#!/usr/bin/env python
"""Interactive interpreter for python-csp, with online help.
Features:
* CSP primitives are imported automatically.
* CSP help is built in via. the 'info' command.
* History is saved between sessions in C{~/.csp-console-history}.
* Tab-completion can be used to complete keywords or variables.
Copyright (C) Sarah Mount, 2009.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
"""
try:
import readline
except ImportError:
print("Module readline not available.")
else:
import rlcompleter
readline.parse_and_bind("tab: complete")
import atexit
import code
import os
import sys
__author__ = 'Sarah Mount '
__date__ = 'December 2008'
class _Printer(object):
"""Print documentation in twenty-line chunks.
Based on a class of the same name from the site.py module.
"""
MAXLINES = 20
def __init__(self, documentation):
self.__lines = documentation.split('\n')
self.__linecnt = len(self.__lines)
return
def __call__(self):
prompt = '\n*** Hit Return for more, or q (and Return) to quit: '
lineno = 0
while True:
try:
for i in range(lineno, lineno + self.MAXLINES):
print(self.__lines[i])
except IndexError:
break
else:
lineno += self.MAXLINES
key = None
while key not in ('', 'q', 'Q'):
key = input(prompt)
if key == 'q':
break
print()
class TabSafeCompleter(rlcompleter.Completer):
"""Enable safe use of Tab for either tab completion or nested scope.
"""
def complete(self, text, state):
if text == '':
return ['\t', None][state]
else:
return rlcompleter.Completer.complete(self, text, state)
class CSPConsole(code.InteractiveConsole):
"""python-csp interactive console with REPL.
Features:
* CSP channel server is started automatically.
* CSP primitives are imported automatically.
* CSP help is built in via. the 'info' command.
* History is saved between sessions in C{~/.csp-console-history}.
* Tab-completion can be used to complete keywords or variables.
"""
# From the docs of the readline module.
def __init__(self, locals=None, filename="",
histfile=os.path.expanduser("~/.csp-console-history")):
code.InteractiveConsole.__init__(self)
self.init_history(histfile)
def init_history(self, histfile):
readline.parse_and_bind("tab: complete")
delims = ' \t\n`!@#$%^&*()-=+[{]}\\|;:,<>?'
readline.set_completer_delims(delims)
readline.set_completer(TabSafeCompleter().complete)
if hasattr(readline, "read_history_file"):
try:
readline.read_history_file(histfile)
except IOError:
pass
atexit.register(self.save_history, histfile)
def save_history(self, histfile):
readline.write_history_file(histfile)
def raw_input(self, *args):
line = code.InteractiveConsole.raw_input(self, *args)
if line == _INFOCSP:
_Printer(_cspinfo)()
return ''
elif line in _INFO:
_Printer(_INFO[line][1])()
return ''
elif line.startswith('info '):
print()
print('No info available on that topic. Try one of these:')
print()
print(_commands)
return ''
else:
return line
def _createBuiltinDocs():
"""Automatically create documentation for built-in process and guards.
This function iterates over the documentation strings in the
csp.builtins module and produces a larger documentation string
describing every name which does not begin with an underscore and
is not an imported module or CSP type.
"""
head = "\n*** python-csp: Info on built-in processes and guards. ***"
foot = "\n\n*** For more info, type 'info' at the prompt. ***\n"
docs = """ """
docstrings = {}
import csp.builtins
from csp.cspprocess import _CSPTYPES
cspnames = [klass.__name__ for klass in _CSPTYPES]
# Names imported by builtins
imports = ['copy', 'gc', 'inspect', 'operator', 'os', 'process', 'random',
'socket', 'sys', 'tempfile', 'threading', 'time', 'hmac',
'wraps', 'hashlib', 'psyco', 'pickle', 'logging', 'uuid']
exceptions = ['CorruptedData', 'NoGuardInAlt', 'ChannelPoison',
'ChannelAbort', 'ProcessSuspend']
baseclasses = ['CSPOpMixin', 'CSPProcess', 'Guard',
'Channel', 'FileChannel', 'process', 'NetworkChannel']
for name in dir(csp.builtins):
if (name in cspnames or name.startswith('_') or name in imports
or name in exceptions or name in baseclasses or name == 'DEBUG'
or name == 'SECURITY_ON'):
continue
qualname = 'csp.builtins' + '.' + name
if eval(qualname+'.__doc__'):
docstrings[name] = eval(qualname+'.__doc__')
del csp.cspprocess
names = list(docstrings.keys())
names.sort()
for name in names:
docs += '\n' + name + ':\n' + docstrings[name]
return head + '\n' + docs + foot
_INFOCSP = 'info'
_proc = """
*** python-csp: Info on processes. ***
There are two ways to create a new CSP process. Firstly, you can use
the @process decorator to convert a function definition into a CSP
Process. Once the function has been defined, calling it will return a
new CSPProcess object which can be started manually, or used in an
expression:
>>> @process
... def foo(n):
... print 'n:', n
...
>>> foo(100).start()
>>> n: 100
>>> foo(10) // (foo(20),)
n: 10
n: 20
>>>
Alternatively, you can create a CSPProcess object directly and pass a
function (and its arguments) to the CSPProcess constructor:
>>> def foo(n):
... print 'n:', n
...
>>> p = CSPProcess(foo, 100)
>>> p.start()
>>> n: 100
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_server = """
*** python-csp: Info on server processes. ***
A server process is one which runs in an infinite loop. You can create
a "normal" process which runs in an infinite loop, but by using server
processes you allow the python-csp debugger to correctly generate
information about your programs.
There are two ways to create a new CSP server process. Firstly, you
can use the @forever decorator to convert a generator into a CSPServer
object. Once the function has been defined, calling it will return a
new CSPServer object which can be started manually, or used in an
expression:
>>> @forever
... def integers():
... n = 0
... while True:
... print n
... n += 1
... yield
...
>>> integers().start()
>>> 0
1
2
3
4
5
...
KeyboardInterrupt
>>>
Alternatively, you can create a CSPServer object directly and pass a
function (and its arguments) to the CSPServer constructor:
>>> def integers():
... n = 0
... while True:
... print n
... n += 1
... yield
...
>>> i = CSPServer(integers)
>>> i.start()
>>> 0
1
2
3
4
5
...
KeyboardInterrupt
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_par = """
*** python-csp: Info on Par. ***
There are two ways to run processes in parallel. Firstly, given two
(or more) processes you can parallelize them with the // operator, like this:
>>> @process
... def foo(n):
... print 'n:', n
...
>>> foo(1) // (foo(2), foo(3))
n: 2
n: 1
n: 3
>>>
Notice that the // operator takes a CSPProcess on the left hand side
and a sequence of processes on the right hand side.
Alternatively, you can create a Par object which is a sort of CSP
process and start that process manually:
>>> p = Par(foo(100), foo(200), foo(300))
>>> p.start()
n: 100
n: 300
n: 200
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_seq = """
*** python-csp: Info on Seq. ***
There are two ways to run processes in sequence. Firstly, given two
(or more) processes you can sequence them with the > operator, like this:
>>> @process
... def foo(n):
... print 'n:', n
...
>>> foo(1) > foo(2) > foo(3)
n: 1
n: 2
n: 3
>>>
Secondly, you can create a Seq object which is a sort of CSP process
and start that process manually:
>>> s = Seq(foo(100), foo(200), foo(300))
>>> s.start()
n: 100
n: 200
n: 300
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_skip = """*** python-csp: Info on Skip. ***
Skip is a built in guard type that can be used with Alt
objects. Skip() is a default guard which is always ready and has no
effect. This is useful where you have a loop which calls select(),
pri_select() or fair_select() on an Alt object repeatedly and you do
not wish the select statement to block waiting for a channel write, or
other synchronisation. The following is a trivial example of an Alt
which uses Skip():
>>> alt = Alt(Skip())
>>> for i in xrange(5):
... print alt.select()
...
Skip
Skip
Skip
Skip
Skip
>>>
Where you have an Alt() object which mixes Skip() with other guard
types, be sure to complete all necessary channel reads or other
synchronisations, otherwise your code will hang.
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_timer = """*** python-csp: Info on timer guards. ***
Timer objects are a type of CSP guard, like Channel types and Skip
guards. Timer objects allow code to wait for a specific period of time
before synchronising on a timer event. This can be done in a number of
ways: either by sleeping for a period of time (similar to time.sleep
in the standard library), or by setting the timer to become selectable
(by an Alt object) after a specific period of time. For example:
>>> timer = Timer()
>>> timer.sleep(5) # sleep for 5 seconds
>>>
>>> alt = Alt(timer)
>>> timer.set_alarm(3) # become selectable 3 seconds from now
>>> alt.select() # will wait 3 seconds
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_alt = """
*** python-csp: Info on Alt. ***
python-csp process will often have access to several different
channels, or other guard types such as timer guards, and will have to
choose one of them to read from. For example, in a producer/consumer
or worker/farmer model, many producer or worker processes will be
writing values to channels and one consumer or farmer process will be
aggregating them in some way. It would be inefficient for the consumer
or farmer to read from each channel in turn, as some channels might
take longer than others. Instead, python-csp provides support for
ALTing (or ALTernating), which enables a process to read from the
first channel (or timer, or other guard) in a list to become ready.
The simplest way to choose between channels (or other guards) is to
use choice operator: "|", as in the example below:
>>> @process
... def send_msg(chan, msg):
... chan.write(msg)
...
>>> @process
... def choice(chan1, chan2):
... # Choice chooses a channel on which to call read()
... print chan1 | chan2
... print chan1 | chan2
...
>>> c1, c2 = Channel(), Channel()
>>> choice(c1, c2) // (send_msg(c1, 'yes'), send_msg(c2, 'no'))
yes
no
>>>
Secondly, you can create an Alt object explicitly, and call its
select() method to perform a channel read on the next available
channel. If more than one channel is available to read from, then an
available channel is chosen at random (for this reason, ALTing is
sometimes called "non-deterministic choice":
>>> @process
... def send_msg(chan, msg):
... chan.write(msg)
...
>>> @process
... def alt_example(chan1, chan2):
... alt = Alt(chan1, chan2)
... print alt.select()
... print alt.select()
...
>>> c1, c2 = Channel(), Channel()
>>> Par(send_msg(c1, 'yes'), send_msg(c2, 'no'), alt_example(c1, c2)).start()
yes
no
>>>
In addition to the select() method, which chooses an available guard
at random, Alt provides two similar methods, fair_select() and
pri_select(). fair_select() will choose not to select the previously
selected guard, unless it is the only guard available. This ensures
that no guard will be starved twice in a row. pri_select() will select
available channels in the order in which they were passed to the Alt()
constructor, giving a simple implementation of guard priority.
Lastly, Alt() can be used with the repetition operator (*) to create a
generator:
>>> @process
... def send_msg(chan, msg):
... chan.write(msg)
...
>>> @process
... def gen_example(chan1, chan2):
... gen = Alt(chan1, chan2) * 2
... print gen.next()
... print gen.next()
...
>>> c1, c2 = Channel(), Channel()
>>> Par(send_msg(c1, 'yes'), send_msg(c2, 'no'), gen_example(c1, c2)).start()
yes
no
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_channel = """
*** python-csp: Info on channels. ***
A CSP channel can be created with the Channel class:
>>> c = Channel()
>>>
Each Channel object should have a unique name in the network:
>>> print c.name
1ca98e40-5558-11df-8e5b-002421449824
>>>
The Channel can then be passed as an argument to any CSP process and
then be used either to read (using the .read() method) or to write
(using the .write() method). For example:
>>> @process
... def send(cout, data):
... cout.write(data)
...
>>> @process
... def recv(cin):
... print 'Got:', cin.read()
...
>>> c = Channel()
>>> send(c, 100) // (recv(c),)
Got: 100
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_poison = """
*** python-csp: Info on channel poisoning. ***
A set of communicating processes can be terminated by "poisoning" any
of the channels used by those processes. This can be achieved by
calling the poison() method on any channel. For example:
>>> @process
... def send5(cout):
... for i in xrange(5):
... print 'send5 sending:', i
... cout.write(i)
... time.sleep(random.random() * 5)
... return
...
>>> @process
... def recv(cin):
... for i in xrange(5):
... data = cin.read()
... print 'recv got:', data
... time.sleep(random.random() * 5)
... return
...
>>> @process
... def interrupt(chan):
... time.sleep(random.random() * 7)
... print 'Poisoning channel:', chan.name
... chan.poison()
... return
...
>>> doomed = Channel()
>>> send(doomed) // (recv(doomed), poison(doomed))
send5 sending: 0
recv got: 0
send5 sending: 1
recv got: 1
send5 sending: 2
recv got: 2
send5 sending: 3
recv got: 3
send5 sending: 4
recv got: 4
Poisoning channel: 5c906e38-5559-11df-8503-002421449824
>>>
*** For more info, type '%s' at the prompt. ***
""" % (_INFOCSP)
_builtin = _createBuiltinDocs()
# COMMAND -> (descriptor, docstring)
_INFO = {'info process':('processes', _proc),
'info server':('CSPServer', _server),
'info par':('Parallel', _par),
'info seq':('Sequence', _seq),
'info alt':('Alternative', _alt),
'info skip':('Skip', _skip),
'info timer':('Timer', _timer),
'info channel':('channels', _channel),
'info poison':('poisoning', _poison),
'info builtin':('built-ins', _builtin)}
_ban = """\npython-csp (c) 2008. Licensed under the GPL(v2).
Type "%s" for more information.
Press Ctrl-C to close the CSP channel server.
""" % (_INFOCSP)
_cspinfo = """
*** python-csp: general info ***
python-csp is an implementation of Hoare's Communicating Sequential
Processes in Python. For specific info on any aspect of CSP, use the
following:
"""
_commands = ""
for key in _INFO:
c = "For info on %s, type: \t%s\n" % (_INFO[key][0], key)
_commands += c
_cspinfo += _commands
if __name__ == '__main__':
c = CSPConsole(locals=locals())
# Don't expect the csp types to be available in locals()
c.push('from csp.cspprocess import *')
c.push('from csp.builtins import *')
c.interact(banner=_ban)