chore: refine trailing slashes with wildcards and params

Author: kettanaito

README.md

@@ -54,6 +54,33 @@ This function supports the following features:
 
 `matchPattern` uses token-based comparision to completely forego regular expressions, which should, technically, make it more performant and less prone to vulnerabilities. Doesn't promise full feature parity with `path-to-regexp` but currently uses its test suite as the compliance bar.
 
+### Trailing slashes
+
+The pattern is the source of truth. If it ends with a trailing slash, then the input must also end with it to match. If the pattern doesn't end with a trailing slash, then the trailing slash in the input is ignored when matching.
+
+```ts
+// No trailing slash in the pattern? Ignore it.
+matchPattern('/api', '/api') // ✅
+matchPattern('/api/', '/api') // ✅
+
+// Trailing slash in the pattern? It's required.
+matchPattern('/api/', '/api/') // ✅
+matchPattern('/api', '/api/') // ❌
+```
+
+> This is to accommodate to JavaScript developers not being used to providing trailing slashes.
+
+### Wildcards
+
+Wildcards _do not require value_ at their position.
+
+```ts
+matchPattern('/user/', '/user/*') // ✅ { params: { '0': ''} }
+matchPattern('/user', '/user/*') // ❌
+```
+
+> Note that the slash before the wildcard is still treated as required.
+
 ## Benchmarks
 
 ```sh

src/index.ts

@@ -338,17 +338,21 @@ function matchTokens(
 
     // Check emptiness before allocating the captured substring.
     const allowEmpty =
-      token.type === TokenType.Param &&
-      (token.modifier === '?' || token.modifier === '*')
+      token.type === TokenType.Wildcard ||
+      (token.type === TokenType.Param &&
+        (token.modifier === '?' || token.modifier === '*'))
 
     if (!allowEmpty && position === endPosition) {
       return NO_MATCH
     }
 
     if (token.type === TokenType.Wildcard) {
-      params[String(wildcardIndex++)] = decode(
-        inputString.slice(position, endPosition),
-      )
+      if (position !== endPosition) {
+        params[String(wildcardIndex)] = decode(
+          inputString.slice(position, endPosition),
+        )
+      }
+      wildcardIndex++
     } else if (position !== endPosition) {
       const captured = decode(inputString.slice(position, endPosition))
       const existing = params[token.name]
@@ -432,7 +436,7 @@ export function matchPattern(
 
   // Pure literal patterns are just a string equality check.
   // Try raw first, then decoded (for encoded inputs like %C3%A9 vs é).
-  // When the pattern doesn't end with '/', also match with trailing
+  // When the pattern doesn't end with '/', also try with trailing
   // slash stripped from the input.
   if (isLiteralOnly) {
     if (inputString === pattern || decode(inputString) === pattern) {

tests/index.test.ts

@@ -79,10 +79,8 @@ it.each<
     'http://localhost/user/*/*',
     MATCHES_WITH_PARAMS({ '0': '123', '1': 'settings' }),
   ],
-
-  /* Wildcard non-match */
   ['http://localhost', 'http://localhost/*', NO_MATCH],
-  ['http://localhost/', 'http://localhost/*', NO_MATCH],
+  ['http://localhost/', 'http://localhost/*', MATCHES_WITHOUT_PARAMS],
 
   /* Three or more wildcards */
   [