Shader: Attribute can now have expressions as values and struct fields can be conditionally supported

include/Nazara/Shader/Ast/Attribute.hpp

@@ -9,17 +9,52 @@
 
 #include <Nazara/Prerequisites.hpp>
 #include <Nazara/Shader/Ast/Enums.hpp>
+#include <memory>
+#include <optional>
 #include <variant>
 
 namespace Nz::ShaderAst
 {
+	struct Expression;
+
+	using ExpressionPtr = std::unique_ptr<Expression>;
+
+	template<typename T>
+	class AttributeValue
+	{
+		public:
+			AttributeValue() = default;
+			AttributeValue(T value);
+			AttributeValue(ExpressionPtr expr);
+			AttributeValue(const AttributeValue&) = default;
+			AttributeValue(AttributeValue&&) = default;
+			~AttributeValue() = default;
+
+			ExpressionPtr&& GetExpression() &&;
+			const ExpressionPtr& GetExpression() const &;
+			const T& GetResultingValue() const;
+
+			bool IsExpression() const;
+			bool IsResultingValue() const;
+
+			bool HasValue() const;
+
+			AttributeValue& operator=(const AttributeValue&) = default;
+			AttributeValue& operator=(AttributeValue&&) = default;
+
+		private:
+			std::variant<std::monostate, T, ExpressionPtr> m_value;
+	};
+
 	struct Attribute
 	{
-		using Param = std::variant<std::monostate, long long, std::string>;
+		using Param = std::optional<ExpressionPtr>;
 
 		AttributeType type;
 		Param args;
 	};
 }
 
+#include <Nazara/Shader/Ast/Attribute.inl>
+
 #endif