A finite state machine specialized for regular-expression-based text filters, this module defines the following classes:
Exception classes:
Functions:
(See the individual classes, methods, and attributes for details.)
Import it: import statemachine or from statemachine import .... You will also need to import re.
Derive a subclass of State (or StateWS) for each state in your state machine:
class MyState(statemachine.State):
Within the state's class definition:
Include a pattern for each transition, in State.patterns:
patterns = {'atransition': r'pattern', ...}
Include a list of initial transitions to be set up automatically, in State.initial_transitions:
initial_transitions = ['atransition', ...]
Define a method for each transition, with the same name as the transition pattern:
def atransition(self, match, context, next_state): # do something result = [...] # a list return context, next_state, result # context, next_state may be altered
Transition methods may raise an EOFError to cut processing short.
You may wish to override the State.bof() and/or State.eof() implicit transition methods, which handle the beginning- and end-of-file.
In order to handle nested processing, you may wish to override the attributes State.nested_sm and/or State.nested_sm_kwargs.
If you are using StateWS as a base class, in order to handle nested indented blocks, you may wish to:
Create a state machine object:
sm = StateMachine(state_classes=[MyState, ...], initial_state='MyState')
Obtain the input text, which needs to be converted into a tab-free list of one-line strings. For example, to read text from a file called 'inputfile':
input_string = open('inputfile').read() input_lines = statemachine.string2lines(input_string)
Run the state machine on the input text and collect the results, a list:
results = sm.run(input_lines)
Remove any lingering circular references:
sm.unlink()