LibWeb: Add and implement CSSPropertyRule IDL and bindings

Author: https://github.com/a-ungurianu 🔰
Commit: 50d64b0fb7
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1777
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/AtkinsSJ ✅

Userland/Libraries/LibWeb/CSS/CSSPropertyRule.cpp

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2024, Alex Ungurianu <alex@ungurianu.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Bindings/CSSPropertyRulePrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/CSS/CSSPropertyRule.h>
+#include <LibWeb/CSS/Serialize.h>
+
+namespace Web::CSS {
+
+JS_DEFINE_ALLOCATOR(CSSPropertyRule);
+
+JS::NonnullGCPtr<CSSPropertyRule> CSSPropertyRule::create(JS::Realm& realm, FlyString name, FlyString syntax, bool inherits, Optional<String> initial_value)
+{
+    return realm.heap().allocate<CSSPropertyRule>(realm, realm, move(name), move(syntax), inherits, move(initial_value));
+}
+
+CSSPropertyRule::CSSPropertyRule(JS::Realm& realm, FlyString name, FlyString syntax, bool inherits, Optional<String> initial_value)
+    : CSSRule(realm)
+    , m_name(move(name))
+    , m_syntax(move(syntax))
+    , m_inherits(inherits)
+    , m_initial_value(move(initial_value))
+{
+}
+
+void CSSPropertyRule::initialize(JS::Realm& realm)
+{
+    Base::initialize(realm);
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSPropertyRule);
+}
+
+// https://www.w3.org/TR/cssom-1/#serialize-a-css-rule
+String CSSPropertyRule::serialized() const
+{
+    StringBuilder builder;
+
+    // Serialization algorithm is defined in the spec below
+    // https://drafts.css-houdini.org/css-properties-values-api/#the-css-property-rule-interface
+
+    // To serialize a CSSPropertyRule, return the concatenation of the following:
+
+    // 1. The string "@property" followed by a single SPACE (U+0020).
+    // 2. The result of performing serialize an identifier on the rule’s name, followed by a single SPACE (U+0020).
+    builder.appendff("@property {} ", serialize_an_identifier(name()));
+
+    // 3. The string "{ ", i.e., a single LEFT CURLY BRACKET (U+007B), followed by a SPACE (U+0020).
+    builder.append("{ "sv);
+
+    // 4. The string "syntax:", followed by a single SPACE (U+0020).
+    // 5. The result of performing serialize a string on the rule’s syntax, followed by a single SEMICOLON (U+003B), followed by a SPACE (U+0020).
+    builder.appendff("syntax: {}; ", serialize_a_string(syntax()));
+
+    // 6. The string "inherits:", followed by a single SPACE (U+0020).
+    // 7. For the rule’s inherits attribute, one of the following depending on the attribute’s value:
+    //      true:  The string "true" followed by a single SEMICOLON (U+003B), followed by a SPACE (U+0020).
+    //      false: The string "false" followed by a single SEMICOLON (U+003B), followed by a SPACE (U+0020).
+    builder.appendff("inherits: {}; ", inherits());
+
+    // 8. If the rule’s initial-value is present, follow these substeps:
+    if (initial_value().has_value()) {
+        // 1. The string "initial-value:".
+        // 2. The result of performing serialize a CSS value in the rule’s initial-value followed by a single SEMICOLON (U+003B), followed by a SPACE (U+0020).
+        // FIXME: Follow the spec for serializing the value whenever we actually have a CSS value here.
+        builder.appendff("initial-value: {}; ", initial_value());
+    }
+    // 9. A single RIGHT CURLY BRACKET (U+007D).
+    builder.append("}"sv);
+
+    return MUST(builder.to_string());
+}
+
+}