Support zero (default) initialization for struct types

libs/interpreter/include/pslang/interpreter/context.hpp

@@ -54,4 +54,6 @@ namespace pslang::interpreter
 
 	void dump(std::ostream & out, context const & context);
 
+	value zero_value(context & context, types::type const & type);
+
 }

libs/interpreter/source/context.cpp

@@ -1,9 +1,54 @@
 #include <pslang/interpreter/context.hpp>
+#include <pslang/types/type_visitor.hpp>
 #include <pslang/types/print.hpp>
 
 namespace pslang::interpreter
 {
 
+	namespace
+	{
+
+		struct zero_value_visitor
+		{
+			interpreter::context & context;
+
+			value operator()(types::unit_type const &)
+			{
+				return unit_value{};
+			}
+
+			template <typename T>
+			value operator()(types::primitive_type_base<T> const &)
+			{
+				return primitive_value{primitive_value_base<T>{.value = {}}};
+			}
+
+			value operator()(types::array_type const & array_type)
+			{
+				array_value result{.element_type = array_type.element_type};
+				for (std::uint64_t i = 0; i < array_type.size; ++i)
+					result.elements.push_back(std::make_unique<value>(types::apply(*this, *array_type.element_type)));
+				return std::move(result);
+			}
+
+			value operator()(types::function_type const &)
+			{
+				throw std::runtime_error("Cannot zero-initialize a function type");
+			}
+
+			value operator()(types::named_type const & named_type)
+			{
+				auto const & struct_data = context.scope_stack.at(named_type.level).structs.at(named_type.name);
+
+				struct_value result{.struct_type = std::make_unique<types::type>(named_type)};
+				for (auto const & field : struct_data.fields)
+					result.fields[field.name] = std::make_unique<value>(types::apply(*this, *field.type));
+				return std::move(result);
+			}
+		};
+
+	}
+
 	context empty_context()
 	{
 		context result;
@@ -27,4 +72,9 @@ namespace pslang::interpreter
 		std::cout << std::flush;
 	}
 
+	value zero_value(context & context, types::type const & type)
+	{
+		return types::apply(zero_value_visitor{context}, type);
+	}
+
 }

libs/interpreter/source/eval.cpp

@@ -514,6 +514,9 @@ namespace pslang::interpreter
 				{
 					if (auto jt = it->structs.find(identifier->name); jt != it->structs.end())
 					{
+						if (function_call.arguments.empty())
+							return zero_value(context, types::named_type{.name = identifier->name, .level = identifier->level});
+
 						if (jt->second.fields.size() != function_call.arguments.size())
 						{
 							std::ostringstream os;

libs/types/include/pslang/types/type_visitor.hpp

@@ -14,19 +14,19 @@ namespace pslang::types
 			Visitor & visitor;
 
 			template <typename Type>
-			void operator()(Type const & type)
+			auto operator()(Type const & type)
 			{
-				visitor(type);
+				return visitor(type);
 			}
 
-			void operator()(types::primitive_type const & type)
+			auto operator()(types::primitive_type const & type)
 			{
-				std::visit(*this, type);
+				return std::visit(*this, type);
 			}
 
-			void operator()(types::type const & type)
+			auto operator()(types::type const & type)
 			{
-				std::visit(*this, type);
+				return std::visit(*this, type);
 			}
 		};
 
@@ -36,36 +36,36 @@ namespace pslang::types
 			Visitor & visitor;
 
 			template <typename Type>
-			void operator()(Type & type)
+			auto operator()(Type & type)
 			{
-				visitor(type);
+				return visitor(type);
 			}
 
-			void operator()(types::primitive_type & type)
+			auto operator()(types::primitive_type & type)
 			{
-				std::visit(*this, type);
+				return std::visit(*this, type);
 			}
 
-			void operator()(types::type & type)
+			auto operator()(types::type & type)
 			{
-				std::visit(*this, type);
+				return std::visit(*this, type);
 			}
 		};
 
 	}
 
 	template <typename Visitor>
-	void apply(Visitor && visitor, type const & type)
+	auto apply(Visitor && visitor, type const & type)
 	{
 		detail::const_visitor_helper<Visitor> helper{visitor};
-		helper(type);
+		return helper(type);
 	}
 
 	template <typename Visitor>
-	void apply(Visitor && visitor, type & type)
+	auto apply(Visitor && visitor, type & type)
 	{
 		detail::visitor_helper<Visitor> helper{visitor};
-		helper(type);
+		return helper(type);
 	}
 
 }