Add interpreter::value_visitor

libs/interpreter/include/pslang/interpreter/value_visitor.hpp

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <pslang/interpreter/value.hpp>
+
+namespace pslang::interpreter
+{
+
+	namespace detail
+	{
+
+		template <typename Visitor>
+		struct const_value_visitor_helper
+		{
+			Visitor & visitor;
+
+			template <typename Value>
+			auto operator()(Value const & value)
+			{
+				return visitor(value);
+			}
+
+			auto operator()(value const & value)
+			{
+				return std::visit(*this, value);
+			}
+
+			auto operator()(primitive_value const & value)
+			{
+				return std::visit(*this, value);
+			}
+		};
+
+		template <typename Visitor>
+		struct value_visitor_helper
+		{
+			Visitor & visitor;
+
+			template <typename Value>
+			auto operator()(Value & value)
+			{
+				return visitor(value);
+			}
+
+			auto operator()(value & value)
+			{
+				return std::visit(*this, value);
+			}
+
+			auto operator()(primitive_value & value)
+			{
+				return std::visit(*this, value);
+			}
+		};
+
+	}
+
+	template <typename Visitor>
+	auto apply(Visitor && visitor, value const & value)
+	{
+		detail::const_value_visitor_helper<Visitor> helper{visitor};
+		return helper(value);
+	}
+
+	template <typename Visitor>
+	auto apply(Visitor && visitor, value & value)
+	{
+		detail::value_visitor_helper<Visitor> helper{visitor};
+		return helper(value);
+	}
+
+}

libs/interpreter/source/value.cpp

@@ -1,4 +1,5 @@
 #include <pslang/interpreter/value.hpp>
+#include <pslang/interpreter/value_visitor.hpp>
 #include <pslang/types/print.hpp>
 
 #include <iomanip>
@@ -9,33 +10,30 @@ namespace pslang::interpreter
 	namespace
 	{
 
-		types::type type_of_impl(unit_value const &)
+		struct type_of_visitor
+		{
+			types::type operator()(unit_value const &)
 			{
 				return types::unit_type{};
 			}
 
 			template <typename T>
-		types::type type_of_impl(primitive_value_base<T> const &)
+			types::type operator()(primitive_value_base<T> const &)
 			{
 				return types::primitive_type(types::primitive_type_base<T>{});
 			}
 
-		types::type type_of_impl(primitive_value const & value)
+			types::type operator()(array_value const & value)
-		{
-			return std::visit([](auto const & value){ return type_of_impl(value); }, value);
-		}
-
-		types::type type_of_impl(array_value const & value)
 			{
 				return types::array_type{.element_type = value.element_type, .size = value.elements.size()};
 			}
 
-		types::type type_of_impl(struct_value const & value)
+			types::type operator()(struct_value const & value)
 			{
 				return *value.struct_type;
 			}
 
-		types::type type_of_impl(function_value const & value)
+			types::type operator()(function_value const & value)
 			{
 				types::function_type result;
 				for (auto const & argument : value.arguments)
@@ -43,19 +41,19 @@ namespace pslang::interpreter
 				result.result = value.return_type;
 				return result;
 			}
+		};
 
-		types::type type_of_impl(value const & value)
+		struct print_visitor
 		{
-			return std::visit([](auto const & value){ return type_of_impl(value); }, value);
+			std::ostream & out;
-		}
 
-		void print_impl(std::ostream & out, unit_value const &)
+			void operator()(unit_value const &)
 			{
 				out << "unit";
 			}
 
 			template <typename T>
-		void print_impl(std::ostream & out, primitive_value_base<T> const & value)
+			void operator()(primitive_value_base<T> const & value)
 			{
 				if constexpr (std::is_same_v<T, bool>)
 				{
@@ -83,24 +81,19 @@ namespace pslang::interpreter
 				}
 			}
 
-		void print_impl(std::ostream & out, primitive_value const & value)
+			void operator()(array_value const & value)
-		{
-			std::visit([&](auto const & value){ return print_impl(out, value); }, value);
-		}
-
-		void print_impl(std::ostream & out, array_value const & value)
 			{
 				out << "[";
 				for (std::size_t i = 0; i < value.elements.size(); ++i)
 				{
 					if (i > 0)
 						out << ", ";
-				print(out, *value.elements[i]);
+					apply(*this, *value.elements[i]);
 				}
 				out << "]";
 			}
 
-		void print_impl(std::ostream & out, struct_value const & value)
+			void operator()(struct_value const & value)
 			{
 				out << "{";
 				bool first = true;
@@ -110,31 +103,27 @@ namespace pslang::interpreter
 						out << ", ";
 					first = false;
 					out << field.first << " = ";
-				print(out, *field.second);
+					apply(*this, *field.second);
 				}
 				out << "}";
 			}
 
-		void print_impl(std::ostream & out, function_value const & value)
+			void operator()(function_value const & value)
 			{
 				out << "func";
 			}
-
+		};
-		void print_impl(std::ostream & out, value const & value)
-		{
-			std::visit([&](auto const & value){ return print_impl(out, value); }, value);
-		}
 
 	}
 
 	types::type type_of(value const & value)
 	{
-		return type_of_impl(value);
+		return apply(type_of_visitor{}, value);
 	}
 
 	void print(std::ostream & out, value const & value)
 	{
-		print_impl(out, value);
+		apply(print_visitor{out}, value);
 	}
 
 }