Improvements to tab completion in Qt GUI with new api.

All tests in main test suite pass at the moment.

IPython/core/completer.py

@@ -347,6 +347,8 b' class IPCompleter(Completer):'
 
         self.magic_escape = ESC_MAGIC
 
+        self.splitter = CompletionSplitter()
+
         # Readline-dependent code
         self.use_readline = use_readline
         if use_readline:
@@ -662,16 +664,20 b' class IPCompleter(Completer):'
             
         return None
                
-    def complete(self, text, line_buffer, cursor_pos=None):
+    def complete(self, text=None, line_buffer=None, cursor_pos=None):
         """Return the state-th possible completion for 'text'.
 
         This is called successively with state == 0, 1, 2, ... until it
         returns None.  The completion should begin with 'text'.
 
+        Note that both the text and the line_buffer are optional, but at least
+        one of them must be given.
+
         Parameters
         ----------
-          text : string
-            Text to perform the completion on.
+          text : string, optional
+            Text to perform the completion on.  If not given, the line buffer
+            is split using the instance's CompletionSplitter object.
 
           line_buffer : string, optional
             If not given, the completer attempts to obtain the current line
@@ -683,7 +689,20 b' class IPCompleter(Completer):'
             Index of the cursor in the full line buffer.  Should be provided by
             remote frontends where kernel has no access to frontend state.
         """
-        #io.rprint('COMP', text, line_buffer, cursor_pos)  # dbg
+        #io.rprint('COMP1 %r %r %r' % (text, line_buffer, cursor_pos))  # dbg
+
+        # if the cursor position isn't given, the only sane assumption we can
+        # make is that it's at the end of the line (the common case)
+        if cursor_pos is None:
+            cursor_pos = len(line_buffer) if text is None else len(text)
+
+        # if text is either None or an empty string, rely on the line buffer
+        if not text:
+            text = self.splitter.split_line(line_buffer, cursor_pos)
+
+        # If no line buffer is given, assume the input text is all there was
+        if line_buffer is None:
+            line_buffer = text
         
         magic_escape = self.magic_escape
         self.full_lbuf = line_buffer
@@ -692,6 +711,8 b' class IPCompleter(Completer):'
         if text.startswith('~'):
             text = os.path.expanduser(text)
 
+        #io.rprint('COMP2 %r %r %r' % (text, line_buffer, cursor_pos))  # dbg
+
         # Start with a clean slate of completions
         self.matches[:] = []
         custom_res = self.dispatch_custom_completer(text)
@@ -716,8 +737,8 b' class IPCompleter(Completer):'
         # simply collapse the dict into a list for readline, but we'd have
         # richer completion semantics in other evironments.
         self.matches = sorted(set(self.matches))
-        #io.rprint('MATCHES', self.matches) # dbg
-        return self.matches
+        #io.rprint('COMP TEXT, MATCHES: %r, %r' % (text, self.matches)) # dbg
+        return text, self.matches
 
     def rlcomplete(self, text, state):
         """Return the state-th possible completion for 'text'.

IPython/core/interactiveshell.py

@@ -1370,13 +1370,15 b' class InteractiveShell(Configurable, Magic):'
     #-------------------------------------------------------------------------
 
     def complete(self, text, line=None, cursor_pos=None):
-        """Return a sorted list of all possible completions on text.
+        """Return the completed text and a list of completions.
 
         Parameters
         ----------
 
            text : string
-             A string of text to be completed on.
+             A string of text to be completed on.  It can be given as empty and
+             instead a line/position pair are given.  In this case, the
+             completer itself will split the line like readline does.
 
            line : string, optional
              The complete line that text is part of.
@@ -1384,6 +1386,14 b' class InteractiveShell(Configurable, Magic):'
            cursor_pos : int, optional
              The position of the cursor on the input line.
 
+        Returns
+        -------
+          text : string
+            The actual text that was completed.
+
+          matches : list
+            A sorted list with all possible completions.
+
         The optional arguments allow the completion to take more context into
         account, and are part of the low-level completion API.
         
@@ -1394,21 +1404,15 b' class InteractiveShell(Configurable, Magic):'
 
         Simple usage example:
 
-        In [7]: x = 'hello'
-
-        In [8]: x
-        Out[8]: 'hello'
-
-        In [9]: print x
-        hello
+        In [1]: x = 'hello'
 
-        In [10]: _ip.complete('x.l')
-        Out[10]: ['x.ljust', 'x.lower', 'x.lstrip']
+        In [2]: _ip.complete('x.l')
+        Out[2]: ('x.l', ['x.ljust', 'x.lower', 'x.lstrip'])
         """
 
         # Inject names into __builtin__ so we can complete on the added names.
         with self.builtin_trap:
-            return self.Completer.complete(text,line_buffer=text)
+            return self.Completer.complete(text, line, cursor_pos)
 
     def set_custom_completer(self,completer,pos=0):
         """Adds a new custom completer function.

IPython/core/tests/test_completer.py

@@ -69,10 +69,9 b' class CompletionSplitterTestCase(unittest.TestCase):'
         self.sp = completer.CompletionSplitter()
 
     def test_delim_setting(self):
-        self.sp.delims = ' '
-        # Validate that property handling works ok
-        nt.assert_equal(self.sp.delims, ' ')
-        nt.assert_equal(self.sp.delim_expr, '[\ ]')
+        self.sp.set_delims(' ')
+        nt.assert_equal(self.sp.get_delims(), ' ')
+        nt.assert_equal(self.sp._delim_expr, '[\ ]')
 
     def test_spaces(self):
         """Test with only spaces as split chars."""

IPython/frontend/qt/console/frontend_widget.py

@@ -181,7 +181,10 b' class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):'
         cursor = self._get_cursor()
         if rep['parent_header']['msg_id'] == self._complete_id and \
                 cursor.position() == self._complete_pos:
-            text = '.'.join(self._get_context())
+            # The completer tells us what text was actually used for the
+            # matching, so we must move that many characters left to apply the
+            # completions.
+            text = rep['content']['matched_text']
             cursor.movePosition(QtGui.QTextCursor.Left, n=len(text))
             self._complete_with_items(cursor, rep['content']['matches'])
 
@@ -294,14 +297,22 b' class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):'
         """ Performs completion at the current cursor location.
         """
         # Decide if it makes sense to do completion
-        context = self._get_context()
-        if not context:
+
+        # We should return only if the line is empty.  Otherwise, let the
+        # kernel split the line up.
+        line = self._get_input_buffer_cursor_line()
+        if not line:
             return False
 
+        # We let the kernel split the input line, so we *always* send an empty
+        # text field.  Readline-based frontends do get a real text field which
+        # they can use.
+        text = ''
+        
         # Send the completion request to the kernel
         self._complete_id = self.kernel_manager.xreq_channel.complete(
-            '.'.join(context),                       # text 
-            self._get_input_buffer_cursor_line(),    # line 
+            text,                                      # text
+            line,                                      # line
             self._get_input_buffer_cursor_column(),  # cursor_pos
             self.input_buffer)                       # block 
         self._complete_pos = self._get_cursor().position()