feat(utils): reverse resolve alias

.github/workflows/ci.yml

@@ -16,8 +16,8 @@ jobs:
       - run: corepack enable
       - uses: actions/setup-node@v4
         with:
-          node-version: 16
-          cache: "pnpm"
+          node-version: "18"
+          cache: pnpm
       - run: pnpm install
       - run: pnpm lint
       - run: pnpm build

README.md

@@ -46,7 +46,7 @@ Pathe exports some extra utilities that do not exist in standard Node.js [path m
 In order to use them, you can import from `pathe/utils` subpath:
 
 ```js
-import { filename, normalizeAliases, resolveAlias } from 'pathe/utils'
+import { filename, normalizeAliases, resolveAlias, reverseResolveAlias } from 'pathe/utils'
 ```
 
 ## License

src/utils.ts

@@ -57,6 +57,28 @@ export function resolveAlias(path: string, aliases: Record<string, string>) {
   return _path;
 }
 
+export function reverseResolveAlias(
+  path: string,
+  aliases: Record<string, string>,
+) {
+  const _path = normalizeWindowsPath(path);
+  aliases = normalizeAliases(aliases);
+
+  for (const [to, alias] of Object.entries(aliases).reverse()) {
+    if (!_path.startsWith(alias)) {
+      continue;
+    }
+
+    // Strip trailing slash from alias for check
+    const _alias = hasTrailingSlash(alias) ? alias.slice(0, -1) : alias;
+
+    if (hasTrailingSlash(_path[_alias.length])) {
+      return join(to, _path.slice(alias.length));
+    }
+  }
+  return _path;
+}
+
 const FILENAME_RE = /(^|[/\\])([^/\\]+?)(?=(\.[^.]+)?$)/;
 
 export function filename(path: string) {

test/utils.spec.ts

@@ -1,6 +1,11 @@
 import { describe, expect, it } from "vitest";
 
-import { normalizeAliases, filename, resolveAlias } from "../src/utils";
+import {
+  normalizeAliases,
+  filename,
+  resolveAlias,
+  reverseResolveAlias,
+} from "../src/utils";
 
 describe("alias", () => {
   const _aliases = {
@@ -56,6 +61,33 @@ describe("alias", () => {
       expect(resolveAlias("~win/foo/bar", aliases)).toBe("C:/src/foo/bar");
     });
   });
+
+  describe("reverseResolveAlias", () => {
+    for (const [to, from] of Object.entries(aliases)) {
+      it(from, () => {
+        expect(reverseResolveAlias(from, aliases)).toBe(to);
+      });
+    }
+    it("respects path separators", () => {
+      const aliases = {
+        "~": "/root",
+        "~assets": "/root/some/assets",
+      };
+      expect(
+        reverseResolveAlias("/root/some/assets/smth.jpg", aliases),
+      ).toMatchInlineSnapshot('"~assets/smth.jpg"');
+    });
+    it("unchanged", () => {
+      expect(reverseResolveAlias("foo/bar.js", aliases)).toBe("foo/bar.js");
+      expect(reverseResolveAlias("./bar.js", aliases)).toBe("./bar.js");
+    });
+    it("respect ending with /", () => {
+      expect(reverseResolveAlias("/src/foo/bar", aliases)).toBe("~/foo/bar");
+      expect(reverseResolveAlias("C:/src/foo/bar", aliases)).toBe(
+        "~win/foo/bar",
+      );
+    });
+  });
 });
 
 describe("filename", () => {