchClause {
+        if cc.param.is_some() {
+            return cc;
+        }
+
+        CatchClause {
+            param: Some(private_ident!("e").into()),
+            ..cc
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::optional_catch_binding as tr;
+
+    test!(
+        ::swc_ecma_parser::Syntax::default(),
+        |_| tr(),
+        issue_411,
+        "try {} catch {}",
+        "try {} catch(e) {}"
+    );
+}