UserScript/include/UserScript.h

#pragma once
#include <memory>
#include <string>
#include <variant>
#include <vector>
#include <optional>

namespace scripting {
	struct null {};
	struct array;
	
	using script_value = std::variant<null, int32_t, std::string, array>;
	struct script_variable {
		std::string name;
	};
	
	struct code_location {
		std::shared_ptr<const std::string> line_contents;
		int32_t line_number;
		int32_t column_number;
	};
	
	struct script_error {
		std::shared_ptr<const code_location> location;
		std::string message;
	};
	
	struct array {
		std::vector<script_value> value;
		operator std::vector<script_value>&() {
			return value;
		}
	};
	
	using argument = std::variant<script_value, script_variable>;
	
	class UserScript;
	
	struct function_impl {
		virtual std::optional<script_value> apply(UserScript* self, std::vector<argument>, std::optional<script_error>&) = 0;
		virtual ~function_impl() = default;
	};
	
	using function = std::unique_ptr<function_impl>;
	
	class UserScript {
	public:
		virtual std::optional<std::reference_wrapper<script_value>> getValue(const std::string& name) = 0;
		virtual bool setValue(const std::string& name, script_value value) = 0;
		virtual void registerFunction(std::string name, function fn) = 0;
		virtual script_value resolve(const std::string& name) = 0;
		virtual std::variant<script_value, std::vector<script_error>> executeAtOnce(std::string code) = 0;
		virtual std::vector<script_error> prepare(std::string code) = 0;
		virtual std::optional<script_error> stepOnce() = 0;
		virtual ~UserScript() = default;
	};
	
	std::unique_ptr<UserScript> prepare_interpreter(const std::string& code);
}