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119 lines
3.1 KiB
ReStructuredText
119 lines
3.1 KiB
ReStructuredText
====================
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Finite State Machine
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====================
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A finite-state machine (FSM) or finite-state automaton (FSA, plural: automata), finite automaton,
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or simply a state machine, is a mathematical model of computation.
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It is an abstract machine that can be in exactly one of a finite number of states at any given time.
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The FSM can change from one state to another in response to some inputs;
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the change from one state to another is called a transition.
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An FSM is defined by a list of its states, its initial state,
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and the inputs that trigger each transition.
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.. raw:: html
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<hr>
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Source: `WikiPedia <wiki>`_
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Usage example
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=============
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Not all functionality of the bot can be implemented as single handler,
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for example you will need to collect some data from user in separated steps you will need to use FSM.
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.. image:: ../../_static/fsm_example.png
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:alt: FSM Example
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Let's see how to do that step-by-step
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Step by step
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------------
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Before handle any states you will need to specify what kind of states you want to handle
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 15
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:lines: 15-18
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And then write handler for each state separately from the start of dialog
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Here is dialog can be started only via command :code:`/start`, so lets handle it and make transition user to state :code:`Form.name`
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 21
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:lines: 21-27
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After that you will need to save some data to the storage and make transition to next step.
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 48
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:lines: 48-63
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At the next steps user can make different answers, it can be `yes`, `no` or any other
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Handle :code:`yes` and soon we need to handle :code:`Form.language` state
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 77
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:lines: 77-84
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Handle :code:`no`
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 66
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:lines: 66-74
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And handle any other answers
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 87
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:lines: 87-89
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All possible cases of `like_bots` step was covered, let's implement finally step
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 92
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:lines: 92-102
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And now you have covered all steps from the image, but you can make possibility to cancel conversation, lets do that via command or text
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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:lineno-start: 30
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:lines: 30-45
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Complete example
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----------------
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.. literalinclude:: ../../../examples/finite_state_machine.py
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:language: python
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:linenos:
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Read more
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=========
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.. toctree::
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storages
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.. _wiki: https://en.wikipedia.org/wiki/Finite-state_machine
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