LibWeb: Implement @supports serialization

Userland/Libraries/LibWeb/CSS/CSSSupportsRule.cpp

@@ -17,8 +17,7 @@ CSSSupportsRule::CSSSupportsRule(NonnullRefPtr<Supports>&& supports, NonnullRefP
 
 String CSSSupportsRule::condition_text() const
 {
-    // FIXME: Serializing supports rules!
+    return m_supports->to_string();
-    return "<supports-condition>";
 }
 
 void CSSSupportsRule::set_condition_text(String text)

Userland/Libraries/LibWeb/CSS/Supports.cpp

@@ -73,4 +73,44 @@ bool Supports::Feature::evaluate() const
         });
 }
 
+String Supports::Declaration::to_string() const
+{
+    return String::formatted("({})", declaration);
+}
+
+String Supports::Selector::to_string() const
+{
+    return String::formatted("selector({})", selector);
+}
+
+String Supports::Feature::to_string() const
+{
+    return value.visit([](auto& it) { return it.to_string(); });
+}
+
+String Supports::InParens::to_string() const
+{
+    return value.visit(
+        [](NonnullOwnPtr<Condition> const& condition) -> String { return String::formatted("({})", condition->to_string()); },
+        [](auto& it) -> String { return it.to_string(); });
+}
+
+String Supports::Condition::to_string() const
+{
+    switch (type) {
+    case Type::Not:
+        return String::formatted("not {}", children.first().to_string());
+    case Type::And:
+        return String::join(" and ", children);
+    case Type::Or:
+        return String::join(" or ", children);
+    }
+    VERIFY_NOT_REACHED();
+}
+
+String Supports::to_string() const
+{
+    return m_condition->to_string();
+}
+
 }

Userland/Libraries/LibWeb/CSS/Supports.h

@@ -24,16 +24,19 @@ public:
     struct Declaration {
         String declaration;
         bool evaluate() const;
+        String to_string() const;
     };
 
     struct Selector {
         String selector;
         bool evaluate() const;
+        String to_string() const;
     };
 
     struct Feature {
         Variant<Declaration, Selector> value;
         bool evaluate() const;
+        String to_string() const;
     };
 
     struct Condition;
@@ -41,6 +44,7 @@ public:
         Variant<NonnullOwnPtr<Condition>, Feature, GeneralEnclosed> value;
 
         bool evaluate() const;
+        String to_string() const;
     };
 
     struct Condition {
@@ -53,6 +57,7 @@ public:
         Vector<InParens> children;
 
         bool evaluate() const;
+        String to_string() const;
     };
 
     static NonnullRefPtr<Supports> create(NonnullOwnPtr<Condition>&& condition)
@@ -61,6 +66,7 @@ public:
     }
 
     bool matches() const { return m_matches; }
+    String to_string() const;
 
 private:
     Supports(NonnullOwnPtr<Condition>&&);
@@ -70,3 +76,11 @@ private:
 };
 
 }
+
+template<>
+struct AK::Formatter<Web::CSS::Supports::InParens> : AK::Formatter<StringView> {
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::Supports::InParens const& in_parens)
+    {
+        return Formatter<StringView>::format(builder, in_parens.to_string());
+    }
+};