From fe7bac73f0813fb4601d0ad85ca5c14904d31756 Mon Sep 17 00:00:00 2001
From: Sam Atkins <sam@ladybird.org>
Date: Wed, 21 May 2025 16:56:49 +0100
Subject: [PATCH] LibWeb/CSS: Stub out a function for serializing
 ComponentValue sequences

This is very hacky and wrong, but it means there's one place to fix,
instead of one for UnresolvedStyleValue, and one for invalid
MediaFeatureValues which I'm about to implement.
---
 Libraries/LibWeb/CSS/Serialize.cpp                   | 12 +++++++++++-
 Libraries/LibWeb/CSS/Serialize.h                     |  9 ++++++++-
 .../LibWeb/CSS/StyleValues/UnresolvedStyleValue.cpp  |  5 +++--
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Libraries/LibWeb/CSS/Serialize.cpp b/Libraries/LibWeb/CSS/Serialize.cpp
index 165730de2e1..fddc2dcc68b 100644
--- a/Libraries/LibWeb/CSS/Serialize.cpp
+++ b/Libraries/LibWeb/CSS/Serialize.cpp
@@ -1,11 +1,12 @@
 /*
- * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/StringBuilder.h>
 #include <AK/Utf8View.h>
+#include <LibWeb/CSS/Parser/ComponentValue.h>
 #include <LibWeb/CSS/Serialize.h>
 
 namespace Web::CSS {
@@ -241,4 +242,13 @@ String serialize_a_css_declaration(StringView property, StringView value, Import
     return MUST(builder.to_string());
 }
 
+// https://drafts.csswg.org/css-syntax/#serialization
+String serialize_a_series_of_component_values(ReadonlySpan<Parser::ComponentValue> component_values, InsertWhitespace insert_whitespace)
+{
+    // FIXME: There are special rules here where we should insert a comment between certain tokens. Do that!
+    if (insert_whitespace == InsertWhitespace::Yes)
+        return MUST(String::join(' ', component_values));
+    return MUST(String::join(""sv, component_values));
+}
+
 }
diff --git a/Libraries/LibWeb/CSS/Serialize.h b/Libraries/LibWeb/CSS/Serialize.h
index 03c206ef893..ec8050686a8 100644
--- a/Libraries/LibWeb/CSS/Serialize.h
+++ b/Libraries/LibWeb/CSS/Serialize.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -46,4 +46,11 @@ void serialize_a_comma_separated_list(StringBuilder& builder, Vector<T> const& i
 
 String serialize_a_css_declaration(StringView property, StringView value, Important = Important::No);
 
+enum class InsertWhitespace : u8 {
+    No,
+    Yes,
+};
+// FIXME: Remove InsertWhitespace param once style value parsing stops discarding whitespace tokens.
+String serialize_a_series_of_component_values(ReadonlySpan<Parser::ComponentValue>, InsertWhitespace = InsertWhitespace::No);
+
 }
diff --git a/Libraries/LibWeb/CSS/StyleValues/UnresolvedStyleValue.cpp b/Libraries/LibWeb/CSS/StyleValues/UnresolvedStyleValue.cpp
index aee35f548e2..062cc6e3d61 100644
--- a/Libraries/LibWeb/CSS/StyleValues/UnresolvedStyleValue.cpp
+++ b/Libraries/LibWeb/CSS/StyleValues/UnresolvedStyleValue.cpp
@@ -7,8 +7,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include "UnresolvedStyleValue.h"
 #include <AK/StringBuilder.h>
+#include <LibWeb/CSS/Serialize.h>
+#include <LibWeb/CSS/StyleValues/UnresolvedStyleValue.h>
 
 namespace Web::CSS {
 
@@ -17,7 +18,7 @@ String UnresolvedStyleValue::to_string(SerializationMode) const
     if (m_original_source_text.has_value())
         return *m_original_source_text;
 
-    return MUST(String::join(' ', m_values));
+    return serialize_a_series_of_component_values(m_values, InsertWhitespace::Yes);
 }
 
 bool UnresolvedStyleValue::equals(CSSStyleValue const& other) const