more fixes and tests

Author: mbostock

src/javascript/__snapshots__/typescript.test.ts.snap

@@ -0,0 +1,66 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`transpiles TypeScript class expressions 1`] = `
+"class Foo {
+}
+"
+`;
+
+exports[`transpiles TypeScript expressions 1`] = `"(1 + 2)"`;
+
+exports[`transpiles TypeScript expressions 2`] = `"(1, 2)"`;
+
+exports[`transpiles TypeScript expressions 3`] = `"(1, 2)"`;
+
+exports[`transpiles TypeScript expressions 4`] = `"((1), (2))"`;
+
+exports[`transpiles TypeScript expressions 5`] = `"((1 + 2))"`;
+
+exports[`transpiles TypeScript expressions 6`] = `"({ x: 42 })"`;
+
+exports[`transpiles TypeScript expressions 7`] = `"(({ x: 42 }))"`;
+
+exports[`transpiles TypeScript function expressions 1`] = `
+"function foo() { }
+"
+`;
+
+exports[`transpiles TypeScript imports 1`] = `
+"import { foo } from "npm:bar";
+"
+`;
+
+exports[`transpiles TypeScript imports 2`] = `""`;
+
+exports[`transpiles TypeScript statements 1`] = `
+"1 + 2;
+"
+`;
+
+exports[`transpiles TypeScript statements 2`] = `
+"1, 2;
+"
+`;
+
+exports[`transpiles TypeScript statements 3`] = `
+"(1), (2);
+"
+`;
+
+exports[`transpiles TypeScript statements 4`] = `
+"(1 + 2);
+"
+`;
+
+exports[`transpiles TypeScript statements 5`] = `
+"{
+    x: 42;
+}
+;
+"
+`;
+
+exports[`transpiles TypeScript statements 6`] = `
+"({ x: 42 });
+"
+`;

src/javascript/typescript.test.ts

@@ -0,0 +1,40 @@
+import {assert, expect, it} from "vitest";
+import {transpileTypeScript} from "./typescript.js";
+
+it("transpiles TypeScript expressions", () => {
+  expect(transpileTypeScript("1 + 2")).toMatchSnapshot();
+  expect(transpileTypeScript("1, 2")).toMatchSnapshot();
+  expect(transpileTypeScript("1, 2 // comment")).toMatchSnapshot();
+  expect(transpileTypeScript("(1), (2)")).toMatchSnapshot();
+  expect(transpileTypeScript("(1 + 2)")).toMatchSnapshot();
+  expect(transpileTypeScript("{x: 42}")).toMatchSnapshot();
+  expect(transpileTypeScript("({x: 42})")).toMatchSnapshot();
+});
+
+it("transpiles TypeScript function expressions", () => {
+  expect(transpileTypeScript("function foo() {}")).toMatchSnapshot();
+});
+
+it("transpiles TypeScript class expressions", () => {
+  expect(transpileTypeScript("class Foo {}")).toMatchSnapshot();
+});
+
+it("transpiles TypeScript statements", () => {
+  expect(transpileTypeScript("1 + 2;")).toMatchSnapshot();
+  expect(transpileTypeScript("1, 2;")).toMatchSnapshot();
+  expect(transpileTypeScript("(1), (2);")).toMatchSnapshot();
+  expect(transpileTypeScript("(1 + 2);")).toMatchSnapshot();
+  expect(transpileTypeScript("{x: 42};")).toMatchSnapshot();
+  expect(transpileTypeScript("({x: 42});")).toMatchSnapshot();
+});
+
+it("transpiles TypeScript imports", () => {
+  expect(transpileTypeScript('import {foo} from "npm:bar";')).toMatchSnapshot();
+  expect(transpileTypeScript('import type {foo} from "npm:bar";')).toMatchSnapshot();
+});
+
+it("throws SyntaxError on invalid syntax", () => {
+  assert.throws(() => transpileTypeScript("1) + 2"), SyntaxError);
+  assert.throws(() => transpileTypeScript("(1 + 2"), SyntaxError);
+  assert.throws(() => transpileTypeScript("1 + 2 /* comment"), SyntaxError);
+});

src/javascript/typescript.ts

@@ -16,16 +16,16 @@ const compilerOptions = {
 } as const;
 
 export function transpileTypeScript(input: string): string {
-  const expr = asExpression(input);
+  const expr = maybeExpression(input);
   if (expr) return trimTrailingSemicolon(transpile(expr, compilerOptions));
   parseTypeScript(input); // enforce valid syntax
   return transpile(input, compilerOptions);
 }
 
 /** If the given is an expression (not a statement), returns it with parens. */
-function asExpression(input: string): string | undefined {
-  if (hasUnmatchedParens(input)) return; // disallow funny business
-  const expr = `(${trim(input)})`;
+function maybeExpression(input: string): string | undefined {
+  if (!hasMatchedParens(input)) return; // disallow funny business
+  const expr = withParens(input);
   if (!isSolitaryExpression(expr)) return;
   return expr;
 }
@@ -81,25 +81,25 @@ function* tokenize(input: string): Generator<Token> {
   }
 }
 
-/** Returns true if the specified input has mismatched parens. */
-function hasUnmatchedParens(input: string): boolean {
+/** Returns true if the specified input has matched parens. */
+function hasMatchedParens(input: string): boolean {
   let depth = 0;
   for (const t of tokenize(input)) {
     if (t.type === tokTypes.parenL) ++depth;
-    else if (t.type === tokTypes.parenR && --depth < 0) return true;
+    else if (t.type === tokTypes.parenR && --depth < 0) return false;
   }
-  return false;
+  return depth === 0;
 }
 
-/** Removes leading and trailing whitespace around the specified input. */
-function trim(input: string): string {
+/** Wraps the specified input with parentheses. */
+function withParens(input: string): string {
   let start;
   let end;
   for (const t of tokenize(input)) {
     start ??= t;
     end = t;
   }
-  return input.slice(start?.start, end?.end);
+  return `(${input.slice(start?.start, end?.end)})`;
 }
 
 /** Removes a trailing semicolon, if present. */