Support ArrowFunctionExpression

Author: fisker

src/ast-transform/transforms/index.ts

@@ -1,10 +1,11 @@
 export * from './transform-array-expression.ts';
+export * from './transform-arrow-function-expression.ts';
 export * from './transform-ast-with-source.ts';
 export * from './transform-binary-expression.ts';
 export * from './transform-call-expression.ts';
 export * from './transform-chained-expression.ts';
 export * from './transform-conditional-expression.ts';
-export * from './transform-empty-expression.ts'
+export * from './transform-empty-expression.ts';
 export * from './transform-interpolation.ts';
 export * from './transform-literal.ts';
 export * from './transform-member-expression.ts';

src/ast-transform/transforms/transform-arrow-function-expression.ts

@@ -0,0 +1,26 @@
+import { type ArrowFunction, type AstVisitor } from '@angular/compiler';
+import type * as babel from '@babel/types';
+
+import { type NodeTransformer } from '../node-transformer.ts';
+
+const commonProperties = {
+  id: null,
+  generator: false,
+  async: false,
+  expression: true,
+} as const;
+
+export const visitArrowFunction: AstVisitor['visitArrowFunction'] = (
+  node: ArrowFunction,
+  transformer: NodeTransformer,
+): babel.ArrowFunctionExpression & { id: null } => ({
+  type: 'ArrowFunctionExpression',
+  params: node.parameters.map((parameter) =>
+    transformer.createNode<babel.Identifier>(
+      { type: 'Identifier', name: parameter.name },
+      parameter.sourceSpan,
+    ),
+  ),
+  body: transformer.transformChild(node.body) as babel.Expression,
+  ...commonProperties,
+});

tests/helpers.ts

@@ -46,6 +46,13 @@ export function massageAst(ast: any, parser: 'babel' | 'angular'): any {
       delete ast.extra.trailingComma;
     }
 
+    if (
+      ast.type === 'ArrowFunctionExpression' &&
+      !Object.hasOwn(ast, 'expression')
+    ) {
+      ast.expression = ast.body.type !== 'BlockStatement';
+    }
+
     delete ast.loc;
   }
 

tests/transform.test.ts

@@ -500,6 +500,16 @@ const testCases: TestCase[] = [
     expectedEstreeType: 'ObjectExpression',
     text: ' ( ( {foo: tag ` a ${ b } ` } ) ) ',
   },
+  {
+    expectedAngularType: 'ArrowFunction',
+    expectedEstreeType: 'ArrowFunctionExpression',
+    text: ' ( ( () => ( ( 1 ) ) ) ) ',
+  },
+  {
+    expectedAngularType: 'ArrowFunction',
+    expectedEstreeType: 'ArrowFunctionExpression',
+    text: ' ( ( (a) => ( ( 1 ) ) ) ) ',
+  },
 ];
 
 const IS_CI = Boolean(process.env.CI);