##

# .python.command - Python command emulation module.

##

"""

Create and Execute Python Commands

==================================

The purpose of this module is to simplify the creation of a Python command

interface. Normally, one would want to do this if there is a *common* need

for a certain Python environment that may be, at least, partially initialized

via command line options. A notable case would be a Python environment with a

database connection whose connection parameters came from the command line. That

is, Python + command line driven configuration.

The module also provides an extended interactive console that provides backslash

commands for editing and executing temporary files. Use ``python -m

pythoncommand`` to try it out.

Simple usage::

import sys

import os

import optparse

import pythoncommand as pycmd

op = optparse.OptionParser(

"%prog [options] [script] [script arguments]",

version = '1.0',

)

op.disable_interspersed_args()

# Basically, the standard -m and -c. (Some additional ones for fun)

op.add_options(pycmd.default_optparse_options)

co, ca = op.parse_args(args[1:])

# This initializes an execution instance which gathers all the information

# about the code to be ran when ``pyexe`` is called.

pyexe = pycmd.Execution(ca,

context = getattr(co, 'python_context', ()),

loader = getattr(co, 'python_main', None),

)

# And run it. Any exceptions will be printed via print_exception.

rv = pyexe()

sys.exit(rv)

"""

import os

import sys

import re

import code

import types

import optparse

import subprocess

import contextlib

from gettext import gettext as _

from traceback import print_exception

from pkgutil import get_loader as module_loader

class single_loader(object):

"""

used for "loading" string modules(think -c)

"""

def __init__(self, source):

self.source = source

def get_filename(self, fullpath):

if fullpath == self.source:

return '<command>'

def get_code(self, fullpath):

if fullpath == self.source:

return compile(self.source, '<command>', 'exec')

def get_source(self, fullpath):

if fullpath == self.source:

return self.source

class file_loader(object):

"""

used for "loading" scripts

"""

def __init__(self, filepath, fileobj = None):

self.filepath = filepath

if fileobj is not None:

self._source = fileobj.read()

def get_filename(self, fullpath):

if fullpath == self.filepath:

return self.filepath

def get_source(self, fullpath):

if fullpath == self.filepath:

return self._read()

def _read(self):

if hasattr(self, '_source'):

return self._source

f = open(self.filepath)

try:

return f.read()

finally:

f.close()

def get_code(self, fullpath):

if fullpath != self.filepath:

return

return compile(self._read(), self.filepath, 'exec')

def extract_filepath(x):

if x.startswith('file://'):

return x[7:]

return None

def extract_module(x):

if x.startswith('module:'):

return x[7:]

return None

module_loader_descriptor = (

'Python module', module_loader, extract_module

)

file_loader_descriptor = (

'Python script', file_loader, extract_filepath

)

single_loader_descriptor = (

'Python command', single_loader, lambda x: x

)

_directory = (

module_loader_descriptor,

file_loader_descriptor,

)

directory = list(_directory)

def find_loader(ident, dir = directory):

for x in dir:

xid = x[2](ident)

if xid is not None:

return x

##

# optparse options

##

def append_context(option, opt_str, value, parser):

"""

Add some context to the execution of the Python code using

loader module's directory list of loader descriptions.

If no loader can be found, assume it's a Python command.

"""

pc = getattr(parser.values, option.dest, None) or []

if not pc:

setattr(parser.values, option.dest, pc)

ldesc = find_loader(value)

if ldesc is None:

ldesc = single_loader_descriptor

pc.append((value, ldesc))

def set_python_main(option, opt_str, value, parser):

"""

Set the main Python code; after contexts are initialized, main is ran.

"""

main = (value, option.python_loader)

setattr(parser.values, option.dest, main)

# only terminate parsing if not interspersing arguments

if not parser.allow_interspersed_args:

parser.rargs.insert(0, '--')

context = optparse.make_option(

'-C', '--context',

help = _('Python context code to run[file://,module:,<code>]'),

dest = 'python_context',

action = 'callback',

callback = append_context,

type = 'str'

)

module = optparse.make_option(

'-m',

help = _('Python module to run as script(__main__)'),

dest = 'python_main',

action = 'callback',

callback = set_python_main,

type = 'str'

)

module.python_loader = module_loader_descriptor

command = optparse.make_option(

'-c',

help = _('Python expression to run(__main__)'),

dest = 'python_main',

action = 'callback',

callback = set_python_main,

type = 'str'

)

command.python_loader = single_loader_descriptor

default_optparse_options = [

context, module, command,

]

class ExtendedConsole(code.InteractiveConsole):

"""

Console subclass providing some convenient backslash commands.

"""

def __init__(self, *args, **kw):

import tempfile

self.mktemp = tempfile.mktemp

import shlex

self.split = shlex.split

code.InteractiveConsole.__init__(self, *args, **kw)

self.bsc_map = {}

self.temp_files = {}

self.past_buffers = []

self.register_backslash(r'\?', self.showhelp, "Show this help message.")

self.register_backslash(r'\set', self.bs_set,

"Configure environment variables. \set without arguments to show all")

self.register_backslash(r'\E', self.bs_E,

"Edit a file or a temporary script.")

self.register_backslash(r'\i', self.bs_i,

"Execute a Python script within the interpreter's context.")

self.register_backslash(r'\e', self.bs_e,

"Edit and Execute the file directly in the context.")

self.register_backslash(r'\x', self.bs_x,

"Execute the Python command within this process.")

def interact(self, *args, **kw):

self.showhelp(None, None)

return super().interact(*args,**kw)

def showtraceback(self):

e, v, tb = sys.exc_info()

sys.last_type, sys.last_value, sys.last_traceback = e, v, tb

print_exception(e, v, tb.tb_next or tb)

def register_backslash(self, bscmd, meth, doc):

self.bsc_map[bscmd] = (meth, doc)

def execslash(self, line):

"""

If push() gets a line that starts with a backslash, execute

the command that the backslash sequence corresponds to.

"""

cmd = line.split(None, 1)

cmd.append('')

bsc = self.bsc_map.get(cmd[0])

if bsc is None:

self.write("ERROR: unknown backslash command: %s%s"%(cmd, os.linesep))

else:

return bsc[0](cmd[0], cmd[1])

def showhelp(self, cmd, arg):

i = list(self.bsc_map.items())

i.sort(key = lambda x: x[0])

helplines = os.linesep.join([

' %s%s%s' %(

x[0], ' ' * (8 - len(x[0])), x[1][1]

) for x in i

])

self.write("Backslash Commands:%s%s%s" %(

os.linesep*2, helplines, os.linesep*2

))

def bs_set(self, cmd, arg):

"""

Set a value in the interpreter's environment.

"""

if arg:

for x in self.split(arg):

if '=' in x:

k, v = x.split('=', 1)

os.environ[k] = v

self.write("%s=%s%s" %(k, v, os.linesep))

elif x:

self.write("%s=%s%s" %(x, os.environ.get(x, ''), os.linesep))

else:

for k,v in os.environ.items():

self.write("%s=%s%s" %(k, v, os.linesep))

def resolve_path(self, path, dont_create = False):

"""

Get the path of the given string; if the path is not

absolute and does not contain path separators, identify

it as a temporary file.

"""

if not os.path.isabs(path) and not os.path.sep in path:

# clean it up to avoid typos

path = path.strip().lower()

tmppath = self.temp_files.get(path)

if tmppath is None:

if dont_create is False:

tmppath = self.mktemp(

suffix = '.py',

prefix = '_console_%s_' %(path,)

)

self.temp_files[path] = tmppath

else:

return path

return tmppath

return path

def execfile(self, filepath):

src = open(filepath)

try:

try:

co = compile(src.read(), filepath, 'exec')

except SyntaxError:

co = None

print_exception(*sys.exc_info())

finally:

src.close()

if co is not None:

try:

exec(co, self.locals, self.locals)

except:

e, v, tb = sys.exc_info()

print_exception(e, v, tb.tb_next or tb)

def editfiles(self, filepaths):

sp = list(filepaths)

# ;)

sp.insert(0, os.environ.get('EDITOR', 'vi'))

return subprocess.call(sp)

def bs_i(self, cmd, arg):

'execute the files'

for x in self.split(arg) or ('',):

p = self.resolve_path(x, dont_create = True)

self.execfile(p)

def bs_E(self, cmd, arg):

'edit the files, but *only* edit them'

self.editfiles([self.resolve_path(x) for x in self.split(arg) or ('',)])

def bs_e(self, cmd, arg):

'edit *and* execute the files'

filepaths = [self.resolve_path(x) for x in self.split(arg) or ('',)]

self.editfiles(filepaths)

for x in filepaths:

self.execfile(x)

def bs_x(self, cmd, arg):

rv = -1

if len(cmd) > 1:

a = self.split(arg)

a.insert(0, '\\x')

try:

rv = command(argv = a)

except SystemExit as se:

rv = se.code

self.write("[Return Value: %d]%s" %(rv, os.linesep))

def push(self, line):

# Has to be a ps1 context.

if not self.buffer and line.startswith('\\'):

try:

self.execslash(line)

except:

# print the exception, but don't raise.

e, v, tb = sys.exc_info()

print_exception(e, v, tb.tb_next or tb)

else:

return code.InteractiveConsole.push(self, line)

@contextlib.contextmanager

def postmortem(funcpath):

if not funcpath:

yield None

else:

pm = funcpath.split('.')

attr = pm.pop(-1)

modpath = '.'.join(pm)

try:

m = __import__(modpath, fromlist = modpath)

pmobject = getattr(m, attr, None)

except ValueError:

pmobject = None

sys.stderr.write(

"%sERROR: no object at %r for postmortem%s"%(

os.linesep, funcpath, os.linesep

)

)

try:

yield None

except:

try:

sys.last_type, sys.last_value, sys.last_traceback = sys.exc_info()

pmobject()

except:

sys.stderr.write(

"[Exception raised by Postmortem]" + os.linesep

)

print_exception(*sys.exc_info())

raise

class Execution(object):

"""

Given argv and context make an execution instance that, when called, will

execute the configured Python code.

This class provides the ability to identify what the main part of the

execution of the configured Python code. For instance, shall it execute a

console, the file that the first argument points to, a -m option module

appended to the python_context option value, or the code given within -c?

"""

def __init__(self,

args, context = (),

main = None,

loader = None,

stdin = sys.stdin

):

"""

args

The arguments passed to the script; usually sys.argv after being

processed by optparse(ca).

context

A list of loader descriptors that will be used to establish the

context of __main__ module.

main

Overload to explicitly state what main is. None will cause the

class to attempt to fill in the attribute using 'args' and other

system objects like sys.stdin.

"""

self.args = args

self.context = context and list(context) or ()

if main is not None:

self.main = main

elif loader is not None:

# Main explicitly stated, resolve the path and the loader

path, ldesc = loader

ltitle, rloader, xpath = ldesc

l = rloader(path)

if l is None:

raise ImportError(

"%s %r does not exist or cannot be read" %(

ltitle, path

)

)

self.main = (path, l)

# If there are args, but no main, run the first arg.

elif args:

fp = self.args[0]

f = open(fp)

try:

l = file_loader(fp, fileobj = f)

finally:

f.close()

self.main = (self.args[0], l)

self.args = self.args[1:]

# There is no main, no loader, and no args.

# If stdin is not a tty, use stdin as the main file.

elif not stdin.isatty():

l = file_loader('<stdin>', fileobj = stdin)

self.main = ('<stdin>', l)

# tty and no "main".

else:

# console

self.main = (None, None)

self.reset_module__main__()

def reset_module__main__(self):

mod = types.ModuleType('__main__')

mod.__builtins__ = __builtins__

mod.__package__ = None

self.module__main__ = mod

path = getattr(self.main[1], 'fullname', None)

if path is not None:

mod.__package__ = '.'.join(path.split('.')[:-1])

def _call(self,

console = ExtendedConsole,

context = None

):

"""

Initialize the context and run main in the given locals

(Note: tramples on sys.argv, __main__ in sys.modules)

(Use __call__ instead)

"""

sys.modules['__main__'] = self.module__main__

md = self.module__main__.__dict__

# Establish execution context in the locals;

# iterate over all the loaders in self.context and

for path, ldesc in self.context:

ltitle, loader, xpath = ldesc

rpath = xpath(path)

li = loader(rpath)

if li is None:

sys.stderr.write(

"%s %r does not exist or cannot be read%s" %(

ltitle, rpath, os.linesep

)

)

return 1

try:

code = li.get_code(rpath)

except:

print_exception(*sys.exc_info())

return 1

self.module__main__.__file__ = getattr(

li, 'get_filename', lambda x: x

)(rpath)

self.module__main__.__loader__ = li

try:

exec(code, md, md)

except:

e, v, tb = sys.exc_info()

print_exception(e, v, tb.tb_next or tb)

return 1

if self.main == (None, None):

# It's interactive.

sys.argv = self.args or ['<console>']

# Use readline if available

try:

import readline

except ImportError:

pass

ic = console(locals = md)

try:

ic.interact()

except SystemExit as e:

return e.code

return 0

else:

# It's ultimately a code object.

path, loader = self.main

self.module__main__.__file__ = getattr(

loader, 'get_filename', lambda x: x

)(path)

sys.argv = list(self.args)

sys.argv.insert(0, self.module__main__.__file__)

try:

code = loader.get_code(path)

except:

print_exception(*sys.exc_info())

return 1

rv = 0

exe_exception = False

try:

if context is not None:

with context:

try:

exec(code, md, md)

except:

exe_exception = True

raise

else:

try:

exec(code, md, md)

except:

exe_exception = True

raise

except SystemExit as e:

# Assume it's an exe_exception as anything ran in `context`

# shouldn't cause an exception.

rv = e.code

e, v, tb = sys.exc_info()

sys.last_type = e

sys.last_value = v

sys.last_traceback = (tb.tb_next or tb)

except:

if exe_exception is False:

raise

rv = 1

e, v, tb = sys.exc_info()

print_exception(e, v, tb.tb_next or tb)

sys.last_type = e

sys.last_value = v

sys.last_traceback = (tb.tb_next or tb)

return rv

def __call__(self, *args, **kw):

storage = (

sys.modules.get('__context__'),

sys.modules.get('__main__'),

sys.argv,

os.environ.copy(),

)

try:

return self._call(*args, **kw)

finally:

sys.modules['__context__'], \

sys.modules['__main__'], \

sys.argv, os.environ = storage

def get_main_source(self):

"""

Get the execution's "__main__" source. Useful for configuring

environmental options derived from "magic" lines.

"""

path, loader = self.main

if path is not None:

return loader.get_source(path)

def command_execution(argv = sys.argv):

'create an execution using the given argv'

# The pwd should be in the path for python commands.

# setuptools' console_scripts appear to strip this out.

if '' not in sys.path:

sys.path.insert(0, '')

op = optparse.OptionParser(

"%prog [options] [script] [script arguments]",

version = '1.0',

)

op.disable_interspersed_args()

op.add_options(default_optparse_options)

co, ca = op.parse_args(argv[1:])

return Execution(ca,

context = getattr(co, 'python_context', ()),

loader = getattr(co, 'python_main', None),

)

def command(argv = sys.argv):

return command_execution(argv = argv)(

context = postmortem(os.environ.get('PYTHON_POSTMORTEM'))

)

if __name__ == '__main__':

sys.exit(command())

##

# vim: ts=3:sw=3:noet: