Support TypeScript mapped type 'as' clauses

babel · Oct 2, 2020 · 8bdf5d9 · 8bdf5d9
1 parent 9808d25
commit 8bdf5d9
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Showing 11 changed files with 358 additions and 3 deletions.
diff --git a/Makefile b/Makefile
@@ -1,6 +1,6 @@
 FLOW_COMMIT = a1f9a4c709dcebb27a5084acf47755fbae699c25
 TEST262_COMMIT = 058adfed86b1d4129996faaf50a85ea55379a66a
-TYPESCRIPT_COMMIT = d779a190535e52896cfe5100101173c00b6b8625
+TYPESCRIPT_COMMIT = da8633212023517630de5f3620a23736b63234b1
 
 FORCE_PUBLISH = "@babel/runtime,@babel/runtime-corejs2,@babel/runtime-corejs3,@babel/standalone"
 

diff --git a/packages/babel-generator/src/generators/typescript.js b/packages/babel-generator/src/generators/typescript.js
@@ -330,7 +330,7 @@ export function TSIndexedAccessType(node) {
 }
 
 export function TSMappedType(node) {
-  const { readonly, typeParameter, optional } = node;
+  const { nameType, optional, readonly, typeParameter } = node;
   this.token("{");
   this.space();
   if (readonly) {
@@ -345,6 +345,14 @@ export function TSMappedType(node) {
   this.word("in");
   this.space();
   this.print(typeParameter.constraint, typeParameter);
+
+  if (nameType) {
+    this.space();
+    this.word("as");
+    this.space();
+    this.print(nameType, node);
+  }
+
   this.token("]");
 
   if (optional) {

diff --git a/packages/babel-generator/test/fixtures/typescript/types-mapped-as/input.js b/packages/babel-generator/test/fixtures/typescript/types-mapped-as/input.js
@@ -0,0 +1,11 @@
+type MappedTypeWithNewKeys<T> = {
+  [K in keyof T as NewKeyType]: T[K]
+};
+
+type RemoveKindField<T> = {
+  [K in keyof T as Exclude<K, "kind">]: T[K]
+};
+
+type PickByValueType<T, U> = {
+  [K in keyof T as T[K] extends U ? K : never]: T[K]
+};
diff --git a/packages/babel-generator/test/fixtures/typescript/types-mapped-as/output.js b/packages/babel-generator/test/fixtures/typescript/types-mapped-as/output.js
@@ -0,0 +1,3 @@
+type MappedTypeWithNewKeys<T> = { [K in keyof T as NewKeyType]: T[K] };
+type RemoveKindField<T> = { [K in keyof T as Exclude<K, "kind">]: T[K] };
+type PickByValueType<T, U> = { [K in keyof T as T[K] extends U ? K : never]: T[K] };
diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
@@ -621,6 +621,11 @@ export default (superClass: Class<Parser>): Class<Parser> =>
 
       this.expect(tt.bracketL);
       node.typeParameter = this.tsParseMappedTypeParameter();
+
+      if (this.eatContextual("as")) {
+        node.nameType = this.tsParseType();
+      }
+
       this.expect(tt.bracketR);
 
       if (this.match(tt.plusMin)) {

diff --git a/packages/babel-parser/src/types.js b/packages/babel-parser/src/types.js
@@ -1339,6 +1339,7 @@ export type TsMappedType = TsTypeBase & {
   typeParameter: TsTypeParameter,
   optional?: true | "+" | "-",
   typeAnnotation: ?TsType,
+  nameType: ?TsType,
 };
 
 export type TsLiteralType = TsTypeBase & {

diff --git a/packages/babel-parser/test/fixtures/typescript/types/mapped-as-invalid/input.ts b/packages/babel-parser/test/fixtures/typescript/types/mapped-as-invalid/input.ts
@@ -0,0 +1 @@
+type Foo<T> = { [K in keyof T as]: T[K] };
diff --git a/packages/babel-parser/test/fixtures/typescript/types/mapped-as-invalid/options.json b/packages/babel-parser/test/fixtures/typescript/types/mapped-as-invalid/options.json
@@ -0,0 +1,7 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "typescript"
+  ],
+  "throws": "Unexpected token (1:32)"
+}
diff --git a/packages/babel-parser/test/fixtures/typescript/types/mapped-as/input.ts b/packages/babel-parser/test/fixtures/typescript/types/mapped-as/input.ts
@@ -0,0 +1,11 @@
+type MappedTypeWithNewKeys<T> = {
+  [K in keyof T as NewKeyType]: T[K]
+};
+
+type RemoveKindField<T> = {
+  [K in keyof T as Exclude<K, "kind">]: T[K]
+};
+
+type PickByValueType<T, U> = {
+  [K in keyof T as T[K] extends U ? K : never]: T[K]
+};