Allow history database access without a shell.

IPython/core/history.py

@@ -1,853 +1,883 b''
 """ History related magics and functionality """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010 The IPython Development Team.
 #
 #  Distributed under the terms of the BSD License.
 #
 #  The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 # Stdlib imports
 import atexit
 import datetime
 import os
 import re
 import sqlite3
 import threading
 
 # Our own packages
 from IPython.config.configurable import Configurable
 
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import io
 from IPython.utils.traitlets import Bool, Dict, Instance, Int, CInt, List, Unicode
 from IPython.utils.warn import warn
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class HistoryAccessor(Configurable):
     """Access the history database without adding to it. For use by standalone
     history tools."""
     # String holding the path to the history file
     hist_file = Unicode(config=True)
 
     # The SQLite database
     db = Instance(sqlite3.Connection)
     
     def __init__(self, hist_file=u'', shell=None, config=None, **traits):
         """Create a new history accessor.
         
         hist_file must be given, either as an argument or through config.
         """
         # We need a pointer back to the shell for various tasks.
         super(HistoryAccessor, self).__init__(shell=shell, config=config,
                                               hist_file=hist_file, **traits)
 
         if self.hist_file == u'':
             # No one has set the hist_file, yet.
             self.hist_file = self._get_hist_file_name(hist_file)
 
         try:
             self.init_db()
         except sqlite3.DatabaseError:
             if os.path.isfile(self.hist_file):
                 # Try to move the file out of the way.
                 newpath = os.path.join(self.shell.profile_dir.location, "hist-corrupt.sqlite")
                 os.rename(self.hist_file, newpath)
                 print("ERROR! History file wasn't a valid SQLite database.",
                 "It was moved to %s" % newpath, "and a new file created.")
                 self.init_db()
             else:
                 # The hist_file is probably :memory: or something else.
                 raise
     
     def _get_hist_file_name(self, hist_file=None):
         "Override to produce a default history file name."
         raise NotImplementedError("No default history file")
     
     def init_db(self):
         """Connect to the database, and create tables if necessary."""
         # use detect_types so that timestamps return datetime objects
         self.db = sqlite3.connect(self.hist_file, detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
         self.db.execute("""CREATE TABLE IF NOT EXISTS sessions (session integer
                         primary key autoincrement, start timestamp,
                         end timestamp, num_cmds integer, remark text)""")
         self.db.execute("""CREATE TABLE IF NOT EXISTS history
                 (session integer, line integer, source text, source_raw text,
                 PRIMARY KEY (session, line))""")
         # Output history is optional, but ensure the table's there so it can be
         # enabled later.
         self.db.execute("""CREATE TABLE IF NOT EXISTS output_history
                         (session integer, line integer, output text,
                         PRIMARY KEY (session, line))""")
         self.db.commit()
 
+    def writeout_cache(self):
+        """Overridden by HistoryManager to dump the cache before certain
+        database lookups."""
+        pass
+
     ## -------------------------------
     ## Methods for retrieving history:
     ## -------------------------------
     def _run_sql(self, sql, params, raw=True, output=False):
         """Prepares and runs an SQL query for the history database.
 
         Parameters
         ----------
         sql : str
           Any filtering expressions to go after SELECT ... FROM ...
         params : tuple
           Parameters passed to the SQL query (to replace "?")
         raw, output : bool
           See :meth:`get_range`
 
         Returns
         -------
         Tuples as :meth:`get_range`
         """
         toget = 'source_raw' if raw else 'source'
         sqlfrom = "history"
         if output:
             sqlfrom = "history LEFT JOIN output_history USING (session, line)"
             toget = "history.%s, output_history.output" % toget
         cur = self.db.execute("SELECT session, line, %s FROM %s " %\
                                 (toget, sqlfrom) + sql, params)
         if output:    # Regroup into 3-tuples, and parse JSON
             return ((ses, lin, (inp, out)) for ses, lin, inp, out in cur)
         return cur
 
-
     def get_session_info(self, session=0):
         """get info about a session
 
         Parameters
         ----------
 
         session : int
             Session number to retrieve. The current session is 0, and negative
             numbers count back from current session, so -1 is previous session.
 
         Returns
         -------
 
         (session_id [int], start [datetime], end [datetime], num_cmds [int], remark [unicode])
 
         Sessions that are running or did not exit cleanly will have `end=None`
         and `num_cmds=None`.
 
         """
 
         if session <= 0:
             session += self.session_number
 
         query = "SELECT * from sessions where session == ?"
         return self.db.execute(query, (session,)).fetchone()
 
-
     def get_tail(self, n=10, raw=True, output=False, include_latest=False):
         """Get the last n lines from the history database.
 
         Parameters
         ----------
         n : int
           The number of lines to get
         raw, output : bool
           See :meth:`get_range`
         include_latest : bool
           If False (default), n+1 lines are fetched, and the latest one
           is discarded. This is intended to be used where the function
           is called by a user command, which it should not return.
 
         Returns
         -------
         Tuples as :meth:`get_range`
         """
         self.writeout_cache()
         if not include_latest:
             n += 1
         cur = self._run_sql("ORDER BY session DESC, line DESC LIMIT ?",
                                 (n,), raw=raw, output=output)
         if not include_latest:
             return reversed(list(cur)[1:])
         return reversed(list(cur))
 
     def search(self, pattern="*", raw=True, search_raw=True,
                                                         output=False):
         """Search the database using unix glob-style matching (wildcards
         * and ?).
 
         Parameters
         ----------
         pattern : str
           The wildcarded pattern to match when searching
         search_raw : bool
           If True, search the raw input, otherwise, the parsed input
         raw, output : bool
           See :meth:`get_range`
 
         Returns
         -------
         Tuples as :meth:`get_range`
         """
         tosearch = "source_raw" if search_raw else "source"
         if output:
             tosearch = "history." + tosearch
         self.writeout_cache()
         return self._run_sql("WHERE %s GLOB ?" % tosearch, (pattern,),
                                     raw=raw, output=output)
 
-    def get_range(self, session=0, start=1, stop=None, raw=True,output=False):
+    def get_range(self, session, start=1, stop=None, raw=True,output=False):
         """Retrieve input by session.
 
         Parameters
         ----------
         session : int
-            Session number to retrieve. The current session is 0, and negative
-            numbers count back from current session, so -1 is previous session.
+            Session number to retrieve.
         start : int
             First line to retrieve.
         stop : int
             End of line range (excluded from output itself). If None, retrieve
             to the end of the session.
         raw : bool
             If True, return untranslated input
         output : bool
             If True, attempt to include output. This will be 'real' Python
             objects for the current session, or text reprs from previous
             sessions if db_log_output was enabled at the time. Where no output
             is found, None is used.
 
         Returns
         -------
         An iterator over the desired lines. Each line is a 3-tuple, either
         (session, line, input) if output is False, or
         (session, line, (input, output)) if output is True.
         """
-        if session == 0 or session==self.session_number:   # Current session
-            return self._get_range_session(start, stop, raw, output)
-        if session < 0:
-            session += self.session_number
-
         if stop:
             lineclause = "line >= ? AND line < ?"
             params = (session, start, stop)
         else:
             lineclause = "line>=?"
             params = (session, start)
 
         return self._run_sql("WHERE session==? AND %s""" % lineclause,
                                     params, raw=raw, output=output)
 
     def get_range_by_str(self, rangestr, raw=True, output=False):
         """Get lines of history from a string of ranges, as used by magic
         commands %hist, %save, %macro, etc.
 
         Parameters
         ----------
         rangestr : str
           A string specifying ranges, e.g. "5 ~2/1-4". See
           :func:`magic_history` for full details.
         raw, output : bool
           As :meth:`get_range`
 
         Returns
         -------
         Tuples as :meth:`get_range`
         """
         for sess, s, e in extract_hist_ranges(rangestr):
             for line in self.get_range(sess, s, e, raw=raw, output=output):
                 yield line
 
 
 class HistoryManager(HistoryAccessor):
     """A class to organize all history-related functionality in one place.
     """
     # Public interface
 
     # An instance of the IPython shell we are attached to
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     # Lists to hold processed and raw history. These start with a blank entry
     # so that we can index them starting from 1
     input_hist_parsed = List([""])
     input_hist_raw = List([""])
     # A list of directories visited during session
     dir_hist = List()
     def _dir_hist_default(self):
         try:
             return [os.getcwdu()]
         except OSError:
             return []
 
     # A dict of output history, keyed with ints from the shell's
     # execution count.
     output_hist = Dict()
     # The text/plain repr of outputs.
     output_hist_reprs = Dict()
 
     # The number of the current session in the history database
     session_number = CInt()
     # Should we log output to the database? (default no)
     db_log_output = Bool(False, config=True)
     # Write to database every x commands (higher values save disk access & power)
     #  Values of 1 or less effectively disable caching. 
     db_cache_size = Int(0, config=True)
     # The input and output caches
     db_input_cache = List()
     db_output_cache = List()
     
     # History saving in separate thread
     save_thread = Instance('IPython.core.history.HistorySavingThread')
     try:               # Event is a function returning an instance of _Event...
         save_flag = Instance(threading._Event)
     except AttributeError:         # ...until Python 3.3, when it's a class.
         save_flag = Instance(threading.Event)
     
     # Private interface
     # Variables used to store the three last inputs from the user.  On each new
     # history update, we populate the user's namespace with these, shifted as
     # necessary.
     _i00 = Unicode(u'')
     _i = Unicode(u'')
     _ii = Unicode(u'')
     _iii = Unicode(u'')
 
     # A regex matching all forms of the exit command, so that we don't store
     # them in the history (it's annoying to rewind the first entry and land on
     # an exit call).
     _exit_re = re.compile(r"(exit|quit)(\s*\(.*\))?$")
 
     def __init__(self, shell=None, config=None, **traits):
         """Create a new history manager associated with a shell instance.
         """
         # We need a pointer back to the shell for various tasks.
         super(HistoryManager, self).__init__(shell=shell, config=config,
             **traits)
         self.save_flag = threading.Event()
         self.db_input_cache_lock = threading.Lock()
         self.db_output_cache_lock = threading.Lock()
         self.save_thread = HistorySavingThread(self)
         self.save_thread.start()
 
         self.new_session()
     
     def _get_hist_file_name(self, hist_file=None):
         profile_dir = self.shell.profile_dir.location
         return os.path.join(profile_dir, 'history.sqlite')
     
     def new_session(self, conn=None):
         """Get a new session number."""
         if conn is None:
             conn = self.db
         
         with conn:
             cur = conn.execute("""INSERT INTO sessions VALUES (NULL, ?, NULL,
                             NULL, "") """, (datetime.datetime.now(),))
             self.session_number = cur.lastrowid
             
     def end_session(self):
         """Close the database session, filling in the end time and line count."""
         self.writeout_cache()
         with self.db:
             self.db.execute("""UPDATE sessions SET end=?, num_cmds=? WHERE
                             session==?""", (datetime.datetime.now(),
                             len(self.input_hist_parsed)-1, self.session_number))
         self.session_number = 0
                             
     def name_session(self, name):
         """Give the current session a name in the history database."""
         with self.db:
             self.db.execute("UPDATE sessions SET remark=? WHERE session==?",
                             (name, self.session_number))
                             
     def reset(self, new_session=True):
         """Clear the session history, releasing all object references, and
         optionally open a new session."""
         self.output_hist.clear()
         # The directory history can't be completely empty
         self.dir_hist[:] = [os.getcwdu()]
         
         if new_session:
             if self.session_number:
                 self.end_session()
             self.input_hist_parsed[:] = [""]
             self.input_hist_raw[:] = [""]
             self.new_session()
     
     # ------------------------------
     # Methods for retrieving history
     # ------------------------------
     def _get_range_session(self, start=1, stop=None, raw=True, output=False):
         """Get input and output history from the current session. Called by
         get_range, and takes similar parameters."""
         input_hist = self.input_hist_raw if raw else self.input_hist_parsed
             
         n = len(input_hist)
         if start < 0:
             start += n
         if not stop or (stop > n):
             stop = n
         elif stop < 0:
             stop += n
         
         for i in range(start, stop):
             if output:
                 line = (input_hist[i], self.output_hist_reprs.get(i))
             else:
                 line = input_hist[i]
             yield (0, i, line)
 
+    def get_range(self, session, start=1, stop=None, raw=True,output=False):
+        """Retrieve input by session.
+        
+        Parameters
+        ----------
+        session : int
+            Session number to retrieve. The current session is 0, and negative
+            numbers count back from current session, so -1 is previous session.
+        start : int
+            First line to retrieve.
+        stop : int
+            End of line range (excluded from output itself). If None, retrieve
+            to the end of the session.
+        raw : bool
+            If True, return untranslated input
+        output : bool
+            If True, attempt to include output. This will be 'real' Python
+            objects for the current session, or text reprs from previous
+            sessions if db_log_output was enabled at the time. Where no output
+            is found, None is used.
+            
+        Returns
+        -------
+        An iterator over the desired lines. Each line is a 3-tuple, either
+        (session, line, input) if output is False, or
+        (session, line, (input, output)) if output is True.
+        """
+        if session <= 0:
+            session += self.session_number
+        if session==self.session_number:          # Current session
+            return self._get_range_session(start, stop, raw, output)
+        return super(HistoryManager, self).get_range(session, start, stop, raw, output)
+
     ## ----------------------------
     ## Methods for storing history:
     ## ----------------------------
     def store_inputs(self, line_num, source, source_raw=None):
         """Store source and raw input in history and create input cache
         variables _i*.
 
         Parameters
         ----------
         line_num : int
           The prompt number of this input.
 
         source : str
           Python input.
 
         source_raw : str, optional
           If given, this is the raw input without any IPython transformations
           applied to it.  If not given, ``source`` is used.
         """
         if source_raw is None:
             source_raw = source
         source = source.rstrip('\n')
         source_raw = source_raw.rstrip('\n')
 
         # do not store exit/quit commands
         if self._exit_re.match(source_raw.strip()):
             return
 
         self.input_hist_parsed.append(source)
         self.input_hist_raw.append(source_raw)
 
         with self.db_input_cache_lock:
             self.db_input_cache.append((line_num, source, source_raw))
             # Trigger to flush cache and write to DB.
             if len(self.db_input_cache) >= self.db_cache_size:
                 self.save_flag.set()
 
         # update the auto _i variables
         self._iii = self._ii
         self._ii = self._i
         self._i = self._i00
         self._i00 = source_raw
 
         # hackish access to user namespace to create _i1,_i2... dynamically
         new_i = '_i%s' % line_num
         to_main = {'_i': self._i,
                    '_ii': self._ii,
                    '_iii': self._iii,
                    new_i : self._i00 }
         self.shell.user_ns.update(to_main)
 
     def store_output(self, line_num):
         """If database output logging is enabled, this saves all the
         outputs from the indicated prompt number to the database. It's
         called by run_cell after code has been executed.
 
         Parameters
         ----------
         line_num : int
           The line number from which to save outputs
         """
         if (not self.db_log_output) or (line_num not in self.output_hist_reprs):
             return
         output = self.output_hist_reprs[line_num]
 
         with self.db_output_cache_lock:
             self.db_output_cache.append((line_num, output))
         if self.db_cache_size <= 1:
             self.save_flag.set()
 
     def _writeout_input_cache(self, conn):
         with conn:
             for line in self.db_input_cache:
                 conn.execute("INSERT INTO history VALUES (?, ?, ?, ?)",
                                 (self.session_number,)+line)
 
     def _writeout_output_cache(self, conn):
         with conn:
             for line in self.db_output_cache:
                 conn.execute("INSERT INTO output_history VALUES (?, ?, ?)",
                                 (self.session_number,)+line)
 
     def writeout_cache(self, conn=None):
         """Write any entries in the cache to the database."""
         if conn is None:
             conn = self.db
 
         with self.db_input_cache_lock:
             try:
                 self._writeout_input_cache(conn)
             except sqlite3.IntegrityError:
                 self.new_session(conn)
                 print("ERROR! Session/line number was not unique in",
                       "database. History logging moved to new session",
                                                 self.session_number)
                 try: # Try writing to the new session. If this fails, don't recurse
                     self._writeout_input_cache(conn)
                 except sqlite3.IntegrityError:
                     pass
             finally:
                 self.db_input_cache = []
 
         with self.db_output_cache_lock:
             try:
                 self._writeout_output_cache(conn)
             except sqlite3.IntegrityError:
                 print("!! Session/line number for output was not unique",
                       "in database. Output will not be stored.")
             finally:
                 self.db_output_cache = []
 
 
 class HistorySavingThread(threading.Thread):
     """This thread takes care of writing history to the database, so that
     the UI isn't held up while that happens.
 
     It waits for the HistoryManager's save_flag to be set, then writes out
     the history cache. The main thread is responsible for setting the flag when
     the cache size reaches a defined threshold."""
     daemon = True
     stop_now = False
     def __init__(self, history_manager):
         super(HistorySavingThread, self).__init__()
         self.history_manager = history_manager
         atexit.register(self.stop)
 
     def run(self):
         # We need a separate db connection per thread:
         try:
             self.db = sqlite3.connect(self.history_manager.hist_file)
             while True:
                 self.history_manager.save_flag.wait()
                 if self.stop_now:
                     return
                 self.history_manager.save_flag.clear()
                 self.history_manager.writeout_cache(self.db)
         except Exception as e:
             print(("The history saving thread hit an unexpected error (%s)."
                    "History will not be written to the database.") % repr(e))
 
     def stop(self):
         """This can be called from the main thread to safely stop this thread.
 
         Note that it does not attempt to write out remaining history before
         exiting. That should be done by calling the HistoryManager's
         end_session method."""
         self.stop_now = True
         self.history_manager.save_flag.set()
         self.join()
 
 
 # To match, e.g. ~5/8-~2/3
 range_re = re.compile(r"""
 ((?P<startsess>~?\d+)/)?
 (?P<start>\d+)                    # Only the start line num is compulsory
 ((?P<sep>[\-:])
  ((?P<endsess>~?\d+)/)?
  (?P<end>\d+))?
 $""", re.VERBOSE)
 
 def extract_hist_ranges(ranges_str):
     """Turn a string of history ranges into 3-tuples of (session, start, stop).
 
     Examples
     --------
     list(extract_input_ranges("~8/5-~7/4 2"))
     [(-8, 5, None), (-7, 1, 4), (0, 2, 3)]
     """
     for range_str in ranges_str.split():
         rmatch = range_re.match(range_str)
         if not rmatch:
             continue
         start = int(rmatch.group("start"))
         end = rmatch.group("end")
         end = int(end) if end else start+1   # If no end specified, get (a, a+1)
         if rmatch.group("sep") == "-":       # 1-3 == 1:4 --> [1, 2, 3]
             end += 1
         startsess = rmatch.group("startsess") or "0"
         endsess = rmatch.group("endsess") or startsess
         startsess = int(startsess.replace("~","-"))
         endsess = int(endsess.replace("~","-"))
         assert endsess >= startsess
 
         if endsess == startsess:
             yield (startsess, start, end)
             continue
         # Multiple sessions in one range:
         yield (startsess, start, None)
         for sess in range(startsess+1, endsess):
             yield (sess, 1, None)
         yield (endsess, 1, end)
 
 def _format_lineno(session, line):
     """Helper function to format line numbers properly."""
     if session == 0:
         return str(line)
     return "%s#%s" % (session, line)
 
 @skip_doctest
 def magic_history(self, parameter_s = ''):
     """Print input history (_i<n> variables), with most recent last.
 
     %history       -> print at most 40 inputs (some may be multi-line)\\
     %history n     -> print at most n inputs\\
     %history n1 n2 -> print inputs between n1 and n2 (n2 not included)\\
 
     By default, input history is printed without line numbers so it can be
     directly pasted into an editor. Use -n to show them.
 
     Ranges of history can be indicated using the syntax:
     4      : Line 4, current session
     4-6    : Lines 4-6, current session
     243/1-5: Lines 1-5, session 243
     ~2/7   : Line 7, session 2 before current
     ~8/1-~6/5 : From the first line of 8 sessions ago, to the fifth line
                 of 6 sessions ago.
     Multiple ranges can be entered, separated by spaces
 
     The same syntax is used by %macro, %save, %edit, %rerun
 
     Options:
 
       -n: print line numbers for each input.
       This feature is only available if numbered prompts are in use.
 
       -o: also print outputs for each input.
 
       -p: print classic '>>>' python prompts before each input.  This is useful
        for making documentation, and in conjunction with -o, for producing
        doctest-ready output.
 
       -r: (default) print the 'raw' history, i.e. the actual commands you typed.
 
       -t: print the 'translated' history, as IPython understands it.  IPython
       filters your input and converts it all into valid Python source before
       executing it (things like magics or aliases are turned into function
       calls, for example). With this option, you'll see the native history
       instead of the user-entered version: '%cd /' will be seen as
       'get_ipython().magic("%cd /")' instead of '%cd /'.
 
       -g: treat the arg as a pattern to grep for in (full) history.
       This includes the saved history (almost all commands ever written).
       Use '%hist -g' to show full saved history (may be very long).
 
       -l: get the last n lines from all sessions. Specify n as a single arg, or
       the default is the last 10 lines.
 
       -f FILENAME: instead of printing the output to the screen, redirect it to
        the given file.  The file is always overwritten, though IPython asks for
        confirmation first if it already exists.
 
     Examples
     --------
     ::
 
       In [6]: %hist -n 4 6
       4:a = 12
       5:print a**2
 
     """
 
     if not self.shell.displayhook.do_full_cache:
         print('This feature is only available if numbered prompts are in use.')
         return
     opts,args = self.parse_options(parameter_s,'noprtglf:',mode='string')
 
     # For brevity
     history_manager = self.shell.history_manager
 
     def _format_lineno(session, line):
         """Helper function to format line numbers properly."""
         if session in (0, history_manager.session_number):
             return str(line)
         return "%s/%s" % (session, line)
 
     # Check if output to specific file was requested.
     try:
         outfname = opts['f']
     except KeyError:
         outfile = io.stdout  # default
         # We don't want to close stdout at the end!
         close_at_end = False
     else:
         if os.path.exists(outfname):
             if not io.ask_yes_no("File %r exists. Overwrite?" % outfname):
                 print('Aborting.')
                 return
 
         outfile = open(outfname,'w')
         close_at_end = True
 
     print_nums = 'n' in opts
     get_output = 'o' in opts
     pyprompts = 'p' in opts
     # Raw history is the default
     raw = not('t' in opts)
 
     default_length = 40
     pattern = None
 
     if 'g' in opts:         # Glob search
         pattern = "*" + args + "*" if args else "*"
         hist = history_manager.search(pattern, raw=raw, output=get_output)
         print_nums = True
     elif 'l' in opts:       # Get 'tail'
         try:
             n = int(args)
         except ValueError, IndexError:
             n = 10
         hist = history_manager.get_tail(n, raw=raw, output=get_output)
     else:
         if args:            # Get history by ranges
             hist = history_manager.get_range_by_str(args, raw, get_output)
         else:               # Just get history for the current session
             hist = history_manager.get_range(raw=raw, output=get_output)
 
     # We could be displaying the entire history, so let's not try to pull it
     # into a list in memory. Anything that needs more space will just misalign.
     width = 4
 
     for session, lineno, inline in hist:
         # Print user history with tabs expanded to 4 spaces.  The GUI clients
         # use hard tabs for easier usability in auto-indented code, but we want
         # to produce PEP-8 compliant history for safe pasting into an editor.
         if get_output:
             inline, output = inline
         inline = inline.expandtabs(4).rstrip()
 
         multiline = "\n" in inline
         line_sep = '\n' if multiline else ' '
         if print_nums:
             print('%s:%s' % (_format_lineno(session, lineno).rjust(width),
                     line_sep),  file=outfile, end='')
         if pyprompts:
             print(">>> ", end="", file=outfile)
             if multiline:
                 inline = "\n... ".join(inline.splitlines()) + "\n..."
         print(inline, file=outfile)
         if get_output and output:
             print(output, file=outfile)
 
     if close_at_end:
         outfile.close()
 
 
 def magic_rep(self, arg):
     r"""Repeat a command, or get command to input line for editing. %recall and
     %rep are equivalent.
 
     - %recall (no arguments):
 
     Place a string version of last computation result (stored in the special '_'
     variable) to the next input prompt. Allows you to create elaborate command
     lines without using copy-paste::
 
          In[1]: l = ["hei", "vaan"]
          In[2]: "".join(l)
         Out[2]: heivaan
          In[3]: %rep
          In[4]: heivaan_ <== cursor blinking
 
     %recall 45
 
     Place history line 45 on the next input prompt. Use %hist to find
     out the number.
 
     %recall 1-4
 
     Combine the specified lines into one cell, and place it on the next
     input prompt. See %history for the slice syntax.
 
     %recall foo+bar
 
     If foo+bar can be evaluated in the user namespace, the result is
     placed at the next input prompt. Otherwise, the history is searched
     for lines which contain that substring, and the most recent one is
     placed at the next input prompt.
     """
     if not arg:                 # Last output
         self.set_next_input(str(self.shell.user_ns["_"]))
         return
                                 # Get history range
     histlines = self.history_manager.get_range_by_str(arg)
     cmd = "\n".join(x[2] for x in histlines)
     if cmd:
         self.set_next_input(cmd.rstrip())
         return
 
     try:                        # Variable in user namespace
         cmd = str(eval(arg, self.shell.user_ns))
     except Exception:           # Search for term in history
         histlines = self.history_manager.search("*"+arg+"*")
         for h in reversed([x[2] for x in histlines]):
             if 'rep' in h:
                 continue
             self.set_next_input(h.rstrip())
             return
     else:
         self.set_next_input(cmd.rstrip())
     print("Couldn't evaluate or find in history:", arg)
 
 def magic_rerun(self, parameter_s=''):
     """Re-run previous input
 
     By default, you can specify ranges of input history to be repeated
     (as with %history). With no arguments, it will repeat the last line.
 
     Options:
 
       -l <n> : Repeat the last n lines of input, not including the
       current command.
 
       -g foo : Repeat the most recent line which contains foo
     """
     opts, args = self.parse_options(parameter_s, 'l:g:', mode='string')
     if "l" in opts:         # Last n lines
         n = int(opts['l'])
         hist = self.history_manager.get_tail(n)
     elif "g" in opts:       # Search
         p = "*"+opts['g']+"*"
         hist = list(self.history_manager.search(p))
         for l in reversed(hist):
             if "rerun" not in l[2]:
                 hist = [l]     # The last match which isn't a %rerun
                 break
         else:
             hist = []          # No matches except %rerun
     elif args:              # Specify history ranges
         hist = self.history_manager.get_range_by_str(args)
     else:                   # Last line
         hist = self.history_manager.get_tail(1)
     hist = [x[2] for x in hist]
     if not hist:
         print("No lines in history match specification")
         return
     histlines = "\n".join(hist)
     print("=== Executing: ===")
     print(histlines)
     print("=== Output: ===")
     self.run_cell("\n".join(hist), store_history=False)
 
 
 def init_ipython(ip):
     ip.define_magic("rep", magic_rep)
     ip.define_magic("recall", magic_rep)
     ip.define_magic("rerun", magic_rerun)
     ip.define_magic("hist",magic_history)    # Alternative name
     ip.define_magic("history",magic_history)
 
     # XXX - ipy_completers are in quarantine, need to be updated to new apis
     #import ipy_completers
     #ipy_completers.quick_completer('%hist' ,'-g -t -r -n')