Correctly export decorated classes (#1153)

Perryvw · web-flow · commit f5b8c018c53d · 2021-11-02T18:20:25.000+01:00
diff --git a/src/transformation/utils/export.ts b/src/transformation/utils/export.ts
@@ -10,10 +10,11 @@ export function hasDefaultExportModifier(node: ts.Node): boolean {
     return (node.modifiers ?? []).some(modifier => modifier.kind === ts.SyntaxKind.DefaultKeyword);
 }
 
-export const createDefaultExportIdentifier = (original: ts.Node): lua.Identifier =>
-    lua.createIdentifier("default", original);
+export function hasExportModifier(node: ts.Node): boolean {
+    return (node.modifiers ?? []).some(modifier => modifier.kind === ts.SyntaxKind.ExportKeyword);
+}
 
-export const createDefaultExportStringLiteral = (original: ts.Node): lua.StringLiteral =>
+export const createDefaultExportStringLiteral = (original?: ts.Node): lua.StringLiteral =>
     lua.createStringLiteral("default", original);
 
 export function getExportedSymbolDeclaration(symbol: ts.Symbol): ts.Declaration | undefined {
@@ -142,3 +143,7 @@ export function createExportedIdentifier(
 
     return lua.createTableIndexExpression(exportTable, lua.createStringLiteral(identifier.text));
 }
+
+export function createDefaultExportExpression(node: ts.Node): lua.AssignmentLeftHandSideExpression {
+    return lua.createTableIndexExpression(createExportsIdentifier(), createDefaultExportStringLiteral(node), node);
+}
diff --git a/src/transformation/visitors/class/index.ts b/src/transformation/visitors/class/index.ts
@@ -5,9 +5,10 @@ import { FunctionVisitor, TransformationContext } from "../../context";
 import { AnnotationKind, getTypeAnnotations } from "../../utils/annotations";
 import { annotationRemoved } from "../../utils/diagnostics";
 import {
-    createDefaultExportIdentifier,
+    createDefaultExportExpression,
     createExportedIdentifier,
     hasDefaultExportModifier,
+    hasExportModifier,
     isSymbolExported,
 } from "../../utils/export";
 import { createSelfIdentifier, unwrapVisitorResult } from "../../utils/lua-ast";
@@ -30,7 +31,7 @@ import { getExtendedNode, getExtendedType, isStaticNode } from "./utils";
 export const transformClassDeclaration: FunctionVisitor<ts.ClassLikeDeclaration> = (declaration, context) => {
     // If declaration is a default export, transform to export variable assignment instead
     if (hasDefaultExportModifier(declaration)) {
-        const left = createExportedIdentifier(context, createDefaultExportIdentifier(declaration));
+        const left = createDefaultExportExpression(declaration);
         const right = transformClassAsExpression(declaration, context);
         return [lua.createAssignmentStatement(left, right, declaration)];
     }
@@ -220,6 +221,15 @@ function transformClassLikeDeclaration(
         );
         const decoratingStatement = lua.createAssignmentStatement(localClassName, decoratingExpression);
         result.push(decoratingStatement);
+
+        if (hasExportModifier(classDeclaration)) {
+            const exportExpression = hasDefaultExportModifier(classDeclaration)
+                ? createDefaultExportExpression(classDeclaration)
+                : createExportedIdentifier(context, className);
+
+            const classAssignment = lua.createAssignmentStatement(exportExpression, localClassName);
+            result.push(classAssignment);
+        }
     }
 
     superInfo.pop();
diff --git a/src/transformation/visitors/modules/export.ts b/src/transformation/visitors/modules/export.ts
@@ -3,7 +3,7 @@ import * as lua from "../../../LuaAST";
 import { assert } from "../../../utils";
 import { FunctionVisitor, TransformationContext } from "../../context";
 import {
-    createDefaultExportIdentifier,
+    createDefaultExportExpression,
     createDefaultExportStringLiteral,
     createExportedIdentifier,
 } from "../../utils/export";
@@ -114,10 +114,9 @@ function transformExportSpecifier(context: TransformationContext, node: ts.Expor
     const exportedExpression = createShorthandIdentifier(context, exportedSymbol, exportedIdentifier);
 
     const isDefault = isDefaultExportSpecifier(node);
-    const identifierToExport = isDefault
-        ? createDefaultExportIdentifier(node)
-        : transformIdentifier(context, node.name);
-    const exportAssignmentLeftHandSide = createExportedIdentifier(context, identifierToExport);
+    const exportAssignmentLeftHandSide = isDefault
+        ? createDefaultExportExpression(node)
+        : createExportedIdentifier(context, transformIdentifier(context, node.name));
 
     return lua.createAssignmentStatement(exportAssignmentLeftHandSide, exportedExpression, node);
 }
diff --git a/test/unit/classes/decorators.spec.ts b/test/unit/classes/decorators.spec.ts
@@ -184,3 +184,56 @@ describe("Decorators /w descriptors", () => {
         }
     );
 });
+
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1149
+test("exported class with decorator", () => {
+    util.testModule`
+        import { MyClass } from "./other";
+        const inst = new MyClass();
+        export const result = inst.foo();
+    `
+        .addExtraFile(
+            "other.ts",
+            `function myDecorator(target: {new(): any}) {
+                return class extends target {
+                    foo() {
+                        return "overridden";
+                    }
+                }
+            }
+
+            @myDecorator
+            export class MyClass {
+                foo() {
+                    return "foo";
+                }
+            }`
+        )
+        .expectToEqual({ result: "overridden" });
+});
+
+test("default exported class with decorator", () => {
+    util.testModule`
+        import MyClass from "./other";
+        const inst = new MyClass();
+        export const result = inst.foo();
+    `
+        .addExtraFile(
+            "other.ts",
+            `function myDecorator(target: {new(): any}) {
+                return class extends target {
+                    foo() {
+                        return "overridden";
+                    }
+                }
+            }
+
+            @myDecorator
+            export default class {
+                foo() {
+                    return "foo";
+                }
+            }`
+        )
+        .expectToEqual({ result: "overridden" });
+});
