Minor improvements to completion

If object being completed is a function, append `()` to match the
convention used in cpython doc. This include methods. Append `()` only
in the _displayed_ menu, does not insert the ().

If completion is relatively to long (mostly if is does not come from
jedi), and use a fully qualified name with more than 3 parts, ellides
the middles one to `…`. (This closes  #9835).

IPython/terminal/ptutils.py

@@ -1,128 +1,150 b''
 """prompt-toolkit utilities
 
 Everything in this module is a private API,
 not to be used outside IPython.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import unicodedata
 from wcwidth import wcwidth
 
 from IPython.core.completer import (
-    IPCompleter, provisionalcompleter, rectify_completions, cursor_to_position,
+    provisionalcompleter, cursor_to_position,
     _deduplicate_completions)
 from prompt_toolkit.completion import Completer, Completion
 from prompt_toolkit.layout.lexers import Lexer
 from prompt_toolkit.layout.lexers import PygmentsLexer
 
 import pygments.lexers as pygments_lexers
 
 _completion_sentinel = object()
 
+def _elide(string, *, min_elide=30):
+    """
+    If a string is long enough, and has at least 2 dots,
+    replace the middle part with ellipses.
+
+    For example:
+    """
+    if len(string) < min_elide:
+        return string
+
+    parts = string.split('.')
+
+    if len(parts) <= 3:
+        return string
+
+    return '{}.{}\N{HORIZONTAL ELLIPSIS}{}.{}'.format(parts[0], parts[1][0], parts[-2][-1], parts[-1])
+
 
 
 
 class IPythonPTCompleter(Completer):
     """Adaptor to provide IPython completions to prompt_toolkit"""
     def __init__(self, ipy_completer=None, shell=None, patch_stdout=None):
         if shell is None and ipy_completer is None:
             raise TypeError("Please pass shell=an InteractiveShell instance.")
         self._ipy_completer = ipy_completer
         self.shell = shell
         if patch_stdout is None:
             raise TypeError("Please pass patch_stdout")
         self.patch_stdout = patch_stdout
 
     @property
     def ipy_completer(self):
         if self._ipy_completer:
             return self._ipy_completer
         else:
             return self.shell.Completer
 
     def get_completions(self, document, complete_event):
         if not document.current_line.strip():
             return
         # Some bits of our completion system may print stuff (e.g. if a module
         # is imported). This context manager ensures that doesn't interfere with
         # the prompt.
 
         with self.patch_stdout(), provisionalcompleter():
             body = document.text
             cursor_row = document.cursor_position_row
             cursor_col = document.cursor_position_col
             cursor_position = document.cursor_position
             offset = cursor_to_position(body, cursor_row, cursor_col)
             yield from self._get_completions(body, offset, cursor_position, self.ipy_completer)
 
     @staticmethod
     def _get_completions(body, offset, cursor_position, ipyc):
         """
         Private equivalent of get_completions() use only for unit_testing.
         """
         debug = getattr(ipyc, 'debug', False)
         completions = _deduplicate_completions(
             body, ipyc.completions(body, offset))
         for c in completions:
             if not c.text:
                 # Guard against completion machinery giving us an empty string.
                 continue
             text = unicodedata.normalize('NFC', c.text)
             # When the first character of the completion has a zero length,
             # then it's probably a decomposed unicode character. E.g. caused by
             # the "\dot" completion. Try to compose again with the previous
             # character.
             if wcwidth(text[0]) == 0:
                 if cursor_position + c.start > 0:
                     char_before = body[c.start - 1]
                     fixed_text = unicodedata.normalize(
                         'NFC', char_before + text)
 
                     # Yield the modified completion instead, if this worked.
                     if wcwidth(text[0:1]) == 1:
                         yield Completion(fixed_text, start_position=c.start - offset - 1)
                         continue
 
             # TODO: Use Jedi to determine meta_text
             # (Jedi currently has a bug that results in incorrect information.)
             # meta_text = ''
             # yield Completion(m, start_position=start_pos,
             #                  display_meta=meta_text)
-            yield Completion(c.text, start_position=c.start - offset, display_meta=c.type)
+            display_text = c.text
+
+            if c.type == 'function':
+                display_text = display_text + '()'
+
+            yield Completion(c.text, start_position=c.start - offset, display=_elide(display_text), display_meta=c.type)
 
 class IPythonPTLexer(Lexer):
     """
     Wrapper around PythonLexer and BashLexer.
     """
     def __init__(self):
         l = pygments_lexers
         self.python_lexer = PygmentsLexer(l.Python3Lexer)
         self.shell_lexer = PygmentsLexer(l.BashLexer)
 
         self.magic_lexers = {
             'HTML': PygmentsLexer(l.HtmlLexer),
             'html': PygmentsLexer(l.HtmlLexer),
             'javascript': PygmentsLexer(l.JavascriptLexer),
             'js': PygmentsLexer(l.JavascriptLexer),
             'perl': PygmentsLexer(l.PerlLexer),
             'ruby': PygmentsLexer(l.RubyLexer),
             'latex': PygmentsLexer(l.TexLexer),
         }
 
     def lex_document(self, cli, document):
         text = document.text.lstrip()
 
         lexer = self.python_lexer
 
         if text.startswith('!') or text.startswith('%%bash'):
             lexer = self.shell_lexer
 
         elif text.startswith('%%'):
             for magic, l in self.magic_lexers.items():
                 if text.startswith('%%' + magic):
                     lexer = l
                     break
 
         return lexer.lex_document(cli, document)