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# stateMachine.py
#
# module to define .pystate import handler
#
#import imputil
import sys
import os
import types
import urlparse
DEBUG = False
from pyparsing import Word, Group, ZeroOrMore, alphas, \
alphanums, ParserElement, ParseException, ParseSyntaxException, \
Empty, LineEnd, OneOrMore, col, Keyword, pythonStyleComment, \
StringEnd, traceParseAction
ident = Word(alphas+"_", alphanums+"_$")
pythonKeywords = """and as assert break class continue def
del elif else except exec finally for from global if import
in is lambda None not or pass print raise return try while with
yield True False"""
pythonKeywords = set(pythonKeywords.split())
def no_keywords_allowed(s,l,t):
wd = t[0]
if wd in pythonKeywords:
errmsg = "cannot not use keyword '%s' " \
"as an identifier" % wd
raise ParseException(s,l,errmsg)
ident.setParseAction(no_keywords_allowed)
stateTransition = ident("fromState") + "->" + ident("toState")
stateMachine = Keyword("statemachine") + \
ident("name") + ":" + \
OneOrMore(Group(stateTransition))("transitions")
namedStateTransition = (ident("fromState") + \
"-(" + ident("transition") + ")->" + \
ident("toState"))
namedStateMachine = Keyword("statemachine") + \
ident("name") + ":" + \
OneOrMore(Group(namedStateTransition))("transitions")
def expand_state_definition(source, loc, tokens):
indent = " " * (col(loc,source)-1)
statedef = []
# build list of states
states = set()
fromTo = {}
for tn in tokens.transitions:
states.add(tn.fromState)
states.add(tn.toState)
fromTo[tn.fromState] = tn.toState
# define base class for state classes
baseStateClass = tokens.name + "State"
statedef.extend([
"class %s(object):" % baseStateClass,
" def __str__(self):",
" return self.__class__.__name__",
" def next_state(self):",
" return self._next_state_class()" ])
# define all state classes
statedef.extend(
"class %s(%s): pass" % (s,baseStateClass)
for s in states )
statedef.extend(
"%s._next_state_class = %s" % (s,fromTo[s])
for s in states if s in fromTo )
return indent + ("\n"+indent).join(statedef)+"\n"
stateMachine.setParseAction(expand_state_definition)
def expand_named_state_definition(source,loc,tokens):
indent = " " * (col(loc,source)-1)
statedef = []
# build list of states and transitions
states = set()
transitions = set()
baseStateClass = tokens.name + "State"
fromTo = {}
for tn in tokens.transitions:
states.add(tn.fromState)
states.add(tn.toState)
transitions.add(tn.transition)
if tn.fromState in fromTo:
fromTo[tn.fromState][tn.transition] = tn.toState
else:
fromTo[tn.fromState] = {tn.transition:tn.toState}
# add entries for terminal states
for s in states:
if s not in fromTo:
fromTo[s] = {}
# define state transition class
statedef.extend([
"class %sTransition:" % baseStateClass,
" def __str__(self):",
" return self.transitionName",
])
statedef.extend(
"%s = %sTransition()" % (tn,baseStateClass)
for tn in transitions)
statedef.extend("%s.transitionName = '%s'" % (tn,tn)
for tn in transitions)
# define base class for state classes
excmsg = "'" + tokens.name + \
'.%s does not support transition "%s"' \
"'% (self, tn)"
statedef.extend([
"class %s(object):" % baseStateClass,
" def __str__(self):",
" return self.__class__.__name__",
" def next_state(self,tn):",
" try:",
" return self.tnmap[tn]()",
" except KeyError:",
" raise Exception(%s)" % excmsg,
" def __getattr__(self,name):",
" raise Exception(%s)" % excmsg,
])
# define all state classes
for s in states:
statedef.append("class %s(%s): pass" %
(s,baseStateClass))
# define state transition maps and transition methods
for s in states:
trns = fromTo[s].items()
statedef.append("%s.tnmap = {%s}" %
(s, ",".join("%s:%s" % tn for tn in trns)) )
statedef.extend([
"%s.%s = staticmethod(lambda : %s())" %
(s,tn_,to_)
for tn_,to_ in trns
])
return indent + ("\n"+indent).join(statedef) + "\n"
namedStateMachine.setParseAction(
expand_named_state_definition)
#======================================================================
# NEW STUFF - Matt Anderson, 2009-11-26
#======================================================================
class SuffixImporter(object):
"""An importer designed using the mechanism defined in :pep:`302`. I read
the PEP, and also used Doug Hellmann's PyMOTW article `Modules and
Imports`_, as a pattern.
.. _`Modules and Imports`: http://www.doughellmann.com/PyMOTW/sys/imports.html
Define a subclass that specifies a :attr:`suffix` attribute, and
implements a :meth:`process_filedata` method. Then call the classmethod
:meth:`register` on your class to actually install it in the appropriate
places in :mod:`sys`. """
scheme = 'suffix'
suffix = None
path_entry = None
@classmethod
def trigger_url(cls):
if cls.suffix is None:
raise ValueError('%s.suffix is not set' % cls.__name__)
return 'suffix:%s' % cls.suffix
@classmethod
def register(cls):
sys.path_hooks.append(cls)
sys.path.append(cls.trigger_url())
def __init__(self, path_entry):
pr = urlparse.urlparse(str(path_entry))
if pr.scheme != self.scheme or pr.path != self.suffix:
raise ImportError()
self.path_entry = path_entry
self._found = {}
def checkpath_iter(self, fullname):
for dirpath in sys.path:
# if the value in sys.path_importer_cache is None, then this
# path *should* be imported by the builtin mechanism, and the
# entry is thus a path to a directory on the filesystem;
# if it's not None, then some other importer is in charge, and
# it probably isn't even a filesystem path
if sys.path_importer_cache.get(dirpath,False) is None:
checkpath = os.path.join(
dirpath,'%s.%s' % (fullname,self.suffix))
yield checkpath
def find_module(self, fullname, path=None):
for checkpath in self.checkpath_iter(fullname):
if os.path.isfile(checkpath):
self._found[fullname] = checkpath
return self
return None
def load_module(self, fullname):
assert fullname in self._found
if fullname in sys.modules:
module = sys.modules[fullname]
else:
sys.modules[fullname] = module = types.ModuleType(fullname)
data = None
f = open(self._found[fullname])
try:
data = f.read()
finally:
f.close()
module.__dict__.clear()
module.__file__ = self._found[fullname]
module.__name__ = fullname
module.__loader__ = self
self.process_filedata(module, data)
return module
def process_filedata(self, module, data):
pass
class PystateImporter(SuffixImporter):
suffix = 'pystate'
def process_filedata(self, module, data):
# MATT-NOTE: re-worked :func:`get_state_machine`
# convert any statemachine expressions
stateMachineExpr = (stateMachine |
namedStateMachine).ignore(
pythonStyleComment)
generated_code = stateMachineExpr.transformString(data)
if DEBUG: print generated_code
# compile code object from generated code
# (strip trailing spaces and tabs, compile doesn't like
# dangling whitespace)
COMPILE_MODE = 'exec'
codeobj = compile(generated_code.rstrip(" \t"),
module.__file__,
COMPILE_MODE)
exec codeobj in module.__dict__
PystateImporter.register()
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