From 7189599019d26c220d2fa2d39be5c6daa60e8a19 Mon Sep 17 00:00:00 2001
From: Viet Huynh <xa.lach@yahoo.com>
Date: Sun, 19 Nov 2023 18:20:47 +0700
Subject: [PATCH] implement memoization for domain normalization

---
 cf_list_create.js |  6 ++++--
 lib/utils.js      | 21 +++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/cf_list_create.js b/cf_list_create.js
index cfecb22..bce748b 100644
--- a/cf_list_create.js
+++ b/cf_list_create.js
@@ -17,6 +17,7 @@ import {
   extractDomain,
   isComment,
   isValidDomain,
+  memoize,
   readFile,
 } from "./lib/utils.js";
 
@@ -33,6 +34,7 @@ let processedDomainCount = 0;
 let unnecessaryDomainCount = 0;
 let duplicateDomainCount = 0;
 let allowedDomainCount = 0;
+const memoizedNormalizeDomain = memoize(normalizeDomain);
 
 // Read allowlist
 console.log(`Processing ${allowlistFilename}`);
@@ -43,7 +45,7 @@ await readFile(resolve(`./${allowlistFilename}`), (line) => {
 
   if (isComment(_line)) return;
 
-  const domain = normalizeDomain(_line, true);
+  const domain = memoizedNormalizeDomain(_line, true);
 
   if (!isValidDomain(domain)) return;
 
@@ -65,7 +67,7 @@ await readFile(resolve(`./${blocklistFilename}`), (line, rl) => {
   if (isComment(_line)) return;
 
   // Remove prefixes and suffixes in hosts, wildcard or adblock format
-  const domain = normalizeDomain(_line);
+  const domain = memoizedNormalizeDomain(_line);
 
   // Check if it is a valid domain which is not a URL or does not contain
   // characters like * in the middle of the domain
diff --git a/lib/utils.js b/lib/utils.js
index 48cee7c..dd91e21 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -90,3 +90,24 @@ export const readFile = async (filePath, onLine) => {
     throw err;
   }
 };
+
+/**
+ * Memoizes a function
+ * @template T The argument type of the function.
+ * @template R The return type of the function.
+ * @param {(...fnArgs: T[]) => R} fn The function to be memoized.
+ */
+export const memoize = (fn) => {
+  const cache = new Map();
+
+  return (...args) => {
+    const key = args.join("-");
+
+    if (cache.has(key)) return cache.get(key);
+
+    const result = fn(...args);
+
+    cache.set(key, result);
+    return result;
+  };
+};