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| This is a summary of FSM implementations in Python right now. | <<TableOfContents>> == Introduction == This is a summary of FSM implementations in Python right now. Licensing remains unclear. |
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| <<TableOfContents>> | == Finite State Machine Editor == |
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| '''[[http://fsme.sourceforge.net/|Finite State Machine Editor]]''' | [[http://fsme.sourceforge.net/|FSME]] is a tool where you can draw FSM diagrams, and then compile to a Python module (or C++ code.) It also makes an XML description of the FSM. |
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| This is a tool where you can draw FSM diagrams, and then compile to a Python module (or C++ code.) It also makes an XML description of the FSM. | Requires QT for the editor. (Not the compiler, though, which probably reads XML.) |
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| Requires QT for the editor. (Not the compiler, though, which probably reads XML.) * [[http://fsme.sourceforge.net/doc/tutorial.html|tutorial]] * [[http://fsme.sourceforge.net/phpwiki/|project wiki]] |
* [[http://fsme.sourceforge.net/doc/tutorial.html|tutorial]] * [[http://fsme.sourceforge.net/phpwiki/|project wiki]] |
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| '''[[http://osteele.com/software/python/fsa/|FSA - Finite State Automation in Python]]''' | == FSA - Finite State Automation in Python == |
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| This seems to be all about '''making''' FSMs, but I don't see a whole lot on how to ''use'' them! | [[http://osteele.com/software/python/fsa/|FSA]] seems to be all about creating finite state machines, but I don't see a whole lot on how to use them. |
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| == Noah Spurrier's FSM == | |
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| '''[[http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/146262|Noah Spurrier's FSM]]''' | http://www.noah.org/python/FSM/ |
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| This is one found on ActiveState; It's purely Python code. You init an FSM, register transitions, and then throw inputs at it. States and inputs must be hashable. | Noah's implementation is pure Python code. You init an FSM, register transitions, and then throw inputs at it. States and inputs must be hashable. |
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| You can also [[http://www.noah.org/python/FSM/|find it on his website.]] | It's fairly similar to Skip's implementation (below). |
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| == fsmpy == | |
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| '''[[http://www.research.att.com/projects/mohri/fsm/doc4/fsmpy.html|fsmpy module]]''' | [[http://www.research.att.com/projects/mohri/fsm/doc4/fsmpy.html|fsmpy module]] |
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| This seems to be a Python wrapper around [[http://www.research.att.com/projects/mohri/fsm/|AT&T's FSM library.]] It's all oriented around "weighted" finite state machines, so I'm not so sure how suitable it is if you just want to use unweighted FSM. | This seems to be a Python wrapper around [[http://www.research.att.com/projects/mohri/fsm/|AT&T's FSM library.]] It's all oriented around "weighted" finite state machines, so I'm not so sure how suitable it is if you just want to use unweighted FSM. |
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| == Decorator-based FSM == | |
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| '''[[http://wiki.python.org/moin/PythonDecoratorLibrary/|Decorator based FSM]]''' | An [[http://wiki.python.org/moin/State Machine via Decorators|example using decorators]] is in the Decorator Library on this site. The module simplifies implementation of FSM's based on UML 2.0 state diagrams. The FSM is implemented as a class, with methods of the class associated with transitions or with states. The design is not the best for constructing FSMs to parse text being somewhat slower than alternatives. |
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| A decorator based FSM can be found in the Decorator Library on this site. The module simplifies implementaion of FSM's based on UML 2.0 state diagrams. The FSM is implemented as a class, with methods of the class associated with transitions or with states. The design is not the best for constructing FSMs to parse text being somewhat slower than alternatives. | == Skip Montanaro's FSM == |
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'''SkipMontanaro's FSM''' [[http://www.python.org/search/hypermail/python-recent/0667.html|From an e-mail.]] |
[[http://www.smontanaro.net/python/fsm.py|fsm.py.]] |
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| I've re-interpreted the code, adding formatting lost in e-mail, and PythonStyle-itizing it a bit. | == python-fsm FSM module with PyGraphViz support == |
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| {{{ #!python """Finite state machine, featuring transition actions.""" |
An concise yet comprehensive implementation based on Wikipedia spec of Finite State Machines. The module can be used to build and further describe finite state automata with DOT graphs. It implements acceptors and transducers (Moore and Mealy machines) and provides an straight-forward way to inject and execute state change actions for entry, exit, input and transition. |
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| FSMError = 'Invalid input to finite state machine' | Licensed under the new BSD license. |
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| class FSM: | [[http://code.google.com/p/python-fsm/]] |
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| """Finite state machine, featuring transition actions. | == fysom == |
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| The class stores a dictionary of (state, input) keys, and (state, action) values. |
A port of Jake Gordon's [[https://github.com/jakesgordon/javascript-state-machine|javascript-state-machine]]. The module lets the user define callbacks for before/after events as well as callbacks on entering/leaving states. Events are exposed as object methods which when called, causes the appropriate state transition. The module also provides asynchronous callback functionality which allows delaying a state transition. |
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| When a (state, input) search is performed: * an exact match is checked first, * (state, None) is checked next. The action is of the following form: * function(current_state, input) """ def __init__(self): self.states = {} self.state = None self.dbg = None def add(self, state, input, newstate, action): """Add a transition to the FSM.""" self.states[(state, input)] = (newstate, action) def execute(self, input): """Perform a transition and execute action.""" si = (self.state, input) sn = (self.state, None) # exact state match? if self.states.has_key(si): newstate, action = self.states[si] # no, how about a None (catch-all) match? elif self.states.has_key(sn): newstate, action = self.states[sn] if self.dbg != None: self.dbg.write('State: %s / Input: %s /' 'Next State: %s / Action: %s\n' % (self.state, input, newstate, action)) apply(action, (self.state, input)) self.state = newstate def start(self, state): """Define the start state. Actually, this just resets the current state. """ self.state = state def debug(self, out): """Assign a writable file to log transitions.""" self.dbg = out }}} |
[[https://github.com/oxplot/fysom]] |
Contents
Introduction
This is a summary of FSM implementations in Python right now. Licensing remains unclear.
For general information about finite state machines, see:
Wikipedia:Finite_state_machine --
excellent!
Finite State Machine Editor
FSME is a tool where you can draw FSM diagrams, and then compile to a Python module (or C++ code.) It also makes an XML description of the FSM.
Requires QT for the editor. (Not the compiler, though, which probably reads XML.)
FSA - Finite State Automation in Python
FSA seems to be all about creating finite state machines, but I don't see a whole lot on how to use them.
Noah Spurrier's FSM
http://www.noah.org/python/FSM/
Noah's implementation is pure Python code. You init an FSM, register transitions, and then throw inputs at it. States and inputs must be hashable.
It's fairly similar to Skip's implementation (below).
fsmpy
This seems to be a Python wrapper around AT&T's FSM library. It's all oriented around "weighted" finite state machines, so I'm not so sure how suitable it is if you just want to use unweighted FSM.
Decorator-based FSM
An example using decorators is in the Decorator Library on this site. The module simplifies implementation of FSM's based on UML 2.0 state diagrams. The FSM is implemented as a class, with methods of the class associated with transitions or with states. The design is not the best for constructing FSMs to parse text being somewhat slower than alternatives.
Skip Montanaro's FSM
Features transition actions.
python-fsm FSM module with PyGraphViz support
An concise yet comprehensive implementation based on Wikipedia spec of Finite State Machines. The module can be used to build and further describe finite state automata with DOT graphs. It implements acceptors and transducers (Moore and Mealy machines) and provides an straight-forward way to inject and execute state change actions for entry, exit, input and transition.
Licensed under the new BSD license.
http://code.google.com/p/python-fsm/
fysom
A port of Jake Gordon's javascript-state-machine. The module lets the user define callbacks for before/after events as well as callbacks on entering/leaving states. Events are exposed as object methods which when called, causes the appropriate state transition. The module also provides asynchronous callback functionality which allows delaying a state transition.