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

include/Nazara/Shader/Ast/Attribute.inl

@@ -0,0 +1,72 @@
+// Copyright (C) 2020 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Shader generator"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Shader/Ast/Attribute.hpp>
+#include <cassert>
+#include <stdexcept>
+#include <Nazara/Shader/Debug.hpp>
+
+namespace Nz::ShaderAst
+{
+	template<typename T>
+	AttributeValue<T>::AttributeValue(T value) :
+	m_value(std::move(value))
+	{
+	}
+
+	template<typename T>
+	AttributeValue<T>::AttributeValue(ExpressionPtr expr)
+	{
+		assert(expr);
+		m_value = std::move(expr);
+	}
+
+	template<typename T>
+	ExpressionPtr&& AttributeValue<T>::GetExpression() &&
+	{
+		if (!IsExpression())
+			throw std::runtime_error("excepted expression");
+
+		return std::get<ExpressionPtr>(std::move(m_value));
+	}
+
+	template<typename T>
+	const ExpressionPtr& AttributeValue<T>::GetExpression() const &
+	{
+		if (!IsExpression())
+			throw std::runtime_error("excepted expression");
+
+		assert(std::get<ExpressionPtr>(m_value));
+		return std::get<ExpressionPtr>(m_value);
+	}
+
+	template<typename T>
+	const T& AttributeValue<T>::GetResultingValue() const
+	{
+		if (!IsResultingValue())
+			throw std::runtime_error("excepted resulting value");
+
+		return std::get<T>(m_value);
+	}
+
+	template<typename T>
+	bool AttributeValue<T>::IsExpression() const
+	{
+		return std::holds_alternative<ExpressionPtr>(m_value);
+	}
+
+	template<typename T>
+	bool AttributeValue<T>::IsResultingValue() const
+	{
+		return std::holds_alternative<T>(m_value);
+	}
+
+	template<typename T>
+	bool AttributeValue<T>::HasValue() const
+	{
+		return !std::holds_alternative<std::monostate>(m_value);
+	}
+}
+
+#include <Nazara/Shader/DebugOff.hpp>