Fix puppet, add immutable puppet with hash

lark/parsers/lalr_parser.py

@@ -95,7 +95,7 @@ class ParserState:
                 assert not is_end
                 state_stack.append(arg)
                 value_stack.append(token)
-                return arg
+                return
             else:
                 # reduce+shift as many times as necessary
                 rule = arg

lark/parsers/lalr_puppet.py

@@ -22,7 +22,7 @@ class ParserPuppet(object):
 
         Note that ``token`` has to be an instance of ``Token``.
         """
-        return self.parser_state.feed_token(token)
+        return self.parser_state.feed_token(token, token.type == '$END')
 
     def __copy__(self):
         """Create a new puppet with a separate state.
@@ -35,15 +35,18 @@ class ParserPuppet(object):
             copy(self.lexer_state),
         )
 
+    def copy(self):
+        return copy(self)
+
     def __eq__(self, other):
         if not isinstance(other, ParserPuppet):
             return False
 
         return self.parser_state == other.parser_state and self.lexer_state == other.lexer_state
 
-    # TODO Provide with an immutable puppet instance
-    # def __hash__(self):
-    #     return hash((self.parser_state, self.lexer_state))
+    def as_immutable(self):
+        p = copy(self)
+        return ImmutableParserPuppet(p.parser, p.parser_state, p.lexer_state)
 
     def pretty(self):
         """Print the output of ``choices()`` in a way that's easier to read."""
@@ -60,7 +63,7 @@ class ParserPuppet(object):
 
         Updated by ``feed_token()``.
         """
-        return self.parser_state.parse_table.states[self.parser_state.position]
+        return self.parser_state.parse_conf.parse_table.states[self.parser_state.position]
 
     def accepts(self):
         accepts = set()
@@ -78,3 +81,16 @@ class ParserPuppet(object):
     def resume_parse(self):
         """Resume parsing from the current puppet state."""
         return self.parser.parse_from_state(self.parser_state)
+
+
+
+class ImmutableParserPuppet(ParserPuppet):
+    result = None
+
+    def __hash__(self):
+        return hash((self.parser_state, self.lexer_state))
+
+    def feed_token(self, token):
+        c = copy(self)
+        c.result = ParserPuppet.feed_token(c, token)
+        return c