LibWeb: Clarify StyleValue API with new naming scheme

This does a few things, that are hard to separate. For a while now, it's
been confuzing what `StyleValue::is_foo()` actually means. It sometimes
was used to check the type, and sometimes to see if it could return a
certain value type. The new naming scheme is:

- `is_length()` - is it a LengthStyleValue?
- `as_length()` - casts it to LengthStyleValue
- `has_length()` - can it return a Length?
- `to_length()` - gets the internal value out (eg, Length)

This also means, no more `static_cast<LengthStyleValue const&>(*this)`
stuff when dealing with StyleValues. :^)

Hopefully this will be a bit clearer going forward. There are lots of
places using the original methods, so I'll be going through them to
hopefully catch any issues.

5 files changed, 260 insertions, 57 deletions

diff --git a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
index a06f40af8d..6338ca22f8 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleProperties.cpp
@@ -268,7 +268,7 @@ Optional<int> StyleProperties::z_index() const
         return {};
     auto& value = maybe_value.value();
 
-    if (value->is_auto())
+    if (value->has_auto())
         return 0;
     if (value->is_numeric())
         return static_cast<int>(static_cast<NumericStyleValue&>(*value).value());
@@ -339,7 +339,7 @@ Optional<CSS::FlexBasisData> StyleProperties::flex_basis() const
     if (value.value()->is_identifier() && value.value()->to_identifier() == CSS::ValueID::Content)
         return { { CSS::FlexBasis::Content, {} } };
 
-    if (value.value()->is_auto())
+    if (value.value()->has_auto())
         return { { CSS::FlexBasis::Auto, {} } };
 
     if (value.value()->is_length())
diff --git a/Userland/Libraries/LibWeb/CSS/StyleValue.cpp b/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
index 5ec38b9866..7e48f460f1 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
@@ -26,14 +26,158 @@ StyleValue::~StyleValue()
 {
 }
 
-bool StyleValue::is_color() const
+BackgroundStyleValue const& StyleValue::as_background() const
 {
-    if (type() == Type::Color)
-        return true;
-    if (type() != Type::Identifier)
-        return false;
+    VERIFY(is_background());
+    return static_cast<BackgroundStyleValue const&>(*this);
+}
+
+BackgroundRepeatStyleValue const& StyleValue::as_background_repeat() const
+{
+    VERIFY(is_background_repeat());
+    return static_cast<BackgroundRepeatStyleValue const&>(*this);
+}
+
+BorderStyleValue const& StyleValue::as_border() const
+{
+    VERIFY(is_border());
+    return static_cast<BorderStyleValue const&>(*this);
+}
+
+BorderRadiusStyleValue const& StyleValue::as_border_radius() const
+{
+    VERIFY(is_border_radius());
+    return static_cast<BorderRadiusStyleValue const&>(*this);
+}
+
+BoxShadowStyleValue const& StyleValue::as_box_shadow() const
+{
+    VERIFY(is_box_shadow());
+    return static_cast<BoxShadowStyleValue const&>(*this);
+}
+
+CalculatedStyleValue const& StyleValue::as_calculated() const
+{
+    VERIFY(is_calculated());
+    return static_cast<CalculatedStyleValue const&>(*this);
+}
+
+ColorStyleValue const& StyleValue::as_color() const
+{
+    VERIFY(is_color());
+    return static_cast<ColorStyleValue const&>(*this);
+}
+
+CustomStyleValue const& StyleValue::as_custom_property() const
+{
+    VERIFY(is_custom_property());
+    return static_cast<CustomStyleValue const&>(*this);
+}
+
+FlexStyleValue const& StyleValue::as_flex() const
+{
+    VERIFY(is_flex());
+    return static_cast<FlexStyleValue const&>(*this);
+}
+
+FlexFlowStyleValue const& StyleValue::as_flex_flow() const
+{
+    VERIFY(is_flex_flow());
+    return static_cast<FlexFlowStyleValue const&>(*this);
+}
+
+FontStyleValue const& StyleValue::as_font() const
+{
+    VERIFY(is_font());
+    return static_cast<FontStyleValue const&>(*this);
+}
 
-    switch (to_identifier()) {
+IdentifierStyleValue const& StyleValue::as_identifier() const
+{
+    VERIFY(is_identifier());
+    return static_cast<IdentifierStyleValue const&>(*this);
+}
+
+ImageStyleValue const& StyleValue::as_image() const
+{
+    VERIFY(is_image());
+    return static_cast<ImageStyleValue const&>(*this);
+}
+
+InheritStyleValue const& StyleValue::as_inherit() const
+{
+    VERIFY(is_inherit());
+    return static_cast<InheritStyleValue const&>(*this);
+}
+
+InitialStyleValue const& StyleValue::as_initial() const
+{
+    VERIFY(is_initial());
+    return static_cast<InitialStyleValue const&>(*this);
+}
+
+LengthStyleValue const& StyleValue::as_length() const
+{
+    VERIFY(is_length());
+    return static_cast<LengthStyleValue const&>(*this);
+}
+
+ListStyleStyleValue const& StyleValue::as_list_style() const
+{
+    VERIFY(is_list_style());
+    return static_cast<ListStyleStyleValue const&>(*this);
+}
+
+NumericStyleValue const& StyleValue::as_numeric() const
+{
+    VERIFY(is_numeric());
+    return static_cast<NumericStyleValue const&>(*this);
+}
+
+OverflowStyleValue const& StyleValue::as_overflow() const
+{
+    VERIFY(is_overflow());
+    return static_cast<OverflowStyleValue const&>(*this);
+}
+
+StringStyleValue const& StyleValue::as_string() const
+{
+    VERIFY(is_string());
+    return static_cast<StringStyleValue const&>(*this);
+}
+
+TextDecorationStyleValue const& StyleValue::as_text_decoration() const
+{
+    VERIFY(is_text_decoration());
+    return static_cast<TextDecorationStyleValue const&>(*this);
+}
+
+TransformationStyleValue const& StyleValue::as_transformation() const
+{
+    VERIFY(is_transformation());
+    return static_cast<TransformationStyleValue const&>(*this);
+}
+
+UnsetStyleValue const& StyleValue::as_unset() const
+{
+    VERIFY(is_unset());
+    return static_cast<UnsetStyleValue const&>(*this);
+}
+
+StyleValueList const& StyleValue::as_value_list() const
+{
+    VERIFY(is_value_list());
+    return static_cast<StyleValueList const&>(*this);
+}
+
+String IdentifierStyleValue::to_string() const
+{
+    return CSS::string_from_value_id(m_id);
+}
+
+bool IdentifierStyleValue::has_color() const
+{
+    switch (m_id) {
     case ValueID::Currentcolor:
     case ValueID::LibwebLink:
     case ValueID::LibwebPaletteActiveLink:
@@ -92,21 +236,8 @@ bool StyleValue::is_color() const
     case ValueID::LibwebPaletteWindowText:
         return true;
     default:
-        break;
+        return false;
     }
-
-    return false;
-}
-
-float StyleValue::as_number() const
-{
-    VERIFY(is_numeric());
-    return static_cast<NumericStyleValue const&>(*this).value();
-}
-
-String IdentifierStyleValue::to_string() const
-{
-    return CSS::string_from_value_id(m_id);
 }
 
 Color IdentifierStyleValue::to_color(Layout::NodeWithStyle const& node) const
@@ -255,5 +386,4 @@ void ImageStyleValue::resource_did_load()
     if (m_document->browsing_context())
         m_document->browsing_context()->set_needs_display({});
 }
-
 }
diff --git a/Userland/Libraries/LibWeb/CSS/StyleValue.h b/Userland/Libraries/LibWeb/CSS/StyleValue.h
index 8a2b78c6aa..9433e8df86 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleValue.h
+++ b/Userland/Libraries/LibWeb/CSS/StyleValue.h
@@ -269,11 +269,11 @@ public:
     bool is_flex() const { return type() == Type::Flex; }
     bool is_flex_flow() const { return type() == Type::FlexFlow; }
     bool is_font() const { return type() == Type::Font; }
-    bool is_identifier() const { return type() == Type::Identifier || is_auto(); }
+    bool is_identifier() const { return type() == Type::Identifier; }
     bool is_image() const { return type() == Type::Image; }
     bool is_inherit() const { return type() == Type::Inherit; }
     bool is_initial() const { return type() == Type::Initial; }
-    virtual bool is_length() const { return type() == Type::Length; }
+    bool is_length() const { return type() == Type::Length; }
     bool is_list_style() const { return type() == Type::ListStyle; }
     bool is_numeric() const { return type() == Type::Numeric; }
     bool is_overflow() const { return type() == Type::Overflow; }
@@ -285,21 +285,67 @@ public:
 
     bool is_builtin() const { return is_inherit() || is_initial() || is_unset(); }
 
-    bool is_builtin_or_dynamic() const
-    {
-        return is_builtin() || is_custom_property() || is_calculated();
-    }
-
-    float as_number() const;
-
-    virtual String to_string() const = 0;
-    virtual Length to_length() const { return {}; }
+    BackgroundRepeatStyleValue const& as_background_repeat() const;
+    BackgroundStyleValue const& as_background() const;
+    BorderRadiusStyleValue const& as_border_radius() const;
+    BorderStyleValue const& as_border() const;
+    BoxShadowStyleValue const& as_box_shadow() const;
+    CalculatedStyleValue const& as_calculated() const;
+    ColorStyleValue const& as_color() const;
+    CustomStyleValue const& as_custom_property() const;
+    FlexFlowStyleValue const& as_flex_flow() const;
+    FlexStyleValue const& as_flex() const;
+    FontStyleValue const& as_font() const;
+    IdentifierStyleValue const& as_identifier() const;
+    ImageStyleValue const& as_image() const;
+    InheritStyleValue const& as_inherit() const;
+    InitialStyleValue const& as_initial() const;
+    LengthStyleValue const& as_length() const;
+    ListStyleStyleValue const& as_list_style() const;
+    NumericStyleValue const& as_numeric() const;
+    OverflowStyleValue const& as_overflow() const;
+    StringStyleValue const& as_string() const;
+    TextDecorationStyleValue const& as_text_decoration() const;
+    TransformationStyleValue const& as_transformation() const;
+    UnsetStyleValue const& as_unset() const;
+    StyleValueList const& as_value_list() const;
+
+    BackgroundRepeatStyleValue& as_background_repeat() { return const_cast<BackgroundRepeatStyleValue&>(const_cast<StyleValue const&>(*this).as_background_repeat()); }
+    BackgroundStyleValue& as_background() { return const_cast<BackgroundStyleValue&>(const_cast<StyleValue const&>(*this).as_background()); }
+    BorderRadiusStyleValue& as_border_radius() { return const_cast<BorderRadiusStyleValue&>(const_cast<StyleValue const&>(*this).as_border_radius()); }
+    BorderStyleValue& as_border() { return const_cast<BorderStyleValue&>(const_cast<StyleValue const&>(*this).as_border()); }
+    BoxShadowStyleValue& as_box_shadow() { return const_cast<BoxShadowStyleValue&>(const_cast<StyleValue const&>(*this).as_box_shadow()); }
+    CalculatedStyleValue& as_calculated() { return const_cast<CalculatedStyleValue&>(const_cast<StyleValue const&>(*this).as_calculated()); }
+    ColorStyleValue& as_color() { return const_cast<ColorStyleValue&>(const_cast<StyleValue const&>(*this).as_color()); }
+    CustomStyleValue& as_custom_property() { return const_cast<CustomStyleValue&>(const_cast<StyleValue const&>(*this).as_custom_property()); }
+    FlexFlowStyleValue& as_flex_flow() { return const_cast<FlexFlowStyleValue&>(const_cast<StyleValue const&>(*this).as_flex_flow()); }
+    FlexStyleValue& as_flex() { return const_cast<FlexStyleValue&>(const_cast<StyleValue const&>(*this).as_flex()); }
+    FontStyleValue& as_font() { return const_cast<FontStyleValue&>(const_cast<StyleValue const&>(*this).as_font()); }
+    IdentifierStyleValue& as_identifier() { return const_cast<IdentifierStyleValue&>(const_cast<StyleValue const&>(*this).as_identifier()); }
+    ImageStyleValue& as_image() { return const_cast<ImageStyleValue&>(const_cast<StyleValue const&>(*this).as_image()); }
+    InheritStyleValue& as_inherit() { return const_cast<InheritStyleValue&>(const_cast<StyleValue const&>(*this).as_inherit()); }
+    InitialStyleValue& as_initial() { return const_cast<InitialStyleValue&>(const_cast<StyleValue const&>(*this).as_initial()); }
+    LengthStyleValue& as_length() { return const_cast<LengthStyleValue&>(const_cast<StyleValue const&>(*this).as_length()); }
+    ListStyleStyleValue& as_list_style() { return const_cast<ListStyleStyleValue&>(const_cast<StyleValue const&>(*this).as_list_style()); }
+    NumericStyleValue& as_numeric() { return const_cast<NumericStyleValue&>(const_cast<StyleValue const&>(*this).as_numeric()); }
+    OverflowStyleValue& as_overflow() { return const_cast<OverflowStyleValue&>(const_cast<StyleValue const&>(*this).as_overflow()); }
+    StringStyleValue& as_string() { return const_cast<StringStyleValue&>(const_cast<StyleValue const&>(*this).as_string()); }
+    TextDecorationStyleValue& as_text_decoration() { return const_cast<TextDecorationStyleValue&>(const_cast<StyleValue const&>(*this).as_text_decoration()); }
+    TransformationStyleValue& as_transformation() { return const_cast<TransformationStyleValue&>(const_cast<StyleValue const&>(*this).as_transformation()); }
+    UnsetStyleValue& as_unset() { return const_cast<UnsetStyleValue&>(const_cast<StyleValue const&>(*this).as_unset()); }
+    StyleValueList& as_value_list() { return const_cast<StyleValueList&>(const_cast<StyleValue const&>(*this).as_value_list()); }
+
+    virtual bool has_auto() const { return false; }
+    virtual bool has_color() const { return false; }
+    virtual bool has_identifier() const { return false; }
+    virtual bool has_length() const { return false; }
+    virtual bool has_number() const { return false; }
 
     virtual Color to_color(Layout::NodeWithStyle const&) const { return {}; }
-
-    CSS::ValueID to_identifier() const;
-
-    virtual bool is_auto() const { return false; }
+    virtual CSS::ValueID to_identifier() const { return ValueID::Invalid; }
+    virtual Length to_length() const { return {}; }
+    virtual float to_number() const { return {}; }
+    virtual String to_string() const = 0;
 
     bool operator==(const StyleValue& other) const { return equals(other); }
     bool operator!=(const StyleValue& other) const { return !(*this == other); }
@@ -621,8 +667,9 @@ public:
     virtual ~ColorStyleValue() override { }
 
     Color color() const { return m_color; }
-    String to_string() const override { return m_color.to_string(); }
-    Color to_color(Layout::NodeWithStyle const&) const override { return m_color; }
+    virtual String to_string() const override { return m_color.to_string(); }
+    virtual bool has_color() const override { return true; }
+    virtual Color to_color(Layout::NodeWithStyle const&) const override { return m_color; }
 
     virtual bool equals(const StyleValue& other) const override
     {
@@ -806,8 +853,12 @@ public:
 
     CSS::ValueID id() const { return m_id; }
 
-    virtual String to_string() const override;
+    virtual bool has_auto() const override { return m_id == ValueID::Auto; }
+    virtual bool has_identifier() const override { return true; }
+    virtual CSS::ValueID to_identifier() const override { return m_id; }
+    virtual bool has_color() const override;
     virtual Color to_color(Layout::NodeWithStyle const& node) const override;
+    virtual String to_string() const override;
 
     virtual bool equals(const StyleValue& other) const override
     {
@@ -892,13 +943,13 @@ public:
     }
     virtual ~LengthStyleValue() override { }
 
+    Length const& length() const { return m_length; }
+
+    virtual bool has_auto() const override { return m_length.is_auto(); }
+    virtual bool has_length() const override { return true; }
     virtual String to_string() const override { return m_length.to_string(); }
     virtual Length to_length() const override { return m_length; }
 
-    const Length& length() const { return m_length; }
-
-    virtual bool is_auto() const override { return m_length.is_auto(); }
-
     virtual bool equals(const StyleValue& other) const override
     {
         if (type() != other.type())
@@ -960,10 +1011,15 @@ public:
         return adopt_ref(*new NumericStyleValue(value));
     }
 
-    virtual bool is_length() const override { return m_value == 0; }
+    virtual bool has_length() const override { return m_value == 0; }
     virtual Length to_length() const override { return Length(0, Length::Type::Px); }
 
+    virtual bool has_number() const override { return true; }
+    virtual float to_number() const override { return m_value; }
+
     float value() const { return m_value; }
+    // FIXME: Store integer values separately
+    i64 int_value() const { return roundf(m_value); }
     String to_string() const override { return String::formatted("{}", m_value); }
 
     virtual bool equals(StyleValue const& other) const override
@@ -1143,12 +1199,4 @@ private:
     NonnullRefPtrVector<StyleValue> m_values;
 };
 
-inline CSS::ValueID StyleValue::to_identifier() const
-{
-    if (type() == Type::Identifier)
-        return static_cast<const IdentifierStyleValue&>(*this).id();
-    if (is_auto())
-        return CSS::ValueID::Auto;
-    return CSS::ValueID::Invalid;
-}
 }
diff --git a/Userland/Libraries/LibWeb/Forward.h b/Userland/Libraries/LibWeb/Forward.h
index 6cf15246f3..45635fd526 100644
--- a/Userland/Libraries/LibWeb/Forward.h
+++ b/Userland/Libraries/LibWeb/Forward.h
@@ -28,8 +28,33 @@ class Selector;
 class StyleProperties;
 class StyleResolver;
 class StyleSheet;
-class StyleValue;
 enum class Display;
+
+class StyleValue;
+class BackgroundRepeatStyleValue;
+class BackgroundStyleValue;
+class BorderRadiusStyleValue;
+class BorderStyleValue;
+class BoxShadowStyleValue;
+class CalculatedStyleValue;
+class ColorStyleValue;
+class CustomStyleValue;
+class FlexFlowStyleValue;
+class FlexStyleValue;
+class FontStyleValue;
+class IdentifierStyleValue;
+class ImageStyleValue;
+class InheritStyleValue;
+class InitialStyleValue;
+class LengthStyleValue;
+class ListStyleStyleValue;
+class NumericStyleValue;
+class OverflowStyleValue;
+class StringStyleValue;
+class TextDecorationStyleValue;
+class TransformationStyleValue;
+class UnsetStyleValue;
+class StyleValueList;
 }
 
 namespace Web::DOM {
diff --git a/Userland/Libraries/LibWeb/Layout/Node.cpp b/Userland/Libraries/LibWeb/Layout/Node.cpp
index d054ac96c3..47bd8f4db6 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.cpp
+++ b/Userland/Libraries/LibWeb/Layout/Node.cpp
@@ -329,13 +329,13 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& specified_style)
     if (computed_values.opacity() == 0)
         m_visible = false;
 
-    if (auto width = specified_style.property(CSS::PropertyID::Width); width.has_value() && !width.value()->is_auto())
+    if (auto width = specified_style.property(CSS::PropertyID::Width); width.has_value() && !width.value()->has_auto())
         m_has_definite_width = true;
     computed_values.set_width(specified_style.length_or_fallback(CSS::PropertyID::Width, {}));
     computed_values.set_min_width(specified_style.length_or_fallback(CSS::PropertyID::MinWidth, {}));
     computed_values.set_max_width(specified_style.length_or_fallback(CSS::PropertyID::MaxWidth, {}));
 
-    if (auto height = specified_style.property(CSS::PropertyID::Height); height.has_value() && !height.value()->is_auto())
+    if (auto height = specified_style.property(CSS::PropertyID::Height); height.has_value() && !height.value()->has_auto())
         m_has_definite_height = true;
     computed_values.set_height(specified_style.length_or_fallback(CSS::PropertyID::Height, {}));
     computed_values.set_min_height(specified_style.length_or_fallback(CSS::PropertyID::MinHeight, {}));