From de33cf6b44a7d60e8e7e4e094970a08abe152a57 Mon Sep 17 00:00:00 2001
From: Romain Menke <romainmenke@gmail.com>
Date: Sat, 16 Sep 2023 22:31:31 +0200
Subject: [PATCH 1/3] improve sourcemap performance

---
 lib/map-generator.js | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/lib/map-generator.js b/lib/map-generator.js
index f6320bc2d..b0b584086 100644
--- a/lib/map-generator.js
+++ b/lib/map-generator.js
@@ -17,6 +17,10 @@ class MapGenerator {
     this.opts = opts
     this.css = cssString
     this.usesFileUrls = !this.mapOpts.from && this.mapOpts.absolute
+
+    this.memoizedFileURLs = new Map();
+    this.memoizedPaths = new Map();
+    this.memoizedURLs = new Map();
   }
 
   addAnnotation() {
@@ -241,9 +245,10 @@ class MapGenerator {
   }
 
   path(file) {
-    if (file.indexOf('<') === 0) return file
-    if (/^\w+:\/\//.test(file)) return file
     if (this.mapOpts.absolute) return file
+    if (file.charCodeAt(0) === 60 /* `<` */) return file
+    if (/^\w+:\/\//.test(file)) return file
+    if (this.memoizedPaths.has(file)) return this.memoizedPaths.get(file);
 
     let from = this.opts.to ? dirname(this.opts.to) : '.'
 
@@ -251,8 +256,9 @@ class MapGenerator {
       from = dirname(resolve(from, this.mapOpts.annotation))
     }
 
-    file = relative(from, file)
-    return file
+    let path = relative(from, file)
+    this.memoizedPaths.set(file, path);
+    return path
   }
 
   previous() {
@@ -318,8 +324,14 @@ class MapGenerator {
   }
 
   toFileUrl(path) {
+    if (this.memoizedFileURLs.has(path)) {
+      return this.memoizedFileURLs.get(path);
+    }
     if (pathToFileURL) {
-      return pathToFileURL(path).toString()
+      let fileURL = pathToFileURL(path).toString()
+      this.memoizedFileURLs.set(path, fileURL)
+
+      return fileURL
     } else {
       throw new Error(
         '`map.absolute` option is not available in this PostCSS build'
@@ -328,10 +340,18 @@ class MapGenerator {
   }
 
   toUrl(path) {
+    if (this.memoizedURLs.has(path)) {
+      return this.memoizedURLs.get(path);
+    }
+
     if (sep === '\\') {
       path = path.replace(/\\/g, '/')
     }
-    return encodeURI(path).replace(/[#?]/g, encodeURIComponent)
+
+    let url = encodeURI(path).replace(/[#?]/g, encodeURIComponent);
+    this.memoizedURLs.set(path, url);
+
+    return url
   }
 }
 

From efa442c3e181b8714302bf0bfdfe92a11b7db3ae Mon Sep 17 00:00:00 2001
From: Romain Menke <11521496+romainmenke@users.noreply.github.com>
Date: Sat, 16 Sep 2023 22:41:08 +0200
Subject: [PATCH 2/3] Update lib/map-generator.js

Co-authored-by: Andrey Sitnik <andrey@sitnik.ru>
---
 lib/map-generator.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/map-generator.js b/lib/map-generator.js
index b0b584086..6fe624dd3 100644
--- a/lib/map-generator.js
+++ b/lib/map-generator.js
@@ -248,7 +248,8 @@ class MapGenerator {
     if (this.mapOpts.absolute) return file
     if (file.charCodeAt(0) === 60 /* `<` */) return file
     if (/^\w+:\/\//.test(file)) return file
-    if (this.memoizedPaths.has(file)) return this.memoizedPaths.get(file);
+    let cached = this.memoizedPaths.get(file)
+    if (cached) return cached
 
     let from = this.opts.to ? dirname(this.opts.to) : '.'
 

From 6a291d64253575f8c407711ae432f7470d1bbd05 Mon Sep 17 00:00:00 2001
From: Romain Menke <romainmenke@gmail.com>
Date: Sat, 16 Sep 2023 22:42:46 +0200
Subject: [PATCH 3/3] apply suggestions from code review

---
 lib/map-generator.js | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/map-generator.js b/lib/map-generator.js
index 6fe624dd3..523b46397 100644
--- a/lib/map-generator.js
+++ b/lib/map-generator.js
@@ -18,9 +18,9 @@ class MapGenerator {
     this.css = cssString
     this.usesFileUrls = !this.mapOpts.from && this.mapOpts.absolute
 
-    this.memoizedFileURLs = new Map();
-    this.memoizedPaths = new Map();
-    this.memoizedURLs = new Map();
+    this.memoizedFileURLs = new Map()
+    this.memoizedPaths = new Map()
+    this.memoizedURLs = new Map()
   }
 
   addAnnotation() {
@@ -258,7 +258,8 @@ class MapGenerator {
     }
 
     let path = relative(from, file)
-    this.memoizedPaths.set(file, path);
+    this.memoizedPaths.set(file, path)
+
     return path
   }
 
@@ -325,9 +326,9 @@ class MapGenerator {
   }
 
   toFileUrl(path) {
-    if (this.memoizedFileURLs.has(path)) {
-      return this.memoizedFileURLs.get(path);
-    }
+    let cached = this.memoizedFileURLs.get(path)
+    if (cached) return cached
+
     if (pathToFileURL) {
       let fileURL = pathToFileURL(path).toString()
       this.memoizedFileURLs.set(path, fileURL)
@@ -341,16 +342,15 @@ class MapGenerator {
   }
 
   toUrl(path) {
-    if (this.memoizedURLs.has(path)) {
-      return this.memoizedURLs.get(path);
-    }
+    let cached = this.memoizedURLs.get(path)
+    if (cached) return cached
 
     if (sep === '\\') {
       path = path.replace(/\\/g, '/')
     }
 
-    let url = encodeURI(path).replace(/[#?]/g, encodeURIComponent);
-    this.memoizedURLs.set(path, url);
+    let url = encodeURI(path).replace(/[#?]/g, encodeURIComponent)
+    this.memoizedURLs.set(path, url)
 
     return url
   }