add hostmask parsing (irctokens.Hostmask("n!u@h"))

irctokens/__init__.py

@@ -1,2 +1,2 @@
-from .protocol import Line, tokenise, format
+from .protocol import Line, tokenise, format, Hostmask
 from .stateful import StatefulDecoder, StatefulEncoder

irctokens/protocol.py

@@ -12,6 +12,16 @@ def _escape_tag(value: str):
         value = value.replace(char, TAG_UNESCAPE[i])
     return value
 
+class Hostmask(object):
+    def __init__(self, source: str):
+        self._raw = source
+        username,      _, hostname = source.partition("@")
+        self.nickname, _, username = username.partition("!")
+        self.username = username or None
+        self.hostname = hostname or None
+    def __str__(self) -> str:
+        return self._raw
+
 class Line(object):
     def __init__(self,
             tags:

test/__init__.py

@@ -2,3 +2,4 @@ from .tokenise        import *
 from .format          import *
 from .stateful_decode import *
 from .stateful_encode import *
+from .hostmask import *

test/hostmask.py

@@ -0,0 +1,28 @@
+import unittest
+import irctokens
+
+class HostmaskTestAll(unittest.TestCase):
+    def test_all(self):
+        hostmask = irctokens.Hostmask("nick!user@host")
+        self.assertEqual(hostmask.nickname, "nick")
+        self.assertEqual(hostmask.username, "user")
+        self.assertEqual(hostmask.hostname, "host")
+
+    def test_no_hostname(self):
+        hostmask = irctokens.Hostmask("nick!user")
+        self.assertEqual(hostmask.nickname, "nick")
+        self.assertEqual(hostmask.username, "user")
+        self.assertIsNone(hostmask.hostname)
+
+    def test_no_ident(self):
+        hostmask = irctokens.Hostmask("nick@host")
+        self.assertEqual(hostmask.nickname, "nick")
+        self.assertIsNone(hostmask.username)
+        self.assertEqual(hostmask.hostname, "host")
+
+    def test_only_nickname(self):
+        hostmask = irctokens.Hostmask("nick")
+        self.assertEqual(hostmask.nickname, "nick")
+        self.assertIsNone(hostmask.username)
+        self.assertIsNone(hostmask.hostname)
+