Add a stringify API

Author: blakeembrey

src/cases.spec.ts

@@ -1,16 +1,23 @@
-import type {
-  MatchOptions,
-  Match,
-  ParseOptions,
-  Token,
-  CompileOptions,
-  ParamData,
+import {
+  type MatchOptions,
+  type Match,
+  type ParseOptions,
+  type Token,
+  type CompileOptions,
+  type ParamData,
+  TokenData,
 } from "./index.js";
 
 export interface ParserTestSet {
   path: string;
   options?: ParseOptions;
-  expected: Token[];
+  expected: TokenData;
+}
+
+export interface StringifyTestSet {
+  data: TokenData;
+  options?: ParseOptions;
+  expected: string;
 }
 
 export interface CompileTestSet {
@@ -34,56 +41,98 @@ export interface MatchTestSet {
 export const PARSER_TESTS: ParserTestSet[] = [
   {
     path: "/",
-    expected: [{ type: "text", value: "/" }],
+    expected: new TokenData([{ type: "text", value: "/" }]),
   },
   {
     path: "/:test",
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: "test" },
-    ],
+    ]),
   },
   {
     path: '/:"0"',
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: "0" },
-    ],
+    ]),
   },
   {
     path: "/:_",
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: "_" },
-    ],
+    ]),
   },
   {
     path: "/:café",
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: "café" },
-    ],
+    ]),
   },
   {
     path: '/:"123"',
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: "123" },
-    ],
+    ]),
   },
   {
     path: '/:"1\\"\\2\\"3"',
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "param", name: '1"2"3' },
-    ],
+    ]),
   },
   {
     path: "/*path",
-    expected: [
+    expected: new TokenData([
       { type: "text", value: "/" },
       { type: "wildcard", name: "path" },
-    ],
+    ]),
+  },
+];
+
+export const STRINGIFY_TESTS: StringifyTestSet[] = [
+  {
+    data: new TokenData([{ type: "text", value: "/" }]),
+    expected: "/",
+  },
+  {
+    data: new TokenData([
+      { type: "text", value: "/" },
+      { type: "param", name: "test" },
+    ]),
+    expected: "/:test",
+  },
+  {
+    data: new TokenData([
+      { type: "text", value: "/" },
+      { type: "param", name: "café" },
+    ]),
+    expected: "/:café",
+  },
+  {
+    data: new TokenData([
+      { type: "text", value: "/" },
+      { type: "param", name: "0" },
+    ]),
+    expected: '/:"0"',
+  },
+  {
+    data: new TokenData([
+      { type: "text", value: "/" },
+      { type: "wildcard", name: "test" },
+    ]),
+    expected: "/*test",
+  },
+  {
+    data: new TokenData([
+      { type: "text", value: "/" },
+      { type: "wildcard", name: "0" },
+    ]),
+    expected: '/*"0"',
   },
 ];
 

src/index.spec.ts

@@ -1,6 +1,11 @@
 import { describe, it, expect } from "vitest";
-import { parse, compile, match } from "./index.js";
-import { PARSER_TESTS, COMPILE_TESTS, MATCH_TESTS } from "./cases.spec.js";
+import { parse, compile, match, stringify } from "./index.js";
+import {
+  PARSER_TESTS,
+  COMPILE_TESTS,
+  MATCH_TESTS,
+  STRINGIFY_TESTS,
+} from "./cases.spec.js";
 
 /**
  * Dynamically generate the entire test suite.
@@ -94,7 +99,17 @@ describe("path-to-regexp", () => {
     ({ path, options, expected }) => {
       it("should parse the path", () => {
         const data = parse(path, options);
-        expect(data.tokens).toEqual(expected);
+        expect(data).toEqual(expected);
+      });
+    },
+  );
+
+  describe.each(STRINGIFY_TESTS)(
+    "stringify $tokens with $options",
+    ({ data, expected }) => {
+      it("should stringify the path", () => {
+        const path = stringify(data);
+        expect(path).toEqual(expected);
       });
     },
   );

src/index.ts

@@ -595,3 +595,30 @@ function negate(delimiter: string, backtrack: string) {
   if (isSimple) return `[^${escape(values.join(""))}]`;
   return `(?:(?!${values.map(escape).join("|")}).)`;
 }
+
+/**
+ * Stringify token data into a path string.
+ */
+export function stringify(data: TokenData) {
+  let result = "";
+  for (const token of data.tokens) result += stringifyToken(token);
+  return result;
+}
+
+function stringifyToken(token: Token) {
+  if (token.type === "text") return token.value;
+  if (token.type === "group") return `{${stringifyToken(token)}}`;
+
+  const isSafe = isNameSafe(token.name);
+  const key = isSafe ? token.name : JSON.stringify(token.name);
+
+  if (token.type === "param") return `:${key}`;
+  if (token.type === "wildcard") return `*${key}`;
+  throw new TypeError(`Unexpected token: ${token}`);
+}
+
+function isNameSafe(name: string) {
+  const [first, ...rest] = name;
+  if (!ID_START.test(first)) return false;
+  return rest.every((char) => ID_CONTINUE.test(char));
+}