4 files changed, 28 insertions, 1 deletions
diff --git a/libpathod/language/actions.py b/libpathod/language/actions.py
index e86394a0..f5b828fe 100644
--- a/libpathod/language/actions.py
+++ b/libpathod/language/actions.py
@@ -45,6 +45,8 @@ class _Action(base.Token):
 
 
 class PauseAt(_Action):
+    unique_name = None
+
     def __init__(self, offset, seconds):
         _Action.__init__(self, offset)
         self.seconds = seconds
@@ -93,6 +95,8 @@ class DisconnectAt(_Action):
 
 
 class InjectAt(_Action):
+    unique_name = None
+
     def __init__(self, offset, value):
         _Action.__init__(self, offset)
         self.value = value
diff --git a/libpathod/language/base.py b/libpathod/language/base.py
index 3773fde1..2a9e4ed3 100644
--- a/libpathod/language/base.py
+++ b/libpathod/language/base.py
@@ -77,6 +77,15 @@ class Token(object):
         """
         return None
 
+    @property
+    def unique_name(self):
+        """
+            Controls uniqueness constraints for tokens. No two tokens with the
+            same name will be allowed. If no uniquness should be applied, this
+            should be None.
+        """
+        return self.__class__.__name__
+
     def resolve(self, settings, msg):
         """
             Resolves this token to ready it for transmission. This means that
diff --git a/libpathod/language/http.py b/libpathod/language/http.py
index 070cc5f4..daee7e54 100644
--- a/libpathod/language/http.py
+++ b/libpathod/language/http.py
@@ -46,6 +46,8 @@ class Method(base.OptionsOrValue):
 
 
 class _HeaderMixin(object):
+    unique_name = None
+
     def format_header(self, key, value):
         return [key, ": ", value, "\r\n"]
 
@@ -166,6 +168,7 @@ class _HTTPMessage(message.Message):
 
 
 class Response(_HTTPMessage):
+    unique_name = None
     comps = (
         Body,
         Header,
diff --git a/libpathod/language/message.py b/libpathod/language/message.py
index b5ef7045..dbc0cfdd 100644
--- a/libpathod/language/message.py
+++ b/libpathod/language/message.py
@@ -1,5 +1,5 @@
 import abc
-from . import actions
+from . import actions, exceptions
 
 LOG_TRUNCATE = 1024
 
@@ -9,6 +9,17 @@ class Message(object):
     logattrs = []
 
     def __init__(self, tokens):
+        track = set([])
+        for i in tokens:
+            if i.unique_name:
+                if i.unique_name in track:
+                    raise exceptions.ParseException(
+                        "Message has multiple %s clauses, "
+                        "but should only have one." % i.unique_name,
+                        0, 0
+                    )
+                else:
+                    track.add(i.unique_name)
         self.tokens = tokens
 
     def toks(self, klass):