/usr/lib/python2.7/dist-packages/automat/_methodical.py is in python-automat 0.6.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 | # -*- test-case-name: automat._test.test_methodical -*-
from functools import wraps
from itertools import count
try:
# Python 3
from inspect import getfullargspec as getArgsSpec
except ImportError:
# Python 2
from inspect import getargspec as getArgsSpec
import attr
from ._core import Transitioner, Automaton
from ._introspection import preserveName
def _keywords_only(f):
"""
Decorate a function so all its arguments must be passed by keyword.
A useful utility for decorators that take arguments so that they don't
accidentally get passed the thing they're decorating as their first
argument.
Only works for methods right now.
"""
@wraps(f)
def g(self, **kw):
return f(self, **kw)
return g
@attr.s(frozen=True)
class MethodicalState(object):
"""
A state for a L{MethodicalMachine}.
"""
machine = attr.ib(repr=False)
method = attr.ib()
serialized = attr.ib(repr=False)
def upon(self, input, enter, outputs, collector=list):
"""
Declare a state transition within the L{MethodicalMachine} associated
with this L{MethodicalState}: upon the receipt of the input C{input},
enter the state C{enter}, emitting each output in C{outputs}.
"""
inputSpec = getArgsSpec(input.method)
for output in outputs:
outputSpec = getArgsSpec(output.method)
if inputSpec != outputSpec:
raise TypeError(
"method {input} signature {inputSignature} "
"does not match output {output} "
"signature {outputSignature}".format(
input=input.method.__name__,
output=output.method.__name__,
inputSignature=inputSpec,
outputSignature=outputSpec,
))
self.machine._oneTransition(self, input, enter, outputs, collector)
def _name(self):
return self.method.__name__
def _transitionerFromInstance(oself, symbol, automaton):
"""
Get a L{Transitioner}
"""
transitioner = getattr(oself, symbol, None)
if transitioner is None:
transitioner = Transitioner(
automaton,
automaton.initialState,
)
setattr(oself, symbol, transitioner)
return transitioner
def _empty():
pass
def _docstring():
"""docstring"""
def assertNoCode(inst, attribute, f):
# The function body must be empty, i.e. "pass" or "return None", which
# both yield the same bytecode: LOAD_CONST (None), RETURN_VALUE. We also
# accept functions with only a docstring, which yields slightly different
# bytecode, because the "None" is put in a different constant slot.
# Unfortunately, this does not catch function bodies that return a
# constant value, e.g. "return 1", because their code is identical to a
# "return None". They differ in the contents of their constant table, but
# checking that would require us to parse the bytecode, find the index
# being returned, then making sure the table has a None at that index.
if f.__code__.co_code not in (_empty.__code__.co_code,
_docstring.__code__.co_code):
raise ValueError("function body must be empty")
@attr.s(cmp=False, hash=False)
class MethodicalInput(object):
"""
An input for a L{MethodicalMachine}.
"""
automaton = attr.ib(repr=False)
method = attr.ib(validator=assertNoCode)
symbol = attr.ib(repr=False)
collectors = attr.ib(default=attr.Factory(dict), repr=False)
def __get__(self, oself, type=None):
"""
Return a function that takes no arguments and returns values returned
by output functions produced by the given L{MethodicalInput} in
C{oself}'s current state.
"""
transitioner = _transitionerFromInstance(oself, self.symbol,
self.automaton)
@preserveName(self.method)
@wraps(self.method)
def doInput(*args, **kwargs):
self.method(oself, *args, **kwargs)
previousState = transitioner._state
(outputs, outTracer) = transitioner.transition(self)
collector = self.collectors[previousState]
values = []
for output in outputs:
if outTracer:
outTracer(output._name())
value = output(oself, *args, **kwargs)
values.append(value)
return collector(values)
return doInput
def _name(self):
return self.method.__name__
@attr.s(frozen=True)
class MethodicalOutput(object):
"""
An output for a L{MethodicalMachine}.
"""
machine = attr.ib(repr=False)
method = attr.ib()
def __get__(self, oself, type=None):
"""
Outputs are private, so raise an exception when we attempt to get one.
"""
raise AttributeError(
"{cls}.{method} is a state-machine output method; "
"to produce this output, call an input method instead.".format(
cls=type.__name__,
method=self.method.__name__
)
)
def __call__(self, oself, *args, **kwargs):
"""
Call the underlying method.
"""
return self.method(oself, *args, **kwargs)
def _name(self):
return self.method.__name__
@attr.s(cmp=False, hash=False)
class MethodicalTracer(object):
automaton = attr.ib(repr=False)
symbol = attr.ib(repr=False)
def __get__(self, oself, type=None):
transitioner = _transitionerFromInstance(oself, self.symbol,
self.automaton)
def setTrace(tracer):
transitioner.setTrace(tracer)
return setTrace
counter = count()
def gensym():
"""
Create a unique Python identifier.
"""
return "_symbol_" + str(next(counter))
class MethodicalMachine(object):
"""
A L{MethodicalMachine} is an interface to an L{Automaton} that uses methods
on a class.
"""
def __init__(self):
self._automaton = Automaton()
self._reducers = {}
self._symbol = gensym()
def __get__(self, oself, type=None):
"""
L{MethodicalMachine} is an implementation detail for setting up
class-level state; applications should never need to access it on an
instance.
"""
if oself is not None:
raise AttributeError(
"MethodicalMachine is an implementation detail.")
return self
@_keywords_only
def state(self, initial=False, terminal=False,
serialized=None):
"""
Declare a state, possibly an initial state or a terminal state.
This is a decorator for methods, but it will modify the method so as
not to be callable any more.
@param initial: is this state the initial state? Only one state on
this L{MethodicalMachine} may be an initial state; more than one is
an error.
@type initial: L{bool}
@param terminal: Is this state a terminal state, i.e. a state that the
machine can end up in? (This is purely informational at this
point.)
@type terminal: L{bool}
@param serialized: a serializable value to be used to represent this
state to external systems. This value should be hashable;
L{unicode} is a good type to use.
@type serialized: a hashable (comparable) value
"""
def decorator(stateMethod):
state = MethodicalState(machine=self,
method=stateMethod,
serialized=serialized)
if initial:
self._automaton.initialState = state
return state
return decorator
@_keywords_only
def input(self):
"""
Declare an input.
This is a decorator for methods.
"""
def decorator(inputMethod):
return MethodicalInput(automaton=self._automaton,
method=inputMethod,
symbol=self._symbol)
return decorator
@_keywords_only
def output(self):
"""
Declare an output.
This is a decorator for methods.
This method will be called when the state machine transitions to this
state as specified in the L{MethodicalMachine.output} method.
"""
def decorator(outputMethod):
return MethodicalOutput(machine=self, method=outputMethod)
return decorator
def _oneTransition(self, startState, inputToken, endState, outputTokens,
collector):
"""
See L{MethodicalState.upon}.
"""
# FIXME: tests for all of this (some of it is wrong)
# if not isinstance(startState, MethodicalState):
# raise NotImplementedError("start state {} isn't a state"
# .format(startState))
# if not isinstance(inputToken, MethodicalInput):
# raise NotImplementedError("start state {} isn't an input"
# .format(inputToken))
# if not isinstance(endState, MethodicalState):
# raise NotImplementedError("end state {} isn't a state"
# .format(startState))
# for output in outputTokens:
# if not isinstance(endState, MethodicalState):
# raise NotImplementedError("output state {} isn't a state"
# .format(endState))
self._automaton.addTransition(startState, inputToken, endState,
tuple(outputTokens))
inputToken.collectors[startState] = collector
@_keywords_only
def serializer(self):
"""
"""
def decorator(decoratee):
@wraps(decoratee)
def serialize(oself):
transitioner = _transitionerFromInstance(oself, self._symbol,
self._automaton)
return decoratee(oself, transitioner._state.serialized)
return serialize
return decorator
@_keywords_only
def unserializer(self):
"""
"""
def decorator(decoratee):
@wraps(decoratee)
def unserialize(oself, *args, **kwargs):
state = decoratee(oself, *args, **kwargs)
mapping = {}
for eachState in self._automaton.states():
mapping[eachState.serialized] = eachState
transitioner = _transitionerFromInstance(
oself, self._symbol, self._automaton)
transitioner._state = mapping[state]
return None # it's on purpose
return unserialize
return decorator
@property
def _setTrace(self):
return MethodicalTracer(self._automaton, self._symbol)
def asDigraph(self):
"""
Generate a L{graphviz.Digraph} that represents this machine's
states and transitions.
@return: L{graphviz.Digraph} object; for more information, please
see the documentation for
U{graphviz<https://graphviz.readthedocs.io/>}
"""
from ._visualize import makeDigraph
return makeDigraph(
self._automaton,
stateAsString=lambda state: state.method.__name__,
inputAsString=lambda input: input.method.__name__,
outputAsString=lambda output: output.method.__name__,
)
|