Don't use tokenutil in v4 msgspec adapter

reimplement javascript token logic from IPython 2, instead.

Avoids jupyter_client dependency on tokenutil,
which should stay with IPython.

jupyter_client/adapter.py

@@ -3,10 +3,10 b''
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
+import re
 import json
 
 from IPython.core.release import kernel_protocol_version_info
-from IPython.utils.tokenutil import token_at_cursor
 
 
 def code_to_line(code, cursor_pos):
@@ -26,6 +26,33 b' def code_to_line(code, cursor_pos):'
     return line, cursor_pos
 
 
+_match_bracket = re.compile(r'\([^\(\)]+\)', re.UNICODE)
+_end_bracket = re.compile(r'\([^\(]*$', re.UNICODE)
+_identifier = re.compile(r'[a-z_][0-9a-z._]*', re.I|re.UNICODE)
+
+def extract_oname_v4(code, cursor_pos):
+    """Reimplement token-finding logic from IPython 2.x javascript
+    
+    for adapting object_info_request from v5 to v4
+    """
+    
+    line, _ = code_to_line(code, cursor_pos)
+    
+    oldline = line
+    line = _match_bracket.sub(u'', line)
+    while oldline != line:
+        oldline = line
+        line = _match_bracket.sub(u'', line)
+
+    # remove everything after last open bracket
+    line = _end_bracket.sub('', line)
+    matches = _identifier.findall(line)
+    if matches:
+        return matches[-1]
+    else:
+        return ''
+
+
 class Adapter(object):
     """Base class for adapting messages
 
@@ -158,7 +185,7 b' class V5toV4(Adapter):'
         line, _ = code_to_line(code, cursor_pos)
 
         new_content = msg['content'] = {}
-        new_content['oname'] = token_at_cursor(code, cursor_pos)
+        new_content['oname'] = extract_oname_v4(code, cursor_pos)
         new_content['detail_level'] = content['detail_level']
         return msg
 

jupyter_client/tests/test_adapter.py

@@ -311,6 +311,20 b' class V5toV4TestCase(AdapterTest):'
         self.assertEqual(v4c['oname'], 'apple')
         self.assertEqual(v5c['detail_level'], v4c['detail_level'])
 
+    def test_inspect_request_token(self):
+        line = 'something(range(10), kwarg=smth) ; xxx.xxx.xxx( firstarg, rand(234,23), kwarg1=2,'
+        msg = self.msg("inspect_request", {
+            'code' : line,
+            'cursor_pos': len(line)-1,
+            'detail_level' : 1,
+        })
+        v5, v4 = self.adapt(msg)
+        self.assertEqual(v4['header']['msg_type'], 'object_info_request')
+        v4c = v4['content']
+        v5c = v5['content']
+        self.assertEqual(v4c['oname'], 'xxx.xxx.xxx')
+        self.assertEqual(v5c['detail_level'], v4c['detail_level'])
+
     def test_inspect_reply(self):
         msg = self.msg("inspect_reply", {
             'name' : 'foo',