https://github.com/mellonis/turing-machine-js
🧘🏼♂️ A convenient Turing machine
https://github.com/mellonis/turing-machine-js
simulator state-machine turing-machine turing-machine-simulator
Last synced: 4 months ago
JSON representation
🧘🏼♂️ A convenient Turing machine
- Host: GitHub
- URL: https://github.com/mellonis/turing-machine-js
- Owner: mellonis
- License: gpl-3.0
- Created: 2019-04-05T23:25:43.000Z (about 7 years ago)
- Default Branch: master
- Last Pushed: 2025-07-21T23:09:06.000Z (11 months ago)
- Last Synced: 2025-12-21T00:35:19.426Z (6 months ago)
- Topics: simulator, state-machine, turing-machine, turing-machine-simulator
- Language: TypeScript
- Homepage:
- Size: 1.3 MB
- Stars: 4
- Watchers: 1
- Forks: 1
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# turing-machine-js
[](https://github.com/mellonis/turing-machine-js/actions/workflows/main.yml)
[](https://coveralls.io/github/mellonis/turing-machine-js?branch=master)
A convenient Turing machine
This repository contains following packages:
* [@turing-machine-js/builder](https://github.com/mellonis/turing-machine-js/tree/master/packages/builder)
* [@turing-machine-js/machine](https://github.com/mellonis/turing-machine-js/tree/master/packages/machine)
* [@turing-machine-js/library-binary-numbers](https://github.com/mellonis/turing-machine-js/tree/master/packages/library-binary-numbers)
# An example
A tape contains `a`, `b` and `c` symbols. The issue is to replace all `b` symbols by `*` symbol.
This example demonstrates an issue solving.
```javascript
import {
Alphabet,
State,
Tape,
TapeBlock,
TuringMachine,
haltState,
ifOtherSymbol,
movements,
} from '@turing-machine-js/machine';
const alphabet = new Alphabet([' ', 'a', 'b', 'c', '*']);
const tape = new Tape({
alphabet,
symbols: ['a', 'b', 'c', 'b', 'a'],
});
const tapeBlock = TapeBlock.fromTapes([tape]);
const machine = new TuringMachine({
tapeBlock,
});
console.log(tape.symbols.join('').trim()); // abcba
machine.run({
initialState: new State({
[tapeBlock.symbol(['b'])]: {
command: [
{
symbol: '*',
movement: movements.right,
},
],
},
[tapeBlock.symbol([tape.alphabet.blankSymbol])]: {
command: [
{
movement: movements.left,
},
],
nextState: haltState,
},
[ifOtherSymbol]: {
command: [
{
movement: movements.right,
},
],
},
}),
});
console.log(tape.symbols.join('').trim()); // a*c*a
```
## Execution steps explanation
- `S` stands for the initial state
- `H` stands for the `haltState`
### Step 1
- Current state: S
- Current symbol: 'a'
- Transition: 'a'/S,R
```
[ abcba ] [ abcba ]
^ >> ^
```
### Step 2
- Current state: S
- Current symbol: 'b'
- Transition: '*'/S,R
```
[ abcba ] [ a*cba ]
^ >> ^
```
### Step 3
- Current state: S
- Current symbol: 'c'
- Transition: 'c'/S,R
```
[ a*cba ] [ a*cba ]
^ >> ^
```
### Step 4
- Current state: S
- Current symbol: 'b'
- Transition: '*'/S,R
```
[ a*cba ] [ a*c*a ]
^ >> ^
```
### Step 5
- Current state: S
- Current symbol: 'a'
- Transition: 'a'/S,R
```
[ a*c*a ] [ a*c*a ]
^ >> ^
```
### Step 6
- Current state: S
- Current symbol: ' '
- Transition: ' '/H,L
```
[ a*c*a ] [ a*c*a ]
^ >> ^
```