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Package docutils :: Module statemachine |
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A finite state machine specialized for regular-expression-based text filters, this module defines the following classes:
StateMachine
, a state machineState
, a state superclassStateMachineWS
, a whitespace-sensitive version of StateMachine
StateWS
, a state superclass for use with StateMachineWS
SearchStateMachine
, uses re.search()
instead of re.match()
SearchStateMachineWS
, uses re.search()
instead of re.match()
ViewList
, extends standard Python lists.StringList
, string-specific ViewList.Exception classes:
StateMachineError
UnknownStateError
DuplicateStateError
UnknownTransitionError
DuplicateTransitionError
TransitionPatternNotFound
TransitionMethodNotFound
UnexpectedIndentationError
TransitionCorrection
: Raised to switch to another transition.StateCorrection
: Raised to switch to another state & transition.Functions:
string2lines()
: split a multi-line string into a list of one-line strings(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:
StateWS.indent_sm
,
StateWS.indent_sm_kwargs
, StateWS.known_indent_sm
, and/or
StateWS.known_indent_sm_kwargs
;StateWS.blank()
method; and/orStateWS.indent()
, StateWS.known_indent()
,
and/or StateWS.firstknown_indent()
methods.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()
Classes | |
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SearchStateMachine |
StateMachine which uses re.search() instead of re.match() . |
SearchStateMachineWS |
StateMachineWS which uses re.search() instead of re.match() . |
State |
State superclass. |
StateMachine |
A finite state machine for text filters using regular expressions. |
StateMachineWS |
StateMachine subclass specialized for whitespace recognition. |
StateWS |
State superclass specialized for whitespace (blank lines & indents). |
StringList |
A ViewList with string-specific methods. |
ViewList |
List with extended functionality: slices of ViewList objects are child lists, linked to their parents. |
_SearchOverride |
Mix-in class to override StateMachine regular expression behavior. |
Exceptions | |
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DuplicateStateError |
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DuplicateTransitionError |
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StateCorrection |
Raise from within a transition method to switch to another state. |
StateMachineError |
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TransitionCorrection |
Raise from within a transition method to switch to another transition. |
TransitionMethodNotFound |
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TransitionPatternNotFound |
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UnexpectedIndentationError |
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UnknownStateError |
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UnknownTransitionError |
Function Summary | |
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Return a list of one-line strings with tabs expanded and no newlines. | |
Return exception information: |
Function Details |
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string2lines(astring, tab_width=8, convert_whitespace=0, whitespace=<_sre.SRE_Pattern object at 0x822b120>)Return a list of one-line strings with tabs expanded and no newlines. Each tab is expanded with between 1 and Parameters:
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_exception_data()Return exception information:
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