Move the implementation of tokenizer functions

The functions are being moved as these can be used by many different implementations of the tokenizer.
So it does not make any sense if they only apply to one implementation of that tokenizer.

Author: QuickWrite

src/luasm.lua

@@ -104,19 +104,33 @@ end
 local Tokenizer = {}
 
 --- Abstract method that must be overridden by a concrete tokenizer.
+--- @return string|nil
 function Tokenizer.get_next_line()
     error("This function has to be implemented!")
-    return false
+    return nil
 end
 
 --- @return boolean
-function Tokenizer:has_next_line()
-    return false
+function Tokenizer:has_line()
+    self.line = self:get_next_line()
+
+    return self.line ~= nil
 end
 
 --- @return string|nil
 function Tokenizer:get_label()
-    return nil
+    if self.luasm.settings.label == nil then
+        return nil
+    end
+
+    local label, rest = self.line:match(self.settings.label)
+
+    if label ~= nil then
+        self.line   = rest
+        self.cursor = self.cursor + #label
+    end
+
+    return label
 end
 
 --- Creates a new tokenizer without a specific implementation.
@@ -181,27 +195,6 @@ function LuASM:string_tokenizer(input)
         return line
     end
 
-    tokenizer.has_line = function()
-        tokenizer.line = tokenizer.get_next_line()
-
-        return tokenizer.line ~= nil
-    end
-
-    tokenizer.get_label = function()
-        if self.settings.label == nil then
-            return nil
-        end
-
-        local label, rest = tokenizer.line:match(self.settings.label)
-
-        if label ~= nil then
-            tokenizer.line   = rest
-            tokenizer.cursor = tokenizer.cursor + #label
-        end
-
-        return label
-    end
-
     return tokenizer
 end