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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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| * [wiki:WikiPedia/Finite_state_machine Wikipedia:Finite_state_machine] -- B) ''excellent!'' B) * [wiki:Wiki/FiniteStateMachine Wiki:FiniteStateMachine] |
* [[WikiPedia:Finite_state_machine|Wikipedia:Finite_state_machine]] -- B) ''excellent!'' B) * [[Wiki:FiniteStateMachine|Wiki:FiniteStateMachine]] |
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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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| '''SkipMontanaro's 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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| [http://www.python.org/search/hypermail/python-recent/0667.html From an e-mail.] | == Skip Montanaro's FSM == [[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 """Finite state machine, featuring transition actions.""" FSMError = 'Invalid input to finite state machine' class FSM: """Finite state machine, featuring transition actions. The class stores a dictionary of (state, input) keys, and (state, action) values. 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 }}} |
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.