@@ -652,6 +652,9 @@ def __init__(self, shell=None, namespace=None, global_namespace=None,
                          self.dict_key_matches,
                          ]
 
+        # This is set externally by InteractiveShell
+        self.custom_completers = None
+
     def all_completions(self, text):
         """
         Wrapper around the complete method for the benefit of emacs.
@@ -1072,6 +1075,9 @@ def latex_matches(self, text):
         return u'', []
 
     def dispatch_custom_completer(self, text):
+        if not self.custom_completers:
+            return
+
         line = self.line_buffer
         if not line.strip():
             return None
 
@@ -37,6 +37,7 @@
 from IPython.core.excolors import exception_colors
 from IPython.testing.skipdoctest import skip_doctest
 
+
 prompt = 'ipdb> '
 
 #We have to check this directly from sys.argv, config struct not yet available
@@ -120,12 +121,6 @@ def __init__(self, colors=None):
             sys.excepthook = functools.partial(BdbQuit_excepthook,
                                                excepthook=sys.excepthook)
             def_colors = 'NoColor'
-            try:
-                # Limited tab completion support
-                import readline
-                readline.parse_and_bind('tab: complete')
-            except ImportError:
-                pass
         else:
             # In ipython, we use its custom exception handler mechanism
             def_colors = ip.colors
@@ -205,7 +200,7 @@ def __init__(self,color_scheme='NoColor',completekey=None,
         except (TypeError, ValueError):
                 raise ValueError("Context must be a positive integer")
 
-        OldPdb.__init__(self,completekey,stdin,stdout)
+        OldPdb.__init__(self, completekey, stdin, stdout)
 
         # IPython changes...
         self.shell = get_ipython()
@@ -245,31 +240,17 @@ def __init__(self,color_scheme='NoColor',completekey=None,
         self.parser = PyColorize.Parser()
 
         # Set the prompt - the default prompt is '(Pdb)'
-        Colors = cst.active_colors
-        if color_scheme == 'NoColor':
-            self.prompt = prompt
-        else:
-            # The colour markers are wrapped by bytes 01 and 02 so that readline
-            # can calculate the width.
-            self.prompt = u'\x01%s\x02%s\x01%s\x02' % (Colors.prompt, prompt, Colors.Normal)
+        self.prompt = prompt
 
     def set_colors(self, scheme):
         """Shorthand access to the color table scheme selector method."""
         self.color_scheme_table.set_active_scheme(scheme)
 
     def interaction(self, frame, traceback):
-        self.shell.set_completer_frame(frame)
-        while True:
-            try:
-                OldPdb.interaction(self, frame, traceback)
-                break
-            except KeyboardInterrupt:
-                self.shell.write('\n' + self.shell.get_exception_only())
-                break
-            finally:
-                # Pdb sets readline delimiters, so set them back to our own
-                if self.shell.readline is not None:
-                    self.shell.readline.set_completer_delims(self.shell.readline_delims)
+        try:
+            OldPdb.interaction(self, frame, traceback)
+        except KeyboardInterrupt:
+            sys.stdout.write('\n' + self.shell.get_exception_only())
 
     def parseline(self, line):
         if line.startswith("!!"):
@@ -284,18 +265,15 @@ def parseline(self, line):
 
     def new_do_up(self, arg):
         OldPdb.do_up(self, arg)
-        self.shell.set_completer_frame(self.curframe)
     do_u = do_up = decorate_fn_with_doc(new_do_up, OldPdb.do_up)
 
     def new_do_down(self, arg):
         OldPdb.do_down(self, arg)
-        self.shell.set_completer_frame(self.curframe)
 
     do_d = do_down = decorate_fn_with_doc(new_do_down, OldPdb.do_down)
 
     def new_do_frame(self, arg):
         OldPdb.do_frame(self, arg)
-        self.shell.set_completer_frame(self.curframe)
 
     def new_do_quit(self, arg):
 
@@ -312,9 +290,6 @@ def new_do_restart(self, arg):
         self.msg("Restart doesn't make sense here. Using 'quit' instead.")
         return self.do_quit(arg)
 
-    def postloop(self):
-        self.shell.set_completer_frame(None)
-
     def print_stack_trace(self, context=None):
         if context is None:
             context = self.context
 
@@ -42,6 +42,7 @@
 from IPython.core.builtin_trap import BuiltinTrap
 from IPython.core.events import EventManager, available_events
 from IPython.core.compilerop import CachingCompiler, check_linecache_ipython
+from IPython.core.debugger import Pdb
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.displayhook import DisplayHook
 from IPython.core.displaypub import DisplayPublisher
@@ -1584,6 +1585,8 @@ def init_history(self):
     # Things related to exception handling and tracebacks (not debugging)
     #-------------------------------------------------------------------------
 
+    debugger_cls = Pdb
+
     def init_traceback_handlers(self, custom_exceptions):
         # Syntax error handler.
         self.SyntaxTB = ultratb.SyntaxTB(color_scheme='NoColor')
@@ -1594,7 +1597,8 @@ def init_traceback_handlers(self, custom_exceptions):
         self.InteractiveTB = ultratb.AutoFormattedTB(mode = 'Plain',
                                                      color_scheme='NoColor',
                                                      tb_offset = 1,
-                                   check_cache=check_linecache_ipython)
+                                   check_cache=check_linecache_ipython,
+                                   debugger_cls=self.debugger_cls)
 
         # The instance will store a pointer to the system-wide exception hook,
         # so that runtime code (such as magics) can access it.  This is because
 
@@ -809,7 +809,7 @@ class VerboseTB(TBTools):
 
     def __init__(self, color_scheme='Linux', call_pdb=False, ostream=None,
                  tb_offset=0, long_header=False, include_vars=True,
-                 check_cache=None):
+                 check_cache=None, debugger_cls = None):
         """Specify traceback offset, headers and color scheme.
 
         Define how many frames to drop from the tracebacks. Calling it with
@@ -830,6 +830,8 @@ def __init__(self, color_scheme='Linux', call_pdb=False, ostream=None,
             check_cache = linecache.checkcache
         self.check_cache = check_cache
 
+        self.debugger_cls = debugger_cls or debugger.Pdb
+
     def format_records(self, records, last_unique, recursion_repeat):
         """Format the stack frames of the traceback"""
         frames = []
@@ -1217,7 +1219,7 @@ def debugger(self, force=False):
 
         if force or self.call_pdb:
             if self.pdb is None:
-                self.pdb = debugger.Pdb(
+                self.pdb = self.debugger_cls(
                     self.color_scheme_table.active_scheme_name)
             # the system displayhook may have changed, restore the original
             # for pdb
@@ -1278,7 +1280,7 @@ class FormattedTB(VerboseTB, ListTB):
     def __init__(self, mode='Plain', color_scheme='Linux', call_pdb=False,
                  ostream=None,
                  tb_offset=0, long_header=False, include_vars=False,
-                 check_cache=None):
+                 check_cache=None, debugger_cls=None):
 
         # NEVER change the order of this list. Put new modes at the end:
         self.valid_modes = ['Plain', 'Context', 'Verbose']
@@ -1287,7 +1289,7 @@ def __init__(self, mode='Plain', color_scheme='Linux', call_pdb=False,
         VerboseTB.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                            ostream=ostream, tb_offset=tb_offset,
                            long_header=long_header, include_vars=include_vars,
-                           check_cache=check_cache)
+                           check_cache=check_cache, debugger_cls=debugger_cls)
 
         # Different types of tracebacks are joined with different separators to
         # form a single string.  They are taken from this dict
 
@@ -0,0 +1,73 @@
+from IPython.core.debugger import Pdb
+
+from IPython.core.completer import IPCompleter
+from .ptutils import IPythonPTCompleter
+
+from prompt_toolkit.token import Token
+from prompt_toolkit.shortcuts import create_prompt_application
+from prompt_toolkit.interface import CommandLineInterface
+from prompt_toolkit.enums import EditingMode
+
+class TerminalPdb(Pdb):
+    def __init__(self, *args, **kwargs):
+        Pdb.__init__(self, *args, **kwargs)
+        self._ptcomp = None
+        self.pt_init()
+
+    def pt_init(self):
+        def get_prompt_tokens(cli):
+            return [(Token.Prompt, self.prompt)]
+
+        if self._ptcomp is None:
+            compl = IPCompleter(shell=self.shell,
+                                        namespace={},
+                                        global_namespace={},
+                                        use_readline=False,
+                                        parent=self.shell,
+                                       )
+            self._ptcomp = IPythonPTCompleter(compl)
+
+        self._pt_app = create_prompt_application(
+                            editing_mode=getattr(EditingMode, self.shell.editing_mode.upper()),
+                            history=self.shell.debugger_history,
+                            completer= self._ptcomp,
+                            enable_history_search=True,
+                            mouse_support=self.shell.mouse_support,
+                            get_prompt_tokens=get_prompt_tokens
+        )
+        self.pt_cli = CommandLineInterface(self._pt_app, eventloop=self.shell._eventloop)
+
+    def cmdloop(self, intro=None):
+        """Repeatedly issue a prompt, accept input, parse an initial prefix
+        off the received input, and dispatch to action methods, passing them
+        the remainder of the line as argument.
+
+        override the same methods from cmd.Cmd to provide prompt toolkit replacement.
+        """
+        if not self.use_rawinput:
+            raise ValueError('Sorry ipdb does not support use_rawinput=False')
+
+        self.preloop()
+
+        try:
+            if intro is not None:
+                self.intro = intro
+            if self.intro:
+                self.stdout.write(str(self.intro)+"\n")
+            stop = None
+            while not stop:
+                if self.cmdqueue:
+                    line = self.cmdqueue.pop(0)
+                else:
+                    self._ptcomp.ipy_completer.namespace = self.curframe_locals
+                    self._ptcomp.ipy_completer.global_namespace = self.curframe.f_globals
+                    try:
+                        line = self.pt_cli.run(reset_current_buffer=True).text
+                    except EOFError:
+                        line = 'EOF'
+                line = self.precmd(line)
+                stop = self.onecmd(line)
+                stop = self.postcmd(stop, line)
+            self.postloop()
+        except Exception:
+            raise
@@ -4,89 +4,32 @@
 import os
 import sys
 import signal
-import unicodedata
 from warnings import warn
-from wcwidth import wcwidth
 
 from IPython.core.error import TryNext
 from IPython.core.interactiveshell import InteractiveShell
-from IPython.utils.py3compat import PY3, cast_unicode_py2, input
+from IPython.utils.py3compat import cast_unicode_py2, input
 from IPython.utils.terminal import toggle_set_term_title, set_term_title
 from IPython.utils.process import abbrev_cwd
 from traitlets import Bool, Unicode, Dict, Integer, observe
 
-from prompt_toolkit.completion import Completer, Completion
 from prompt_toolkit.enums import DEFAULT_BUFFER, SEARCH_BUFFER, EditingMode
 from prompt_toolkit.filters import HasFocus, HasSelection, Condition, ViInsertMode, EmacsInsertMode, IsDone
 from prompt_toolkit.history import InMemoryHistory
 from prompt_toolkit.shortcuts import create_prompt_application, create_eventloop, create_prompt_layout
 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 Lexer
-from prompt_toolkit.layout.lexers import PygmentsLexer
 from prompt_toolkit.layout.processors import ConditionalProcessor, HighlightMatchingBracketProcessor
 from prompt_toolkit.styles import PygmentsStyle, DynamicStyle
 
 from pygments.styles import get_style_by_name, get_all_styles
-from pygments.lexers import Python3Lexer, BashLexer, PythonLexer
 from pygments.token import Token
 
+from .debugger import TerminalPdb
 from .pt_inputhooks import get_inputhook_func
 from .interactiveshell import get_default_editor, TerminalMagics
-
-
-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:
-            m = unicodedata.normalize('NFC', m)
-
-            # 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(m[0]) == 0:
-                if document.cursor_position + start_pos > 0:
-                    char_before = document.text[document.cursor_position + start_pos - 1]
-                    m = unicodedata.normalize('NFC', char_before + m)
-
-                    # Yield the modified completion instead, if this worked.
-                    if wcwidth(m[0:1]) == 1:
-                        yield Completion(m, start_position=start_pos - 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(m, start_position=start_pos)
-
-class IPythonPTLexer(Lexer):
-    """
-    Wrapper around PythonLexer and BashLexer.
-    """
-    def __init__(self):
-        self.python_lexer = PygmentsLexer(Python3Lexer if PY3 else PythonLexer)
-        self.shell_lexer = PygmentsLexer(BashLexer)
-
-    def lex_document(self, cli, document):
-        if document.text.startswith('!'):
-            return self.shell_lexer.lex_document(cli, document)
-        else:
-            return self.python_lexer.lex_document(cli, document)
+from .ptutils import IPythonPTCompleter, IPythonPTLexer
 
 
 class TerminalInteractiveShell(InteractiveShell):
@@ -100,6 +43,8 @@ def _space_for_menu_changed(self, old, new):
         self._update_layout()
 
     pt_cli = None
+    debugger_history = None
+    debugger_cls = TerminalPdb
 
     autoedit_syntax = Bool(False,
         help="auto editing of files with syntax errors.",
@@ -362,6 +307,8 @@ def __init__(self, *args, **kwargs):
         self.init_term_title()
         self.keep_running = True
 
+        self.debugger_history = InMemoryHistory()
+
     def ask_exit(self):
         self.keep_running = False