LibWeb: Add PercentageStyleValue, and parse it

This is in a slightly weird state, where Percentages are sometimes
Lengths and sometimes not, which I will be cleaning up in subsequent
commits, in an attempt not to change all of LibWeb in one go. :^)

5 files changed, 187 insertions, 67 deletions

diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index bff0e7ea12..813d17c314 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -2110,94 +2110,114 @@ RefPtr<StyleValue> Parser::parse_dynamic_value(StyleComponentValueRule const& co
     return {};
 }
 
-Optional<Length> Parser::parse_length(StyleComponentValueRule const& component_value)
+Optional<Parser::Dimension> Parser::parse_dimension(StyleComponentValueRule const& component_value)
 {
-    Length::Type type = Length::Type::Undefined;
-    Optional<float> numeric_value;
-
     if (component_value.is(Token::Type::Dimension)) {
-        numeric_value = component_value.token().dimension_value();
+        float numeric_value = component_value.token().dimension_value();
         auto unit_string = component_value.token().dimension_unit();
-
-        if (unit_string.equals_ignoring_case("px")) {
-            type = Length::Type::Px;
-        } else if (unit_string.equals_ignoring_case("pt")) {
-            type = Length::Type::Pt;
-        } else if (unit_string.equals_ignoring_case("pc")) {
-            type = Length::Type::Pc;
-        } else if (unit_string.equals_ignoring_case("mm")) {
-            type = Length::Type::Mm;
-        } else if (unit_string.equals_ignoring_case("rem")) {
-            type = Length::Type::Rem;
-        } else if (unit_string.equals_ignoring_case("em")) {
-            type = Length::Type::Em;
-        } else if (unit_string.equals_ignoring_case("ex")) {
-            type = Length::Type::Ex;
-        } else if (unit_string.equals_ignoring_case("ch")) {
-            type = Length::Type::Ch;
-        } else if (unit_string.equals_ignoring_case("vw")) {
-            type = Length::Type::Vw;
-        } else if (unit_string.equals_ignoring_case("vh")) {
-            type = Length::Type::Vh;
-        } else if (unit_string.equals_ignoring_case("vmax")) {
-            type = Length::Type::Vmax;
-        } else if (unit_string.equals_ignoring_case("vmin")) {
-            type = Length::Type::Vmin;
-        } else if (unit_string.equals_ignoring_case("cm")) {
-            type = Length::Type::Cm;
-        } else if (unit_string.equals_ignoring_case("in")) {
-            type = Length::Type::In;
-        } else if (unit_string.equals_ignoring_case("Q")) {
-            type = Length::Type::Q;
-        } else if (unit_string.equals_ignoring_case("%")) {
+        Optional<Length::Type> length_type = Length::Type::Undefined;
+
+        if (unit_string.equals_ignoring_case("px"sv)) {
+            length_type = Length::Type::Px;
+        } else if (unit_string.equals_ignoring_case("pt"sv)) {
+            length_type = Length::Type::Pt;
+        } else if (unit_string.equals_ignoring_case("pc"sv)) {
+            length_type = Length::Type::Pc;
+        } else if (unit_string.equals_ignoring_case("mm"sv)) {
+            length_type = Length::Type::Mm;
+        } else if (unit_string.equals_ignoring_case("rem"sv)) {
+            length_type = Length::Type::Rem;
+        } else if (unit_string.equals_ignoring_case("em"sv)) {
+            length_type = Length::Type::Em;
+        } else if (unit_string.equals_ignoring_case("ex"sv)) {
+            length_type = Length::Type::Ex;
+        } else if (unit_string.equals_ignoring_case("ch"sv)) {
+            length_type = Length::Type::Ch;
+        } else if (unit_string.equals_ignoring_case("vw"sv)) {
+            length_type = Length::Type::Vw;
+        } else if (unit_string.equals_ignoring_case("vh"sv)) {
+            length_type = Length::Type::Vh;
+        } else if (unit_string.equals_ignoring_case("vmax"sv)) {
+            length_type = Length::Type::Vmax;
+        } else if (unit_string.equals_ignoring_case("vmin"sv)) {
+            length_type = Length::Type::Vmin;
+        } else if (unit_string.equals_ignoring_case("cm"sv)) {
+            length_type = Length::Type::Cm;
+        } else if (unit_string.equals_ignoring_case("in"sv)) {
+            length_type = Length::Type::In;
+        } else if (unit_string.equals_ignoring_case("Q"sv)) {
+            length_type = Length::Type::Q;
+        } else if (unit_string.equals_ignoring_case("%"sv)) {
             // A number followed by `%` must always result in a Percentage token.
             VERIFY_NOT_REACHED();
-        } else {
-            return {};
         }
-    } else if (component_value.is(Token::Type::Percentage)) {
-        type = Length::Type::Percentage;
-        numeric_value = component_value.token().percentage();
-    } else if (component_value.is(Token::Type::Ident) && component_value.token().ident().equals_ignoring_case("auto")) {
-        return Length::make_auto();
-    } else if (component_value.is(Token::Type::Number)) {
-        numeric_value = component_value.token().number_value();
-        if (numeric_value == 0) {
-            type = Length::Type::Px;
-        } else if (m_context.in_quirks_mode() && property_has_quirk(m_context.current_property_id(), Quirk::UnitlessLength)) {
+
+        if (length_type.has_value())
+            return Length { numeric_value, length_type.value() };
+    }
+
+    if (component_value.is(Token::Type::Percentage))
+        return Percentage { static_cast<float>(component_value.token().percentage()) };
+
+    if (component_value.is(Token::Type::Number)) {
+        float numeric_value = component_value.token().number_value();
+        if (numeric_value == 0)
+            return Length::make_px(0);
+        if (m_context.in_quirks_mode() && property_has_quirk(m_context.current_property_id(), Quirk::UnitlessLength)) {
             // https://quirks.spec.whatwg.org/#quirky-length-value
             // FIXME: Disallow quirk when inside a CSS sub-expression (like `calc()`)
             // "The <quirky-length> value must not be supported in arguments to CSS expressions other than the rect()
             // expression, and must not be supported in the supports() static method of the CSS interface."
-            type = Length::Type::Px;
+            return Length::make_px(numeric_value);
         }
     }
 
-    if (!numeric_value.has_value())
+    return {};
+}
+
+Optional<Length> Parser::parse_length(StyleComponentValueRule const& component_value)
+{
+    auto dimension = parse_dimension(component_value);
+    if (!dimension.has_value())
         return {};
 
-    return Length(numeric_value.value(), type);
+    if (dimension->is_length())
+        return dimension->length();
+
+    // FIXME: This is a temporary hack until Length is split up fully.
+    if (dimension->is_percentage()) {
+        auto percentage = dimension->percentage();
+        return Length { (float)percentage.value(), Length::Type::Percentage };
+    }
+
+    if (component_value.is(Token::Type::Ident) && component_value.token().ident().equals_ignoring_case("auto"))
+        return Length::make_auto();
+
+    return {};
 }
 
-RefPtr<StyleValue> Parser::parse_length_value(StyleComponentValueRule const& component_value)
+RefPtr<StyleValue> Parser::parse_dimension_value(StyleComponentValueRule const& component_value)
 {
     // Numbers with no units can be lengths, in two situations:
     // 1) We're in quirks mode, and it's an integer.
     // 2) It's a 0.
     // We handle case 1 here. Case 2 is handled by NumericStyleValue pretending to be a LengthStyleValue if it is 0.
 
-    // FIXME: "auto" is also treated as a Length, and most of the time that is how it is used, but not always.
-    // Possibly it should always be an Identifier, and then quietly converted to a Length when needed, like 0 above.
-    // Right now, it instead is quietly converted to an Identifier when needed.
-    if (component_value.is(Token::Type::Dimension) || component_value.is(Token::Type::Percentage)
-        || (component_value.is(Token::Type::Ident) && component_value.token().ident().equals_ignoring_case("auto"sv))
-        || (m_context.in_quirks_mode() && property_has_quirk(m_context.current_property_id(), Quirk::UnitlessLength) && component_value.is(Token::Type::Number) && component_value.token().number_value() != 0)) {
-        auto length = parse_length(component_value);
-        if (length.has_value())
-            return LengthStyleValue::create(length.value());
-    }
+    if (component_value.is(Token::Type::Number) && !(m_context.in_quirks_mode() && property_has_quirk(m_context.current_property_id(), Quirk::UnitlessLength)))
+        return {};
 
-    return {};
+    if (component_value.is(Token::Type::Ident) && component_value.token().ident().equals_ignoring_case("auto"))
+        return LengthStyleValue::create(Length::make_auto());
+
+    auto dimension = parse_dimension(component_value);
+    if (!dimension.has_value())
+        return {};
+
+    if (dimension->is_length())
+        return LengthStyleValue::create(dimension->length());
+    if (dimension->is_percentage())
+        return PercentageStyleValue::create(dimension->percentage());
+    VERIFY_NOT_REACHED();
 }
 
 RefPtr<StyleValue> Parser::parse_numeric_value(StyleComponentValueRule const& component_value)
@@ -3793,8 +3813,8 @@ RefPtr<StyleValue> Parser::parse_css_value(StyleComponentValueRule const& compon
     if (auto color = parse_color_value(component_value))
         return color;
 
-    if (auto length = parse_length_value(component_value))
-        return length;
+    if (auto dimension = parse_dimension_value(component_value))
+        return dimension;
 
     if (auto numeric = parse_numeric_value(component_value))
         return numeric;
@@ -4390,6 +4410,40 @@ RefPtr<StyleValue> Parser::parse_css_value(Badge<StyleComputer>, ParsingContext
     return result.release_value();
 }
 
+bool Parser::Dimension::is_length() const
+{
+    return m_value.has<Length>();
+}
+
+Length Parser::Dimension::length() const
+{
+    return m_value.get<Length>();
+}
+
+bool Parser::Dimension::is_percentage() const
+{
+    return m_value.has<Percentage>();
+}
+
+Percentage Parser::Dimension::percentage() const
+{
+    return m_value.get<Percentage>();
+}
+
+bool Parser::Dimension::is_length_percentage() const
+{
+    return is_length() || is_percentage();
+}
+
+LengthPercentage Parser::Dimension::length_percentage() const
+{
+    if (is_length())
+        return length();
+    if (is_percentage())
+        return percentage();
+    VERIFY_NOT_REACHED();
+}
+
 }
 
 namespace Web {
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
index 592d977776..38713894ed 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
@@ -176,6 +176,30 @@ private:
     [[nodiscard]] RefPtr<PropertyOwningCSSStyleDeclaration> convert_to_declaration(NonnullRefPtr<StyleBlockRule>);
     [[nodiscard]] Optional<StyleProperty> convert_to_style_property(StyleDeclarationRule const&);
 
+    class Dimension {
+    public:
+        Dimension(Length&& value)
+            : m_value(move(value))
+        {
+        }
+        Dimension(Percentage&& value)
+            : m_value(move(value))
+        {
+        }
+
+        bool is_length() const;
+        Length length() const;
+
+        bool is_percentage() const;
+        Percentage percentage() const;
+
+        bool is_length_percentage() const;
+        LengthPercentage length_percentage() const;
+
+    private:
+        Variant<Length, Percentage> m_value;
+    };
+    Optional<Dimension> parse_dimension(StyleComponentValueRule const&);
     Optional<Color> parse_color(StyleComponentValueRule const&);
     Optional<Length> parse_length(StyleComponentValueRule const&);
 
@@ -189,7 +213,7 @@ private:
     RefPtr<StyleValue> parse_css_value(StyleComponentValueRule const&);
     RefPtr<StyleValue> parse_builtin_value(StyleComponentValueRule const&);
     RefPtr<StyleValue> parse_dynamic_value(StyleComponentValueRule const&);
-    RefPtr<StyleValue> parse_length_value(StyleComponentValueRule const&);
+    RefPtr<StyleValue> parse_dimension_value(StyleComponentValueRule const&);
     RefPtr<StyleValue> parse_numeric_value(StyleComponentValueRule const&);
     RefPtr<StyleValue> parse_identifier_value(StyleComponentValueRule const&);
     RefPtr<StyleValue> parse_color_value(StyleComponentValueRule const&);
diff --git a/Userland/Libraries/LibWeb/CSS/StyleValue.cpp b/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
index bffce543c3..57fee4632d 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleValue.cpp
@@ -139,6 +139,12 @@ OverflowStyleValue const& StyleValue::as_overflow() const
     return static_cast<OverflowStyleValue const&>(*this);
 }
 
+PercentageStyleValue const& StyleValue::as_percentage() const
+{
+    VERIFY(is_percentage());
+    return static_cast<PercentageStyleValue const&>(*this);
+}
+
 PositionStyleValue const& StyleValue::as_position() const
 {
     VERIFY(is_position());
diff --git a/Userland/Libraries/LibWeb/CSS/StyleValue.h b/Userland/Libraries/LibWeb/CSS/StyleValue.h
index 0e9598aa88..0e195b84e3 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleValue.h
+++ b/Userland/Libraries/LibWeb/CSS/StyleValue.h
@@ -25,6 +25,7 @@
 #include <LibWeb/CSS/Display.h>
 #include <LibWeb/CSS/Length.h>
 #include <LibWeb/CSS/Parser/StyleComponentValueRule.h>
+#include <LibWeb/CSS/Percentage.h>
 #include <LibWeb/CSS/PropertyID.h>
 #include <LibWeb/CSS/ValueID.h>
 #include <LibWeb/Forward.h>
@@ -284,6 +285,7 @@ public:
         ListStyle,
         Numeric,
         Overflow,
+        Percentage,
         Position,
         String,
         TextDecoration,
@@ -314,6 +316,7 @@ public:
     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; }
+    bool is_percentage() const { return type() == Type::Percentage; }
     bool is_position() const { return type() == Type::Position; }
     bool is_string() const { return type() == Type::String; }
     bool is_text_decoration() const { return type() == Type::TextDecoration; }
@@ -343,6 +346,7 @@ public:
     ListStyleStyleValue const& as_list_style() const;
     NumericStyleValue const& as_numeric() const;
     OverflowStyleValue const& as_overflow() const;
+    PercentageStyleValue const& as_percentage() const;
     PositionStyleValue const& as_position() const;
     StringStyleValue const& as_string() const;
     TextDecorationStyleValue const& as_text_decoration() const;
@@ -370,6 +374,7 @@ public:
     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()); }
+    PercentageStyleValue& as_percentage() { return const_cast<PercentageStyleValue&>(const_cast<StyleValue const&>(*this).as_percentage()); }
     PositionStyleValue& as_position() { return const_cast<PositionStyleValue&>(const_cast<StyleValue const&>(*this).as_position()); }
     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()); }
@@ -1173,6 +1178,36 @@ private:
     NonnullRefPtr<StyleValue> m_overflow_y;
 };
 
+class PercentageStyleValue final : public StyleValue {
+public:
+    static NonnullRefPtr<PercentageStyleValue> create(Percentage&& percentage)
+    {
+        return adopt_ref(*new PercentageStyleValue(move(percentage)));
+    }
+    virtual ~PercentageStyleValue() override { }
+
+    Percentage const& percentage() const { return m_percentage; }
+    Percentage& percentage() { return m_percentage; }
+
+    // FIXME: This is a temporary hack until we fully separate Length and Percentage.
+    bool has_length() const override { return true; }
+    Length to_length() const override { return { m_percentage.value(), Length::Type::Percentage }; }
+
+    virtual String to_string() const override
+    {
+        return m_percentage.to_string();
+    }
+
+private:
+    PercentageStyleValue(Percentage&& percentage)
+        : StyleValue(Type::Percentage)
+        , m_percentage(percentage)
+    {
+    }
+
+    Percentage m_percentage;
+};
+
 class PositionStyleValue final : public StyleValue {
 public:
     static NonnullRefPtr<PositionStyleValue> create(PositionEdge edge_x, Length const& offset_x, PositionEdge edge_y, Length const& offset_y)
diff --git a/Userland/Libraries/LibWeb/Forward.h b/Userland/Libraries/LibWeb/Forward.h
index 0454931ec4..48f72e22e6 100644
--- a/Userland/Libraries/LibWeb/Forward.h
+++ b/Userland/Libraries/LibWeb/Forward.h
@@ -55,6 +55,7 @@ class MediaQueryListEvent;
 class NumericStyleValue;
 class OverflowStyleValue;
 class Percentage;
+class PercentageStyleValue;
 class PositionStyleValue;
 class PropertyOwningCSSStyleDeclaration;
 class Screen;