LibWeb/CSS: Implement CSSMathNegate

Author: https://github.com/AtkinsSJ
Commit: f2ec04d20d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5955
Reviewed-by: https://github.com/trflynn89

Libraries/LibWeb/CSS/CSSMathNegate.cpp

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "CSSMathNegate.h"
+#include <LibWeb/Bindings/CSSMathNegatePrototype.h>
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+
+namespace Web::CSS {
+
+GC_DEFINE_ALLOCATOR(CSSMathNegate);
+
+GC::Ref<CSSMathNegate> CSSMathNegate::create(JS::Realm& realm, NumericType type, GC::Ref<CSSNumericValue> values)
+{
+    return realm.create<CSSMathNegate>(realm, move(type), move(values));
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-cssmathnegate-cssmathnegate
+WebIDL::ExceptionOr<GC::Ref<CSSMathNegate>> CSSMathNegate::construct_impl(JS::Realm& realm, CSSNumberish value)
+{
+    // The CSSMathNegate(arg) constructor must, when called, perform the following steps:
+    // 1. Replace arg with the result of rectifying a numberish value for arg.
+    auto converted_value = rectify_a_numberish_value(realm, value);
+
+    // 2. Return a new CSSMathNegate whose value internal slot is set to arg.
+    return CSSMathNegate::create(realm, converted_value->type(), converted_value);
+}
+
+CSSMathNegate::CSSMathNegate(JS::Realm& realm, NumericType type, GC::Ref<CSSNumericValue> values)
+    : CSSMathValue(realm, Bindings::CSSMathOperator::Negate, move(type))
+    , m_value(move(values))
+{
+}
+
+CSSMathNegate::~CSSMathNegate() = default;
+
+void CSSMathNegate::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(CSSMathNegate);
+    Base::initialize(realm);
+}
+
+void CSSMathNegate::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_value);
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#serialize-a-cssmathvalue
+String CSSMathNegate::serialize_math_value(Nested nested, Parens parens) const
+{
+    // NB: Only steps 1 and 4 apply here.
+    // 1. Let s initially be the empty string.
+    StringBuilder s;
+
+    // 4. Otherwise, if this is a CSSMathNegate:
+    {
+        // 1. If paren-less is true, continue to the next step; otherwise, if nested is true, append "(" to s;
+        //    otherwise, append "calc(" to s.
+        if (parens == Parens::With) {
+            if (nested == Nested::Yes) {
+                s.append("("sv);
+            } else {
+                s.append("calc("sv);
+            }
+        }
+
+        // 2. Append "-" to s.
+        s.append("-"sv);
+
+        // 3. Serialize this’s value internal slot with nested set to true, and append the result to s.
+        s.append(m_value->to_string({ .nested = true }));
+
+        // 4. If paren-less is false, append ")" to s,
+        if (parens == Parens::With)
+            s.append(")"sv);
+
+        // 5. Return s.
+        return s.to_string_without_validation();
+    }
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-cssmathnegate-value
+GC::Ref<CSSNumericValue> CSSMathNegate::value() const
+{
+    return m_value;
+}
+
+}