POC for custom route patterns

Author: hansott

library/helpers/buildRouteFromURL.test.ts

@@ -198,3 +198,15 @@ t.test("it detects numeric comma separated arrays", async (t) => {
   t.same(buildRouteFromURL("/users/1,2,3_"), "/users/1,2,3_");
   t.same(buildRouteFromURL("/users/1,2,3a"), "/users/1,2,3a");
 });
+
+t.test("it supports custom patterns", async () => {
+  t.same(
+    buildRouteFromURL("/prefix-103799/api/dashboard", ["prefix-{digits}"]),
+    "/:custom/api/dashboard"
+  );
+
+  t.same(
+    buildRouteFromURL("/blog/01-31513/slug", ["{digits}-{digits}"]),
+    "/blog/:custom/slug"
+  );
+});

library/helpers/buildRouteFromURL.ts

@@ -1,3 +1,5 @@
+import { safeCreateRegExp } from "../agent/safeCreateRegExp";
+import { escapeStringRegexp } from "./escapeStringRegexp";
 import { looksLikeASecret } from "./looksLikeASecret";
 import { safeDecodeURIComponent } from "./safeDecodeURIComponent";
 import { tryParseURLPath } from "./tryParseURLPath";
@@ -15,7 +17,7 @@ const HASH = /^(?:[a-f0-9]{32}|[a-f0-9]{40}|[a-f0-9]{64}|[a-f0-9]{128})$/i;
 const HASH_LENGTHS = [32, 40, 64, 128];
 const NUMBER_ARRAY = /^\d+(?:,\d+)*$/;
 
-export function buildRouteFromURL(url: string) {
+export function buildRouteFromURL(url: string, custom: string[] = []) {
   let path = tryParseURLPath(url);
 
   if (!path) {
@@ -29,7 +31,10 @@ export function buildRouteFromURL(url: string) {
     }
   }
 
-  const route = path.split("/").map(replaceURLSegmentWithParam).join("/");
+  const route = path
+    .split("/")
+    .map(replaceURLSegmentWithCustomParam(custom))
+    .join("/");
 
   if (route === "/") {
     return "/";
@@ -42,6 +47,46 @@ export function buildRouteFromURL(url: string) {
   return route;
 }
 
+function compileCustom(pattern: string) {
+  if (!pattern.includes("{") || !pattern.includes("}")) {
+    return undefined;
+  }
+
+  const supported: Record<string, string> = {
+    "{digits}": `\\d+`,
+    "{alpha}": "[a-zA-Z]+",
+  };
+
+  // Split the pattern into tokens (placeholders and literals)
+  const placeholderRegex = /(\{[a-zA-Z]+})/g;
+  const parts = pattern.split(placeholderRegex);
+  const regexParts = parts.map((part) => {
+    if (supported[part]) {
+      return supported[part];
+    }
+
+    return escapeStringRegexp(part);
+  });
+
+  return safeCreateRegExp(`^${regexParts.join("")}$`, "");
+}
+
+function replaceURLSegmentWithCustomParam(custom: string[]) {
+  const customPatterns = custom
+    .map(compileCustom)
+    .filter((p) => p !== undefined);
+
+  return (segment: string) => {
+    for (const pattern of customPatterns) {
+      if (pattern && pattern.test(segment)) {
+        return `:custom`;
+      }
+    }
+
+    return replaceURLSegmentWithParam(segment);
+  };
+}
+
 function replaceURLSegmentWithParam(segment: string) {
   const charCode = segment.charCodeAt(0);
   const startsWithNumber = charCode >= 48 && charCode <= 57; // ASCII codes for '0' to '9'