Get naked '?' to work, and in-spec with the new inputsplitter design.

IPython/core/interactiveshell.py

@@ -1,2151 +1,2156 b''
 # -*- coding: utf-8 -*-
 """Main IPython class."""
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2001 Janko Hauser <[e-mail]>
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #  Copyright (C) 2008-2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import with_statement
 from __future__ import absolute_import
 
 import __builtin__
 import abc
 import codeop
 import exceptions
 import new
 import os
 import re
 import string
 import sys
 import tempfile
 from contextlib import nested
 
 from IPython.config.configurable import Configurable
 from IPython.core import debugger, oinspect
 from IPython.core import history as ipcorehist
+from IPython.core import page
 from IPython.core import prefilter
 from IPython.core import shadowns
 from IPython.core import ultratb
 from IPython.core.alias import AliasManager
 from IPython.core.builtin_trap import BuiltinTrap
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.displayhook import DisplayHook
 from IPython.core.error import UsageError
 from IPython.core.extensions import ExtensionManager
 from IPython.core.fakemodule import FakeModule, init_fakemod_dict
 from IPython.core.inputlist import InputList
 from IPython.core.logger import Logger
 from IPython.core.magic import Magic
 from IPython.core.payload import PayloadManager
 from IPython.core.plugin import PluginManager
 from IPython.core.prefilter import PrefilterManager
 from IPython.external.Itpl import ItplNS
 from IPython.utils import PyColorize
 from IPython.utils import io
 from IPython.utils import pickleshare
 from IPython.utils.doctestreload import doctest_reload
 from IPython.utils.io import ask_yes_no, rprint
 from IPython.utils.ipstruct import Struct
 from IPython.utils.path import get_home_dir, get_ipython_dir, HomeDirError
 from IPython.utils.process import getoutput, getoutputerror
 from IPython.utils.strdispatch import StrDispatch
 from IPython.utils.syspathcontext import prepended_to_syspath
 from IPython.utils.text import num_ini_spaces
 from IPython.utils.traitlets import (Int, Str, CBool, CaselessStrEnum, Enum,
                                      List, Unicode, Instance, Type)
 from IPython.utils.warn import warn, error, fatal
 import IPython.core.hooks
 
 # from IPython.utils import growl
 # growl.start("IPython")
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 # compiled regexps for autoindent management
 dedent_re = re.compile(r'^\s+raise|^\s+return|^\s+pass')
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 # store the builtin raw_input globally, and use this always, in case user code
 # overwrites it (like wx.py.PyShell does)
 raw_input_original = raw_input
 
 def softspace(file, newvalue):
     """Copied from code.py, to remove the dependency"""
 
     oldvalue = 0
     try:
         oldvalue = file.softspace
     except AttributeError:
         pass
     try:
         file.softspace = newvalue
     except (AttributeError, TypeError):
         # "attribute-less object" or "read-only attributes"
         pass
     return oldvalue
 
 
 def no_op(*a, **kw): pass
 
 class SpaceInInput(exceptions.Exception): pass
 
 class Bunch: pass
 
 
 def get_default_colors():
     if sys.platform=='darwin':
         return "LightBG"
     elif os.name=='nt':
         return 'Linux'
     else:
         return 'Linux'
 
 
 class SeparateStr(Str):
     """A Str subclass to validate separate_in, separate_out, etc.
 
     This is a Str based trait that converts '0'->'' and '\\n'->'\n'.
     """
 
     def validate(self, obj, value):
         if value == '0': value = ''
         value = value.replace('\\n','\n')
         return super(SeparateStr, self).validate(obj, value)
 
 class MultipleInstanceError(Exception):
     pass
 
 
 #-----------------------------------------------------------------------------
 # Main IPython class
 #-----------------------------------------------------------------------------
 
 
 class InteractiveShell(Configurable, Magic):
     """An enhanced, interactive shell for Python."""
 
     _instance = None
     autocall = Enum((0,1,2), default_value=1, config=True)
     # TODO: remove all autoindent logic and put into frontends.
     # We can't do this yet because even runlines uses the autoindent.
     autoindent = CBool(True, config=True)
     automagic = CBool(True, config=True)
     cache_size = Int(1000, config=True)
     color_info = CBool(True, config=True)
     colors = CaselessStrEnum(('NoColor','LightBG','Linux'), 
                              default_value=get_default_colors(), config=True)
     debug = CBool(False, config=True)
     deep_reload = CBool(False, config=True)
     displayhook_class = Type(DisplayHook)
     filename = Str("<ipython console>")
     ipython_dir= Unicode('', config=True) # Set to get_ipython_dir() in __init__
     logstart = CBool(False, config=True)
     logfile = Str('', config=True)
     logappend = Str('', config=True)
     object_info_string_level = Enum((0,1,2), default_value=0,
                                     config=True)
     pdb = CBool(False, config=True)
     pprint = CBool(True, config=True)
     profile = Str('', config=True)
     prompt_in1 = Str('In [\\#]: ', config=True)
     prompt_in2 = Str('   .\\D.: ', config=True)
     prompt_out = Str('Out[\\#]: ', config=True)
     prompts_pad_left = CBool(True, config=True)
     quiet = CBool(False, config=True)
 
     # The readline stuff will eventually be moved to the terminal subclass
     # but for now, we can't do that as readline is welded in everywhere.
     readline_use = CBool(True, config=True)
     readline_merge_completions = CBool(True, config=True)
     readline_omit__names = Enum((0,1,2), default_value=0, config=True)
     readline_remove_delims = Str('-/~', config=True)
     readline_parse_and_bind = List([
             'tab: complete',
             '"\C-l": clear-screen',
             'set show-all-if-ambiguous on',
             '"\C-o": tab-insert',
             '"\M-i": "    "',
             '"\M-o": "\d\d\d\d"',
             '"\M-I": "\d\d\d\d"',
             '"\C-r": reverse-search-history',
             '"\C-s": forward-search-history',
             '"\C-p": history-search-backward',
             '"\C-n": history-search-forward',
             '"\e[A": history-search-backward',
             '"\e[B": history-search-forward',
             '"\C-k": kill-line',
             '"\C-u": unix-line-discard',
         ], allow_none=False, config=True)
 
     # TODO: this part of prompt management should be moved to the frontends.
     # Use custom TraitTypes that convert '0'->'' and '\\n'->'\n'
     separate_in = SeparateStr('\n', config=True)
     separate_out = SeparateStr('', config=True)
     separate_out2 = SeparateStr('', config=True)
     system_header = Str('IPython system call: ', config=True)
     system_verbose = CBool(False, config=True)
     wildcards_case_sensitive = CBool(True, config=True)
     xmode = CaselessStrEnum(('Context','Plain', 'Verbose'), 
                             default_value='Context', config=True)
 
     # Subcomponents of InteractiveShell
     alias_manager = Instance('IPython.core.alias.AliasManager')
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager')
     builtin_trap = Instance('IPython.core.builtin_trap.BuiltinTrap')
     display_trap = Instance('IPython.core.display_trap.DisplayTrap')
     extension_manager = Instance('IPython.core.extensions.ExtensionManager')
     plugin_manager = Instance('IPython.core.plugin.PluginManager')
     payload_manager = Instance('IPython.core.payload.PayloadManager')
 
     def __init__(self, config=None, ipython_dir=None,
                  user_ns=None, user_global_ns=None,
                  custom_exceptions=((),None)):
 
         # This is where traits with a config_key argument are updated
         # from the values on config.
         super(InteractiveShell, self).__init__(config=config)
 
         # These are relatively independent and stateless
         self.init_ipython_dir(ipython_dir)
         self.init_instance_attrs()
 
         # Create namespaces (user_ns, user_global_ns, etc.)
         self.init_create_namespaces(user_ns, user_global_ns)
         # This has to be done after init_create_namespaces because it uses
         # something in self.user_ns, but before init_sys_modules, which
         # is the first thing to modify sys.
         # TODO: When we override sys.stdout and sys.stderr before this class
         # is created, we are saving the overridden ones here. Not sure if this
         # is what we want to do.
         self.save_sys_module_state()
         self.init_sys_modules()
 
         self.init_history()
         self.init_encoding()
         self.init_prefilter()
 
         Magic.__init__(self, self)
 
         self.init_syntax_highlighting()
         self.init_hooks()
         self.init_pushd_popd_magic()
         # self.init_traceback_handlers use to be here, but we moved it below
         # because it and init_io have to come after init_readline.
         self.init_user_ns()
         self.init_logger()
         self.init_alias()
         self.init_builtins()
 
         # pre_config_initialization
         self.init_shadow_hist()
 
         # The next section should contain averything that was in ipmaker.
         self.init_logstart()
 
         # The following was in post_config_initialization
         self.init_inspector()
         # init_readline() must come before init_io(), because init_io uses
         # readline related things.
         self.init_readline()
         # TODO: init_io() needs to happen before init_traceback handlers
         # because the traceback handlers hardcode the stdout/stderr streams.
         # This logic in in debugger.Pdb and should eventually be changed.
         self.init_io()
         self.init_traceback_handlers(custom_exceptions)
         self.init_prompts()
         self.init_displayhook()
         self.init_reload_doctest()
         self.init_magics()
         self.init_pdb()
         self.init_extension_manager()
         self.init_plugin_manager()
         self.init_payload()
         self.hooks.late_startup_hook()
 
     @classmethod
     def instance(cls, *args, **kwargs):
         """Returns a global InteractiveShell instance."""
         if cls._instance is None:
             inst = cls(*args, **kwargs)
             # Now make sure that the instance will also be returned by
             # the subclasses instance attribute.
             for subclass in cls.mro():
                 if issubclass(cls, subclass) and issubclass(subclass, InteractiveShell):
                     subclass._instance = inst
                 else:
                     break
         if isinstance(cls._instance, cls):
             return cls._instance
         else:
             raise MultipleInstanceError(
                 'Multiple incompatible subclass instances of '
                 'InteractiveShell are being created.'
             )
 
     @classmethod
     def initialized(cls):
         return hasattr(cls, "_instance")
 
     def get_ipython(self):
         """Return the currently running IPython instance."""
         return self
 
     #-------------------------------------------------------------------------
     # Trait changed handlers
     #-------------------------------------------------------------------------
 
     def _ipython_dir_changed(self, name, new):
         if not os.path.isdir(new):
             os.makedirs(new, mode = 0777)
 
     def set_autoindent(self,value=None):
         """Set the autoindent flag, checking for readline support.
 
         If called with no arguments, it acts as a toggle."""
 
         if not self.has_readline:
             if os.name == 'posix':
                 warn("The auto-indent feature requires the readline library")
             self.autoindent = 0
             return
         if value is None:
             self.autoindent = not self.autoindent
         else:
             self.autoindent = value
 
     #-------------------------------------------------------------------------
     # init_* methods called by __init__
     #-------------------------------------------------------------------------
 
     def init_ipython_dir(self, ipython_dir):
         if ipython_dir is not None:
             self.ipython_dir = ipython_dir
             self.config.Global.ipython_dir = self.ipython_dir
             return
 
         if hasattr(self.config.Global, 'ipython_dir'):
             self.ipython_dir = self.config.Global.ipython_dir
         else:
             self.ipython_dir = get_ipython_dir()
 
         # All children can just read this
         self.config.Global.ipython_dir = self.ipython_dir
 
     def init_instance_attrs(self):
         self.more = False
 
         # command compiler
         self.compile = codeop.CommandCompiler()
 
         # User input buffer
         self.buffer = []
 
         # Make an empty namespace, which extension writers can rely on both
         # existing and NEVER being used by ipython itself.  This gives them a
         # convenient location for storing additional information and state
         # their extensions may require, without fear of collisions with other
         # ipython names that may develop later.
         self.meta = Struct()
 
         # Object variable to store code object waiting execution.  This is
         # used mainly by the multithreaded shells, but it can come in handy in
         # other situations.  No need to use a Queue here, since it's a single
         # item which gets cleared once run.
         self.code_to_run = None
 
         # Temporary files used for various purposes.  Deleted at exit.
         self.tempfiles = []
 
         # Keep track of readline usage (later set by init_readline)
         self.has_readline = False
 
         # keep track of where we started running (mainly for crash post-mortem)
         # This is not being used anywhere currently.
         self.starting_dir = os.getcwd()
 
         # Indentation management
         self.indent_current_nsp = 0
 
     def init_encoding(self):
         # Get system encoding at startup time.  Certain terminals (like Emacs
         # under Win32 have it set to None, and we need to have a known valid
         # encoding to use in the raw_input() method
         try:
             self.stdin_encoding = sys.stdin.encoding or 'ascii'
         except AttributeError:
             self.stdin_encoding = 'ascii'
 
     def init_syntax_highlighting(self):
         # Python source parser/formatter for syntax highlighting
         pyformat = PyColorize.Parser().format
         self.pycolorize = lambda src: pyformat(src,'str',self.colors)
 
     def init_pushd_popd_magic(self):
         # for pushd/popd management
         try:
             self.home_dir = get_home_dir()
         except HomeDirError, msg:
             fatal(msg)
 
         self.dir_stack = []
 
     def init_logger(self):
         self.logger = Logger(self, logfname='ipython_log.py', logmode='rotate')
         # local shortcut, this is used a LOT
         self.log = self.logger.log
 
     def init_logstart(self):
         if self.logappend:
             self.magic_logstart(self.logappend + ' append')
         elif self.logfile:
             self.magic_logstart(self.logfile)
         elif self.logstart:
             self.magic_logstart()
 
     def init_builtins(self):
         self.builtin_trap = BuiltinTrap(shell=self)
 
     def init_inspector(self):
         # Object inspector
         self.inspector = oinspect.Inspector(oinspect.InspectColors,
                                             PyColorize.ANSICodeColors,
                                             'NoColor',
                                             self.object_info_string_level)
 
     def init_io(self):
         import IPython.utils.io
         if sys.platform == 'win32' and self.has_readline:
             Term = io.IOTerm(
                 cout=self.readline._outputfile,cerr=self.readline._outputfile
             )
         else:
             Term = io.IOTerm()
         io.Term = Term
 
     def init_prompts(self):
         # TODO: This is a pass for now because the prompts are managed inside
         # the DisplayHook. Once there is a separate prompt manager, this 
         # will initialize that object and all prompt related information.
         pass
 
     def init_displayhook(self):
         # Initialize displayhook, set in/out prompts and printing system
         self.displayhook = self.displayhook_class(
             shell=self,
             cache_size=self.cache_size,
             input_sep = self.separate_in,
             output_sep = self.separate_out,
             output_sep2 = self.separate_out2,
             ps1 = self.prompt_in1,
             ps2 = self.prompt_in2,
             ps_out = self.prompt_out,
             pad_left = self.prompts_pad_left
         )
         # This is a context manager that installs/revmoes the displayhook at
         # the appropriate time.
         self.display_trap = DisplayTrap(hook=self.displayhook)
 
     def init_reload_doctest(self):
         # Do a proper resetting of doctest, including the necessary displayhook
         # monkeypatching
         try:
             doctest_reload()
         except ImportError:
             warn("doctest module does not exist.")
 
     #-------------------------------------------------------------------------
     # Things related to injections into the sys module
     #-------------------------------------------------------------------------
 
     def save_sys_module_state(self):
         """Save the state of hooks in the sys module.
 
         This has to be called after self.user_ns is created.
         """
         self._orig_sys_module_state = {}
         self._orig_sys_module_state['stdin'] = sys.stdin
         self._orig_sys_module_state['stdout'] = sys.stdout
         self._orig_sys_module_state['stderr'] = sys.stderr
         self._orig_sys_module_state['excepthook'] = sys.excepthook
         try:
             self._orig_sys_modules_main_name = self.user_ns['__name__']
         except KeyError:
             pass
 
     def restore_sys_module_state(self):
         """Restore the state of the sys module."""
         try:
             for k, v in self._orig_sys_module_state.items():
                 setattr(sys, k, v)
         except AttributeError:
             pass
         try:
             delattr(sys, 'ipcompleter')
         except AttributeError:
             pass
         # Reset what what done in self.init_sys_modules
         try:
             sys.modules[self.user_ns['__name__']] = self._orig_sys_modules_main_name
         except (AttributeError, KeyError):
             pass
 
     #-------------------------------------------------------------------------
     # Things related to hooks
     #-------------------------------------------------------------------------
 
     def init_hooks(self):
         # hooks holds pointers used for user-side customizations
         self.hooks = Struct()
 
         self.strdispatchers = {}
 
         # Set all default hooks, defined in the IPython.hooks module.
         hooks = IPython.core.hooks
         for hook_name in hooks.__all__:
             # default hooks have priority 100, i.e. low; user hooks should have
             # 0-100 priority
             self.set_hook(hook_name,getattr(hooks,hook_name), 100)
 
     def set_hook(self,name,hook, priority = 50, str_key = None, re_key = None):
         """set_hook(name,hook) -> sets an internal IPython hook.
 
         IPython exposes some of its internal API as user-modifiable hooks.  By
         adding your function to one of these hooks, you can modify IPython's 
         behavior to call at runtime your own routines."""
 
         # At some point in the future, this should validate the hook before it
         # accepts it.  Probably at least check that the hook takes the number
         # of args it's supposed to.
         
         f = new.instancemethod(hook,self,self.__class__)
 
         # check if the hook is for strdispatcher first
         if str_key is not None:
             sdp = self.strdispatchers.get(name, StrDispatch())
             sdp.add_s(str_key, f, priority )
             self.strdispatchers[name] = sdp
             return
         if re_key is not None:
             sdp = self.strdispatchers.get(name, StrDispatch())
             sdp.add_re(re.compile(re_key), f, priority )
             self.strdispatchers[name] = sdp
             return
             
         dp = getattr(self.hooks, name, None)
         if name not in IPython.core.hooks.__all__:
             print "Warning! Hook '%s' is not one of %s" % (name, IPython.core.hooks.__all__ )
         if not dp:
             dp = IPython.core.hooks.CommandChainDispatcher()
         
         try:
             dp.add(f,priority)
         except AttributeError:
             # it was not commandchain, plain old func - replace
             dp = f
 
         setattr(self.hooks,name, dp)
 
     #-------------------------------------------------------------------------
     # Things related to the "main" module
     #-------------------------------------------------------------------------
 
     def new_main_mod(self,ns=None):
         """Return a new 'main' module object for user code execution.
         """
         main_mod = self._user_main_module
         init_fakemod_dict(main_mod,ns)
         return main_mod
 
     def cache_main_mod(self,ns,fname):
         """Cache a main module's namespace.
 
         When scripts are executed via %run, we must keep a reference to the
         namespace of their __main__ module (a FakeModule instance) around so
         that Python doesn't clear it, rendering objects defined therein
         useless.
 
         This method keeps said reference in a private dict, keyed by the
         absolute path of the module object (which corresponds to the script
         path).  This way, for multiple executions of the same script we only
         keep one copy of the namespace (the last one), thus preventing memory
         leaks from old references while allowing the objects from the last
         execution to be accessible.
 
         Note: we can not allow the actual FakeModule instances to be deleted,
         because of how Python tears down modules (it hard-sets all their
         references to None without regard for reference counts).  This method
         must therefore make a *copy* of the given namespace, to allow the
         original module's __dict__ to be cleared and reused.
 
         
         Parameters
         ----------
           ns : a namespace (a dict, typically)
 
           fname : str
             Filename associated with the namespace.
 
         Examples
         --------
 
         In [10]: import IPython
 
         In [11]: _ip.cache_main_mod(IPython.__dict__,IPython.__file__)
 
         In [12]: IPython.__file__ in _ip._main_ns_cache
         Out[12]: True
         """
         self._main_ns_cache[os.path.abspath(fname)] = ns.copy()
 
     def clear_main_mod_cache(self):
         """Clear the cache of main modules.
 
         Mainly for use by utilities like %reset.
 
         Examples
         --------
 
         In [15]: import IPython
 
         In [16]: _ip.cache_main_mod(IPython.__dict__,IPython.__file__)
 
         In [17]: len(_ip._main_ns_cache) > 0
         Out[17]: True
 
         In [18]: _ip.clear_main_mod_cache()
 
         In [19]: len(_ip._main_ns_cache) == 0
         Out[19]: True
         """
         self._main_ns_cache.clear()
 
     #-------------------------------------------------------------------------
     # Things related to debugging
     #-------------------------------------------------------------------------
 
     def init_pdb(self):
         # Set calling of pdb on exceptions
         # self.call_pdb is a property
         self.call_pdb = self.pdb
 
     def _get_call_pdb(self):
         return self._call_pdb
 
     def _set_call_pdb(self,val):
 
         if val not in (0,1,False,True):
             raise ValueError,'new call_pdb value must be boolean'
 
         # store value in instance
         self._call_pdb = val
 
         # notify the actual exception handlers
         self.InteractiveTB.call_pdb = val
 
     call_pdb = property(_get_call_pdb,_set_call_pdb,None,
                         'Control auto-activation of pdb at exceptions')
 
     def debugger(self,force=False):
         """Call the pydb/pdb debugger.
 
         Keywords:
 
           - force(False): by default, this routine checks the instance call_pdb
           flag and does not actually invoke the debugger if the flag is false.
           The 'force' option forces the debugger to activate even if the flag
           is false.
         """
 
         if not (force or self.call_pdb):
             return
 
         if not hasattr(sys,'last_traceback'):
             error('No traceback has been produced, nothing to debug.')
             return
 
         # use pydb if available
         if debugger.has_pydb:
             from pydb import pm
         else:
             # fallback to our internal debugger
             pm = lambda : self.InteractiveTB.debugger(force=True)
         self.history_saving_wrapper(pm)()
 
     #-------------------------------------------------------------------------
     # Things related to IPython's various namespaces
     #-------------------------------------------------------------------------
 
     def init_create_namespaces(self, user_ns=None, user_global_ns=None):
         # Create the namespace where the user will operate.  user_ns is
         # normally the only one used, and it is passed to the exec calls as
         # the locals argument.  But we do carry a user_global_ns namespace
         # given as the exec 'globals' argument,  This is useful in embedding
         # situations where the ipython shell opens in a context where the
         # distinction between locals and globals is meaningful.  For
         # non-embedded contexts, it is just the same object as the user_ns dict.
 
         # FIXME. For some strange reason, __builtins__ is showing up at user
         # level as a dict instead of a module. This is a manual fix, but I
         # should really track down where the problem is coming from. Alex
         # Schmolck reported this problem first.
 
         # A useful post by Alex Martelli on this topic:
         # Re: inconsistent value from __builtins__
         # Von: Alex Martelli <[e-mail]>
         # Datum: Freitag 01 Oktober 2004 04:45:34 nachmittags/abends
         # Gruppen: comp.lang.python
 
         # Michael Hohn <[e-mail]> wrote:
         # > >>> print type(builtin_check.get_global_binding('__builtins__'))
         # > <type 'dict'>
         # > >>> print type(__builtins__)
         # > <type 'module'>
         # > Is this difference in return value intentional?
 
         # Well, it's documented that '__builtins__' can be either a dictionary
         # or a module, and it's been that way for a long time. Whether it's
         # intentional (or sensible), I don't know. In any case, the idea is
         # that if you need to access the built-in namespace directly, you
         # should start with "import __builtin__" (note, no 's') which will
         # definitely give you a module. Yeah, it's somewhat confusing:-(.
 
         # These routines return properly built dicts as needed by the rest of
         # the code, and can also be used by extension writers to generate
         # properly initialized namespaces.
         user_ns, user_global_ns = self.make_user_namespaces(user_ns, user_global_ns)
 
         # Assign namespaces
         # This is the namespace where all normal user variables live
         self.user_ns = user_ns
         self.user_global_ns = user_global_ns
 
         # An auxiliary namespace that checks what parts of the user_ns were
         # loaded at startup, so we can list later only variables defined in
         # actual interactive use.  Since it is always a subset of user_ns, it
         # doesn't need to be separately tracked in the ns_table.
         self.user_ns_hidden = {}
 
         # A namespace to keep track of internal data structures to prevent
         # them from cluttering user-visible stuff.  Will be updated later
         self.internal_ns = {}
 
         # Now that FakeModule produces a real module, we've run into a nasty
         # problem: after script execution (via %run), the module where the user
         # code ran is deleted.  Now that this object is a true module (needed
         # so docetst and other tools work correctly), the Python module
         # teardown mechanism runs over it, and sets to None every variable
         # present in that module.  Top-level references to objects from the
         # script survive, because the user_ns is updated with them.  However,
         # calling functions defined in the script that use other things from
         # the script will fail, because the function's closure had references
         # to the original objects, which are now all None.  So we must protect
         # these modules from deletion by keeping a cache.
         # 
         # To avoid keeping stale modules around (we only need the one from the
         # last run), we use a dict keyed with the full path to the script, so
         # only the last version of the module is held in the cache.  Note,
         # however, that we must cache the module *namespace contents* (their
         # __dict__).  Because if we try to cache the actual modules, old ones
         # (uncached) could be destroyed while still holding references (such as
         # those held by GUI objects that tend to be long-lived)>
         # 
         # The %reset command will flush this cache.  See the cache_main_mod()
         # and clear_main_mod_cache() methods for details on use.
 
         # This is the cache used for 'main' namespaces
         self._main_ns_cache = {}
         # And this is the single instance of FakeModule whose __dict__ we keep
         # copying and clearing for reuse on each %run
         self._user_main_module = FakeModule()
 
         # A table holding all the namespaces IPython deals with, so that
         # introspection facilities can search easily.
         self.ns_table = {'user':user_ns,
                          'user_global':user_global_ns,
                          'internal':self.internal_ns,
                          'builtin':__builtin__.__dict__
                          }
 
         # Similarly, track all namespaces where references can be held and that
         # we can safely clear (so it can NOT include builtin).  This one can be
         # a simple list.
         self.ns_refs_table = [ user_ns, user_global_ns, self.user_ns_hidden,
                                self.internal_ns, self._main_ns_cache ]
 
     def make_user_namespaces(self, user_ns=None, user_global_ns=None):
         """Return a valid local and global user interactive namespaces.
 
         This builds a dict with the minimal information needed to operate as a
         valid IPython user namespace, which you can pass to the various
         embedding classes in ipython. The default implementation returns the
         same dict for both the locals and the globals to allow functions to
         refer to variables in the namespace. Customized implementations can
         return different dicts. The locals dictionary can actually be anything
         following the basic mapping protocol of a dict, but the globals dict
         must be a true dict, not even a subclass. It is recommended that any
         custom object for the locals namespace synchronize with the globals
         dict somehow.
 
         Raises TypeError if the provided globals namespace is not a true dict.
 
         Parameters
         ----------
         user_ns : dict-like, optional
             The current user namespace. The items in this namespace should
             be included in the output. If None, an appropriate blank
             namespace should be created.
         user_global_ns : dict, optional
             The current user global namespace. The items in this namespace
             should be included in the output. If None, an appropriate
             blank namespace should be created.
 
         Returns
         -------
             A pair of dictionary-like object to be used as the local namespace
             of the interpreter and a dict to be used as the global namespace.
         """
 
 
         # We must ensure that __builtin__ (without the final 's') is always
         # available and pointing to the __builtin__ *module*.  For more details:
         # http://mail.python.org/pipermail/python-dev/2001-April/014068.html
 
         if user_ns is None:
             # Set __name__ to __main__ to better match the behavior of the
             # normal interpreter.
             user_ns = {'__name__'     :'__main__',
                        '__builtin__' : __builtin__,
                        '__builtins__' : __builtin__,
                       }
         else:
             user_ns.setdefault('__name__','__main__')
             user_ns.setdefault('__builtin__',__builtin__)
             user_ns.setdefault('__builtins__',__builtin__)
 
         if user_global_ns is None:
             user_global_ns = user_ns
         if type(user_global_ns) is not dict:
             raise TypeError("user_global_ns must be a true dict; got %r"
                 % type(user_global_ns))
 
         return user_ns, user_global_ns
 
     def init_sys_modules(self):
         # We need to insert into sys.modules something that looks like a
         # module but which accesses the IPython namespace, for shelve and
         # pickle to work interactively. Normally they rely on getting
         # everything out of __main__, but for embedding purposes each IPython
         # instance has its own private namespace, so we can't go shoving
         # everything into __main__.
 
         # note, however, that we should only do this for non-embedded
         # ipythons, which really mimic the __main__.__dict__ with their own
         # namespace.  Embedded instances, on the other hand, should not do
         # this because they need to manage the user local/global namespaces
         # only, but they live within a 'normal' __main__ (meaning, they
         # shouldn't overtake the execution environment of the script they're
         # embedded in).
 
         # This is overridden in the InteractiveShellEmbed subclass to a no-op.
 
         try:
             main_name = self.user_ns['__name__']
         except KeyError:
             raise KeyError('user_ns dictionary MUST have a "__name__" key')
         else:
             sys.modules[main_name] = FakeModule(self.user_ns)
 
     def init_user_ns(self):
         """Initialize all user-visible namespaces to their minimum defaults.
 
         Certain history lists are also initialized here, as they effectively
         act as user namespaces.
 
         Notes
         -----
         All data structures here are only filled in, they are NOT reset by this
         method.  If they were not empty before, data will simply be added to
         therm.
         """
         # This function works in two parts: first we put a few things in
         # user_ns, and we sync that contents into user_ns_hidden so that these
         # initial variables aren't shown by %who.  After the sync, we add the
         # rest of what we *do* want the user to see with %who even on a new
         # session (probably nothing, so theye really only see their own stuff)
 
         # The user dict must *always* have a __builtin__ reference to the
         # Python standard __builtin__ namespace,  which must be imported.
         # This is so that certain operations in prompt evaluation can be
         # reliably executed with builtins.  Note that we can NOT use
         # __builtins__ (note the 's'),  because that can either be a dict or a
         # module, and can even mutate at runtime, depending on the context
         # (Python makes no guarantees on it).  In contrast, __builtin__ is
         # always a module object, though it must be explicitly imported.
         
         # For more details:
         # http://mail.python.org/pipermail/python-dev/2001-April/014068.html
         ns = dict(__builtin__ = __builtin__)
         
         # Put 'help' in the user namespace
         try:
             from site import _Helper
             ns['help'] = _Helper()
         except ImportError:
             warn('help() not available - check site.py')
 
         # make global variables for user access to the histories
         ns['_ih'] = self.input_hist
         ns['_oh'] = self.output_hist
         ns['_dh'] = self.dir_hist
 
         ns['_sh'] = shadowns
 
         # user aliases to input and output histories.  These shouldn't show up
         # in %who, as they can have very large reprs.
         ns['In']  = self.input_hist
         ns['Out'] = self.output_hist
 
         # Store myself as the public api!!!
         ns['get_ipython'] = self.get_ipython
 
         # Sync what we've added so far to user_ns_hidden so these aren't seen
         # by %who
         self.user_ns_hidden.update(ns)
 
         # Anything put into ns now would show up in %who.  Think twice before
         # putting anything here, as we really want %who to show the user their
         # stuff, not our variables.
         
         # Finally, update the real user's namespace
         self.user_ns.update(ns)
 
 
     def reset(self):
         """Clear all internal namespaces.
 
         Note that this is much more aggressive than %reset, since it clears
         fully all namespaces, as well as all input/output lists.
         """
         for ns in self.ns_refs_table:
             ns.clear()
 
         self.alias_manager.clear_aliases()
 
         # Clear input and output histories
         self.input_hist[:] = []
         self.input_hist_raw[:] = []
         self.output_hist.clear()
 
         # Restore the user namespaces to minimal usability
         self.init_user_ns()
 
         # Restore the default and user aliases
         self.alias_manager.init_aliases()
 
     def reset_selective(self, regex=None):
         """Clear selective variables from internal namespaces based on a specified regular expression.
 
         Parameters
         ----------
         regex : string or compiled pattern, optional
             A regular expression pattern that will be used in searching variable names in the users 
             namespaces.
         """
         if regex is not None:
             try:
                 m = re.compile(regex)
             except TypeError:
                 raise TypeError('regex must be a string or compiled pattern')
             # Search for keys in each namespace that match the given regex
             # If a match is found, delete the key/value pair.
             for ns in self.ns_refs_table:
                 for var in ns:
                     if m.search(var):
                         del ns[var]        
         
     def push(self, variables, interactive=True):
         """Inject a group of variables into the IPython user namespace.
 
         Parameters
         ----------
         variables : dict, str or list/tuple of str
             The variables to inject into the user's namespace.  If a dict,
             a simple update is done.  If a str, the string is assumed to 
             have variable names separated by spaces.  A list/tuple of str
             can also be used to give the variable names.  If just the variable
             names are give (list/tuple/str) then the variable values looked
             up in the callers frame.
         interactive : bool
             If True (default), the variables will be listed with the ``who``
             magic.
         """
         vdict = None
 
         # We need a dict of name/value pairs to do namespace updates.
         if isinstance(variables, dict):
             vdict = variables
         elif isinstance(variables, (basestring, list, tuple)):
             if isinstance(variables, basestring):
                 vlist = variables.split()
             else:
                 vlist = variables
             vdict = {}
             cf = sys._getframe(1)
             for name in vlist:
                 try:
                     vdict[name] = eval(name, cf.f_globals, cf.f_locals)
                 except:
                     print ('Could not get variable %s from %s' %
                            (name,cf.f_code.co_name))
         else:
             raise ValueError('variables must be a dict/str/list/tuple')
             
         # Propagate variables to user namespace
         self.user_ns.update(vdict)
 
         # And configure interactive visibility
         config_ns = self.user_ns_hidden
         if interactive:
             for name, val in vdict.iteritems():
                 config_ns.pop(name, None)
         else:
             for name,val in vdict.iteritems():
                 config_ns[name] = val
 
     #-------------------------------------------------------------------------
     # Things related to history management
     #-------------------------------------------------------------------------
 
     def init_history(self):
         # List of input with multi-line handling.
         self.input_hist = InputList()
         # This one will hold the 'raw' input history, without any
         # pre-processing.  This will allow users to retrieve the input just as
         # it was exactly typed in by the user, with %hist -r.
         self.input_hist_raw = InputList()
 
         # list of visited directories
         try:
             self.dir_hist = [os.getcwd()]
         except OSError:
             self.dir_hist = []
 
         # dict of output history
         self.output_hist = {}
 
         # Now the history file
         if self.profile:
             histfname = 'history-%s' % self.profile
         else:
             histfname = 'history'
         self.histfile = os.path.join(self.ipython_dir, histfname)
 
         # Fill the history zero entry, user counter starts at 1
         self.input_hist.append('\n')
         self.input_hist_raw.append('\n')
 
     def init_shadow_hist(self):
         try:
             self.db = pickleshare.PickleShareDB(self.ipython_dir + "/db")
         except exceptions.UnicodeDecodeError:
             print "Your ipython_dir can't be decoded to unicode!"
             print "Please set HOME environment variable to something that"
             print r"only has ASCII characters, e.g. c:\home"
             print "Now it is", self.ipython_dir
             sys.exit()
         self.shadowhist = ipcorehist.ShadowHist(self.db)
 
     def savehist(self):
         """Save input history to a file (via readline library)."""
 
         try:
             self.readline.write_history_file(self.histfile)
         except:
             print 'Unable to save IPython command history to file: ' + \
                   `self.histfile`
 
     def reloadhist(self):
         """Reload the input history from disk file."""
 
         try:
             self.readline.clear_history()
             self.readline.read_history_file(self.shell.histfile)
         except AttributeError:
             pass
 
     def history_saving_wrapper(self, func):
         """ Wrap func for readline history saving
 
         Convert func into callable that saves & restores
         history around the call """
 
         if self.has_readline:
             from IPython.utils import rlineimpl as readline
         else:
             return func
 
         def wrapper():
             self.savehist()
             try:
                 func()
             finally:
                 readline.read_history_file(self.histfile)
         return wrapper
 
     def get_history(self, index=None, raw=False, output=True):
         """Get the history list.
 
         Get the input and output history.
 
         Parameters
         ----------
         index : n or (n1, n2) or None
             If n, then the last entries. If a tuple, then all in
             range(n1, n2). If None, then all entries. Raises IndexError if
             the format of index is incorrect.
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
 
         Returns
         -------
         If output is True, then return a dict of tuples, keyed by the prompt
         numbers and with values of (input, output). If output is False, then
         a dict, keyed by the prompt number with the values of input. Raises
         IndexError if no history is found.
         """
         if raw:
             input_hist = self.input_hist_raw
         else:
             input_hist = self.input_hist
         if output:
             output_hist = self.user_ns['Out']
         n = len(input_hist)
         if index is None:
             start=0; stop=n
         elif isinstance(index, int):
             start=n-index; stop=n
         elif isinstance(index, tuple) and len(index) == 2:
             start=index[0]; stop=index[1]
         else:
             raise IndexError('Not a valid index for the input history: %r' % index)
         hist = {}
         for i in range(start, stop):
             if output:
                 hist[i] = (input_hist[i], output_hist.get(i))
             else:
                 hist[i] = input_hist[i]
         if len(hist)==0:
             raise IndexError('No history for range of indices: %r' % index)
         return hist
 
     #-------------------------------------------------------------------------
     # Things related to exception handling and tracebacks (not debugging)
     #-------------------------------------------------------------------------
 
     def init_traceback_handlers(self, custom_exceptions):
         # Syntax error handler.
         self.SyntaxTB = ultratb.SyntaxTB(color_scheme='NoColor')
         
         # The interactive one is initialized with an offset, meaning we always
         # want to remove the topmost item in the traceback, which is our own
         # internal code. Valid modes: ['Plain','Context','Verbose']
         self.InteractiveTB = ultratb.AutoFormattedTB(mode = 'Plain',
                                                      color_scheme='NoColor',
                                                      tb_offset = 1)
 
         # 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
         # during the read-eval loop, it may get temporarily overwritten.
         self.sys_excepthook = sys.excepthook
 
         # and add any custom exception handlers the user may have specified
         self.set_custom_exc(*custom_exceptions)
 
         # Set the exception mode
         self.InteractiveTB.set_mode(mode=self.xmode)
 
     def set_custom_exc(self, exc_tuple, handler):
         """set_custom_exc(exc_tuple,handler)
 
         Set a custom exception handler, which will be called if any of the
         exceptions in exc_tuple occur in the mainloop (specifically, in the
         runcode() method.
 
         Inputs:
 
           - exc_tuple: a *tuple* of valid exceptions to call the defined
           handler for.  It is very important that you use a tuple, and NOT A
           LIST here, because of the way Python's except statement works.  If
           you only want to trap a single exception, use a singleton tuple:
 
             exc_tuple == (MyCustomException,)
 
           - handler: this must be defined as a function with the following
           basic interface::
 
             def my_handler(self, etype, value, tb, tb_offset=None)
                 ...
                 # The return value must be
                 return structured_traceback
 
           This will be made into an instance method (via new.instancemethod)
           of IPython itself, and it will be called if any of the exceptions
           listed in the exc_tuple are caught.  If the handler is None, an
           internal basic one is used, which just prints basic info.
 
         WARNING: by putting in your own exception handler into IPython's main
         execution loop, you run a very good chance of nasty crashes.  This
         facility should only be used if you really know what you are doing."""
 
         assert type(exc_tuple)==type(()) , \
                "The custom exceptions must be given AS A TUPLE."
 
         def dummy_handler(self,etype,value,tb):
             print '*** Simple custom exception handler ***'
             print 'Exception type :',etype
             print 'Exception value:',value
             print 'Traceback      :',tb
             print 'Source code    :','\n'.join(self.buffer)
 
         if handler is None: handler = dummy_handler
 
         self.CustomTB = new.instancemethod(handler,self,self.__class__)
         self.custom_exceptions = exc_tuple
 
     def excepthook(self, etype, value, tb):
       """One more defense for GUI apps that call sys.excepthook.
 
       GUI frameworks like wxPython trap exceptions and call
       sys.excepthook themselves.  I guess this is a feature that
       enables them to keep running after exceptions that would
       otherwise kill their mainloop. This is a bother for IPython
       which excepts to catch all of the program exceptions with a try:
       except: statement.
 
       Normally, IPython sets sys.excepthook to a CrashHandler instance, so if
       any app directly invokes sys.excepthook, it will look to the user like
       IPython crashed.  In order to work around this, we can disable the
       CrashHandler and replace it with this excepthook instead, which prints a
       regular traceback using our InteractiveTB.  In this fashion, apps which
       call sys.excepthook will generate a regular-looking exception from
       IPython, and the CrashHandler will only be triggered by real IPython
       crashes.
 
       This hook should be used sparingly, only in places which are not likely
       to be true IPython errors.
       """
       self.showtraceback((etype,value,tb),tb_offset=0)
 
     def showtraceback(self,exc_tuple = None,filename=None,tb_offset=None,
                       exception_only=False):
         """Display the exception that just occurred.
 
         If nothing is known about the exception, this is the method which
         should be used throughout the code for presenting user tracebacks,
         rather than directly invoking the InteractiveTB object.
 
         A specific showsyntaxerror() also exists, but this method can take
         care of calling it if needed, so unless you are explicitly catching a
         SyntaxError exception, don't try to analyze the stack manually and
         simply call this method."""
         
         try:
             if exc_tuple is None:
                 etype, value, tb = sys.exc_info()
             else:
                 etype, value, tb = exc_tuple
 
             if etype is None:
                 if hasattr(sys, 'last_type'):
                     etype, value, tb = sys.last_type, sys.last_value, \
                                        sys.last_traceback
                 else:
                     self.write_err('No traceback available to show.\n')
                     return
     
             if etype is SyntaxError:
                 # Though this won't be called by syntax errors in the input
                 # line, there may be SyntaxError cases whith imported code.
                 self.showsyntaxerror(filename)
             elif etype is UsageError:
                 print "UsageError:", value
             else:
                 # WARNING: these variables are somewhat deprecated and not
                 # necessarily safe to use in a threaded environment, but tools
                 # like pdb depend on their existence, so let's set them.  If we
                 # find problems in the field, we'll need to revisit their use.
                 sys.last_type = etype
                 sys.last_value = value
                 sys.last_traceback = tb
     
                 if etype in self.custom_exceptions:
                     # FIXME: Old custom traceback objects may just return a
                     # string, in that case we just put it into a list
                     stb = self.CustomTB(etype, value, tb, tb_offset)
                     if isinstance(ctb, basestring):
                         stb = [stb]
                 else:
                     if exception_only:
                         stb = ['An exception has occurred, use %tb to see '
                                'the full traceback.\n']
                         stb.extend(self.InteractiveTB.get_exception_only(etype,
                                                                          value))
                     else:
                         stb = self.InteractiveTB.structured_traceback(etype,
                                                 value, tb, tb_offset=tb_offset)
                         # FIXME: the pdb calling should be done by us, not by
                         # the code computing the traceback.
                         if self.InteractiveTB.call_pdb:
                             # pdb mucks up readline, fix it back
                             self.set_completer()
 
                 # Actually show the traceback
                 self._showtraceback(etype, value, stb)
                 
         except KeyboardInterrupt:
             self.write_err("\nKeyboardInterrupt\n")
 
     def _showtraceback(self, etype, evalue, stb):
         """Actually show a traceback.
 
         Subclasses may override this method to put the traceback on a different
         place, like a side channel.
         """
         # FIXME: this should use the proper write channels, but our test suite
         # relies on it coming out of stdout...
         print >> sys.stdout, self.InteractiveTB.stb2text(stb)
 
     def showsyntaxerror(self, filename=None):
         """Display the syntax error that just occurred.
 
         This doesn't display a stack trace because there isn't one.
 
         If a filename is given, it is stuffed in the exception instead
         of what was there before (because Python's parser always uses
         "<string>" when reading from a string).
         """
         etype, value, last_traceback = sys.exc_info()
 
         # See note about these variables in showtraceback() above
         sys.last_type = etype
         sys.last_value = value
         sys.last_traceback = last_traceback
         
         if filename and etype is SyntaxError:
             # Work hard to stuff the correct filename in the exception
             try:
                 msg, (dummy_filename, lineno, offset, line) = value
             except:
                 # Not the format we expect; leave it alone
                 pass
             else:
                 # Stuff in the right filename
                 try:
                     # Assume SyntaxError is a class exception
                     value = SyntaxError(msg, (filename, lineno, offset, line))
                 except:
                     # If that failed, assume SyntaxError is a string
                     value = msg, (filename, lineno, offset, line)
         stb = self.SyntaxTB.structured_traceback(etype, value, [])
         self._showtraceback(etype, value, stb)
 
     #-------------------------------------------------------------------------
     # Things related to tab completion
     #-------------------------------------------------------------------------
 
     def complete(self, text, line=None, cursor_pos=None):
         """Return the completed text and a list of completions.
 
         Parameters
         ----------
 
            text : string
              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.
 
            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.
         
         This is a wrapper around the completion mechanism, similar to what
         readline does at the command line when the TAB key is hit.  By
         exposing it as a method, it can be used by other non-readline
         environments (such as GUIs) for text completion.
 
         Simple usage example:
 
         In [1]: x = 'hello'
 
         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, cursor_pos)
 
     def set_custom_completer(self, completer, pos=0):
         """Adds a new custom completer function.
 
         The position argument (defaults to 0) is the index in the completers
         list where you want the completer to be inserted."""
 
         newcomp = new.instancemethod(completer,self.Completer,
                                      self.Completer.__class__)
         self.Completer.matchers.insert(pos,newcomp)
 
     def set_completer(self):
         """Reset readline's completer to be our own."""
         self.readline.set_completer(self.Completer.rlcomplete)
 
     def set_completer_frame(self, frame=None):
         """Set the frame of the completer."""
         if frame:
             self.Completer.namespace = frame.f_locals
             self.Completer.global_namespace = frame.f_globals
         else:
             self.Completer.namespace = self.user_ns
             self.Completer.global_namespace = self.user_global_ns
 
     #-------------------------------------------------------------------------
     # Things related to readline
     #-------------------------------------------------------------------------
 
     def init_readline(self):
         """Command history completion/saving/reloading."""
 
         if self.readline_use:
             import IPython.utils.rlineimpl as readline
 
         self.rl_next_input = None
         self.rl_do_indent = False
 
         if not self.readline_use or not readline.have_readline:
             self.has_readline = False
             self.readline = None
             # Set a number of methods that depend on readline to be no-op
             self.savehist = no_op
             self.reloadhist = no_op
             self.set_completer = no_op
             self.set_custom_completer = no_op
             self.set_completer_frame = no_op
             warn('Readline services not available or not loaded.')
         else:
             self.has_readline = True
             self.readline = readline
             sys.modules['readline'] = readline
             import atexit
             from IPython.core.completer import IPCompleter
             self.Completer = IPCompleter(self,
                                          self.user_ns,
                                          self.user_global_ns,
                                          self.readline_omit__names,
                                          self.alias_manager.alias_table)
             sdisp = self.strdispatchers.get('complete_command', StrDispatch())
             self.strdispatchers['complete_command'] = sdisp
             self.Completer.custom_completers = sdisp
             # Platform-specific configuration
             if os.name == 'nt':
                 self.readline_startup_hook = readline.set_pre_input_hook
             else:
                 self.readline_startup_hook = readline.set_startup_hook
 
             # Load user's initrc file (readline config)
             # Or if libedit is used, load editrc.
             inputrc_name = os.environ.get('INPUTRC')
             if inputrc_name is None:
                 home_dir = get_home_dir()
                 if home_dir is not None:
                     inputrc_name = '.inputrc'
                     if readline.uses_libedit:
                         inputrc_name = '.editrc'
                     inputrc_name = os.path.join(home_dir, inputrc_name)
             if os.path.isfile(inputrc_name):
                 try:
                     readline.read_init_file(inputrc_name)
                 except:
                     warn('Problems reading readline initialization file <%s>'
                          % inputrc_name)
             
             # save this in sys so embedded copies can restore it properly
             sys.ipcompleter = self.Completer.rlcomplete
             self.set_completer()
 
             # Configure readline according to user's prefs
             # This is only done if GNU readline is being used.  If libedit
             # is being used (as on Leopard) the readline config is
             # not run as the syntax for libedit is different.
             if not readline.uses_libedit:
                 for rlcommand in self.readline_parse_and_bind:
                     #print "loading rl:",rlcommand  # dbg
                     readline.parse_and_bind(rlcommand)
 
             # Remove some chars from the delimiters list.  If we encounter
             # unicode chars, discard them.
             delims = readline.get_completer_delims().encode("ascii", "ignore")
             delims = delims.translate(string._idmap,
                                       self.readline_remove_delims)
             readline.set_completer_delims(delims)
             # otherwise we end up with a monster history after a while:
             readline.set_history_length(1000)
             try:
                 #print '*** Reading readline history'  # dbg
                 readline.read_history_file(self.histfile)
             except IOError:
                 pass  # It doesn't exist yet.
 
             atexit.register(self.atexit_operations)
             del atexit
 
         # Configure auto-indent for all platforms
         self.set_autoindent(self.autoindent)
 
     def set_next_input(self, s):
         """ Sets the 'default' input string for the next command line.
         
         Requires readline.
         
         Example:
         
         [D:\ipython]|1> _ip.set_next_input("Hello Word")
         [D:\ipython]|2> Hello Word_  # cursor is here        
         """
 
         self.rl_next_input = s
 
     # Maybe move this to the terminal subclass?
     def pre_readline(self):
         """readline hook to be used at the start of each line.
 
         Currently it handles auto-indent only."""
 
         if self.rl_do_indent:
             self.readline.insert_text(self._indent_current_str())
         if self.rl_next_input is not None:
             self.readline.insert_text(self.rl_next_input)
             self.rl_next_input = None
 
     def _indent_current_str(self):
         """return the current level of indentation as a string"""
         return self.indent_current_nsp * ' '
 
     #-------------------------------------------------------------------------
     # Things related to magics
     #-------------------------------------------------------------------------
 
     def init_magics(self):
         # FIXME: Move the color initialization to the DisplayHook, which
         # should be split into a prompt manager and displayhook. We probably
         # even need a centralize colors management object.
         self.magic_colors(self.colors)
         # History was moved to a separate module
         from . import history
         history.init_ipython(self)
 
     def magic(self,arg_s):
         """Call a magic function by name.
 
         Input: a string containing the name of the magic function to call and any
         additional arguments to be passed to the magic.
 
         magic('name -opt foo bar') is equivalent to typing at the ipython
         prompt:
 
         In[1]: %name -opt foo bar
 
         To call a magic without arguments, simply use magic('name').
 
         This provides a proper Python function to call IPython's magics in any
         valid Python code you can type at the interpreter, including loops and
         compound statements.
         """
         args = arg_s.split(' ',1)
         magic_name = args[0]
         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
 
         try:
             magic_args = args[1]
         except IndexError:
             magic_args = ''
         fn = getattr(self,'magic_'+magic_name,None)
         if fn is None:
             error("Magic function `%s` not found." % magic_name)
         else:
             magic_args = self.var_expand(magic_args,1)
             with nested(self.builtin_trap,):
                 result = fn(magic_args)
                 return result
 
     def define_magic(self, magicname, func):
         """Expose own function as magic function for ipython 
     
         def foo_impl(self,parameter_s=''):
             'My very own magic!. (Use docstrings, IPython reads them).'
             print 'Magic function. Passed parameter is between < >:'
             print '<%s>' % parameter_s
             print 'The self object is:',self
     
         self.define_magic('foo',foo_impl)
         """
         
         import new
         im = new.instancemethod(func,self, self.__class__)
         old = getattr(self, "magic_" + magicname, None)
         setattr(self, "magic_" + magicname, im)
         return old
 
     #-------------------------------------------------------------------------
     # Things related to macros
     #-------------------------------------------------------------------------
 
     def define_macro(self, name, themacro):
         """Define a new macro
 
         Parameters
         ----------
         name : str
             The name of the macro.
         themacro : str or Macro
             The action to do upon invoking the macro.  If a string, a new 
             Macro object is created by passing the string to it.
         """
         
         from IPython.core import macro
 
         if isinstance(themacro, basestring):
             themacro = macro.Macro(themacro)
         if not isinstance(themacro, macro.Macro):
             raise ValueError('A macro must be a string or a Macro instance.')
         self.user_ns[name] = themacro
 
     #-------------------------------------------------------------------------
     # Things related to the running of system commands
     #-------------------------------------------------------------------------
 
     def system(self, cmd):
         """Make a system call, using IPython."""
         return self.hooks.shell_hook(self.var_expand(cmd, depth=2))
 
     #-------------------------------------------------------------------------
     # Things related to aliases
     #-------------------------------------------------------------------------
 
     def init_alias(self):
         self.alias_manager = AliasManager(shell=self, config=self.config)
         self.ns_table['alias'] = self.alias_manager.alias_table,
 
     #-------------------------------------------------------------------------
     # Things related to extensions and plugins
     #-------------------------------------------------------------------------
 
     def init_extension_manager(self):
         self.extension_manager = ExtensionManager(shell=self, config=self.config)
 
     def init_plugin_manager(self):
         self.plugin_manager = PluginManager(config=self.config)
 
     #-------------------------------------------------------------------------
     # Things related to payloads
     #-------------------------------------------------------------------------
 
     def init_payload(self):
         self.payload_manager = PayloadManager(config=self.config)
 
     #-------------------------------------------------------------------------
     # Things related to the prefilter
     #-------------------------------------------------------------------------
 
     def init_prefilter(self):
         self.prefilter_manager = PrefilterManager(shell=self, config=self.config)
         # Ultimately this will be refactored in the new interpreter code, but
         # for now, we should expose the main prefilter method (there's legacy
         # code out there that may rely on this).
         self.prefilter = self.prefilter_manager.prefilter_lines
 
     #-------------------------------------------------------------------------
     # Things related to the running of code
     #-------------------------------------------------------------------------
 
     def ex(self, cmd):
         """Execute a normal python statement in user namespace."""
         with nested(self.builtin_trap,):
             exec cmd in self.user_global_ns, self.user_ns
 
     def ev(self, expr):
         """Evaluate python expression expr in user namespace.
 
         Returns the result of evaluation
         """
         with nested(self.builtin_trap,):
             return eval(expr, self.user_global_ns, self.user_ns)
 
     def safe_execfile(self, fname, *where, **kw):
         """A safe version of the builtin execfile().
 
         This version will never throw an exception, but instead print
         helpful error messages to the screen.  This only works on pure
         Python files with the .py extension.
 
         Parameters
         ----------
         fname : string
             The name of the file to be executed.
         where : tuple
             One or two namespaces, passed to execfile() as (globals,locals).
             If only one is given, it is passed as both.
         exit_ignore : bool (False)
             If True, then silence SystemExit for non-zero status (it is always
             silenced for zero status, as it is so common).
         """
         kw.setdefault('exit_ignore', False)
 
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we have a .py file
         if not fname.endswith('.py'):
             warn('File must end with .py to be run using execfile: <%s>' % fname)
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
 
         with prepended_to_syspath(dname):
             try:
                 execfile(fname,*where)
             except SystemExit, status:
                 # If the call was made with 0 or None exit status (sys.exit(0)
                 # or sys.exit() ), don't bother showing a traceback, as both of
                 # these are considered normal by the OS:
                 # > python -c'import sys;sys.exit(0)'; echo $?
                 # 0
                 # > python -c'import sys;sys.exit()'; echo $?
                 # 0
                 # For other exit status, we show the exception unless
                 # explicitly silenced, but only in short form.
                 if status.code not in (0, None) and not kw['exit_ignore']:
                     self.showtraceback(exception_only=True)
             except:
                 self.showtraceback()
 
     def safe_execfile_ipy(self, fname):
         """Like safe_execfile, but for .ipy files with IPython syntax.
 
         Parameters
         ----------
         fname : str
             The name of the file to execute.  The filename must have a
             .ipy extension.
         """
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we have a .py file
         if not fname.endswith('.ipy'):
             warn('File must end with .py to be run using execfile: <%s>' % fname)
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
 
         with prepended_to_syspath(dname):
             try:
                 with open(fname) as thefile:
                     script = thefile.read()
                     # self.runlines currently captures all exceptions
                     # raise in user code.  It would be nice if there were
                     # versions of runlines, execfile that did raise, so
                     # we could catch the errors.
                     self.runlines(script, clean=True)
             except:
                 self.showtraceback()
                 warn('Unknown failure executing file: <%s>' % fname)
 
     def runlines(self, lines, clean=False):
         """Run a string of one or more lines of source.
 
         This method is capable of running a string containing multiple source
         lines, as if they had been entered at the IPython prompt.  Since it
         exposes IPython's processing machinery, the given strings can contain
         magic calls (%magic), special shell access (!cmd), etc.
         """
         
         if isinstance(lines, (list, tuple)):
             lines = '\n'.join(lines)
 
         if clean:
             lines = self._cleanup_ipy_script(lines)
 
         # We must start with a clean buffer, in case this is run from an
         # interactive IPython session (via a magic, for example).
         self.resetbuffer()
         lines = lines.splitlines()
         more = 0
 
         with nested(self.builtin_trap, self.display_trap):
             for line in lines:
                 # skip blank lines so we don't mess up the prompt counter, but do
                 # NOT skip even a blank line if we are in a code block (more is
                 # true)
             
                 if line or more:
                     # push to raw history, so hist line numbers stay in sync
                     self.input_hist_raw.append("# " + line + "\n")
                     prefiltered = self.prefilter_manager.prefilter_lines(line,more)
                     more = self.push_line(prefiltered)
                     # IPython's runsource returns None if there was an error
                     # compiling the code.  This allows us to stop processing right
                     # away, so the user gets the error message at the right place.
                     if more is None:
                         break
                 else:
                     self.input_hist_raw.append("\n")
             # final newline in case the input didn't have it, so that the code
             # actually does get executed
             if more:
                 self.push_line('\n')
 
     def runsource(self, source, filename='<input>', symbol='single'):
         """Compile and run some source in the interpreter.
 
         Arguments are as for compile_command().
 
         One several things can happen:
 
         1) The input is incorrect; compile_command() raised an
         exception (SyntaxError or OverflowError).  A syntax traceback
         will be printed by calling the showsyntaxerror() method.
 
         2) The input is incomplete, and more input is required;
         compile_command() returned None.  Nothing happens.
 
         3) The input is complete; compile_command() returned a code
         object.  The code is executed by calling self.runcode() (which
         also handles run-time exceptions, except for SystemExit).
 
         The return value is:
 
           - True in case 2
 
           - False in the other cases, unless an exception is raised, where
           None is returned instead.  This can be used by external callers to
           know whether to continue feeding input or not.
 
         The return value can be used to decide whether to use sys.ps1 or
         sys.ps2 to prompt the next line."""
 
         # if the source code has leading blanks, add 'if 1:\n' to it
         # this allows execution of indented pasted code. It is tempting
         # to add '\n' at the end of source to run commands like ' a=1'
         # directly, but this fails for more complicated scenarios
         source=source.encode(self.stdin_encoding)
         if source[:1] in [' ', '\t']:
             source = 'if 1:\n%s' % source
 
         try:
             code = self.compile(source,filename,symbol)
         except (OverflowError, SyntaxError, ValueError, TypeError, MemoryError):
             # Case 1
             self.showsyntaxerror(filename)
             return None
 
         if code is None:
             # Case 2
             return True
 
         # Case 3
         # We store the code object so that threaded shells and
         # custom exception handlers can access all this info if needed.
         # The source corresponding to this can be obtained from the
         # buffer attribute as '\n'.join(self.buffer).
         self.code_to_run = code
         # now actually execute the code object
         if self.runcode(code) == 0:
             return False
         else:
             return None
 
     def runcode(self,code_obj):
         """Execute a code object.
 
         When an exception occurs, self.showtraceback() is called to display a
         traceback.
 
         Return value: a flag indicating whether the code to be run completed
         successfully:
 
           - 0: successful execution.
           - 1: an error occurred.
         """
 
         # Set our own excepthook in case the user code tries to call it
         # directly, so that the IPython crash handler doesn't get triggered
         old_excepthook,sys.excepthook = sys.excepthook, self.excepthook
 
         # we save the original sys.excepthook in the instance, in case config
         # code (such as magics) needs access to it.
         self.sys_excepthook = old_excepthook
         outflag = 1  # happens in more places, so it's easier as default
         try:
             try:
                 self.hooks.pre_runcode_hook()
                 #rprint('Running code') # dbg
                 exec code_obj in self.user_global_ns, self.user_ns
             finally:
                 # Reset our crash handler in place
                 sys.excepthook = old_excepthook
         except SystemExit:
             self.resetbuffer()
             self.showtraceback(exception_only=True)
             warn("To exit: use any of 'exit', 'quit', %Exit or Ctrl-D.", level=1)
         except self.custom_exceptions:
             etype,value,tb = sys.exc_info()
             self.CustomTB(etype,value,tb)
         except:
             self.showtraceback()
         else:
             outflag = 0
             if softspace(sys.stdout, 0):
                 print
         # Flush out code object which has been run (and source)
         self.code_to_run = None
         return outflag
         
     def push_line(self, line):
         """Push a line to the interpreter.
 
         The line should not have a trailing newline; it may have
         internal newlines.  The line is appended to a buffer and the
         interpreter's runsource() method is called with the
         concatenated contents of the buffer as source.  If this
         indicates that the command was executed or invalid, the buffer
         is reset; otherwise, the command is incomplete, and the buffer
         is left as it was after the line was appended.  The return
         value is 1 if more input is required, 0 if the line was dealt
         with in some way (this is the same as runsource()).
         """
 
         # autoindent management should be done here, and not in the
         # interactive loop, since that one is only seen by keyboard input.  We
         # need this done correctly even for code run via runlines (which uses
         # push).
 
         #print 'push line: <%s>' % line  # dbg
         for subline in line.splitlines():
             self._autoindent_update(subline)
         self.buffer.append(line)
         more = self.runsource('\n'.join(self.buffer), self.filename)
         if not more:
             self.resetbuffer()
         return more
 
     def resetbuffer(self):
         """Reset the input buffer."""
         self.buffer[:] = []
 
     def _is_secondary_block_start(self, s):
         if not s.endswith(':'):
             return False
         if (s.startswith('elif') or 
             s.startswith('else') or 
             s.startswith('except') or
             s.startswith('finally')):
             return True
 
     def _cleanup_ipy_script(self, script):
         """Make a script safe for self.runlines()
 
         Currently, IPython is lines based, with blocks being detected by
         empty lines.  This is a problem for block based scripts that may
         not have empty lines after blocks.  This script adds those empty
         lines to make scripts safe for running in the current line based
         IPython.
         """
         res = []
         lines = script.splitlines()
         level = 0
 
         for l in lines:
             lstripped = l.lstrip()
             stripped = l.strip()                
             if not stripped:
                 continue
             newlevel = len(l) - len(lstripped)                    
             if level > 0 and newlevel == 0 and \
                    not self._is_secondary_block_start(stripped): 
                 # add empty line
                 res.append('')
             res.append(l)
             level = newlevel
 
         return '\n'.join(res) + '\n'
 
     def _autoindent_update(self,line):
         """Keep track of the indent level."""
 
         #debugx('line')
         #debugx('self.indent_current_nsp')
         if self.autoindent:
             if line:
                 inisp = num_ini_spaces(line)
                 if inisp < self.indent_current_nsp:
                     self.indent_current_nsp = inisp
 
                 if line[-1] == ':':
                     self.indent_current_nsp += 4
                 elif dedent_re.match(line):
                     self.indent_current_nsp -= 4
             else:
                 self.indent_current_nsp = 0
 
     #-------------------------------------------------------------------------
     # Things related to GUI support and pylab
     #-------------------------------------------------------------------------
 
     def enable_pylab(self, gui=None):
         raise NotImplementedError('Implement enable_pylab in a subclass')
 
     #-------------------------------------------------------------------------
     # Utilities
     #-------------------------------------------------------------------------
 
     def getoutput(self, cmd):
         return getoutput(self.var_expand(cmd,depth=2),
                          header=self.system_header,
                          verbose=self.system_verbose)
 
     def getoutputerror(self, cmd):
         return getoutputerror(self.var_expand(cmd,depth=2),
                               header=self.system_header,
                               verbose=self.system_verbose)
 
     def var_expand(self,cmd,depth=0):
         """Expand python variables in a string.
 
         The depth argument indicates how many frames above the caller should
         be walked to look for the local namespace where to expand variables.
 
         The global namespace for expansion is always the user's interactive
         namespace.
         """
 
         return str(ItplNS(cmd,
                           self.user_ns,  # globals
                           # Skip our own frame in searching for locals:
                           sys._getframe(depth+1).f_locals # locals
                           ))
 
     def mktempfile(self,data=None):
         """Make a new tempfile and return its filename.
 
         This makes a call to tempfile.mktemp, but it registers the created
         filename internally so ipython cleans it up at exit time.
 
         Optional inputs:
 
           - data(None): if data is given, it gets written out to the temp file
           immediately, and the file is closed again."""
 
         filename = tempfile.mktemp('.py','ipython_edit_')
         self.tempfiles.append(filename)
         
         if data:
             tmp_file = open(filename,'w')
             tmp_file.write(data)
             tmp_file.close()
         return filename
 
     # TODO:  This should be removed when Term is refactored.
     def write(self,data):
         """Write a string to the default output"""
         io.Term.cout.write(data)
 
     # TODO:  This should be removed when Term is refactored.
     def write_err(self,data):
         """Write a string to the default error output"""
         io.Term.cerr.write(data)
 
     def ask_yes_no(self,prompt,default=True):
         if self.quiet:
             return True
         return ask_yes_no(prompt,default)
+    
+    def show_usage(self):
+        """Show a usage message"""
+        page.page(IPython.core.usage.interactive_usage)
 
     #-------------------------------------------------------------------------
     # Things related to IPython exiting
     #-------------------------------------------------------------------------
 
     def atexit_operations(self):
         """This will be executed at the time of exit.
 
         Saving of persistent data should be performed here.
         """
         self.savehist()
 
         # Cleanup all tempfiles left around
         for tfile in self.tempfiles:
             try:
                 os.unlink(tfile)
             except OSError:
                 pass
 
         # Clear all user namespaces to release all references cleanly.
         self.reset()
 
         # Run user hooks
         self.hooks.shutdown_hook()
 
     def cleanup(self):
         self.restore_sys_module_state()
 
 
 class InteractiveShellABC(object):
     """An abstract base class for InteractiveShell."""
     __metaclass__ = abc.ABCMeta
 
 InteractiveShellABC.register(InteractiveShell)

IPython/core/prefilter.py

@@ -1,1022 +1,1022 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 Prefiltering components.
 
 Prefilters transform user input before it is exec'd by Python.  These
 transforms are used to implement additional syntax such as !ls and %magic.
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 * Dan Milstein
 * Ville Vainio
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import __builtin__
 import codeop
 import re
 
 from IPython.core.alias import AliasManager
 from IPython.core.autocall import IPyAutocall
 from IPython.config.configurable import Configurable
 from IPython.core.splitinput import split_user_input
 from IPython.core import page
 
 from IPython.utils.traitlets import List, Int, Any, Str, CBool, Bool, Instance
 import IPython.utils.io
 from IPython.utils.text import make_quoted_expr
 from IPython.utils.autoattr import auto_attr
 
 #-----------------------------------------------------------------------------
 # Global utilities, errors and constants
 #-----------------------------------------------------------------------------
 
 # Warning, these cannot be changed unless various regular expressions
 # are updated in a number of places.  Not great, but at least we told you.
 ESC_SHELL  = '!'
 ESC_SH_CAP = '!!'
 ESC_HELP   = '?'
 ESC_MAGIC  = '%'
 ESC_QUOTE  = ','
 ESC_QUOTE2 = ';'
 ESC_PAREN  = '/'
 
 
 class PrefilterError(Exception):
     pass
 
 
 # RegExp to identify potential function names
 re_fun_name = re.compile(r'[a-zA-Z_]([a-zA-Z0-9_.]*) *$')
 
 # RegExp to exclude strings with this start from autocalling.  In
 # particular, all binary operators should be excluded, so that if foo is
 # callable, foo OP bar doesn't become foo(OP bar), which is invalid.  The
 # characters '!=()' don't need to be checked for, as the checkPythonChars
 # routine explicitely does so, to catch direct calls and rebindings of
 # existing names.
 
 # Warning: the '-' HAS TO BE AT THE END of the first group, otherwise
 # it affects the rest of the group in square brackets.
 re_exclude_auto = re.compile(r'^[,&^\|\*/\+-]'
                              r'|^is |^not |^in |^and |^or ')
 
 # try to catch also methods for stuff in lists/tuples/dicts: off
 # (experimental). For this to work, the line_split regexp would need
 # to be modified so it wouldn't break things at '['. That line is
 # nasty enough that I shouldn't change it until I can test it _well_.
 #self.re_fun_name = re.compile (r'[a-zA-Z_]([a-zA-Z0-9_.\[\]]*) ?$')
 
 
 # Handler Check Utilities
 def is_shadowed(identifier, ip):
     """Is the given identifier defined in one of the namespaces which shadow
     the alias and magic namespaces?  Note that an identifier is different
     than ifun, because it can not contain a '.' character."""
     # This is much safer than calling ofind, which can change state
     return (identifier in ip.user_ns \
             or identifier in ip.internal_ns \
             or identifier in ip.ns_table['builtin'])
 
 
 #-----------------------------------------------------------------------------
 # The LineInfo class used throughout
 #-----------------------------------------------------------------------------
 
 
 class LineInfo(object):
     """A single line of input and associated info.
 
     Includes the following as properties: 
 
     line
       The original, raw line
     
     continue_prompt
       Is this line a continuation in a sequence of multiline input?
     
     pre
       The initial esc character or whitespace.
     
     pre_char
       The escape character(s) in pre or the empty string if there isn't one.
       Note that '!!' is a possible value for pre_char.  Otherwise it will
       always be a single character.
     
     pre_whitespace
       The leading whitespace from pre if it exists.  If there is a pre_char,
       this is just ''.
     
     ifun
       The 'function part', which is basically the maximal initial sequence
       of valid python identifiers and the '.' character.  This is what is
       checked for alias and magic transformations, used for auto-calling,
       etc.
     
     the_rest
       Everything else on the line.
     """
     def __init__(self, line, continue_prompt):
         self.line            = line
         self.continue_prompt = continue_prompt
         self.pre, self.ifun, self.the_rest = split_user_input(line)
 
         self.pre_char       = self.pre.strip()
         if self.pre_char:
             self.pre_whitespace = '' # No whitespace allowd before esc chars
         else: 
             self.pre_whitespace = self.pre
 
         self._oinfo = None
 
     def ofind(self, ip):
         """Do a full, attribute-walking lookup of the ifun in the various
         namespaces for the given IPython InteractiveShell instance.
 
         Return a dict with keys: found,obj,ospace,ismagic
 
         Note: can cause state changes because of calling getattr, but should
         only be run if autocall is on and if the line hasn't matched any
         other, less dangerous handlers.
 
         Does cache the results of the call, so can be called multiple times
         without worrying about *further* damaging state.
         """
         if not self._oinfo:
             # ip.shell._ofind is actually on the Magic class!
             self._oinfo = ip.shell._ofind(self.ifun)
         return self._oinfo
 
     def __str__(self):                                                         
         return "Lineinfo [%s|%s|%s]" %(self.pre, self.ifun, self.the_rest) 
 
 
 #-----------------------------------------------------------------------------
 # Main Prefilter manager
 #-----------------------------------------------------------------------------
 
 
 class PrefilterManager(Configurable):
     """Main prefilter component.
 
     The IPython prefilter is run on all user input before it is run.  The
     prefilter consumes lines of input and produces transformed lines of 
     input.
 
     The iplementation consists of two phases:
 
     1. Transformers
     2. Checkers and handlers
 
     Over time, we plan on deprecating the checkers and handlers and doing
     everything in the transformers.
 
     The transformers are instances of :class:`PrefilterTransformer` and have
     a single method :meth:`transform` that takes a line and returns a
     transformed line.  The transformation can be accomplished using any
     tool, but our current ones use regular expressions for speed.  We also
     ship :mod:`pyparsing` in :mod:`IPython.external` for use in transformers.
 
     After all the transformers have been run, the line is fed to the checkers,
     which are instances of :class:`PrefilterChecker`.  The line is passed to
     the :meth:`check` method, which either returns `None` or a 
     :class:`PrefilterHandler` instance.  If `None` is returned, the other
     checkers are tried.  If an :class:`PrefilterHandler` instance is returned,
     the line is passed to the :meth:`handle` method of the returned
     handler and no further checkers are tried.
     
     Both transformers and checkers have a `priority` attribute, that determines
     the order in which they are called.  Smaller priorities are tried first.
 
     Both transformers and checkers also have `enabled` attribute, which is
     a boolean that determines if the instance is used.
 
     Users or developers can change the priority or enabled attribute of
     transformers or checkers, but they must call the :meth:`sort_checkers`
     or :meth:`sort_transformers` method after changing the priority.
     """
 
     multi_line_specials = CBool(True, config=True)
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
 
     def __init__(self, shell=None, config=None):
         super(PrefilterManager, self).__init__(shell=shell, config=config)
         self.shell = shell
         self.init_transformers()
         self.init_handlers()
         self.init_checkers()
 
     #-------------------------------------------------------------------------
     # API for managing transformers
     #-------------------------------------------------------------------------
 
     def init_transformers(self):
         """Create the default transformers."""
         self._transformers = []
         for transformer_cls in _default_transformers:
             transformer_cls(
                 shell=self.shell, prefilter_manager=self, config=self.config
             )
 
     def sort_transformers(self):
         """Sort the transformers by priority.
 
         This must be called after the priority of a transformer is changed.
         The :meth:`register_transformer` method calls this automatically.
         """
         self._transformers.sort(cmp=lambda x,y: x.priority-y.priority)
 
     @property
     def transformers(self):
         """Return a list of checkers, sorted by priority."""
         return self._transformers
 
     def register_transformer(self, transformer):
         """Register a transformer instance."""
         if transformer not in self._transformers:
             self._transformers.append(transformer)
             self.sort_transformers()
 
     def unregister_transformer(self, transformer):
         """Unregister a transformer instance."""
         if transformer in self._transformers:
             self._transformers.remove(transformer)
 
     #-------------------------------------------------------------------------
     # API for managing checkers
     #-------------------------------------------------------------------------
 
     def init_checkers(self):
         """Create the default checkers."""
         self._checkers = []
         for checker in _default_checkers:
             checker(
                 shell=self.shell, prefilter_manager=self, config=self.config
             )
 
     def sort_checkers(self):
         """Sort the checkers by priority.
 
         This must be called after the priority of a checker is changed.
         The :meth:`register_checker` method calls this automatically.
         """
         self._checkers.sort(cmp=lambda x,y: x.priority-y.priority)
 
     @property
     def checkers(self):
         """Return a list of checkers, sorted by priority."""
         return self._checkers
 
     def register_checker(self, checker):
         """Register a checker instance."""
         if checker not in self._checkers:
             self._checkers.append(checker)
             self.sort_checkers()
 
     def unregister_checker(self, checker):
         """Unregister a checker instance."""
         if checker in self._checkers:
             self._checkers.remove(checker)
 
     #-------------------------------------------------------------------------
     # API for managing checkers
     #-------------------------------------------------------------------------
 
     def init_handlers(self):
         """Create the default handlers."""
         self._handlers = {}
         self._esc_handlers = {}
         for handler in _default_handlers:
             handler(
                 shell=self.shell, prefilter_manager=self, config=self.config
             )
 
     @property
     def handlers(self):
         """Return a dict of all the handlers."""
         return self._handlers
 
     def register_handler(self, name, handler, esc_strings):
         """Register a handler instance by name with esc_strings."""
         self._handlers[name] = handler
         for esc_str in esc_strings:
             self._esc_handlers[esc_str] = handler
 
     def unregister_handler(self, name, handler, esc_strings):
         """Unregister a handler instance by name with esc_strings."""
         try:
             del self._handlers[name]
         except KeyError:
             pass
         for esc_str in esc_strings:
             h = self._esc_handlers.get(esc_str)
             if h is handler:
                 del self._esc_handlers[esc_str]
 
     def get_handler_by_name(self, name):
         """Get a handler by its name."""
         return self._handlers.get(name)
 
     def get_handler_by_esc(self, esc_str):
         """Get a handler by its escape string."""
         return self._esc_handlers.get(esc_str)
 
     #-------------------------------------------------------------------------
     # Main prefiltering API
     #-------------------------------------------------------------------------
 
     def prefilter_line_info(self, line_info):
         """Prefilter a line that has been converted to a LineInfo object.
 
         This implements the checker/handler part of the prefilter pipe.
         """
         # print "prefilter_line_info: ", line_info
         handler = self.find_handler(line_info)
         return handler.handle(line_info)
 
     def find_handler(self, line_info):
         """Find a handler for the line_info by trying checkers."""
         for checker in self.checkers:
             if checker.enabled:
                 handler = checker.check(line_info)
                 if handler:
                     return handler
         return self.get_handler_by_name('normal')
 
     def transform_line(self, line, continue_prompt):
         """Calls the enabled transformers in order of increasing priority."""
         for transformer in self.transformers:
             if transformer.enabled:
                 line = transformer.transform(line, continue_prompt)
         return line
 
     def prefilter_line(self, line, continue_prompt=False):
         """Prefilter a single input line as text.
 
         This method prefilters a single line of text by calling the
         transformers and then the checkers/handlers.
         """
 
         # print "prefilter_line: ", line, continue_prompt
         # All handlers *must* return a value, even if it's blank ('').
 
         # Lines are NOT logged here. Handlers should process the line as
         # needed, update the cache AND log it (so that the input cache array
         # stays synced).
 
         # save the line away in case we crash, so the post-mortem handler can
         # record it
         self.shell._last_input_line = line
 
         if not line:
             # Return immediately on purely empty lines, so that if the user
             # previously typed some whitespace that started a continuation
             # prompt, he can break out of that loop with just an empty line.
             # This is how the default python prompt works.
 
             # Only return if the accumulated input buffer was just whitespace!
             if ''.join(self.shell.buffer).isspace():
                 self.shell.buffer[:] = []
             return ''
 
         # At this point, we invoke our transformers.
         if not continue_prompt or (continue_prompt and self.multi_line_specials):
             line = self.transform_line(line, continue_prompt)
 
         # Now we compute line_info for the checkers and handlers
         line_info = LineInfo(line, continue_prompt)
         
         # the input history needs to track even empty lines
         stripped = line.strip()
 
         normal_handler = self.get_handler_by_name('normal')
         if not stripped:
             if not continue_prompt:
                 self.shell.displayhook.prompt_count -= 1
 
             return normal_handler.handle(line_info)
 
         # special handlers are only allowed for single line statements
         if continue_prompt and not self.multi_line_specials:
             return normal_handler.handle(line_info)
 
         prefiltered = self.prefilter_line_info(line_info)
         # print "prefiltered line: %r" % prefiltered
         return prefiltered
 
     def prefilter_lines(self, lines, continue_prompt=False):
         """Prefilter multiple input lines of text.
 
         This is the main entry point for prefiltering multiple lines of
         input.  This simply calls :meth:`prefilter_line` for each line of
         input.
 
         This covers cases where there are multiple lines in the user entry,
         which is the case when the user goes back to a multiline history
         entry and presses enter.
         """
         llines = lines.rstrip('\n').split('\n')
         # We can get multiple lines in one shot, where multiline input 'blends'
         # into one line, in cases like recalling from the readline history
         # buffer.  We need to make sure that in such cases, we correctly
         # communicate downstream which line is first and which are continuation
         # ones.
         if len(llines) > 1:
             out = '\n'.join([self.prefilter_line(line, lnum>0)
                              for lnum, line in enumerate(llines) ])
         else:
             out = self.prefilter_line(llines[0], continue_prompt)
             
         return out
 
 #-----------------------------------------------------------------------------
 # Prefilter transformers
 #-----------------------------------------------------------------------------
 
 
 class PrefilterTransformer(Configurable):
     """Transform a line of user input."""
 
     priority = Int(100, config=True)
     # Transformers don't currently use shell or prefilter_manager, but as we
     # move away from checkers and handlers, they will need them.
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager')
     enabled = Bool(True, config=True)
 
     def __init__(self, shell=None, prefilter_manager=None, config=None):
         super(PrefilterTransformer, self).__init__(
             shell=shell, prefilter_manager=prefilter_manager, config=config
         )
         self.prefilter_manager.register_transformer(self)
 
     def transform(self, line, continue_prompt):
         """Transform a line, returning the new one."""
         return None
 
     def __repr__(self):
         return "<%s(priority=%r, enabled=%r)>" % (
             self.__class__.__name__, self.priority, self.enabled)
 
 
 _assign_system_re = re.compile(r'(?P<lhs>(\s*)([\w\.]+)((\s*,\s*[\w\.]+)*))'
                                r'\s*=\s*!(?P<cmd>.*)')
 
 
 class AssignSystemTransformer(PrefilterTransformer):
     """Handle the `files = !ls` syntax."""
 
     priority = Int(100, config=True)
 
     def transform(self, line, continue_prompt):
         m = _assign_system_re.match(line)
         if m is not None:
             cmd = m.group('cmd')
             lhs = m.group('lhs')
             expr = make_quoted_expr("sc -l =%s" % cmd)
             new_line = '%s = get_ipython().magic(%s)' % (lhs, expr)
             return new_line
         return line
 
 
 _assign_magic_re = re.compile(r'(?P<lhs>(\s*)([\w\.]+)((\s*,\s*[\w\.]+)*))'
                                r'\s*=\s*%(?P<cmd>.*)')
 
 class AssignMagicTransformer(PrefilterTransformer):
     """Handle the `a = %who` syntax."""
 
     priority = Int(200, config=True)
 
     def transform(self, line, continue_prompt):
         m = _assign_magic_re.match(line)
         if m is not None:
             cmd = m.group('cmd')
             lhs = m.group('lhs')
             expr = make_quoted_expr(cmd)
             new_line = '%s = get_ipython().magic(%s)' % (lhs, expr)
             return new_line
         return line
 
 
 _classic_prompt_re = re.compile(r'(^[ \t]*>>> |^[ \t]*\.\.\. )')
 
 class PyPromptTransformer(PrefilterTransformer):
     """Handle inputs that start with '>>> ' syntax."""
 
     priority = Int(50, config=True)
 
     def transform(self, line, continue_prompt):
 
         if not line or line.isspace() or line.strip() == '...':
             # This allows us to recognize multiple input prompts separated by
             # blank lines and pasted in a single chunk, very common when
             # pasting doctests or long tutorial passages.
             return ''
         m = _classic_prompt_re.match(line)
         if m:
             return line[len(m.group(0)):]
         else:
             return line
 
 
 _ipy_prompt_re = re.compile(r'(^[ \t]*In \[\d+\]: |^[ \t]*\ \ \ \.\.\.+: )')
 
 class IPyPromptTransformer(PrefilterTransformer):
     """Handle inputs that start classic IPython prompt syntax."""
 
     priority = Int(50, config=True)
 
     def transform(self, line, continue_prompt):
 
         if not line or line.isspace() or line.strip() == '...':
             # This allows us to recognize multiple input prompts separated by
             # blank lines and pasted in a single chunk, very common when
             # pasting doctests or long tutorial passages.
             return ''
         m = _ipy_prompt_re.match(line)
         if m:
             return line[len(m.group(0)):]
         else:
             return line
 
 #-----------------------------------------------------------------------------
 # Prefilter checkers
 #-----------------------------------------------------------------------------
 
 
 class PrefilterChecker(Configurable):
     """Inspect an input line and return a handler for that line."""
 
     priority = Int(100, config=True)
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager')
     enabled = Bool(True, config=True)
 
     def __init__(self, shell=None, prefilter_manager=None, config=None):
         super(PrefilterChecker, self).__init__(
             shell=shell, prefilter_manager=prefilter_manager, config=config
         )
         self.prefilter_manager.register_checker(self)
 
     def check(self, line_info):
         """Inspect line_info and return a handler instance or None."""
         return None
 
     def __repr__(self):
         return "<%s(priority=%r, enabled=%r)>" % (
             self.__class__.__name__, self.priority, self.enabled)
 
 
 class EmacsChecker(PrefilterChecker):
 
     priority = Int(100, config=True)
     enabled = Bool(False, config=True)
 
     def check(self, line_info):
         "Emacs ipython-mode tags certain input lines."
         if line_info.line.endswith('# PYTHON-MODE'):
             return self.prefilter_manager.get_handler_by_name('emacs')
         else:
             return None
 
 
 class ShellEscapeChecker(PrefilterChecker):
 
     priority = Int(200, config=True)
 
     def check(self, line_info):
         if line_info.line.lstrip().startswith(ESC_SHELL):
             return self.prefilter_manager.get_handler_by_name('shell')
 
 
 class IPyAutocallChecker(PrefilterChecker):
 
     priority = Int(300, config=True)
 
     def check(self, line_info):
         "Instances of IPyAutocall in user_ns get autocalled immediately"
         obj = self.shell.user_ns.get(line_info.ifun, None)
         if isinstance(obj, IPyAutocall):
             obj.set_ip(self.shell)
             return self.prefilter_manager.get_handler_by_name('auto')
         else:
             return None
 
 
 class MultiLineMagicChecker(PrefilterChecker):
 
     priority = Int(400, config=True)
 
     def check(self, line_info):
         "Allow ! and !! in multi-line statements if multi_line_specials is on"
         # Note that this one of the only places we check the first character of
         # ifun and *not* the pre_char.  Also note that the below test matches
         # both ! and !!.    
         if line_info.continue_prompt \
             and self.prefilter_manager.multi_line_specials:
                 if line_info.ifun.startswith(ESC_MAGIC):
                     return self.prefilter_manager.get_handler_by_name('magic')
         else:
             return None
 
 
 class EscCharsChecker(PrefilterChecker):
 
     priority = Int(500, config=True)
 
     def check(self, line_info):
         """Check for escape character and return either a handler to handle it,
         or None if there is no escape char."""
         if line_info.line[-1] == ESC_HELP \
                and line_info.pre_char != ESC_SHELL \
                and line_info.pre_char != ESC_SH_CAP:
             # the ? can be at the end, but *not* for either kind of shell escape,
             # because a ? can be a vaild final char in a shell cmd
             return self.prefilter_manager.get_handler_by_name('help')
         else:
             # This returns None like it should if no handler exists
             return self.prefilter_manager.get_handler_by_esc(line_info.pre_char)
 
 
 class AssignmentChecker(PrefilterChecker):
 
     priority = Int(600, config=True)
 
     def check(self, line_info):
         """Check to see if user is assigning to a var for the first time, in
         which case we want to avoid any sort of automagic / autocall games.
     
         This allows users to assign to either alias or magic names true python
         variables (the magic/alias systems always take second seat to true
         python code).  E.g. ls='hi', or ls,that=1,2"""
         if line_info.the_rest:
             if line_info.the_rest[0] in '=,':
                 return self.prefilter_manager.get_handler_by_name('normal')
         else:
             return None
 
 
 class AutoMagicChecker(PrefilterChecker):
 
     priority = Int(700, config=True)
 
     def check(self, line_info):
         """If the ifun is magic, and automagic is on, run it.  Note: normal,
         non-auto magic would already have been triggered via '%' in
         check_esc_chars. This just checks for automagic.  Also, before
         triggering the magic handler, make sure that there is nothing in the
         user namespace which could shadow it."""
         if not self.shell.automagic or not hasattr(self.shell,'magic_'+line_info.ifun):
             return None
 
         # We have a likely magic method.  Make sure we should actually call it.
         if line_info.continue_prompt and not self.prefilter_manager.multi_line_specials:
             return None
 
         head = line_info.ifun.split('.',1)[0]
         if is_shadowed(head, self.shell):
             return None
 
         return self.prefilter_manager.get_handler_by_name('magic')
 
 
 class AliasChecker(PrefilterChecker):
 
     priority = Int(800, config=True)
 
     def check(self, line_info):
         "Check if the initital identifier on the line is an alias."
         # Note: aliases can not contain '.'
         head = line_info.ifun.split('.',1)[0]
         if line_info.ifun not in self.shell.alias_manager \
                or head not in self.shell.alias_manager \
                or is_shadowed(head, self.shell):
             return None
 
         return self.prefilter_manager.get_handler_by_name('alias')
 
 
 class PythonOpsChecker(PrefilterChecker):
 
     priority = Int(900, config=True)
 
     def check(self, line_info):
         """If the 'rest' of the line begins with a function call or pretty much
         any python operator, we should simply execute the line (regardless of
         whether or not there's a possible autocall expansion).  This avoids
         spurious (and very confusing) geattr() accesses."""
         if line_info.the_rest and line_info.the_rest[0] in '!=()<>,+*/%^&|':
             return self.prefilter_manager.get_handler_by_name('normal')
         else:
             return None
 
 
 class AutocallChecker(PrefilterChecker):
 
     priority = Int(1000, config=True)
 
     def check(self, line_info):
         "Check if the initial word/function is callable and autocall is on."
         if not self.shell.autocall:
             return None
 
         oinfo = line_info.ofind(self.shell) # This can mutate state via getattr
         if not oinfo['found']:
             return None
         
         if callable(oinfo['obj']) \
                and (not re_exclude_auto.match(line_info.the_rest)) \
                and re_fun_name.match(line_info.ifun):
             return self.prefilter_manager.get_handler_by_name('auto')
         else:
             return None
 
 
 #-----------------------------------------------------------------------------
 # Prefilter handlers
 #-----------------------------------------------------------------------------
 
 
 class PrefilterHandler(Configurable):
 
     handler_name = Str('normal')
     esc_strings = List([])
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager')
 
     def __init__(self, shell=None, prefilter_manager=None, config=None):
         super(PrefilterHandler, self).__init__(
             shell=shell, prefilter_manager=prefilter_manager, config=config
         )
         self.prefilter_manager.register_handler(
             self.handler_name,
             self,
             self.esc_strings
         )
 
     def handle(self, line_info):
         # print "normal: ", line_info
         """Handle normal input lines. Use as a template for handlers."""
 
         # With autoindent on, we need some way to exit the input loop, and I
         # don't want to force the user to have to backspace all the way to
         # clear the line.  The rule will be in this case, that either two
         # lines of pure whitespace in a row, or a line of pure whitespace but
         # of a size different to the indent level, will exit the input loop.
         line = line_info.line
         continue_prompt = line_info.continue_prompt
 
         if (continue_prompt and
             self.shell.autoindent and
             line.isspace() and
             
             (0 < abs(len(line) - self.shell.indent_current_nsp) <= 2
              or
              not self.shell.buffer
              or
              (self.shell.buffer[-1]).isspace()
              )
             ):
             line = ''
 
         self.shell.log(line, line, continue_prompt)
         return line
 
     def __str__(self):
         return "<%s(name=%s)>" % (self.__class__.__name__, self.handler_name)
 
 
 class AliasHandler(PrefilterHandler):
 
     handler_name = Str('alias')
 
     def handle(self, line_info):
         """Handle alias input lines. """
         transformed = self.shell.alias_manager.expand_aliases(line_info.ifun,line_info.the_rest)
         # pre is needed, because it carries the leading whitespace.  Otherwise
         # aliases won't work in indented sections.
         line_out = '%sget_ipython().system(%s)' % (line_info.pre_whitespace,
                                          make_quoted_expr(transformed))
         
         self.shell.log(line_info.line, line_out, line_info.continue_prompt)
         return line_out
 
 
 class ShellEscapeHandler(PrefilterHandler):
 
     handler_name = Str('shell')
     esc_strings = List([ESC_SHELL, ESC_SH_CAP])
 
     def handle(self, line_info):
         """Execute the line in a shell, empty return value"""
         magic_handler = self.prefilter_manager.get_handler_by_name('magic')
 
         line = line_info.line
         if line.lstrip().startswith(ESC_SH_CAP):
             # rewrite LineInfo's line, ifun and the_rest to properly hold the
             # call to %sx and the actual command to be executed, so
             # handle_magic can work correctly.  Note that this works even if
             # the line is indented, so it handles multi_line_specials
             # properly.
             new_rest = line.lstrip()[2:]
             line_info.line = '%ssx %s' % (ESC_MAGIC, new_rest)
             line_info.ifun = 'sx'
             line_info.the_rest = new_rest
             return magic_handler.handle(line_info)
         else:
             cmd = line.lstrip().lstrip(ESC_SHELL)
             line_out = '%sget_ipython().system(%s)' % (line_info.pre_whitespace,
                                              make_quoted_expr(cmd))
         # update cache/log and return
         self.shell.log(line, line_out, line_info.continue_prompt)
         return line_out
 
 
 class MagicHandler(PrefilterHandler):
 
     handler_name = Str('magic')
     esc_strings = List([ESC_MAGIC])
 
     def handle(self, line_info):
         """Execute magic functions."""
         ifun    = line_info.ifun
         the_rest = line_info.the_rest
         cmd = '%sget_ipython().magic(%s)' % (line_info.pre_whitespace,
                                    make_quoted_expr(ifun + " " + the_rest))
         self.shell.log(line_info.line, cmd, line_info.continue_prompt)
         return cmd
 
 
 class AutoHandler(PrefilterHandler):
 
     handler_name = Str('auto')
     esc_strings = List([ESC_PAREN, ESC_QUOTE, ESC_QUOTE2])
 
     def handle(self, line_info):
         """Handle lines which can be auto-executed, quoting if requested."""
         line    = line_info.line
         ifun    = line_info.ifun
         the_rest = line_info.the_rest
         pre     = line_info.pre
         continue_prompt = line_info.continue_prompt
         obj = line_info.ofind(self)['obj']
         #print 'pre <%s> ifun <%s> rest <%s>' % (pre,ifun,the_rest)  # dbg
 
         # This should only be active for single-line input!
         if continue_prompt:
             self.shell.log(line,line,continue_prompt)
             return line
 
         force_auto = isinstance(obj, IPyAutocall)
         auto_rewrite = True
         
         if pre == ESC_QUOTE:
             # Auto-quote splitting on whitespace
             newcmd = '%s("%s")' % (ifun,'", "'.join(the_rest.split()) )
         elif pre == ESC_QUOTE2:
             # Auto-quote whole string
             newcmd = '%s("%s")' % (ifun,the_rest)
         elif pre == ESC_PAREN:
             newcmd = '%s(%s)' % (ifun,",".join(the_rest.split()))
         else:
             # Auto-paren.
             # We only apply it to argument-less calls if the autocall
             # parameter is set to 2.  We only need to check that autocall is <
             # 2, since this function isn't called unless it's at least 1.
             if not the_rest and (self.shell.autocall < 2) and not force_auto:
                 newcmd = '%s %s' % (ifun,the_rest)
                 auto_rewrite = False
             else:
                 if not force_auto and the_rest.startswith('['):
                     if hasattr(obj,'__getitem__'):
                         # Don't autocall in this case: item access for an object
                         # which is BOTH callable and implements __getitem__.
                         newcmd = '%s %s' % (ifun,the_rest)
                         auto_rewrite = False
                     else:
                         # if the object doesn't support [] access, go ahead and
                         # autocall
                         newcmd = '%s(%s)' % (ifun.rstrip(),the_rest)
                 elif the_rest.endswith(';'):
                     newcmd = '%s(%s);' % (ifun.rstrip(),the_rest[:-1])
                 else:
                     newcmd = '%s(%s)' % (ifun.rstrip(), the_rest)
 
         if auto_rewrite:
             rw = self.shell.displayhook.prompt1.auto_rewrite() + newcmd
             
             try:
                 # plain ascii works better w/ pyreadline, on some machines, so
                 # we use it and only print uncolored rewrite if we have unicode
                 rw = str(rw)
                 print >>IPython.utils.io.Term.cout, rw
             except UnicodeEncodeError:
                 print "-------------->" + newcmd
             
         # log what is now valid Python, not the actual user input (without the
         # final newline)
         self.shell.log(line,newcmd,continue_prompt)
         return newcmd
 
 
 class HelpHandler(PrefilterHandler):
 
     handler_name = Str('help')
     esc_strings = List([ESC_HELP])
 
     def handle(self, line_info):
         """Try to get some help for the object.
 
         obj? or ?obj   -> basic information.
         obj?? or ??obj -> more details.
         """
         normal_handler = self.prefilter_manager.get_handler_by_name('normal')
         line = line_info.line
         # We need to make sure that we don't process lines which would be
         # otherwise valid python, such as "x=1 # what?"
         try:
             codeop.compile_command(line)
         except SyntaxError:
             # We should only handle as help stuff which is NOT valid syntax
             if line[0]==ESC_HELP:
                 line = line[1:]
             elif line[-1]==ESC_HELP:
                 line = line[:-1]
             self.shell.log(line, '#?'+line, line_info.continue_prompt)
             if line:
                 #print 'line:<%r>' % line  # dbg
                 self.shell.magic_pinfo(line)
             else:
-                page.page(self.shell.usage, screen_lines=self.shell.usable_screen_length)
+                self.shell.show_usage()
             return '' # Empty string is needed here!
         except:
             raise
             # Pass any other exceptions through to the normal handler
             return normal_handler.handle(line_info)
         else:
             # If the code compiles ok, we should handle it normally
             return normal_handler.handle(line_info)
 
 
 class EmacsHandler(PrefilterHandler):
 
     handler_name = Str('emacs')
     esc_strings = List([])
 
     def handle(self, line_info):
         """Handle input lines marked by python-mode."""
 
         # Currently, nothing is done.  Later more functionality can be added
         # here if needed.
 
         # The input cache shouldn't be updated
         return line_info.line
 
 
 #-----------------------------------------------------------------------------
 # Defaults
 #-----------------------------------------------------------------------------
 
 
 _default_transformers = [
     AssignSystemTransformer,
     AssignMagicTransformer,
     PyPromptTransformer,
     IPyPromptTransformer,
 ]
 
 _default_checkers = [
     EmacsChecker,
     ShellEscapeChecker,
     IPyAutocallChecker,
     MultiLineMagicChecker,
     EscCharsChecker,
     AssignmentChecker,
     AutoMagicChecker,
     AliasChecker,
     PythonOpsChecker,
     AutocallChecker
 ]
 
 _default_handlers = [
     PrefilterHandler,
     AliasHandler,
     ShellEscapeHandler,
     MagicHandler,
     AutoHandler,
     HelpHandler,
     EmacsHandler
 ]