TypeScriptToLua · Perryvw · May 2, 2019 · May 2, 2019 · May 2, 2019
diff --git a/build_lualib.ts b/build_lualib.ts
@@ -8,11 +8,15 @@ import { LuaLib } from "./src/LuaLib";
 const options: tstl.CompilerOptions = {
     skipLibCheck: true,
     types: [],
+    target: ts.ScriptTarget.ESNext,
+    lib: ["lib.esnext.d.ts"],
+
+    outDir: path.join(__dirname, "./dist/lualib"),
+    rootDir: path.join(__dirname, "./src/lualib"),
+
     luaLibImport: tstl.LuaLibImportKind.None,
     luaTarget: tstl.LuaTarget.Lua51,
     noHeader: true,
-    outDir: path.join(__dirname, "./dist/lualib"),
-    rootDir: path.join(__dirname, "./src/lualib"),
 };
 
 // TODO: Check diagnostics

diff --git a/src/LuaLib.ts b/src/LuaLib.ts
@@ -27,6 +27,7 @@ export enum LuaLibFeature {
     FunctionCall = "FunctionCall",
     Index = "Index",
     InstanceOf = "InstanceOf",
+    InstanceOfObject = "InstanceOfObject",
     Iterator = "Iterator",
     Map = "Map",
     NewIndex = "NewIndex",
@@ -51,6 +52,7 @@ export enum LuaLibFeature {
 const luaLibDependencies: {[lib in LuaLibFeature]?: LuaLibFeature[]} = {
     ArrayFlat: [LuaLibFeature.ArrayConcat],
     ArrayFlatMap: [LuaLibFeature.ArrayConcat],
+    InstanceOf: [LuaLibFeature.Symbol],
     Iterator: [LuaLibFeature.Symbol],
     ObjectFromEntries: [LuaLibFeature.Iterator, LuaLibFeature.Symbol],
     Map: [LuaLibFeature.InstanceOf, LuaLibFeature.Iterator, LuaLibFeature.Symbol],

diff --git a/src/LuaTransformer.ts b/src/LuaTransformer.ts
@@ -2658,14 +2658,18 @@ export class LuaTransformer {
                 );
 
             case ts.SyntaxKind.InstanceOfKeyword:
-                const decorators = tsHelper.getCustomDecorators(
-                    this.checker.getTypeAtLocation(expression.right),
-                    this.checker
-                );
+                const rhsType = this.checker.getTypeAtLocation(expression.right);
+                const decorators = tsHelper.getCustomDecorators(rhsType, this.checker);
+
                 if (decorators.has(DecoratorKind.Extension) || decorators.has(DecoratorKind.MetaExtension)) {
                     // Cannot use instanceof on extension classes
                     throw TSTLErrors.InvalidInstanceOfExtension(expression);
                 }
+
+                if (tsHelper.isStandardLibraryType(rhsType, "ObjectConstructor", this.program)) {
+                    return this.transformLuaLibFunction(LuaLibFeature.InstanceOfObject, expression, lhs);
+                }
+
                 return this.transformLuaLibFunction(LuaLibFeature.InstanceOf, expression, lhs, rhs);
 
             case ts.SyntaxKind.CommaToken:
@@ -4533,11 +4537,6 @@ export class LuaTransformer {
     }
 
     private importLuaLibFeature(feature: LuaLibFeature): void {
-        // Add additional lib requirements
-        if (feature === LuaLibFeature.Map || feature === LuaLibFeature.Set) {
-            this.luaLibFeatureSet.add(LuaLibFeature.InstanceOf);
-        }
-
         this.luaLibFeatureSet.add(feature);
     }
 

diff --git a/src/lualib/InstanceOf.ts b/src/lualib/InstanceOf.ts
@@ -7,6 +7,15 @@ interface LuaObject {
 }
 
 function __TS__InstanceOf(this: void, obj: LuaObject, classTbl: LuaClass): boolean {
+    if (typeof classTbl !== "object") {
+        // tslint:disable-next-line: no-string-throw
+        throw "Right-hand side of 'instanceof' is not an object";
+    }
+
+    if (classTbl[Symbol.hasInstance] !== undefined) {
+        return !!classTbl[Symbol.hasInstance](obj);
+    }
+
     if (obj !== undefined) {
         let luaClass = obj.constructor;
         while (luaClass !== undefined) {

diff --git a/src/lualib/InstanceOfObject.ts b/src/lualib/InstanceOfObject.ts
@@ -0,0 +1,4 @@
+function __TS__InstanceOfObject(this: void, value: unknown): boolean {
+    const valueType = type(value);
+    return valueType === "table" || valueType === "function";
+}
diff --git a/src/lualib/Symbol.ts b/src/lualib/Symbol.ts
@@ -17,4 +17,5 @@ function __TS__Symbol(description?: string | number): symbol {
 
 Symbol = {
     iterator: __TS__Symbol('Symbol.iterator'),
+    hasInstance: __TS__Symbol('Symbol.hasInstance'),
 } as any;
diff --git a/src/lualib/declarations/global.d.ts b/src/lualib/declarations/global.d.ts
@@ -0,0 +1,4 @@
+declare function type(
+    this: void,
+    value: any
+): "nil" | "number" | "string" | "boolean" | "table" | "function" | "thread" | "userdata";
diff --git a/test/unit/typechecking.spec.ts b/test/unit/typechecking.spec.ts
@@ -50,7 +50,7 @@ test("instanceof", () => {
         "class myClass {} let inst = new myClass(); return inst instanceof myClass;",
     );
 
-    expect(result).toBeTruthy();
+    expect(result).toBe(true);
 });
 
 test("instanceof inheritance", () => {
@@ -60,7 +60,7 @@ test("instanceof inheritance", () => {
         let inst = new childClass(); return inst instanceof myClass;
     `);
 
-    expect(result).toBeTruthy();
+    expect(result).toBe(true);
 });
 
 test("instanceof inheritance false", () => {
@@ -73,15 +73,33 @@ test("instanceof inheritance false", () => {
     expect(result).toBe(false);
 });
 
+test("{} instanceof Object", () => {
+    const result = util.transpileAndExecute("return {} instanceof Object;");
+
+    expect(result).toBe(true);
+});
+
+test("function instanceof Object", () => {
+    const result = util.transpileAndExecute("return (() => {}) instanceof Object;");
+
+    expect(result).toBe(true);
+});
+
 test("null instanceof Object", () => {
-    const result = util.transpileAndExecute("return (<any>null) instanceof Object;");
+    const result = util.transpileAndExecute("return (null as any) instanceof Object;");
 
     expect(result).toBe(false);
 });
 
+test("instanceof undefined", () => {
+    expect(() => {
+        util.transpileAndExecute("return {} instanceof (undefined as any);");
+    }).toThrow("Right-hand side of 'instanceof' is not an object");
+});
+
 test("null instanceof Class", () => {
     const result = util.transpileAndExecute(
-        "class myClass {} return (<any>null) instanceof myClass;",
+        "class myClass {} return (null as any) instanceof myClass;",
     );
 
     expect(result).toBe(false);
@@ -108,5 +126,23 @@ test("instanceof export", () => {
         "result",
     );
 
-    expect(result).toBeTruthy();
+    expect(result).toBe(true);
+});
+
+test("instanceof Symbol.hasInstance", () => {
+    const result = util.transpileAndExecute(`
+        class myClass {
+            static [Symbol.hasInstance]() {
+                return false;
+            }
+        }
+
+        const inst = new myClass();
+        const isInstanceOld = inst instanceof myClass;
+        myClass[Symbol.hasInstance] = () => true;
+        const isInstanceNew = inst instanceof myClass;
+        return isInstanceOld !== isInstanceNew;
+    `);
+
+    expect(result).toBe(true);
 });