What is Finite-state machine?
Context
FSM refers to classes of automata
The finite state machine (FSM) is a software design pattern where a given model transitions to other behavioral states through external input.
Example using if else
Let's say we have a simple task where we check, for example, a traffic light and perform actions depending on the current state.
function trafficLightAction(color) { if (color === 'green') { console.log('Go'); } else if (color === 'yellow') { console.log('Slow down'); } else if (color === 'red') { console.log('Stop'); } else { console.log('Invalid color'); } } // Function call examples trafficLightAction('green'); // Return: Go trafficLightAction('yellow'); // Return: Slow down trafficLightAction('red'); // Return: Stop trafficLightAction('blue'); // Return: Invalid color Example with using Finite-state machine (FSM)
Now let's implement the same functionality using a state machine. A state machine will be an object where each key (state) is associated with a specific action.
const trafficLightFSM = { green: () => console.log('Go'), yellow: () => console.log('Slow down'), red: () => console.log('Stop'), invalid: () => console.log('Invalid color'), }; function trafficLightActionFSM(color) { const action = trafficLightFSM[color] || trafficLightFSM['invalid']; action(); } // Function call examples trafficLightActionFSM('green'); // Return: Go trafficLightActionFSM('yellow'); // Return: Slow down trafficLightActionFSM('red'); // Return: Stop trafficLightActionFSM('blue'); // Return: Invalid color Now, our traffic light will works well.
Disclaimer:
Several levels of additional tests would not hurt here, and perhaps another programming language ;)
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