parser: refactor variables and symbols table into their own class

While symtab for now has only static members, it will allow for a
change in the future for each profile to have their own symbols like
profile_name, etc.

parser/variable.h

@@ -0,0 +1,58 @@
+/*
+ *   Copyright (c) 2025
+ *   Canonical Ltd. (All rights reserved)
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of version 2 of the GNU General Public
+ *   License published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, contact Canonical Ltd.
+ */
+
+#ifndef __AA_VARIABLE_H
+#define __AA_VARIABLE_H
+
+#include <set>
+#include <string>
+#include "parser.h"
+
+enum var_type {
+	sd_boolean,
+	sd_set,
+};
+
+class variable {
+public:
+	enum var_type type;
+	std::string var_name;
+	int boolean;
+	std::set<std::string> values;
+	std::set<std::string> expanded;
+	std::string expanding_by = "";
+	bool expanding = false;
+
+	variable(const char *var_name, struct value_list *values);
+	variable(const char *var_name, const char *value);
+	variable(const char *var_name, int boolean);
+
+	int add_set_value(struct value_list *value);
+	int expand_variable(void);
+	static int expand_by_alternation(char **name);
+	void dump_set_values(std::set<std::string> values);
+	void dump(bool expanded);
+
+	virtual ~variable() {};
+
+	/* strip off surrounding delimiters around variables */
+	static char *process_var(const char *var);
+};
+
+std::tuple<std::string, std::string, std::string> extract_variable(const std::string& input);
+
+#endif /* __AA_VARIABLE_H */