Refactor i18n checks on request handling

[javivelasco]

Currently there is a lot of mutation in the Next.js Server and the checks for Locale are directly coded in the general request handler. Ideally, we should have a function where we just pass the request input (url + headers + config) and generate a bunch of metadata that analyzes it generating all metadata we might require for both the URL and i18n + basePath information.

This PR brings:

• A new parsing function parseUrl that joins parsing an absolute/relative URL into a data structure compatible with the Node parsing output but missing redundant properties.
• A wrapper parseNextURL that extends parseUrl analyzing i18n and basePath based on the provided configuration, url and headers. This function is pure and stateless so it can be used outside of the Next.js context.
• Types improvements and reuse.
• Refactors next-server.ts request handling using the above mentioned functions so that the code there just apply effects to the req object and the parsedUrl.query leaving the code much more straightforward.
• Refactors getRouteRegex decomposing in two different functions where getParametrizedRoute can be used to retrieve the serializable data that is used to generate the Regex.

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
buildDuration	16.8s	16.3s	-473ms
buildDurationCached	3.8s	3.6s	-214ms
nodeModulesSize	49.5 MB	49.5 MB	⚠️ +8.35 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.795	2.88	⚠️ +0.08
/ avg req/sec	894.44	868.19	⚠️ -26.25
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.696	1.787	⚠️ +0.09
/error-in-render avg req/sec	1474.14	1399.34	⚠️ -74.8

Client Bundles (main, webpack, commons) Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
359.HASH.js gzip	2.96 kB	2.96 kB	✓
745.HASH.js gzip	180 B	180 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	20.9 kB	21 kB	⚠️ +82 B
webpack-HASH.js gzip	1.53 kB	1.53 kB	✓
Overall change	67.8 kB	67.9 kB	⚠️ +82 B

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
polyfills-HASH.js gzip	31.1 kB	31.1 kB	✓
Overall change	31.1 kB	31.1 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
_app-HASH.js gzip	803 B	803 B	✓
_error-HASH.js gzip	3.06 kB	3.06 kB	✓
amp-HASH.js gzip	554 B	554 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.52 kB	2.52 kB	✓
head-HASH.js gzip	2.28 kB	2.28 kB	✓
hooks-HASH.js gzip	903 B	903 B	✓
image-HASH.js gzip	5.61 kB	5.61 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	319 B	319 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	19.1 kB	19.1 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
_buildManifest.js gzip	490 B	490 B	✓
Overall change	490 B	490 B	✓

Rendered Page Sizes Overall decrease ✓

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
index.html gzip	531 B	530 B	-1 B
link.html gzip	544 B	542 B	-2 B
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	-3 B

Diffs

Diff for main-HASH.js

@@ -5890,6 +5890,7 @@
       Object.defineProperty(exports, "__esModule", {
         value: true
       });
+      exports.getParametrizedRoute = getParametrizedRoute;
       exports.getRouteRegex = getRouteRegex; // this isn't importing the escape-string-regex module
       // to reduce bytes
 
@@ -5917,10 +5918,8 @@
         };
       }
 
-      function getRouteRegex(normalizedRoute) {
-        var segments = (normalizedRoute.replace(/\/$/, "") || "/")
-          .slice(1)
-          .split("/");
+      function getParametrizedRoute(route) {
+        var segments = (route.replace(/\/$/, "") || "/").slice(1).split("/");
         var groups = {};
         var groupIndex = 1;
         var parameterizedRoute = segments
@@ -5957,11 +5956,29 @@
         }
 
         return {
-          re: new RegExp("^".concat(parameterizedRoute, "(?:/)?$")),
+          parameterizedRoute: parameterizedRoute,
           groups: groups
         };
       }
 
+      function getRouteRegex(normalizedRoute) {
+        var result = getParametrizedRoute(normalizedRoute);
+
+        if ("routeKeys" in result) {
+          return {
+            re: new RegExp("^".concat(result.parameterizedRoute, "(?:/)?$")),
+            groups: result.groups,
+            routeKeys: result.routeKeys,
+            namedRegex: "^".concat(result.namedParameterizedRoute, "(?:/)?$")
+          };
+        }
+
+        return {
+          re: new RegExp("^".concat(result.parameterizedRoute, "(?:/)?$")),
+          groups: result.groups
+        };
+      }
+
       /***/
     },

Diff for index.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-286fcf1894d7baae7f35.js"
+      src="/_next/static/chunks/main-01e3b7fe776dde9adc16.js"
       defer=""
     ></script>
     <script

Diff for link.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-286fcf1894d7baae7f35.js"
+      src="/_next/static/chunks/main-01e3b7fe776dde9adc16.js"
       defer=""
     ></script>
     <script

Diff for withRouter.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/main-286fcf1894d7baae7f35.js"
+      src="/_next/static/chunks/main-01e3b7fe776dde9adc16.js"
       defer=""
     ></script>
     <script

---

Webpack 4 Mode (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
buildDuration	13.6s	12.9s	-707ms
buildDurationCached	5.1s	4.8s	-299ms
nodeModulesSize	49.5 MB	49.5 MB	⚠️ +8.35 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.838	2.798	-0.04
/ avg req/sec	881.05	893.36	+12.31
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.702	1.811	⚠️ +0.11
/error-in-render avg req/sec	1468.67	1380.15	⚠️ -88.52

Client Bundles (main, webpack, commons) Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
17.HASH.js gzip	2.98 kB	2.98 kB	✓
18.HASH.js gzip	185 B	185 B	✓
677f882d2ed8..HASH.js gzip	13.7 kB	13.7 kB	⚠️ +70 B
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	8.4 kB	8.4 kB	✓
webpack-HASH.js gzip	1.22 kB	1.22 kB	✓
Overall change	68.4 kB	68.5 kB	⚠️ +70 B

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
polyfills-HASH.js gzip	31.3 kB	31.3 kB	✓
Overall change	31.3 kB	31.3 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
_app-HASH.js gzip	791 B	791 B	✓
_error-HASH.js gzip	3.76 kB	3.76 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.71 kB	2.71 kB	✓
head-HASH.js gzip	2.97 kB	2.97 kB	✓
hooks-HASH.js gzip	911 B	911 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	3.02 kB	3.02 kB	✓
withRouter-HASH.js gzip	294 B	294 B	✓
e025d2764813..52f.css gzip	125 B	125 B	✓
Overall change	17.6 kB	17.6 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
_buildManifest.js gzip	500 B	500 B	✓
Overall change	500 B	500 B	✓

Rendered Page Sizes Overall decrease ✓

	vercel/next.js canary	javivelasco/next.js refactor-locale-detection	Change
index.html gzip	577 B	576 B	-1 B
link.html gzip	587 B	587 B	✓
withRouter.html gzip	569 B	568 B	-1 B
Overall change	1.73 kB	1.73 kB	-2 B

Diffs

Diff for 677f882d2ed8..c4df.HASH.js

@@ -3471,6 +3471,7 @@
       Object.defineProperty(exports, "__esModule", {
         value: true
       });
+      exports.getParametrizedRoute = getParametrizedRoute;
       exports.getRouteRegex = getRouteRegex; // this isn't importing the escape-string-regex module
       // to reduce bytes
 
@@ -3498,10 +3499,8 @@
         };
       }
 
-      function getRouteRegex(normalizedRoute) {
-        var segments = (normalizedRoute.replace(/\/$/, "") || "/")
-          .slice(1)
-          .split("/");
+      function getParametrizedRoute(route) {
+        var segments = (route.replace(/\/$/, "") || "/").slice(1).split("/");
         var groups = {};
         var groupIndex = 1;
         var parameterizedRoute = segments
@@ -3538,11 +3537,29 @@
         }
 
         return {
-          re: new RegExp("^".concat(parameterizedRoute, "(?:/)?$")),
+          parameterizedRoute: parameterizedRoute,
           groups: groups
         };
       }
 
+      function getRouteRegex(normalizedRoute) {
+        var result = getParametrizedRoute(normalizedRoute);
+
+        if ("routeKeys" in result) {
+          return {
+            re: new RegExp("^".concat(result.parameterizedRoute, "(?:/)?$")),
+            groups: result.groups,
+            routeKeys: result.routeKeys,
+            namedRegex: "^".concat(result.namedParameterizedRoute, "(?:/)?$")
+          };
+        }
+
+        return {
+          re: new RegExp("^".concat(result.parameterizedRoute, "(?:/)?$")),
+          groups: result.groups
+        };
+      }
+
       /***/
     },

Diff for index.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.726ef802be8b1e2738a9.js"
+      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.478e7617d8bdd88fdbea.js"
       defer=""
     ></script>
     <script

Diff for link.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.726ef802be8b1e2738a9.js"
+      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.478e7617d8bdd88fdbea.js"
       defer=""
     ></script>
     <script

Diff for withRouter.html

@@ -19,7 +19,7 @@
       defer=""
     ></script>
     <script
-      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.726ef802be8b1e2738a9.js"
+      src="/_next/static/chunks/677f882d2ed86fa3467b8979053c1a4c3f8bc4df.478e7617d8bdd88fdbea.js"
       defer=""
     ></script>
     <script

Commit: 124264e

[ijjk]

Looks good, thanks!