fix: print valid TypeScript for asserts predicates, qualified namespaces, and computed signature keys

.changeset/ts-token-emission.md

@@ -0,0 +1,11 @@
+---
+'esrap': patch
+---
+
+fix: print valid TypeScript for `asserts` predicates, qualified namespaces, and computed signature keys
+
+These were previously emitted as invalid output:
+
+- `asserts` type predicates were printed in the wrong order (`asserts x is T` became `x asserts T`)
+- qualified namespace/module names were mangled (`namespace A.B.C` became `namespace Anamespace Bnamespace C`)
+- computed keys in method/property signatures lost their brackets (`interface I { [Symbol.iterator](): T }` became `Symbol.iterator(): T`)

src/languages/ts/index.js

@@ -1872,7 +1872,9 @@ export default (options = {}) => {
 		},
 
 		TSPropertySignature(node, context) {
+			if (node.computed) context.write('[');
 			context.visit(node.key);
+			if (node.computed) context.write(']');
 			if (node.optional) context.write('?');
 			if (node.typeAnnotation) context.visit(node.typeAnnotation);
 		},
@@ -1985,19 +1987,14 @@ export default (options = {}) => {
 		},
 
 		TSTypePredicate(node, context) {
-			if (node.parameterName) {
-				context.visit(node.parameterName);
-			} else if (node.typeAnnotation) {
-				context.visit(node.typeAnnotation);
-			}
+			// `asserts` precedes the parameter name; `is <type>` follows it. Forms:
+			// `x is T`, `asserts x is T`, `asserts x`
+			if (node.asserts) context.write('asserts ');
 
-			if (node.asserts) {
-				context.write(' asserts ');
-			} else {
-				context.write(' is ');
-			}
+			if (node.parameterName) context.visit(node.parameterName);
 
 			if (node.typeAnnotation) {
+				context.write(' is ');
 				context.visit(node.typeAnnotation.typeAnnotation);
 			}
 		},
@@ -2083,7 +2080,9 @@ export default (options = {}) => {
 		},
 
 		TSMethodSignature(node, context) {
+			if (node.computed) context.write('[');
 			context.visit(node.key);
+			if (node.computed) context.write(']');
 
 			context.write('(');
 			sequence(
@@ -2241,8 +2240,17 @@ export default (options = {}) => {
 				context.visit(node.id);
 			}
 
-			if (!node.body) return;
-			context.visit(node.body);
+			// a qualified name (`namespace A.B.C`) is represented as nested
+			// `TSModuleDeclaration`s whose body is the next name part, not a block
+			let body = /** @type {any} */ (node.body);
+			while (body && body.type === 'TSModuleDeclaration') {
+				context.write('.');
+				context.visit(body.id);
+				body = body.body;
+			}
+
+			if (!body) return;
+			context.visit(body);
 		},
 
 		TSNonNullExpression(node, context) {

test/samples/ts-module-declaration/expected.ts

@@ -4,4 +4,12 @@ declare global {
 	}
 }
 
+namespace A.B.C {
+	export const x = 1;
+}
+
+namespace D {
+	export const x = 1;
+}
+
 export {};

test/samples/ts-module-declaration/expected.ts.map

@@ -5,7 +5,7 @@
     "input.js"
   ],
   "sourcesContent": [
-    "declare global {\n\tnamespace App {\n\t\tinterface Error {\n\t\t\tfoo: string;\n\t\t}\n\t}\n}\n\nexport {};\n"
+    "declare global {\n\tnamespace App {\n\t\tinterface Error {\n\t\t\tfoo: string;\n\t\t}\n\t}\n}\n\nnamespace A.B.C {\n\texport const x = 1;\n}\n\nnamespace D {\n\texport const x = 1;\n}\n\nexport {};\n"
   ],
-  "mappings": "QAAQ,MAAM;WACH,GAAG;YACF,KAAK,GACd,GAAG,EAAE,MAAM;;;;AAKd,OAAO"
+  "mappings": "QAAQ,MAAM;WACH,GAAG;YACF,KAAK,GACd,GAAG,EAAE,MAAM;;;;UAKJ,CAAC,CAAC,CAAC,CAAC,CAAC;CACd,MAAM,CAAC,MAAM,AAAA,CAAC,GAAG,CAAC;;;UAGT,CAAC;CACV,MAAM,CAAC,MAAM,AAAA,CAAC,GAAG,CAAC;;;AAGnB,OAAO"
 }

test/samples/ts-module-declaration/input.ts

@@ -6,4 +6,12 @@ declare global {
 	}
 }
 
+namespace A.B.C {
+	export const x = 1;
+}
+
+namespace D {
+	export const x = 1;
+}
+
 export {};

test/samples/ts-signatures/expected.ts

@@ -5,4 +5,7 @@ interface Constructable {
 	(name: string): string
 }
 
-type Constructor = { new(): object; new(name: string, age: number): Person };
+interface Signatures { [Symbol.iterator](): number; x(): void; [k: string]: number }
+
+type Constructor = { new(): object; new(name: string, age: number): Person };
+type Computed = { [Symbol.iterator](): number };

test/samples/ts-signatures/expected.ts.map

@@ -5,7 +5,7 @@
     "input.js"
   ],
   "sourcesContent": [
-    "interface Constructable {\n\tnew (): any;\n\tnew (value: string): MyClass;\n\tnew <T>(value: T): GenericClass<T>;\n\t(name: string): string;\n}\n\ntype Constructor = {\n\tnew (): object;\n\tnew (name: string, age: number): Person;\n};\n"
+    "interface Constructable {\n\tnew (): any;\n\tnew (value: string): MyClass;\n\tnew <T>(value: T): GenericClass<T>;\n\t(name: string): string;\n}\n\ninterface Signatures {\n\t[Symbol.iterator](): number;\n\tx(): void;\n\t[k: string]: number;\n}\n\ntype Constructor = {\n\tnew (): object;\n\tnew (name: string, age: number): Person;\n};\n\ntype Computed = {\n\t[Symbol.iterator](): number;\n};\n"
   ],
-  "mappings": "UAAU,aAAa;QACd,GAAG;KACN,KAAa,EAAN,MAAM,GAAG,OAAO;KACvB,CAAC,EAAE,KAAQ,EAAD,CAAC,GAAG,YAAY,CAAC,CAAC;EAChC,IAAY,EAAN,MAAM,GAAG,MAAM;;;KAGlB,WAAW,YACP,MAAM,MACT,IAAY,EAAN,MAAM,EAAE,GAAW,EAAN,MAAM,GAAG,MAAM"
+  "mappings": "UAAU,aAAa;QACd,GAAG;KACN,KAAa,EAAN,MAAM,GAAG,OAAO;KACvB,CAAC,EAAE,KAAQ,EAAD,CAAC,GAAG,YAAY,CAAC,CAAC;EAChC,IAAY,EAAN,MAAM,GAAG,MAAM;;;UAGb,UAAU,IAClB,MAAM,CAAC,QAAQ,KAAK,MAAM,EAC3B,CAAC,IAAI,IAAI,GACR,CAAS,EAAN,MAAM,GAAG,MAAM;;KAGf,WAAW,YACP,MAAM,MACT,IAAY,EAAN,MAAM,EAAE,GAAW,EAAN,MAAM,GAAG,MAAM;KAGnC,QAAQ,MACX,MAAM,CAAC,QAAQ,KAAK,MAAM"
 }

test/samples/ts-signatures/input.ts

@@ -5,7 +5,17 @@ interface Constructable {
 	(name: string): string;
 }
 
+interface Signatures {
+	[Symbol.iterator](): number;
+	x(): void;
+	[k: string]: number;
+}
+
 type Constructor = {
 	new (): object;
 	new (name: string, age: number): Person;
 };
+
+type Computed = {
+	[Symbol.iterator](): number;
+};

test/samples/ts-types/expected.ts

@@ -11,6 +11,13 @@ type H = this;
 
 type I = `Hello, ${keyof C}`;
 type J = () => this is string;
+type P = (x: unknown) => asserts x is string;
+
+function assertsString(x): asserts x is string {}
+function assertsValue(x): asserts x {}
+function assertsThis(x): asserts this is Foo {}
+function isString(x): x is string {}
+
 type Bird = { legs: 2 };
 type Dog = { legs: 4 };
 type Wolf = { legs: 4 };

test/samples/ts-types/expected.ts.map

@@ -5,7 +5,7 @@
     "input.js"
   ],
   "sourcesContent": [
-    "type A = [x: number, y: string];\ntype B = { a: string; b: number };\n\ntype C = 'foo' | 'bar';\ntype D = C | A | B | 'foobar';\n\ntype E = A & B;\ntype F = C & 'foobar';\n\n// TODO: commented because acorn doesn't support intrinsic but oxc does\n// type G = { [a in C]: string };\n\ntype H = this;\ntype I = `Hello, ${keyof C}`;\ntype J = () => this is string;\n\ntype Bird = { legs: 2 };\ntype Dog = { legs: 4 };\ntype Wolf = { legs: 4 };\ntype Animals = Bird | Dog | Wolf;\ntype HasFourLegs<Animal> = Animal extends { legs: 4 } ? Animal : never;\ntype FourLegs = HasFourLegs<Animals>;\n\ntype T = [('a' | 'b')?];\n\ntype CT = new (tpl: TemplateStringsArray, ...args: Array<unknown>) => (replacements: B) => A;\n\ntype X = [...number[]];\ntype TupleWithRest = [number, ...(1 extends 2 ? string[] : number[])];\n\n// TODO: commented because acorn doesn't support intrinsic but oxc does\n// type Uppercase<S extends string> = intrinsic;\n"
+    "type A = [x: number, y: string];\ntype B = { a: string; b: number };\n\ntype C = 'foo' | 'bar';\ntype D = C | A | B | 'foobar';\n\ntype E = A & B;\ntype F = C & 'foobar';\n\n// TODO: commented because acorn doesn't support intrinsic but oxc does\n// type G = { [a in C]: string };\n\ntype H = this;\ntype I = `Hello, ${keyof C}`;\ntype J = () => this is string;\ntype P = (x: unknown) => asserts x is string;\n\nfunction assertsString(x): asserts x is string {}\nfunction assertsValue(x): asserts x {}\nfunction assertsThis(x): asserts this is Foo {}\nfunction isString(x): x is string {}\n\ntype Bird = { legs: 2 };\ntype Dog = { legs: 4 };\ntype Wolf = { legs: 4 };\ntype Animals = Bird | Dog | Wolf;\ntype HasFourLegs<Animal> = Animal extends { legs: 4 } ? Animal : never;\ntype FourLegs = HasFourLegs<Animals>;\n\ntype T = [('a' | 'b')?];\n\ntype CT = new (tpl: TemplateStringsArray, ...args: Array<unknown>) => (replacements: B) => A;\n\ntype X = [...number[]];\ntype TupleWithRest = [number, ...(1 extends 2 ? string[] : number[])];\n\n// TODO: commented because acorn doesn't support intrinsic but oxc does\n// type Uppercase<S extends string> = intrinsic;\n"
   ],
-  "mappings": "KAAK,CAAC,IAAI,CAAC,EAAE,MAAM,EAAE,CAAC,EAAE,MAAM;KACzB,CAAC,KAAK,CAAC,EAAE,MAAM,EAAE,CAAC,EAAE,MAAM;KAE1B,CAAC,GAAG,KAAK,GAAG,KAAK;KACjB,CAAC,GAAG,CAAC,GAAG,CAAC,GAAG,CAAC,GAAG,QAAQ;KAExB,CAAC,GAAG,CAAC,GAAG,CAAC;KACT,CAAC,GAAG,CAAC,GAAG,QAAQ;;;;KAKhB,CAAC,GAAG,IAAI;;KACR,CAAC,mBAAmB,CAAC;KACrB,CAAC,SAAS,IAAI,IAAI,MAAM;KAExB,IAAI,KAAK,IAAI,EAAE,CAAC;KAChB,GAAG,KAAK,IAAI,EAAE,CAAC;KACf,IAAI,KAAK,IAAI,EAAE,CAAC;KAChB,OAAO,GAAG,IAAI,GAAG,GAAG,GAAG,IAAI;KAC3B,WAAW,CAAC,MAAM,IAAI,MAAM,WAAW,IAAI,EAAE,CAAC,KAAK,MAAM,GAAG,KAAK;KACjE,QAAQ,GAAG,WAAW,CAAC,OAAO;KAE9B,CAAC,KAAK,GAAG,GAAG,GAAG;KAEf,EAAE,QAAQ,GAAyB,EAApB,oBAAoB,KAAK,IAAI,EAAE,KAAK,CAAC,OAAO,OAAO,YAAe,EAAD,CAAC,KAAK,CAAC;KAEvF,CAAC,OAAO,MAAM;KACd,aAAa,IAAI,MAAM,MAAM,CAAC,SAAS,CAAC,GAAG,MAAM,KAAK,MAAM;;;"
+  "mappings": "KAAK,CAAC,IAAI,CAAC,EAAE,MAAM,EAAE,CAAC,EAAE,MAAM;KACzB,CAAC,KAAK,CAAC,EAAE,MAAM,EAAE,CAAC,EAAE,MAAM;KAE1B,CAAC,GAAG,KAAK,GAAG,KAAK;KACjB,CAAC,GAAG,CAAC,GAAG,CAAC,GAAG,CAAC,GAAG,QAAQ;KAExB,CAAC,GAAG,CAAC,GAAG,CAAC;KACT,CAAC,GAAG,CAAC,GAAG,QAAQ;;;;KAKhB,CAAC,GAAG,IAAI;;KACR,CAAC,mBAAmB,CAAC;KACrB,CAAC,SAAS,IAAI,IAAI,MAAM;KACxB,CAAC,IAAI,CAAU,EAAP,OAAO,aAAa,CAAC,IAAI,MAAM;;AAE5C,QAAQ,CAAC,aAAa,CAAC,CAAC,WAAW,CAAC,IAAI,MAAM,CAAC,CAAC,AAAA,CAAC;AACjD,QAAQ,CAAC,YAAY,CAAC,CAAC,WAAW,CAAC,CAAC,CAAC,AAAA,CAAC;AACtC,QAAQ,CAAC,WAAW,CAAC,CAAC,WAAW,IAAI,IAAI,GAAG,CAAC,CAAC,AAAA,CAAC;AAC/C,QAAQ,CAAC,QAAQ,CAAC,CAAC,GAAG,CAAC,IAAI,MAAM,CAAC,CAAC,AAAA,CAAC;;KAE/B,IAAI,KAAK,IAAI,EAAE,CAAC;KAChB,GAAG,KAAK,IAAI,EAAE,CAAC;KACf,IAAI,KAAK,IAAI,EAAE,CAAC;KAChB,OAAO,GAAG,IAAI,GAAG,GAAG,GAAG,IAAI;KAC3B,WAAW,CAAC,MAAM,IAAI,MAAM,WAAW,IAAI,EAAE,CAAC,KAAK,MAAM,GAAG,KAAK;KACjE,QAAQ,GAAG,WAAW,CAAC,OAAO;KAE9B,CAAC,KAAK,GAAG,GAAG,GAAG;KAEf,EAAE,QAAQ,GAAyB,EAApB,oBAAoB,KAAK,IAAI,EAAE,KAAK,CAAC,OAAO,OAAO,YAAe,EAAD,CAAC,KAAK,CAAC;KAEvF,CAAC,OAAO,MAAM;KACd,aAAa,IAAI,MAAM,MAAM,CAAC,SAAS,CAAC,GAAG,MAAM,KAAK,MAAM;;;"
 }

test/samples/ts-types/input.ts

@@ -13,6 +13,12 @@ type F = C & 'foobar';
 type H = this;
 type I = `Hello, ${keyof C}`;
 type J = () => this is string;
+type P = (x: unknown) => asserts x is string;
+
+function assertsString(x): asserts x is string {}
+function assertsValue(x): asserts x {}
+function assertsThis(x): asserts this is Foo {}
+function isString(x): x is string {}
 
 type Bird = { legs: 2 };
 type Dog = { legs: 4 };