prevent tag replacements overlapping each other

irctokens/protocol.py

@@ -1,15 +1,17 @@
 from typing import Dict, List, Optional
 
-TAG_ESCAPE =   ["\\",   " ",  ";",   "\r",  "\n"]
-TAG_UNESCAPE = ["\\\\", "\s", "\:", r"\r", r"\n"]
+TAG_UNESCAPED = ["\\",   " ",   ";",   "\r",  "\n"]
+TAG_ESCAPED =   ["\\\\", "\\s", "\\:", "\\r", "\\n"]
 
 def _unescape_tag(value: str):
-    for i, char in enumerate(TAG_UNESCAPE):
-        value = value.replace(char, TAG_ESCAPE[i])
-    return value
+    parts = value.split("\\\\")
+    for i, piece in enumerate(TAG_ESCAPED):
+        for j, part in enumerate(parts):
+            parts[j] = part.replace(piece, TAG_UNESCAPED[i])
+    return "\\".join(parts)
 def _escape_tag(value: str):
-    for i, char in enumerate(TAG_ESCAPE):
-        value = value.replace(char, TAG_UNESCAPE[i])
+    for i, char in enumerate(TAG_UNESCAPED):
+        value = value.replace(char, TAG_ESCAPED[i])
     return value
 
 class Hostmask(object):

test/format.py

@@ -5,7 +5,7 @@ class FormatTestTags(unittest.TestCase):
     def test(self):
         line = irctokens.format("PRIVMSG", ["#channel", "hello"],
             tags={"id": "\\" + " " + ";" + "\r\n"})
-        self.assertEqual(line, r"@id=\\\s\:\r\n PRIVMSG #channel hello")
+        self.assertEqual(line, "@id=\\\\\\s\\:\\r\\n PRIVMSG #channel hello")
 
     def test_missing(self):
         line = irctokens.format("PRIVMSG", ["#channel", "hello"])

test/tokenise.py

@@ -18,6 +18,10 @@ class TokenTestTags(unittest.TestCase):
         line = irctokens.tokenise(r"@id=1\\\:\r\n\s2 PRIVMSG #channel")
         self.assertEqual(line.tags["id"], "1\\;\r\n 2")
 
+    def test_overlap(self):
+        line = irctokens.tokenise(r"@id=1\\\s\\s PRIVMSG #channel")
+        self.assertEqual(line.tags["id"], "1\\ \\s")
+
 class TokenTestSource(unittest.TestCase):
     def test_without_tags(self):
         line = irctokens.tokenise(":nick!user@host PRIVMSG #channel")