Don't try to complete on an empty line

IPython/terminal/ptshell.py

@@ -1,115 +1,118 b''
 from IPython.core.interactiveshell import InteractiveShell
 
 from prompt_toolkit.completion import Completer, Completion
 from prompt_toolkit.history import InMemoryHistory
 from prompt_toolkit.shortcuts import create_prompt_application
 from prompt_toolkit.interface import CommandLineInterface
 from prompt_toolkit.key_binding.manager import KeyBindingManager
 from prompt_toolkit.keys import Keys
 from prompt_toolkit.layout.lexers import PygmentsLexer
 from prompt_toolkit.styles import PygmentsStyle
 
 from pygments.lexers import Python3Lexer
 from pygments.token import Token
 
 
 class IPythonPTCompleter(Completer):
     """Adaptor to provide IPython completions to prompt_toolkit"""
     def __init__(self, ipy_completer):
         self.ipy_completer = ipy_completer
 
     def get_completions(self, document, complete_event):
+        if not document.current_line.strip():
+            return
+
         used, matches = self.ipy_completer.complete(
                             line_buffer=document.current_line,
                             cursor_pos=document.cursor_position_col
         )
         start_pos = -len(used)
         for m in matches:
             yield Completion(m, start_position=start_pos)
 
 
 class PTInteractiveShell(InteractiveShell):
     colors_force = True
 
     pt_cli = None
 
     def get_prompt_tokens(self, cli):
         return [
             (Token.Prompt, 'In ['),
             (Token.PromptNum, str(self.execution_count)),
             (Token.Prompt, ']: '),
         ]
 
 
     def init_prompt_toolkit_cli(self):
         kbmanager = KeyBindingManager.for_prompt()
         @kbmanager.registry.add_binding(Keys.ControlJ) # Ctrl+J == Enter, seemingly
         def _(event):
             b = event.current_buffer
             if not b.document.on_last_line:
                 b.newline()
                 return
 
             status, indent = self.input_splitter.check_complete(b.document.text)
 
             if (status != 'incomplete') and b.accept_action.is_returnable:
                 b.accept_action.validate_and_handle(event.cli, b)
             else:
                 b.insert_text('\n' + (' ' * (indent or 0)))
 
         @kbmanager.registry.add_binding(Keys.ControlC)
         def _(event):
             event.current_buffer.reset()
 
         # Pre-populate history from IPython's history database
         history = InMemoryHistory()
         last_cell = u""
         for _, _, cell in self.history_manager.get_tail(self.history_load_length,
                                                         include_latest=True):
             # Ignore blank lines and consecutive duplicates
             cell = cell.rstrip()
             if cell and (cell != last_cell):
                 history.append(cell)
 
         style = PygmentsStyle.from_defaults({
             Token.Prompt: '#009900',
             Token.PromptNum: '#00ff00 bold',
             Token.Number: '#007700',
             Token.Operator: '#bbbbbb',
         })
 
         app = create_prompt_application(multiline=True,
                             lexer=PygmentsLexer(Python3Lexer),
                             get_prompt_tokens=self.get_prompt_tokens,
                             key_bindings_registry=kbmanager.registry,
                             history=history,
                             completer=IPythonPTCompleter(self.Completer),
                             style=style,
         )
 
         self.pt_cli = CommandLineInterface(app)
 
     def __init__(self, *args, **kwargs):
         super(PTInteractiveShell, self).__init__(*args, **kwargs)
         self.init_prompt_toolkit_cli()
         self.keep_running = True
 
     def ask_exit(self):
         self.keep_running = False
 
     def interact(self):
         while self.keep_running:
             print(self.separate_in, end='')
             try:
                 document = self.pt_cli.run()
             except EOFError:
                 if self.ask_yes_no('Do you really want to exit ([y]/n)?','y','n'):
                     self.ask_exit()
 
             else:
                 if document:
                     self.run_cell(document.text, store_history=True)
 
 
 if __name__ == '__main__':
     PTInteractiveShell.instance().interact()