From cdb57b38439488b0bdc9103b5a8a8ac539c396c7 Mon Sep 17 00:00:00 2001
From: jvoisin <julien.voisin@dustri.org>
Date: Tue, 17 Jun 2025 23:11:44 +0200
Subject: [PATCH] perf(sanitizer): minor simplifications of the sanitizer

- Factorize some conditions
- Remove useless `default` case and move the return at the end of the functions
- Use strings.CutPrefix instead of strings.HasPrefix + strings.TrimPrefix
- Use switch-case constructs instead of slices.Contains, as this reduces the
  complexity of the functions and allows them to be inlined, as well as helping
  the compiler to optimize them, as it sucks at interprocedural optimizations.
---
 internal/reader/sanitizer/sanitizer.go | 52 ++++++++++++++------------
 1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/internal/reader/sanitizer/sanitizer.go b/internal/reader/sanitizer/sanitizer.go
index 7db80ee4..299a976b 100644
--- a/internal/reader/sanitizer/sanitizer.go
+++ b/internal/reader/sanitizer/sanitizer.go
@@ -322,15 +322,20 @@ func sanitizeAttributes(parsedBaseUrl *url.URL, baseURL, tagName string, attribu
 			value = "http://www.w3.org/1998/Math/MathML"
 		}
 
-		if tagName == "img" && attribute.Key == "fetchpriority" {
-			if !isValidFetchPriorityValue(value) {
-				continue
-			}
-		}
-
-		if tagName == "img" && attribute.Key == "decoding" {
-			if !isValidDecodingValue(value) {
-				continue
+		if tagName == "img" {
+			switch attribute.Key {
+			case "fetchpriority":
+				if !isValidFetchPriorityValue(value) {
+					continue
+				}
+			case "decoding":
+				if !isValidDecodingValue(value) {
+					continue
+				}
+			case "width", "height":
+				if isImageLargerThanLayout || !isPositiveInteger(value) {
+					continue
+				}
 			}
 		}
 
@@ -338,12 +343,6 @@ func sanitizeAttributes(parsedBaseUrl *url.URL, baseURL, tagName string, attribu
 			value = sanitizeSrcsetAttr(baseURL, value)
 		}
 
-		if tagName == "img" && (attribute.Key == "width" || attribute.Key == "height") {
-			if isImageLargerThanLayout || !isPositiveInteger(value) {
-				continue
-			}
-		}
-
 		if isExternalResourceAttribute(attribute.Key) {
 			switch {
 			case tagName == "iframe":
@@ -511,11 +510,11 @@ func rewriteIframeURL(link string) string {
 
 	switch strings.TrimPrefix(u.Hostname(), "www.") {
 	case "youtube.com":
-		if strings.HasPrefix(u.Path, "/embed/") {
+		if pathWithoutEmbed, ok := strings.CutPrefix(u.Path, "/embed/"); ok {
 			if len(u.RawQuery) > 0 {
-				return config.Opts.YouTubeEmbedUrlOverride() + strings.TrimPrefix(u.Path, "/embed/") + "?" + u.RawQuery
+				return config.Opts.YouTubeEmbedUrlOverride() + pathWithoutEmbed + "?" + u.RawQuery
 			}
-			return config.Opts.YouTubeEmbedUrlOverride() + strings.TrimPrefix(u.Path, "/embed/")
+			return config.Opts.YouTubeEmbedUrlOverride() + pathWithoutEmbed
 		}
 	case "player.vimeo.com":
 		// See https://help.vimeo.com/hc/en-us/articles/12426260232977-About-Player-parameters
@@ -534,9 +533,8 @@ func isBlockedTag(tagName string) bool {
 	switch tagName {
 	case "noscript", "script", "style":
 		return true
-	default:
-		return false
 	}
+	return false
 }
 
 func sanitizeSrcsetAttr(baseURL, value string) string {
@@ -581,11 +579,17 @@ func getIntegerAttributeValue(name string, attributes []html.Attribute) int {
 }
 
 func isValidFetchPriorityValue(value string) bool {
-	allowedValues := []string{"high", "low", "auto"}
-	return slices.Contains(allowedValues, value)
+	switch value {
+	case "high", "low", "auto":
+		return true
+	}
+	return false
 }
 
 func isValidDecodingValue(value string) bool {
-	allowedValues := []string{"sync", "async", "auto"}
-	return slices.Contains(allowedValues, value)
+	switch value {
+	case "sync", "async", "auto":
+		return true
+	}
+	return false
 }