Implement functions

src/main.rs

@@ -90,13 +90,58 @@ impl Program {
         println!("{:?}", self.funcs);
     }
 
+    fn parse_funcs(&mut self, instruction: &String) -> u32 {
+        // Opcode is the first character, arguments are everything after the first char
+        let opcode = instruction.chars().collect::<Vec<char>>()[0];
+        let arguments = &instruction[1..];
+
+        // Only a subset of opcodes, because the others don't make sense in a function
+        match opcode {
+            'a' => eval::do_math(self.args_or_vars(arguments), '+'),
+            's' => eval::do_math(self.args_or_vars(arguments), '-'),
+            'm' => eval::do_math(self.args_or_vars(arguments), '*'),
+            'd' => eval::do_math(self.args_or_vars(arguments), '/'),
+            'l' => {self.add_var(arguments);0}
+            _ => panic!("SyntaxError: No such opcode: {}", self.pc),
+        }
+    }
+
+    fn args_or_funcs(&mut self, arguments: &str) -> String {
+        let mut builder = String::from("");
+        let argument_vec: Vec<char> = arguments.chars().collect();
+
+        for index in 0..argument_vec.len() {
+            let current_char = argument_vec[index];
+            let str_to_push: String;
+
+            if current_char == '*' {
+                let func_name = argument_vec[index+1];
+                let body: String;
+
+                let key = (self).funcs.get(&func_name);
+                match key {
+                    Some(content) => body = content.to_owned(),
+                    None => panic!("ValueError: function {} has not been defined yet!", func_name)
+                }
+
+                str_to_push = self.parse_funcs(&body).to_string();
+            } else {
+                str_to_push = current_char.to_string();
+            }
+
+            builder.push_str(&str_to_push);
+        }
+
+        builder
+    }
+
     fn parse(&mut self, instruction: &String) {
         // Opcode is the first character, arguments are everything after the first char
         let opcode = instruction.chars().collect::<Vec<char>>()[0];
         let arguments = &instruction[1..];
 
         match opcode {
-            'p' => println!("{}", self.args_or_vars(arguments)),
+            'p' => println!("{}", self.args_or_funcs(&self.args_or_vars(arguments))),
             'a' => println!("{}", eval::do_math(self.args_or_vars(arguments), '+')),
             's' => println!("{}", eval::do_math(self.args_or_vars(arguments), '-')),
             'm' => println!("{}", eval::do_math(self.args_or_vars(arguments), '*')),