Add pseudo classes to the style sheet index

Include/RmlUi/Core/StyleSheetTypes.h

@@ -88,7 +88,7 @@ struct StyleSheetIndex {
 	using NodeIndex = UnorderedMap<std::size_t, NodeList>;
 
 	// The following objects are given in prioritized order. Any nodes in the first object will not be contained in the next one and so on.
-	NodeIndex ids, classes, tags;
+	NodeIndex ids, classes, pseudo_classes, tags;
 	NodeList other;
 };
 } // namespace Rml

Source/Core/StyleSheet.cpp

@@ -194,6 +194,7 @@ SharedPtr<const ElementDefinition> StyleSheet::GetElementDefinition(const Elemen
 	const String& tag = element->GetTagName();
 	const String& id = element->GetId();
 	const StringList& class_names = element->GetStyle()->GetClassNameList();
+	const PseudoClassMap& pseudo_classes = element->GetStyle()->GetActivePseudoClasses();
 
 	// First, look up the indexed requirements. 
 	if (!id.empty())
@@ -202,6 +203,9 @@ SharedPtr<const ElementDefinition> StyleSheet::GetElementDefinition(const Elemen
 	for (const String& name : class_names)
 		AddApplicableNodes(styled_node_index.classes, name);
 
+	for (const auto& pseudo : pseudo_classes)
+		AddApplicableNodes(styled_node_index.pseudo_classes, pseudo.first);
+
 	AddApplicableNodes(styled_node_index.tags, tag);
 
 	// Also check all remaining nodes that don't contain any indexed requirements.

Source/Core/StyleSheetNode.cpp

@@ -146,6 +146,10 @@ void StyleSheetNode::BuildIndex(StyleSheetIndex& styled_node_index) const
 			// class with the most unique name. For example by adding the class from this node's list that has the fewest existing matches.
 			IndexInsertNode(styled_node_index.classes, class_names.front(), this);
 		}
+		else if (!pseudo_class_names.empty())
+		{
+			IndexInsertNode(styled_node_index.pseudo_classes, pseudo_class_names.front(), this);
+		}
 		else if (!tag.empty())
 		{
 			IndexInsertNode(styled_node_index.tags, tag, this);
@@ -266,22 +270,22 @@ bool StyleSheetNode::IsApplicable(const Element* const in_element) const
 	// Determine whether the element matches the current node and its entire lineage. The entire hierarchy of
 	// the element's document will be considered during the match as necessary.
 
+	if (!tag.empty() && tag != in_element->GetTagName())
+		return false;
+
 	for (const String& name : pseudo_class_names)
 	{
 		if (!in_element->IsPseudoClassSet(name))
 			return false;
 	}
 
-	if (!id.empty() && id != in_element->GetId())
-		return false;
-
 	for (const String& name : class_names)
 	{
 		if (!in_element->IsClassSet(name))
 			return false;
 	}
 
-	if (!tag.empty() && tag != in_element->GetTagName())
+	if (!id.empty() && id != in_element->GetId())
 		return false;
 
 	const Element* element = in_element;