add union types

README.md

@@ -181,11 +181,11 @@ This is a list of features in TypeScript that are planned or implemented:
 * [x] `satisfies` type operator
 * [x] primitive type annotations
 * [ ] literal type annotations
-* [ ] union type annotations
+* [x] union type annotations
 * [ ] intersection type annotations
 * [ ] tuple type annotations
 * [ ] array type annotations
-* [ ] [WIP] object type annotations
+* [x] object type annotations
 * [ ] type guards
 * [ ] `interface` type statement
 * [x] `type` type statement

spec/type_union.ts

@@ -0,0 +1,5 @@
+type Foo = string | number | boolean;
+
+export const a: Foo = 'foo';
+export const b: Foo = 42;
+export const c: Foo = true;

spec/type_union.ts.stdout

@@ -0,0 +1,5 @@
+{
+  "a": "foo",
+  "b": 42,
+  "c": true
+}

src/parser.rs

@@ -987,7 +987,13 @@ fn type_object(input: Span) -> IResult<Span, TypeDecl> {
 
 fn type_expr(i: Span) -> IResult<Span, TypeDecl> {
     let (i, td) = alt((type_primitive, type_object))(i)?;
-    Ok((i, td))
+
+    let Ok((i, _)) = space_delimited(char::<Span, Error>('|'))(i) else {
+        return Ok((i, td))
+    };
+
+    let (i, _rhs) = type_expr(i)?;
+    Ok((i, TypeDecl::Any)) // union, but not yet implemented
 }
 
 fn argument(i: Span) -> IResult<Span, (Span, TypeDecl)> {