Add static method for parsing single mbox messages

lib/nntp/tiny/mbox.py

@@ -99,6 +99,34 @@ class MBoxMessage():
     def is_first_line(self):
         return len(self.headers) == 1 and self.body == ''
 
+    @staticmethod
+    def each_line(text: str):
+        start = 0
+        end   = len(text)
+
+        while True:
+            try:
+                index = text.index('\n', start, end)
+
+                yield text[start:index+1]
+
+                start = index + 1
+
+                if start == end:
+                    break
+            except ValueError:
+                yield text[start:end]
+                break
+
+    @staticmethod
+    def parse(text: str):
+        message = MBoxMessage()
+
+        for line in MBoxMessage.each_line(text):
+            message.add(line)
+
+        return message
+
 class MBoxReader():
     __slots__ = 'path', 'fh', 'line', 'buf', 'message',