Implement logic with regexp rather than custom parsing

Author: eemeli

fluent-langneg/src/accepted_languages.ts

@@ -1,28 +1,20 @@
-function parseAcceptLanguageEntry(entry: string): { lang: string; q: number } {
-  const langWithQ = entry.split(";").map(u => u.trim());
-  let q = 1.0;
-  if (langWithQ.length > 1) {
-    const qVal = langWithQ[1].split("=").map(u => u.trim());
-    if (qVal.length === 2 && qVal[0].toLowerCase() === "q") {
-      const qn = Number(qVal[1]);
-      q = isNaN(qn) ? 0.0 : qn;
-    }
-  }
-  return { lang: langWithQ[0], q };
-}
+const entryRegexp =
+  //      locale     ;    q     = qval
+  /(?:^|,)([^,;]+)(?:;\s*[qQ]\s*=([^,;]+))?/g;
 
 export function acceptedLanguages(acceptLanguageHeader = ""): string[] {
   if (typeof acceptLanguageHeader !== "string") {
     throw new TypeError("Argument must be a string");
   }
-  const tokens = acceptLanguageHeader
-    .split(",")
-    .map(t => t.trim())
-    .filter(t => t !== "");
-  const langsWithQ = Array.from(tokens.map(parseAcceptLanguageEntry).entries());
+
+  const langsWithQ: Array<{ lang: string; q: number; index: number }> = [];
+  for (const token of acceptLanguageHeader.matchAll(entryRegexp)) {
+    const q = token[2] ? parseFloat(token[2]) || 0 : 1;
+    langsWithQ.push({ lang: token[1].trim(), q, index: token.index });
+  }
+
   // order by q descending, keeping the header order for equal weights
-  langsWithQ.sort(([aidx, aval], [bidx, bval]) =>
-    aval.q === bval.q ? aidx - bidx : bval.q - aval.q
-  );
-  return langsWithQ.map(([, val]) => val.lang);
+  langsWithQ.sort((a, b) => (a.q === b.q ? a.index - b.index : b.q - a.q));
+
+  return langsWithQ.map(val => val.lang);
 }

fluent-langneg/test/headers_test.js

@@ -37,7 +37,7 @@ suite("parse headers", () => {
       acceptedLanguages(
         "en;q=no, fr;z=0.9, de;q=0.7;q=9, *;q=0.5, fr-CH;q=a=0.1"
       ),
-      ["fr", "fr-CH", "de", "*", "en"]
+      ["fr", "de", "*", "en", "fr-CH"]
     );
   });