LibWeb: Use Optional<String> for encoding_from_content_type

This patch changes the encoding_from_content_type function to only
return an encoding if it actually finds one, and leave it up to the
caller to decided on a default to use.

It also modifies the caller to expect an Optional<String> (instead of
relying on the null state of the String class) as a return value and
separates the encoding and MIME type determination. This will be built
upon in a further commit.

1 files changed, 14 insertions, 6 deletions

diff --git a/Userland/Libraries/LibWeb/Loader/Resource.cpp b/Userland/Libraries/LibWeb/Loader/Resource.cpp
index 9231ec341e..0892cc61c9 100644
--- a/Userland/Libraries/LibWeb/Loader/Resource.cpp
+++ b/Userland/Libraries/LibWeb/Loader/Resource.cpp
@@ -41,7 +41,7 @@ void Resource::for_each_client(Function<void(ResourceClient&)> callback)
     }
 }
 
-static String encoding_from_content_type(const String& content_type)
+static Optional<String> encoding_from_content_type(const String& content_type)
 {
     auto offset = content_type.index_of("charset=");
     if (offset.has_value()) {
@@ -53,7 +53,7 @@ static String encoding_from_content_type(const String& content_type)
         return encoding;
     }
 
-    return "utf-8";
+    return {};
 }
 
 static String mime_type_from_content_type(const String& content_type)
@@ -74,20 +74,28 @@ void Resource::did_load(Badge<ResourceLoader>, ReadonlyBytes data, const HashMap
     m_loaded = true;
 
     auto content_type = headers.get("Content-Type");
+
     if (content_type.has_value()) {
         dbgln_if(RESOURCE_DEBUG, "Content-Type header: '{}'", content_type.value());
-        m_encoding = encoding_from_content_type(content_type.value());
         m_mime_type = mime_type_from_content_type(content_type.value());
     } else if (url().protocol() == "data" && !url().data_mime_type().is_empty()) {
         dbgln_if(RESOURCE_DEBUG, "This is a data URL with mime-type _{}_", url().data_mime_type());
-        m_encoding = "utf-8"; // FIXME: This doesn't seem nice.
         m_mime_type = url().data_mime_type();
     } else {
-        dbgln_if(RESOURCE_DEBUG, "No Content-Type header to go on! Guessing based on filename...");
-        m_encoding = "utf-8"; // FIXME: This doesn't seem nice.
         m_mime_type = Core::guess_mime_type_based_on_filename(url().path());
     }
 
+    if (content_type.has_value()) {
+        auto encoding = encoding_from_content_type(content_type.value());
+        if (encoding.has_value()) {
+            dbgln_if(RESOURCE_DEBUG, "Set encoding '{}' from Content-Type", encoding.has_value());
+            m_encoding = encoding.value();
+        } else {
+            // FIXME: This doesn't seem nice.
+            m_encoding = "utf-8";
+        }
+    }
+
     for_each_client([](auto& client) {
         client.resource_did_load();
     });