LibWeb/CSS: Add String->ValueType conversion function

And also move this out of PropertyID.h because it's a separate thing.

I considered generating this but there's really not much to it.

Libraries/LibWeb/CSS/CSSNumericType.cpp

@@ -10,6 +10,7 @@
 #include <LibWeb/CSS/Length.h>
 #include <LibWeb/CSS/Resolution.h>
 #include <LibWeb/CSS/Time.h>
+#include <LibWeb/CSS/ValueType.h>
 
 namespace Web::CSS {
 
@@ -31,28 +32,9 @@ Optional<CSSNumericType::BaseType> CSSNumericType::base_type_from_value_type(Val
     case ValueType::Time:
         return BaseType::Time;
 
-    case ValueType::BackgroundPosition:
+    default:
-    case ValueType::BasicShape:
-    case ValueType::Color:
-    case ValueType::Counter:
-    case ValueType::CustomIdent:
-    case ValueType::EasingFunction:
-    case ValueType::FilterValueList:
-    case ValueType::FitContent:
-    case ValueType::Image:
-    case ValueType::Integer:
-    case ValueType::Number:
-    case ValueType::OpenTypeTag:
-    case ValueType::Paint:
-    case ValueType::Position:
-    case ValueType::Ratio:
-    case ValueType::Rect:
-    case ValueType::String:
-    case ValueType::Url:
         return {};
     }
-
-    VERIFY_NOT_REACHED();
 }
 
 // https://drafts.css-houdini.org/css-typed-om-1/#cssnumericvalue-create-a-type

Libraries/LibWeb/CSS/ValueType.cpp

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/CSS/ValueType.h>
+
+namespace Web::CSS {
+
+Optional<ValueType> value_type_from_string(StringView name)
+{
+    if (string.equals_ignoring_ascii_case("angle"sv))
+        return ValueType::Angle;
+    if (string.equals_ignoring_ascii_case("background-position"sv))
+        return ValueType::BackgroundPosition;
+    if (string.equals_ignoring_ascii_case("basic-shape"sv))
+        return ValueType::BasicShape;
+    if (string.equals_ignoring_ascii_case("color"sv))
+        return ValueType::Color;
+    if (string.equals_ignoring_ascii_case("counter"sv))
+        return ValueType::Counter;
+    if (string.equals_ignoring_ascii_case("custom-ident"sv))
+        return ValueType::CustomIdent;
+    if (string.equals_ignoring_ascii_case("easing-function"sv))
+        return ValueType::EasingFunction;
+    if (string.equals_ignoring_ascii_case("filter-value-list"sv))
+        return ValueType::FilterValueList;
+    if (string.equals_ignoring_ascii_case("fit-content"sv))
+        return ValueType::FitContent;
+    if (string.equals_ignoring_ascii_case("flex"sv))
+        return ValueType::Flex;
+    if (string.equals_ignoring_ascii_case("frequency"sv))
+        return ValueType::Frequency;
+    if (string.equals_ignoring_ascii_case("image"sv))
+        return ValueType::Image;
+    if (string.equals_ignoring_ascii_case("integer"sv))
+        return ValueType::Integer;
+    if (string.equals_ignoring_ascii_case("length"sv))
+        return ValueType::Length;
+    if (string.equals_ignoring_ascii_case("number"sv))
+        return ValueType::Number;
+    if (string.equals_ignoring_ascii_case("opentype-tag"sv))
+        return ValueType::OpenTypeTag;
+    if (string.equals_ignoring_ascii_case("paint"sv))
+        return ValueType::Paint;
+    if (string.equals_ignoring_ascii_case("percentage"sv))
+        return ValueType::Percentage;
+    if (string.equals_ignoring_ascii_case("position"sv))
+        return ValueType::Position;
+    if (string.equals_ignoring_ascii_case("ratio"sv))
+        return ValueType::Ratio;
+    if (string.equals_ignoring_ascii_case("rect"sv))
+        return ValueType::Rect;
+    if (string.equals_ignoring_ascii_case("resolution"sv))
+        return ValueType::Resolution;
+    if (string.equals_ignoring_ascii_case("string"sv))
+        return ValueType::String;
+    if (string.equals_ignoring_ascii_case("time"sv))
+        return ValueType::Time;
+    if (string.equals_ignoring_ascii_case("url"sv))
+        return ValueType::Url;
+    return {};
+}
+
+}

Libraries/LibWeb/CSS/ValueType.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Web::CSS {
+
+enum class ValueType : u8 {
+    Angle,
+    BackgroundPosition,
+    BasicShape,
+    Color,
+    Counter,
+    CustomIdent,
+    EasingFunction,
+    FilterValueList,
+    FitContent,
+    Flex,
+    Frequency,
+    Image,
+    Integer,
+    Length,
+    Number,
+    OpenTypeTag,
+    Paint,
+    Percentage,
+    Position,
+    Ratio,
+    Rect,
+    Resolution,
+    String,
+    Time,
+    Url,
+};
+
+Optional<ValueType> value_type_from_string(StringView);
+
+}

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp

@@ -165,6 +165,7 @@ ErrorOr<void> generate_header_file(JsonObject& properties, JsonObject& logical_p
 #include <AK/Variant.h>
 #include <LibJS/Forward.h>
 #include <LibWeb/CSS/Enums.h>
+#include <LibWeb/CSS/ValueType.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::CSS {
@@ -255,33 +256,6 @@ Optional<PropertyID> property_id_from_string(StringView);
 bool is_inherited_property(PropertyID);
 NonnullRefPtr<CSSStyleValue const> property_initial_value(PropertyID);
 
-enum class ValueType {
-    Angle,
-    BackgroundPosition,
-    BasicShape,
-    Color,
-    Counter,
-    CustomIdent,
-    EasingFunction,
-    FilterValueList,
-    FitContent,
-    Flex,
-    Frequency,
-    Image,
-    Integer,
-    Length,
-    Number,
-    OpenTypeTag,
-    Paint,
-    Percentage,
-    Position,
-    Ratio,
-    Rect,
-    Resolution,
-    String,
-    Time,
-    Url,
-};
 bool property_accepts_type(PropertyID, ValueType);
 bool property_accepts_keyword(PropertyID, Keyword);
 Optional<ValueType> property_resolves_percentages_relative_to(PropertyID);